* [PATCH] asm-generic/io.h: Skip trace helpers if rwmmio events are disabled
@ 2025-03-30 16:42 Varad Gautam
2025-04-07 16:13 ` Varad Gautam
0 siblings, 1 reply; 8+ messages in thread
From: Varad Gautam @ 2025-03-30 16:42 UTC (permalink / raw)
To: linux-arch
Cc: Arnd Bergmann, Sai Prakash Ranjan, linux-kernel, Varad Gautam, stable
With `CONFIG_TRACE_MMIO_ACCESS=y`, the `{read,write}{b,w,l,q}{_relaxed}()`
mmio accessors unconditionally call `log_{post_}{read,write}_mmio()`
helpers, which in turn call the ftrace ops for `rwmmio` trace events
This adds a performance penalty per mmio accessor call, even when
`rwmmio` events are disabled at runtime (~80% overhead on local
measurement).
Guard these with `tracepoint_enabled()`.
Signed-off-by: Varad Gautam <varadgautam@google.com>
Fixes: 210031971cdd ("asm-generic/io: Add logging support for MMIO accessors")
Cc: <stable@vger.kernel.org>
---
include/asm-generic/io.h | 98 +++++++++++++++++++++++++++-------------
1 file changed, 66 insertions(+), 32 deletions(-)
diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index 3c61c29ff6ab..a9b5da547523 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -75,6 +75,7 @@
#if IS_ENABLED(CONFIG_TRACE_MMIO_ACCESS) && !(defined(__DISABLE_TRACE_MMIO__))
#include <linux/tracepoint-defs.h>
+#define rwmmio_tracepoint_enabled(tracepoint) tracepoint_enabled(tracepoint)
DECLARE_TRACEPOINT(rwmmio_write);
DECLARE_TRACEPOINT(rwmmio_post_write);
DECLARE_TRACEPOINT(rwmmio_read);
@@ -91,6 +92,7 @@ void log_post_read_mmio(u64 val, u8 width, const volatile void __iomem *addr,
#else
+#define rwmmio_tracepoint_enabled(tracepoint) false
static inline void log_write_mmio(u64 val, u8 width, volatile void __iomem *addr,
unsigned long caller_addr, unsigned long caller_addr0) {}
static inline void log_post_write_mmio(u64 val, u8 width, volatile void __iomem *addr,
@@ -189,11 +191,13 @@ static inline u8 readb(const volatile void __iomem *addr)
{
u8 val;
- log_read_mmio(8, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_read))
+ log_read_mmio(8, addr, _THIS_IP_, _RET_IP_);
__io_br();
val = __raw_readb(addr);
__io_ar(val);
- log_post_read_mmio(val, 8, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_post_read))
+ log_post_read_mmio(val, 8, addr, _THIS_IP_, _RET_IP_);
return val;
}
#endif
@@ -204,11 +208,13 @@ static inline u16 readw(const volatile void __iomem *addr)
{
u16 val;
- log_read_mmio(16, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_read))
+ log_read_mmio(16, addr, _THIS_IP_, _RET_IP_);
__io_br();
val = __le16_to_cpu((__le16 __force)__raw_readw(addr));
__io_ar(val);
- log_post_read_mmio(val, 16, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_post_read))
+ log_post_read_mmio(val, 16, addr, _THIS_IP_, _RET_IP_);
return val;
}
#endif
@@ -219,11 +225,13 @@ static inline u32 readl(const volatile void __iomem *addr)
{
u32 val;
- log_read_mmio(32, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_read))
+ log_read_mmio(32, addr, _THIS_IP_, _RET_IP_);
__io_br();
val = __le32_to_cpu((__le32 __force)__raw_readl(addr));
__io_ar(val);
- log_post_read_mmio(val, 32, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_post_read))
+ log_post_read_mmio(val, 32, addr, _THIS_IP_, _RET_IP_);
return val;
}
#endif
@@ -235,11 +243,13 @@ static inline u64 readq(const volatile void __iomem *addr)
{
u64 val;
- log_read_mmio(64, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_read))
+ log_read_mmio(64, addr, _THIS_IP_, _RET_IP_);
__io_br();
val = __le64_to_cpu((__le64 __force)__raw_readq(addr));
__io_ar(val);
- log_post_read_mmio(val, 64, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_post_read))
+ log_post_read_mmio(val, 64, addr, _THIS_IP_, _RET_IP_);
return val;
}
#endif
@@ -249,11 +259,13 @@ static inline u64 readq(const volatile void __iomem *addr)
#define writeb writeb
static inline void writeb(u8 value, volatile void __iomem *addr)
{
- log_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_write))
+ log_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
__io_bw();
__raw_writeb(value, addr);
__io_aw();
- log_post_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_post_write))
+ log_post_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
}
#endif
@@ -261,11 +273,13 @@ static inline void writeb(u8 value, volatile void __iomem *addr)
#define writew writew
static inline void writew(u16 value, volatile void __iomem *addr)
{
- log_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_write))
+ log_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
__io_bw();
__raw_writew((u16 __force)cpu_to_le16(value), addr);
__io_aw();
- log_post_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_post_write))
+ log_post_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
}
#endif
@@ -273,11 +287,13 @@ static inline void writew(u16 value, volatile void __iomem *addr)
#define writel writel
static inline void writel(u32 value, volatile void __iomem *addr)
{
- log_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_write))
+ log_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
__io_bw();
__raw_writel((u32 __force)__cpu_to_le32(value), addr);
__io_aw();
- log_post_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_post_write))
+ log_post_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
}
#endif
@@ -286,11 +302,13 @@ static inline void writel(u32 value, volatile void __iomem *addr)
#define writeq writeq
static inline void writeq(u64 value, volatile void __iomem *addr)
{
- log_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_write))
+ log_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
__io_bw();
__raw_writeq((u64 __force)__cpu_to_le64(value), addr);
__io_aw();
- log_post_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_post_write))
+ log_post_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
}
#endif
#endif /* CONFIG_64BIT */
@@ -306,9 +324,11 @@ static inline u8 readb_relaxed(const volatile void __iomem *addr)
{
u8 val;
- log_read_mmio(8, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_read))
+ log_read_mmio(8, addr, _THIS_IP_, _RET_IP_);
val = __raw_readb(addr);
- log_post_read_mmio(val, 8, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_post_read))
+ log_post_read_mmio(val, 8, addr, _THIS_IP_, _RET_IP_);
return val;
}
#endif
@@ -319,9 +339,11 @@ static inline u16 readw_relaxed(const volatile void __iomem *addr)
{
u16 val;
- log_read_mmio(16, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_read))
+ log_read_mmio(16, addr, _THIS_IP_, _RET_IP_);
val = __le16_to_cpu((__le16 __force)__raw_readw(addr));
- log_post_read_mmio(val, 16, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_post_read))
+ log_post_read_mmio(val, 16, addr, _THIS_IP_, _RET_IP_);
return val;
}
#endif
@@ -332,9 +354,11 @@ static inline u32 readl_relaxed(const volatile void __iomem *addr)
{
u32 val;
- log_read_mmio(32, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_read))
+ log_read_mmio(32, addr, _THIS_IP_, _RET_IP_);
val = __le32_to_cpu((__le32 __force)__raw_readl(addr));
- log_post_read_mmio(val, 32, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_post_read))
+ log_post_read_mmio(val, 32, addr, _THIS_IP_, _RET_IP_);
return val;
}
#endif
@@ -345,9 +369,11 @@ static inline u64 readq_relaxed(const volatile void __iomem *addr)
{
u64 val;
- log_read_mmio(64, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_read))
+ log_read_mmio(64, addr, _THIS_IP_, _RET_IP_);
val = __le64_to_cpu((__le64 __force)__raw_readq(addr));
- log_post_read_mmio(val, 64, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_post_read))
+ log_post_read_mmio(val, 64, addr, _THIS_IP_, _RET_IP_);
return val;
}
#endif
@@ -356,9 +382,11 @@ static inline u64 readq_relaxed(const volatile void __iomem *addr)
#define writeb_relaxed writeb_relaxed
static inline void writeb_relaxed(u8 value, volatile void __iomem *addr)
{
- log_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_write))
+ log_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
__raw_writeb(value, addr);
- log_post_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_post_write))
+ log_post_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
}
#endif
@@ -366,9 +394,11 @@ static inline void writeb_relaxed(u8 value, volatile void __iomem *addr)
#define writew_relaxed writew_relaxed
static inline void writew_relaxed(u16 value, volatile void __iomem *addr)
{
- log_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_write))
+ log_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
__raw_writew((u16 __force)cpu_to_le16(value), addr);
- log_post_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_post_write))
+ log_post_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
}
#endif
@@ -376,9 +406,11 @@ static inline void writew_relaxed(u16 value, volatile void __iomem *addr)
#define writel_relaxed writel_relaxed
static inline void writel_relaxed(u32 value, volatile void __iomem *addr)
{
- log_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_write))
+ log_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
__raw_writel((u32 __force)__cpu_to_le32(value), addr);
- log_post_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_post_write))
+ log_post_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
}
#endif
@@ -386,9 +418,11 @@ static inline void writel_relaxed(u32 value, volatile void __iomem *addr)
#define writeq_relaxed writeq_relaxed
static inline void writeq_relaxed(u64 value, volatile void __iomem *addr)
{
- log_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_write))
+ log_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
__raw_writeq((u64 __force)__cpu_to_le64(value), addr);
- log_post_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
+ if (rwmmio_tracepoint_enabled(rwmmio_post_write))
+ log_post_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
}
#endif
--
2.49.0.472.ge94155a9ec-goog
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH] asm-generic/io.h: Skip trace helpers if rwmmio events are disabled
2025-03-30 16:42 [PATCH] asm-generic/io.h: Skip trace helpers if rwmmio events are disabled Varad Gautam
@ 2025-04-07 16:13 ` Varad Gautam
2025-04-28 19:41 ` Varad Gautam
0 siblings, 1 reply; 8+ messages in thread
From: Varad Gautam @ 2025-04-07 16:13 UTC (permalink / raw)
To: linux-arch; +Cc: Arnd Bergmann, Sai Prakash Ranjan, linux-kernel, stable
On Sun, Mar 30, 2025 at 6:42 PM Varad Gautam <varadgautam@google.com> wrote:
>
> With `CONFIG_TRACE_MMIO_ACCESS=y`, the `{read,write}{b,w,l,q}{_relaxed}()`
> mmio accessors unconditionally call `log_{post_}{read,write}_mmio()`
> helpers, which in turn call the ftrace ops for `rwmmio` trace events
>
> This adds a performance penalty per mmio accessor call, even when
> `rwmmio` events are disabled at runtime (~80% overhead on local
> measurement).
>
> Guard these with `tracepoint_enabled()`.
>
> Signed-off-by: Varad Gautam <varadgautam@google.com>
> Fixes: 210031971cdd ("asm-generic/io: Add logging support for MMIO accessors")
> Cc: <stable@vger.kernel.org>
Ping.
> ---
> include/asm-generic/io.h | 98 +++++++++++++++++++++++++++-------------
> 1 file changed, 66 insertions(+), 32 deletions(-)
>
> diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
> index 3c61c29ff6ab..a9b5da547523 100644
> --- a/include/asm-generic/io.h
> +++ b/include/asm-generic/io.h
> @@ -75,6 +75,7 @@
> #if IS_ENABLED(CONFIG_TRACE_MMIO_ACCESS) && !(defined(__DISABLE_TRACE_MMIO__))
> #include <linux/tracepoint-defs.h>
>
> +#define rwmmio_tracepoint_enabled(tracepoint) tracepoint_enabled(tracepoint)
> DECLARE_TRACEPOINT(rwmmio_write);
> DECLARE_TRACEPOINT(rwmmio_post_write);
> DECLARE_TRACEPOINT(rwmmio_read);
> @@ -91,6 +92,7 @@ void log_post_read_mmio(u64 val, u8 width, const volatile void __iomem *addr,
>
> #else
>
> +#define rwmmio_tracepoint_enabled(tracepoint) false
> static inline void log_write_mmio(u64 val, u8 width, volatile void __iomem *addr,
> unsigned long caller_addr, unsigned long caller_addr0) {}
> static inline void log_post_write_mmio(u64 val, u8 width, volatile void __iomem *addr,
> @@ -189,11 +191,13 @@ static inline u8 readb(const volatile void __iomem *addr)
> {
> u8 val;
>
> - log_read_mmio(8, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_read))
> + log_read_mmio(8, addr, _THIS_IP_, _RET_IP_);
> __io_br();
> val = __raw_readb(addr);
> __io_ar(val);
> - log_post_read_mmio(val, 8, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> + log_post_read_mmio(val, 8, addr, _THIS_IP_, _RET_IP_);
> return val;
> }
> #endif
> @@ -204,11 +208,13 @@ static inline u16 readw(const volatile void __iomem *addr)
> {
> u16 val;
>
> - log_read_mmio(16, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_read))
> + log_read_mmio(16, addr, _THIS_IP_, _RET_IP_);
> __io_br();
> val = __le16_to_cpu((__le16 __force)__raw_readw(addr));
> __io_ar(val);
> - log_post_read_mmio(val, 16, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> + log_post_read_mmio(val, 16, addr, _THIS_IP_, _RET_IP_);
> return val;
> }
> #endif
> @@ -219,11 +225,13 @@ static inline u32 readl(const volatile void __iomem *addr)
> {
> u32 val;
>
> - log_read_mmio(32, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_read))
> + log_read_mmio(32, addr, _THIS_IP_, _RET_IP_);
> __io_br();
> val = __le32_to_cpu((__le32 __force)__raw_readl(addr));
> __io_ar(val);
> - log_post_read_mmio(val, 32, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> + log_post_read_mmio(val, 32, addr, _THIS_IP_, _RET_IP_);
> return val;
> }
> #endif
> @@ -235,11 +243,13 @@ static inline u64 readq(const volatile void __iomem *addr)
> {
> u64 val;
>
> - log_read_mmio(64, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_read))
> + log_read_mmio(64, addr, _THIS_IP_, _RET_IP_);
> __io_br();
> val = __le64_to_cpu((__le64 __force)__raw_readq(addr));
> __io_ar(val);
> - log_post_read_mmio(val, 64, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> + log_post_read_mmio(val, 64, addr, _THIS_IP_, _RET_IP_);
> return val;
> }
> #endif
> @@ -249,11 +259,13 @@ static inline u64 readq(const volatile void __iomem *addr)
> #define writeb writeb
> static inline void writeb(u8 value, volatile void __iomem *addr)
> {
> - log_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_write))
> + log_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> __io_bw();
> __raw_writeb(value, addr);
> __io_aw();
> - log_post_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> + log_post_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> }
> #endif
>
> @@ -261,11 +273,13 @@ static inline void writeb(u8 value, volatile void __iomem *addr)
> #define writew writew
> static inline void writew(u16 value, volatile void __iomem *addr)
> {
> - log_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_write))
> + log_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> __io_bw();
> __raw_writew((u16 __force)cpu_to_le16(value), addr);
> __io_aw();
> - log_post_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> + log_post_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> }
> #endif
>
> @@ -273,11 +287,13 @@ static inline void writew(u16 value, volatile void __iomem *addr)
> #define writel writel
> static inline void writel(u32 value, volatile void __iomem *addr)
> {
> - log_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_write))
> + log_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> __io_bw();
> __raw_writel((u32 __force)__cpu_to_le32(value), addr);
> __io_aw();
> - log_post_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> + log_post_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> }
> #endif
>
> @@ -286,11 +302,13 @@ static inline void writel(u32 value, volatile void __iomem *addr)
> #define writeq writeq
> static inline void writeq(u64 value, volatile void __iomem *addr)
> {
> - log_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_write))
> + log_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> __io_bw();
> __raw_writeq((u64 __force)__cpu_to_le64(value), addr);
> __io_aw();
> - log_post_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> + log_post_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> }
> #endif
> #endif /* CONFIG_64BIT */
> @@ -306,9 +324,11 @@ static inline u8 readb_relaxed(const volatile void __iomem *addr)
> {
> u8 val;
>
> - log_read_mmio(8, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_read))
> + log_read_mmio(8, addr, _THIS_IP_, _RET_IP_);
> val = __raw_readb(addr);
> - log_post_read_mmio(val, 8, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> + log_post_read_mmio(val, 8, addr, _THIS_IP_, _RET_IP_);
> return val;
> }
> #endif
> @@ -319,9 +339,11 @@ static inline u16 readw_relaxed(const volatile void __iomem *addr)
> {
> u16 val;
>
> - log_read_mmio(16, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_read))
> + log_read_mmio(16, addr, _THIS_IP_, _RET_IP_);
> val = __le16_to_cpu((__le16 __force)__raw_readw(addr));
> - log_post_read_mmio(val, 16, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> + log_post_read_mmio(val, 16, addr, _THIS_IP_, _RET_IP_);
> return val;
> }
> #endif
> @@ -332,9 +354,11 @@ static inline u32 readl_relaxed(const volatile void __iomem *addr)
> {
> u32 val;
>
> - log_read_mmio(32, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_read))
> + log_read_mmio(32, addr, _THIS_IP_, _RET_IP_);
> val = __le32_to_cpu((__le32 __force)__raw_readl(addr));
> - log_post_read_mmio(val, 32, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> + log_post_read_mmio(val, 32, addr, _THIS_IP_, _RET_IP_);
> return val;
> }
> #endif
> @@ -345,9 +369,11 @@ static inline u64 readq_relaxed(const volatile void __iomem *addr)
> {
> u64 val;
>
> - log_read_mmio(64, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_read))
> + log_read_mmio(64, addr, _THIS_IP_, _RET_IP_);
> val = __le64_to_cpu((__le64 __force)__raw_readq(addr));
> - log_post_read_mmio(val, 64, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> + log_post_read_mmio(val, 64, addr, _THIS_IP_, _RET_IP_);
> return val;
> }
> #endif
> @@ -356,9 +382,11 @@ static inline u64 readq_relaxed(const volatile void __iomem *addr)
> #define writeb_relaxed writeb_relaxed
> static inline void writeb_relaxed(u8 value, volatile void __iomem *addr)
> {
> - log_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_write))
> + log_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> __raw_writeb(value, addr);
> - log_post_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> + log_post_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> }
> #endif
>
> @@ -366,9 +394,11 @@ static inline void writeb_relaxed(u8 value, volatile void __iomem *addr)
> #define writew_relaxed writew_relaxed
> static inline void writew_relaxed(u16 value, volatile void __iomem *addr)
> {
> - log_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_write))
> + log_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> __raw_writew((u16 __force)cpu_to_le16(value), addr);
> - log_post_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> + log_post_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> }
> #endif
>
> @@ -376,9 +406,11 @@ static inline void writew_relaxed(u16 value, volatile void __iomem *addr)
> #define writel_relaxed writel_relaxed
> static inline void writel_relaxed(u32 value, volatile void __iomem *addr)
> {
> - log_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_write))
> + log_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> __raw_writel((u32 __force)__cpu_to_le32(value), addr);
> - log_post_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> + log_post_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> }
> #endif
>
> @@ -386,9 +418,11 @@ static inline void writel_relaxed(u32 value, volatile void __iomem *addr)
> #define writeq_relaxed writeq_relaxed
> static inline void writeq_relaxed(u64 value, volatile void __iomem *addr)
> {
> - log_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_write))
> + log_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> __raw_writeq((u64 __force)__cpu_to_le64(value), addr);
> - log_post_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> + log_post_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> }
> #endif
>
> --
> 2.49.0.472.ge94155a9ec-goog
>
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH] asm-generic/io.h: Skip trace helpers if rwmmio events are disabled
2025-04-07 16:13 ` Varad Gautam
@ 2025-04-28 19:41 ` Varad Gautam
2025-05-28 11:58 ` Varad Gautam
0 siblings, 1 reply; 8+ messages in thread
From: Varad Gautam @ 2025-04-28 19:41 UTC (permalink / raw)
To: linux-arch; +Cc: Arnd Bergmann, Sai Prakash Ranjan, linux-kernel, stable
On Mon, Apr 7, 2025 at 6:13 PM Varad Gautam <varadgautam@google.com> wrote:
>
> On Sun, Mar 30, 2025 at 6:42 PM Varad Gautam <varadgautam@google.com> wrote:
> >
> > With `CONFIG_TRACE_MMIO_ACCESS=y`, the `{read,write}{b,w,l,q}{_relaxed}()`
> > mmio accessors unconditionally call `log_{post_}{read,write}_mmio()`
> > helpers, which in turn call the ftrace ops for `rwmmio` trace events
> >
> > This adds a performance penalty per mmio accessor call, even when
> > `rwmmio` events are disabled at runtime (~80% overhead on local
> > measurement).
> >
> > Guard these with `tracepoint_enabled()`.
> >
> > Signed-off-by: Varad Gautam <varadgautam@google.com>
> > Fixes: 210031971cdd ("asm-generic/io: Add logging support for MMIO accessors")
> > Cc: <stable@vger.kernel.org>
>
> Ping.
>
Ping.
> > ---
> > include/asm-generic/io.h | 98 +++++++++++++++++++++++++++-------------
> > 1 file changed, 66 insertions(+), 32 deletions(-)
> >
> > diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
> > index 3c61c29ff6ab..a9b5da547523 100644
> > --- a/include/asm-generic/io.h
> > +++ b/include/asm-generic/io.h
> > @@ -75,6 +75,7 @@
> > #if IS_ENABLED(CONFIG_TRACE_MMIO_ACCESS) && !(defined(__DISABLE_TRACE_MMIO__))
> > #include <linux/tracepoint-defs.h>
> >
> > +#define rwmmio_tracepoint_enabled(tracepoint) tracepoint_enabled(tracepoint)
> > DECLARE_TRACEPOINT(rwmmio_write);
> > DECLARE_TRACEPOINT(rwmmio_post_write);
> > DECLARE_TRACEPOINT(rwmmio_read);
> > @@ -91,6 +92,7 @@ void log_post_read_mmio(u64 val, u8 width, const volatile void __iomem *addr,
> >
> > #else
> >
> > +#define rwmmio_tracepoint_enabled(tracepoint) false
> > static inline void log_write_mmio(u64 val, u8 width, volatile void __iomem *addr,
> > unsigned long caller_addr, unsigned long caller_addr0) {}
> > static inline void log_post_write_mmio(u64 val, u8 width, volatile void __iomem *addr,
> > @@ -189,11 +191,13 @@ static inline u8 readb(const volatile void __iomem *addr)
> > {
> > u8 val;
> >
> > - log_read_mmio(8, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_read))
> > + log_read_mmio(8, addr, _THIS_IP_, _RET_IP_);
> > __io_br();
> > val = __raw_readb(addr);
> > __io_ar(val);
> > - log_post_read_mmio(val, 8, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> > + log_post_read_mmio(val, 8, addr, _THIS_IP_, _RET_IP_);
> > return val;
> > }
> > #endif
> > @@ -204,11 +208,13 @@ static inline u16 readw(const volatile void __iomem *addr)
> > {
> > u16 val;
> >
> > - log_read_mmio(16, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_read))
> > + log_read_mmio(16, addr, _THIS_IP_, _RET_IP_);
> > __io_br();
> > val = __le16_to_cpu((__le16 __force)__raw_readw(addr));
> > __io_ar(val);
> > - log_post_read_mmio(val, 16, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> > + log_post_read_mmio(val, 16, addr, _THIS_IP_, _RET_IP_);
> > return val;
> > }
> > #endif
> > @@ -219,11 +225,13 @@ static inline u32 readl(const volatile void __iomem *addr)
> > {
> > u32 val;
> >
> > - log_read_mmio(32, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_read))
> > + log_read_mmio(32, addr, _THIS_IP_, _RET_IP_);
> > __io_br();
> > val = __le32_to_cpu((__le32 __force)__raw_readl(addr));
> > __io_ar(val);
> > - log_post_read_mmio(val, 32, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> > + log_post_read_mmio(val, 32, addr, _THIS_IP_, _RET_IP_);
> > return val;
> > }
> > #endif
> > @@ -235,11 +243,13 @@ static inline u64 readq(const volatile void __iomem *addr)
> > {
> > u64 val;
> >
> > - log_read_mmio(64, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_read))
> > + log_read_mmio(64, addr, _THIS_IP_, _RET_IP_);
> > __io_br();
> > val = __le64_to_cpu((__le64 __force)__raw_readq(addr));
> > __io_ar(val);
> > - log_post_read_mmio(val, 64, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> > + log_post_read_mmio(val, 64, addr, _THIS_IP_, _RET_IP_);
> > return val;
> > }
> > #endif
> > @@ -249,11 +259,13 @@ static inline u64 readq(const volatile void __iomem *addr)
> > #define writeb writeb
> > static inline void writeb(u8 value, volatile void __iomem *addr)
> > {
> > - log_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_write))
> > + log_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> > __io_bw();
> > __raw_writeb(value, addr);
> > __io_aw();
> > - log_post_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> > + log_post_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> > }
> > #endif
> >
> > @@ -261,11 +273,13 @@ static inline void writeb(u8 value, volatile void __iomem *addr)
> > #define writew writew
> > static inline void writew(u16 value, volatile void __iomem *addr)
> > {
> > - log_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_write))
> > + log_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> > __io_bw();
> > __raw_writew((u16 __force)cpu_to_le16(value), addr);
> > __io_aw();
> > - log_post_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> > + log_post_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> > }
> > #endif
> >
> > @@ -273,11 +287,13 @@ static inline void writew(u16 value, volatile void __iomem *addr)
> > #define writel writel
> > static inline void writel(u32 value, volatile void __iomem *addr)
> > {
> > - log_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_write))
> > + log_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> > __io_bw();
> > __raw_writel((u32 __force)__cpu_to_le32(value), addr);
> > __io_aw();
> > - log_post_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> > + log_post_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> > }
> > #endif
> >
> > @@ -286,11 +302,13 @@ static inline void writel(u32 value, volatile void __iomem *addr)
> > #define writeq writeq
> > static inline void writeq(u64 value, volatile void __iomem *addr)
> > {
> > - log_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_write))
> > + log_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> > __io_bw();
> > __raw_writeq((u64 __force)__cpu_to_le64(value), addr);
> > __io_aw();
> > - log_post_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> > + log_post_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> > }
> > #endif
> > #endif /* CONFIG_64BIT */
> > @@ -306,9 +324,11 @@ static inline u8 readb_relaxed(const volatile void __iomem *addr)
> > {
> > u8 val;
> >
> > - log_read_mmio(8, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_read))
> > + log_read_mmio(8, addr, _THIS_IP_, _RET_IP_);
> > val = __raw_readb(addr);
> > - log_post_read_mmio(val, 8, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> > + log_post_read_mmio(val, 8, addr, _THIS_IP_, _RET_IP_);
> > return val;
> > }
> > #endif
> > @@ -319,9 +339,11 @@ static inline u16 readw_relaxed(const volatile void __iomem *addr)
> > {
> > u16 val;
> >
> > - log_read_mmio(16, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_read))
> > + log_read_mmio(16, addr, _THIS_IP_, _RET_IP_);
> > val = __le16_to_cpu((__le16 __force)__raw_readw(addr));
> > - log_post_read_mmio(val, 16, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> > + log_post_read_mmio(val, 16, addr, _THIS_IP_, _RET_IP_);
> > return val;
> > }
> > #endif
> > @@ -332,9 +354,11 @@ static inline u32 readl_relaxed(const volatile void __iomem *addr)
> > {
> > u32 val;
> >
> > - log_read_mmio(32, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_read))
> > + log_read_mmio(32, addr, _THIS_IP_, _RET_IP_);
> > val = __le32_to_cpu((__le32 __force)__raw_readl(addr));
> > - log_post_read_mmio(val, 32, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> > + log_post_read_mmio(val, 32, addr, _THIS_IP_, _RET_IP_);
> > return val;
> > }
> > #endif
> > @@ -345,9 +369,11 @@ static inline u64 readq_relaxed(const volatile void __iomem *addr)
> > {
> > u64 val;
> >
> > - log_read_mmio(64, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_read))
> > + log_read_mmio(64, addr, _THIS_IP_, _RET_IP_);
> > val = __le64_to_cpu((__le64 __force)__raw_readq(addr));
> > - log_post_read_mmio(val, 64, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> > + log_post_read_mmio(val, 64, addr, _THIS_IP_, _RET_IP_);
> > return val;
> > }
> > #endif
> > @@ -356,9 +382,11 @@ static inline u64 readq_relaxed(const volatile void __iomem *addr)
> > #define writeb_relaxed writeb_relaxed
> > static inline void writeb_relaxed(u8 value, volatile void __iomem *addr)
> > {
> > - log_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_write))
> > + log_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> > __raw_writeb(value, addr);
> > - log_post_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> > + log_post_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> > }
> > #endif
> >
> > @@ -366,9 +394,11 @@ static inline void writeb_relaxed(u8 value, volatile void __iomem *addr)
> > #define writew_relaxed writew_relaxed
> > static inline void writew_relaxed(u16 value, volatile void __iomem *addr)
> > {
> > - log_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_write))
> > + log_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> > __raw_writew((u16 __force)cpu_to_le16(value), addr);
> > - log_post_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> > + log_post_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> > }
> > #endif
> >
> > @@ -376,9 +406,11 @@ static inline void writew_relaxed(u16 value, volatile void __iomem *addr)
> > #define writel_relaxed writel_relaxed
> > static inline void writel_relaxed(u32 value, volatile void __iomem *addr)
> > {
> > - log_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_write))
> > + log_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> > __raw_writel((u32 __force)__cpu_to_le32(value), addr);
> > - log_post_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> > + log_post_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> > }
> > #endif
> >
> > @@ -386,9 +418,11 @@ static inline void writel_relaxed(u32 value, volatile void __iomem *addr)
> > #define writeq_relaxed writeq_relaxed
> > static inline void writeq_relaxed(u64 value, volatile void __iomem *addr)
> > {
> > - log_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_write))
> > + log_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> > __raw_writeq((u64 __force)__cpu_to_le64(value), addr);
> > - log_post_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> > + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> > + log_post_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> > }
> > #endif
> >
> > --
> > 2.49.0.472.ge94155a9ec-goog
> >
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH] asm-generic/io.h: Skip trace helpers if rwmmio events are disabled
2025-04-28 19:41 ` Varad Gautam
@ 2025-05-28 11:58 ` Varad Gautam
2025-07-24 11:49 ` Varad Gautam
0 siblings, 1 reply; 8+ messages in thread
From: Varad Gautam @ 2025-05-28 11:58 UTC (permalink / raw)
To: linux-arch; +Cc: Arnd Bergmann, Sai Prakash Ranjan, linux-kernel, stable
On Mon, Apr 28, 2025 at 9:41 PM Varad Gautam <varadgautam@google.com> wrote:
>
> On Mon, Apr 7, 2025 at 6:13 PM Varad Gautam <varadgautam@google.com> wrote:
> >
> > On Sun, Mar 30, 2025 at 6:42 PM Varad Gautam <varadgautam@google.com> wrote:
> > >
> > > With `CONFIG_TRACE_MMIO_ACCESS=y`, the `{read,write}{b,w,l,q}{_relaxed}()`
> > > mmio accessors unconditionally call `log_{post_}{read,write}_mmio()`
> > > helpers, which in turn call the ftrace ops for `rwmmio` trace events
> > >
> > > This adds a performance penalty per mmio accessor call, even when
> > > `rwmmio` events are disabled at runtime (~80% overhead on local
> > > measurement).
> > >
> > > Guard these with `tracepoint_enabled()`.
> > >
> > > Signed-off-by: Varad Gautam <varadgautam@google.com>
> > > Fixes: 210031971cdd ("asm-generic/io: Add logging support for MMIO accessors")
> > > Cc: <stable@vger.kernel.org>
> >
> > Ping.
> >
>
> Ping.
>
Ping. Arnd, can this be picked up into the asm-generic tree?
> > > ---
> > > include/asm-generic/io.h | 98 +++++++++++++++++++++++++++-------------
> > > 1 file changed, 66 insertions(+), 32 deletions(-)
> > >
> > > diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
> > > index 3c61c29ff6ab..a9b5da547523 100644
> > > --- a/include/asm-generic/io.h
> > > +++ b/include/asm-generic/io.h
> > > @@ -75,6 +75,7 @@
> > > #if IS_ENABLED(CONFIG_TRACE_MMIO_ACCESS) && !(defined(__DISABLE_TRACE_MMIO__))
> > > #include <linux/tracepoint-defs.h>
> > >
> > > +#define rwmmio_tracepoint_enabled(tracepoint) tracepoint_enabled(tracepoint)
> > > DECLARE_TRACEPOINT(rwmmio_write);
> > > DECLARE_TRACEPOINT(rwmmio_post_write);
> > > DECLARE_TRACEPOINT(rwmmio_read);
> > > @@ -91,6 +92,7 @@ void log_post_read_mmio(u64 val, u8 width, const volatile void __iomem *addr,
> > >
> > > #else
> > >
> > > +#define rwmmio_tracepoint_enabled(tracepoint) false
> > > static inline void log_write_mmio(u64 val, u8 width, volatile void __iomem *addr,
> > > unsigned long caller_addr, unsigned long caller_addr0) {}
> > > static inline void log_post_write_mmio(u64 val, u8 width, volatile void __iomem *addr,
> > > @@ -189,11 +191,13 @@ static inline u8 readb(const volatile void __iomem *addr)
> > > {
> > > u8 val;
> > >
> > > - log_read_mmio(8, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_read))
> > > + log_read_mmio(8, addr, _THIS_IP_, _RET_IP_);
> > > __io_br();
> > > val = __raw_readb(addr);
> > > __io_ar(val);
> > > - log_post_read_mmio(val, 8, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> > > + log_post_read_mmio(val, 8, addr, _THIS_IP_, _RET_IP_);
> > > return val;
> > > }
> > > #endif
> > > @@ -204,11 +208,13 @@ static inline u16 readw(const volatile void __iomem *addr)
> > > {
> > > u16 val;
> > >
> > > - log_read_mmio(16, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_read))
> > > + log_read_mmio(16, addr, _THIS_IP_, _RET_IP_);
> > > __io_br();
> > > val = __le16_to_cpu((__le16 __force)__raw_readw(addr));
> > > __io_ar(val);
> > > - log_post_read_mmio(val, 16, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> > > + log_post_read_mmio(val, 16, addr, _THIS_IP_, _RET_IP_);
> > > return val;
> > > }
> > > #endif
> > > @@ -219,11 +225,13 @@ static inline u32 readl(const volatile void __iomem *addr)
> > > {
> > > u32 val;
> > >
> > > - log_read_mmio(32, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_read))
> > > + log_read_mmio(32, addr, _THIS_IP_, _RET_IP_);
> > > __io_br();
> > > val = __le32_to_cpu((__le32 __force)__raw_readl(addr));
> > > __io_ar(val);
> > > - log_post_read_mmio(val, 32, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> > > + log_post_read_mmio(val, 32, addr, _THIS_IP_, _RET_IP_);
> > > return val;
> > > }
> > > #endif
> > > @@ -235,11 +243,13 @@ static inline u64 readq(const volatile void __iomem *addr)
> > > {
> > > u64 val;
> > >
> > > - log_read_mmio(64, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_read))
> > > + log_read_mmio(64, addr, _THIS_IP_, _RET_IP_);
> > > __io_br();
> > > val = __le64_to_cpu((__le64 __force)__raw_readq(addr));
> > > __io_ar(val);
> > > - log_post_read_mmio(val, 64, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> > > + log_post_read_mmio(val, 64, addr, _THIS_IP_, _RET_IP_);
> > > return val;
> > > }
> > > #endif
> > > @@ -249,11 +259,13 @@ static inline u64 readq(const volatile void __iomem *addr)
> > > #define writeb writeb
> > > static inline void writeb(u8 value, volatile void __iomem *addr)
> > > {
> > > - log_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_write))
> > > + log_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> > > __io_bw();
> > > __raw_writeb(value, addr);
> > > __io_aw();
> > > - log_post_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> > > + log_post_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> > > }
> > > #endif
> > >
> > > @@ -261,11 +273,13 @@ static inline void writeb(u8 value, volatile void __iomem *addr)
> > > #define writew writew
> > > static inline void writew(u16 value, volatile void __iomem *addr)
> > > {
> > > - log_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_write))
> > > + log_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> > > __io_bw();
> > > __raw_writew((u16 __force)cpu_to_le16(value), addr);
> > > __io_aw();
> > > - log_post_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> > > + log_post_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> > > }
> > > #endif
> > >
> > > @@ -273,11 +287,13 @@ static inline void writew(u16 value, volatile void __iomem *addr)
> > > #define writel writel
> > > static inline void writel(u32 value, volatile void __iomem *addr)
> > > {
> > > - log_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_write))
> > > + log_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> > > __io_bw();
> > > __raw_writel((u32 __force)__cpu_to_le32(value), addr);
> > > __io_aw();
> > > - log_post_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> > > + log_post_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> > > }
> > > #endif
> > >
> > > @@ -286,11 +302,13 @@ static inline void writel(u32 value, volatile void __iomem *addr)
> > > #define writeq writeq
> > > static inline void writeq(u64 value, volatile void __iomem *addr)
> > > {
> > > - log_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_write))
> > > + log_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> > > __io_bw();
> > > __raw_writeq((u64 __force)__cpu_to_le64(value), addr);
> > > __io_aw();
> > > - log_post_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> > > + log_post_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> > > }
> > > #endif
> > > #endif /* CONFIG_64BIT */
> > > @@ -306,9 +324,11 @@ static inline u8 readb_relaxed(const volatile void __iomem *addr)
> > > {
> > > u8 val;
> > >
> > > - log_read_mmio(8, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_read))
> > > + log_read_mmio(8, addr, _THIS_IP_, _RET_IP_);
> > > val = __raw_readb(addr);
> > > - log_post_read_mmio(val, 8, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> > > + log_post_read_mmio(val, 8, addr, _THIS_IP_, _RET_IP_);
> > > return val;
> > > }
> > > #endif
> > > @@ -319,9 +339,11 @@ static inline u16 readw_relaxed(const volatile void __iomem *addr)
> > > {
> > > u16 val;
> > >
> > > - log_read_mmio(16, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_read))
> > > + log_read_mmio(16, addr, _THIS_IP_, _RET_IP_);
> > > val = __le16_to_cpu((__le16 __force)__raw_readw(addr));
> > > - log_post_read_mmio(val, 16, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> > > + log_post_read_mmio(val, 16, addr, _THIS_IP_, _RET_IP_);
> > > return val;
> > > }
> > > #endif
> > > @@ -332,9 +354,11 @@ static inline u32 readl_relaxed(const volatile void __iomem *addr)
> > > {
> > > u32 val;
> > >
> > > - log_read_mmio(32, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_read))
> > > + log_read_mmio(32, addr, _THIS_IP_, _RET_IP_);
> > > val = __le32_to_cpu((__le32 __force)__raw_readl(addr));
> > > - log_post_read_mmio(val, 32, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> > > + log_post_read_mmio(val, 32, addr, _THIS_IP_, _RET_IP_);
> > > return val;
> > > }
> > > #endif
> > > @@ -345,9 +369,11 @@ static inline u64 readq_relaxed(const volatile void __iomem *addr)
> > > {
> > > u64 val;
> > >
> > > - log_read_mmio(64, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_read))
> > > + log_read_mmio(64, addr, _THIS_IP_, _RET_IP_);
> > > val = __le64_to_cpu((__le64 __force)__raw_readq(addr));
> > > - log_post_read_mmio(val, 64, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> > > + log_post_read_mmio(val, 64, addr, _THIS_IP_, _RET_IP_);
> > > return val;
> > > }
> > > #endif
> > > @@ -356,9 +382,11 @@ static inline u64 readq_relaxed(const volatile void __iomem *addr)
> > > #define writeb_relaxed writeb_relaxed
> > > static inline void writeb_relaxed(u8 value, volatile void __iomem *addr)
> > > {
> > > - log_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_write))
> > > + log_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> > > __raw_writeb(value, addr);
> > > - log_post_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> > > + log_post_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> > > }
> > > #endif
> > >
> > > @@ -366,9 +394,11 @@ static inline void writeb_relaxed(u8 value, volatile void __iomem *addr)
> > > #define writew_relaxed writew_relaxed
> > > static inline void writew_relaxed(u16 value, volatile void __iomem *addr)
> > > {
> > > - log_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_write))
> > > + log_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> > > __raw_writew((u16 __force)cpu_to_le16(value), addr);
> > > - log_post_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> > > + log_post_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> > > }
> > > #endif
> > >
> > > @@ -376,9 +406,11 @@ static inline void writew_relaxed(u16 value, volatile void __iomem *addr)
> > > #define writel_relaxed writel_relaxed
> > > static inline void writel_relaxed(u32 value, volatile void __iomem *addr)
> > > {
> > > - log_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_write))
> > > + log_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> > > __raw_writel((u32 __force)__cpu_to_le32(value), addr);
> > > - log_post_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> > > + log_post_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> > > }
> > > #endif
> > >
> > > @@ -386,9 +418,11 @@ static inline void writel_relaxed(u32 value, volatile void __iomem *addr)
> > > #define writeq_relaxed writeq_relaxed
> > > static inline void writeq_relaxed(u64 value, volatile void __iomem *addr)
> > > {
> > > - log_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_write))
> > > + log_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> > > __raw_writeq((u64 __force)__cpu_to_le64(value), addr);
> > > - log_post_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> > > + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> > > + log_post_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> > > }
> > > #endif
> > >
> > > --
> > > 2.49.0.472.ge94155a9ec-goog
> > >
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH] asm-generic/io.h: Skip trace helpers if rwmmio events are disabled
2025-05-28 11:58 ` Varad Gautam
@ 2025-07-24 11:49 ` Varad Gautam
2025-07-26 16:22 ` Arnd Bergmann
0 siblings, 1 reply; 8+ messages in thread
From: Varad Gautam @ 2025-07-24 11:49 UTC (permalink / raw)
To: linux-arch; +Cc: Arnd Bergmann, Sai Prakash Ranjan, linux-kernel, stable
On Wed, May 28, 2025 at 5:28 PM Varad Gautam <varadgautam@google.com> wrote:
>
> On Mon, Apr 28, 2025 at 9:41 PM Varad Gautam <varadgautam@google.com> wrote:
> >
> > On Mon, Apr 7, 2025 at 6:13 PM Varad Gautam <varadgautam@google.com> wrote:
> > >
> > > On Sun, Mar 30, 2025 at 6:42 PM Varad Gautam <varadgautam@google.com> wrote:
> > > >
> > > > With `CONFIG_TRACE_MMIO_ACCESS=y`, the `{read,write}{b,w,l,q}{_relaxed}()`
> > > > mmio accessors unconditionally call `log_{post_}{read,write}_mmio()`
> > > > helpers, which in turn call the ftrace ops for `rwmmio` trace events
> > > >
> > > > This adds a performance penalty per mmio accessor call, even when
> > > > `rwmmio` events are disabled at runtime (~80% overhead on local
> > > > measurement).
> > > >
> > > > Guard these with `tracepoint_enabled()`.
> > > >
> > > > Signed-off-by: Varad Gautam <varadgautam@google.com>
> > > > Fixes: 210031971cdd ("asm-generic/io: Add logging support for MMIO accessors")
> > > > Cc: <stable@vger.kernel.org>
> > >
> > > Ping.
> > >
> >
> > Ping.
> >
>
> Ping. Arnd, can this be picked up into the asm-generic tree?
>
Ping.
> > > > ---
> > > > include/asm-generic/io.h | 98 +++++++++++++++++++++++++++-------------
> > > > 1 file changed, 66 insertions(+), 32 deletions(-)
> > > >
> > > > diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
> > > > index 3c61c29ff6ab..a9b5da547523 100644
> > > > --- a/include/asm-generic/io.h
> > > > +++ b/include/asm-generic/io.h
> > > > @@ -75,6 +75,7 @@
> > > > #if IS_ENABLED(CONFIG_TRACE_MMIO_ACCESS) && !(defined(__DISABLE_TRACE_MMIO__))
> > > > #include <linux/tracepoint-defs.h>
> > > >
> > > > +#define rwmmio_tracepoint_enabled(tracepoint) tracepoint_enabled(tracepoint)
> > > > DECLARE_TRACEPOINT(rwmmio_write);
> > > > DECLARE_TRACEPOINT(rwmmio_post_write);
> > > > DECLARE_TRACEPOINT(rwmmio_read);
> > > > @@ -91,6 +92,7 @@ void log_post_read_mmio(u64 val, u8 width, const volatile void __iomem *addr,
> > > >
> > > > #else
> > > >
> > > > +#define rwmmio_tracepoint_enabled(tracepoint) false
> > > > static inline void log_write_mmio(u64 val, u8 width, volatile void __iomem *addr,
> > > > unsigned long caller_addr, unsigned long caller_addr0) {}
> > > > static inline void log_post_write_mmio(u64 val, u8 width, volatile void __iomem *addr,
> > > > @@ -189,11 +191,13 @@ static inline u8 readb(const volatile void __iomem *addr)
> > > > {
> > > > u8 val;
> > > >
> > > > - log_read_mmio(8, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_read))
> > > > + log_read_mmio(8, addr, _THIS_IP_, _RET_IP_);
> > > > __io_br();
> > > > val = __raw_readb(addr);
> > > > __io_ar(val);
> > > > - log_post_read_mmio(val, 8, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> > > > + log_post_read_mmio(val, 8, addr, _THIS_IP_, _RET_IP_);
> > > > return val;
> > > > }
> > > > #endif
> > > > @@ -204,11 +208,13 @@ static inline u16 readw(const volatile void __iomem *addr)
> > > > {
> > > > u16 val;
> > > >
> > > > - log_read_mmio(16, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_read))
> > > > + log_read_mmio(16, addr, _THIS_IP_, _RET_IP_);
> > > > __io_br();
> > > > val = __le16_to_cpu((__le16 __force)__raw_readw(addr));
> > > > __io_ar(val);
> > > > - log_post_read_mmio(val, 16, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> > > > + log_post_read_mmio(val, 16, addr, _THIS_IP_, _RET_IP_);
> > > > return val;
> > > > }
> > > > #endif
> > > > @@ -219,11 +225,13 @@ static inline u32 readl(const volatile void __iomem *addr)
> > > > {
> > > > u32 val;
> > > >
> > > > - log_read_mmio(32, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_read))
> > > > + log_read_mmio(32, addr, _THIS_IP_, _RET_IP_);
> > > > __io_br();
> > > > val = __le32_to_cpu((__le32 __force)__raw_readl(addr));
> > > > __io_ar(val);
> > > > - log_post_read_mmio(val, 32, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> > > > + log_post_read_mmio(val, 32, addr, _THIS_IP_, _RET_IP_);
> > > > return val;
> > > > }
> > > > #endif
> > > > @@ -235,11 +243,13 @@ static inline u64 readq(const volatile void __iomem *addr)
> > > > {
> > > > u64 val;
> > > >
> > > > - log_read_mmio(64, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_read))
> > > > + log_read_mmio(64, addr, _THIS_IP_, _RET_IP_);
> > > > __io_br();
> > > > val = __le64_to_cpu((__le64 __force)__raw_readq(addr));
> > > > __io_ar(val);
> > > > - log_post_read_mmio(val, 64, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> > > > + log_post_read_mmio(val, 64, addr, _THIS_IP_, _RET_IP_);
> > > > return val;
> > > > }
> > > > #endif
> > > > @@ -249,11 +259,13 @@ static inline u64 readq(const volatile void __iomem *addr)
> > > > #define writeb writeb
> > > > static inline void writeb(u8 value, volatile void __iomem *addr)
> > > > {
> > > > - log_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_write))
> > > > + log_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> > > > __io_bw();
> > > > __raw_writeb(value, addr);
> > > > __io_aw();
> > > > - log_post_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> > > > + log_post_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> > > > }
> > > > #endif
> > > >
> > > > @@ -261,11 +273,13 @@ static inline void writeb(u8 value, volatile void __iomem *addr)
> > > > #define writew writew
> > > > static inline void writew(u16 value, volatile void __iomem *addr)
> > > > {
> > > > - log_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_write))
> > > > + log_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> > > > __io_bw();
> > > > __raw_writew((u16 __force)cpu_to_le16(value), addr);
> > > > __io_aw();
> > > > - log_post_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> > > > + log_post_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> > > > }
> > > > #endif
> > > >
> > > > @@ -273,11 +287,13 @@ static inline void writew(u16 value, volatile void __iomem *addr)
> > > > #define writel writel
> > > > static inline void writel(u32 value, volatile void __iomem *addr)
> > > > {
> > > > - log_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_write))
> > > > + log_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> > > > __io_bw();
> > > > __raw_writel((u32 __force)__cpu_to_le32(value), addr);
> > > > __io_aw();
> > > > - log_post_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> > > > + log_post_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> > > > }
> > > > #endif
> > > >
> > > > @@ -286,11 +302,13 @@ static inline void writel(u32 value, volatile void __iomem *addr)
> > > > #define writeq writeq
> > > > static inline void writeq(u64 value, volatile void __iomem *addr)
> > > > {
> > > > - log_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_write))
> > > > + log_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> > > > __io_bw();
> > > > __raw_writeq((u64 __force)__cpu_to_le64(value), addr);
> > > > __io_aw();
> > > > - log_post_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> > > > + log_post_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> > > > }
> > > > #endif
> > > > #endif /* CONFIG_64BIT */
> > > > @@ -306,9 +324,11 @@ static inline u8 readb_relaxed(const volatile void __iomem *addr)
> > > > {
> > > > u8 val;
> > > >
> > > > - log_read_mmio(8, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_read))
> > > > + log_read_mmio(8, addr, _THIS_IP_, _RET_IP_);
> > > > val = __raw_readb(addr);
> > > > - log_post_read_mmio(val, 8, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> > > > + log_post_read_mmio(val, 8, addr, _THIS_IP_, _RET_IP_);
> > > > return val;
> > > > }
> > > > #endif
> > > > @@ -319,9 +339,11 @@ static inline u16 readw_relaxed(const volatile void __iomem *addr)
> > > > {
> > > > u16 val;
> > > >
> > > > - log_read_mmio(16, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_read))
> > > > + log_read_mmio(16, addr, _THIS_IP_, _RET_IP_);
> > > > val = __le16_to_cpu((__le16 __force)__raw_readw(addr));
> > > > - log_post_read_mmio(val, 16, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> > > > + log_post_read_mmio(val, 16, addr, _THIS_IP_, _RET_IP_);
> > > > return val;
> > > > }
> > > > #endif
> > > > @@ -332,9 +354,11 @@ static inline u32 readl_relaxed(const volatile void __iomem *addr)
> > > > {
> > > > u32 val;
> > > >
> > > > - log_read_mmio(32, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_read))
> > > > + log_read_mmio(32, addr, _THIS_IP_, _RET_IP_);
> > > > val = __le32_to_cpu((__le32 __force)__raw_readl(addr));
> > > > - log_post_read_mmio(val, 32, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> > > > + log_post_read_mmio(val, 32, addr, _THIS_IP_, _RET_IP_);
> > > > return val;
> > > > }
> > > > #endif
> > > > @@ -345,9 +369,11 @@ static inline u64 readq_relaxed(const volatile void __iomem *addr)
> > > > {
> > > > u64 val;
> > > >
> > > > - log_read_mmio(64, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_read))
> > > > + log_read_mmio(64, addr, _THIS_IP_, _RET_IP_);
> > > > val = __le64_to_cpu((__le64 __force)__raw_readq(addr));
> > > > - log_post_read_mmio(val, 64, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_post_read))
> > > > + log_post_read_mmio(val, 64, addr, _THIS_IP_, _RET_IP_);
> > > > return val;
> > > > }
> > > > #endif
> > > > @@ -356,9 +382,11 @@ static inline u64 readq_relaxed(const volatile void __iomem *addr)
> > > > #define writeb_relaxed writeb_relaxed
> > > > static inline void writeb_relaxed(u8 value, volatile void __iomem *addr)
> > > > {
> > > > - log_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_write))
> > > > + log_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> > > > __raw_writeb(value, addr);
> > > > - log_post_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> > > > + log_post_write_mmio(value, 8, addr, _THIS_IP_, _RET_IP_);
> > > > }
> > > > #endif
> > > >
> > > > @@ -366,9 +394,11 @@ static inline void writeb_relaxed(u8 value, volatile void __iomem *addr)
> > > > #define writew_relaxed writew_relaxed
> > > > static inline void writew_relaxed(u16 value, volatile void __iomem *addr)
> > > > {
> > > > - log_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_write))
> > > > + log_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> > > > __raw_writew((u16 __force)cpu_to_le16(value), addr);
> > > > - log_post_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> > > > + log_post_write_mmio(value, 16, addr, _THIS_IP_, _RET_IP_);
> > > > }
> > > > #endif
> > > >
> > > > @@ -376,9 +406,11 @@ static inline void writew_relaxed(u16 value, volatile void __iomem *addr)
> > > > #define writel_relaxed writel_relaxed
> > > > static inline void writel_relaxed(u32 value, volatile void __iomem *addr)
> > > > {
> > > > - log_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_write))
> > > > + log_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> > > > __raw_writel((u32 __force)__cpu_to_le32(value), addr);
> > > > - log_post_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> > > > + log_post_write_mmio(value, 32, addr, _THIS_IP_, _RET_IP_);
> > > > }
> > > > #endif
> > > >
> > > > @@ -386,9 +418,11 @@ static inline void writel_relaxed(u32 value, volatile void __iomem *addr)
> > > > #define writeq_relaxed writeq_relaxed
> > > > static inline void writeq_relaxed(u64 value, volatile void __iomem *addr)
> > > > {
> > > > - log_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_write))
> > > > + log_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> > > > __raw_writeq((u64 __force)__cpu_to_le64(value), addr);
> > > > - log_post_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> > > > + if (rwmmio_tracepoint_enabled(rwmmio_post_write))
> > > > + log_post_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
> > > > }
> > > > #endif
> > > >
> > > > --
> > > > 2.49.0.472.ge94155a9ec-goog
> > > >
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH] asm-generic/io.h: Skip trace helpers if rwmmio events are disabled
2025-07-24 11:49 ` Varad Gautam
@ 2025-07-26 16:22 ` Arnd Bergmann
2025-09-23 11:07 ` Varad Gautam
0 siblings, 1 reply; 8+ messages in thread
From: Arnd Bergmann @ 2025-07-26 16:22 UTC (permalink / raw)
To: Varad Gautam, Linux-Arch; +Cc: Sai Prakash Ranjan, linux-kernel, stable
On Thu, Jul 24, 2025, at 13:49, Varad Gautam wrote:
> On Wed, May 28, 2025 at 5:28 PM Varad Gautam <varadgautam@google.com> wrote:
>>
>> On Mon, Apr 28, 2025 at 9:41 PM Varad Gautam <varadgautam@google.com> wrote:
>> >
>> > On Mon, Apr 7, 2025 at 6:13 PM Varad Gautam <varadgautam@google.com> wrote:
>> > >
>> > > On Sun, Mar 30, 2025 at 6:42 PM Varad Gautam <varadgautam@google.com> wrote:
>> > > >
>> > > > With `CONFIG_TRACE_MMIO_ACCESS=y`, the `{read,write}{b,w,l,q}{_relaxed}()`
>> > > > mmio accessors unconditionally call `log_{post_}{read,write}_mmio()`
>> > > > helpers, which in turn call the ftrace ops for `rwmmio` trace events
>> > > >
>> > > > This adds a performance penalty per mmio accessor call, even when
>> > > > `rwmmio` events are disabled at runtime (~80% overhead on local
>> > > > measurement).
>> > > >
>> > > > Guard these with `tracepoint_enabled()`.
>> > > >
>> > > > Signed-off-by: Varad Gautam <varadgautam@google.com>
>> > > > Fixes: 210031971cdd ("asm-generic/io: Add logging support for MMIO accessors")
>> > > > Cc: <stable@vger.kernel.org>
>> > >
>> > > Ping.
>> > >
>> >
>> > Ping.
>> >
>>
>> Ping. Arnd, can this be picked up into the asm-generic tree?
>>
>
> Ping.
I'm sorry I keep missing this one. It's really too late again for
the merge window, so it won't be in 6.17 either, but I've applied
it locally in my asm-generic branch that I'm planning for 6.18
so I hope I won't miss it again.
I currently have nothing queued up for 6.17 at all, but I already
have some of my own patches that I plan to submit for review after
the merge window and merge through the asm-generic tree.
Arnd
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH] asm-generic/io.h: Skip trace helpers if rwmmio events are disabled
2025-07-26 16:22 ` Arnd Bergmann
@ 2025-09-23 11:07 ` Varad Gautam
2025-09-24 14:25 ` Arnd Bergmann
0 siblings, 1 reply; 8+ messages in thread
From: Varad Gautam @ 2025-09-23 11:07 UTC (permalink / raw)
To: Arnd Bergmann; +Cc: Linux-Arch, Sai Prakash Ranjan, linux-kernel, stable
Hey Arnd,
On Sat, Jul 26, 2025 at 6:22 PM Arnd Bergmann <arnd@arndb.de> wrote:
>
> On Thu, Jul 24, 2025, at 13:49, Varad Gautam wrote:
> > On Wed, May 28, 2025 at 5:28 PM Varad Gautam <varadgautam@google.com> wrote:
> >>
> >> On Mon, Apr 28, 2025 at 9:41 PM Varad Gautam <varadgautam@google.com> wrote:
> >> >
> >> > On Mon, Apr 7, 2025 at 6:13 PM Varad Gautam <varadgautam@google.com> wrote:
> >> > >
> >> > > On Sun, Mar 30, 2025 at 6:42 PM Varad Gautam <varadgautam@google.com> wrote:
> >> > > >
> >> > > > With `CONFIG_TRACE_MMIO_ACCESS=y`, the `{read,write}{b,w,l,q}{_relaxed}()`
> >> > > > mmio accessors unconditionally call `log_{post_}{read,write}_mmio()`
> >> > > > helpers, which in turn call the ftrace ops for `rwmmio` trace events
> >> > > >
> >> > > > This adds a performance penalty per mmio accessor call, even when
> >> > > > `rwmmio` events are disabled at runtime (~80% overhead on local
> >> > > > measurement).
> >> > > >
> >> > > > Guard these with `tracepoint_enabled()`.
> >> > > >
> >> > > > Signed-off-by: Varad Gautam <varadgautam@google.com>
> >> > > > Fixes: 210031971cdd ("asm-generic/io: Add logging support for MMIO accessors")
> >> > > > Cc: <stable@vger.kernel.org>
> >> > >
> >> > > Ping.
> >> > >
> >> >
> >> > Ping.
> >> >
> >>
> >> Ping. Arnd, can this be picked up into the asm-generic tree?
> >>
> >
> > Ping.
>
> I'm sorry I keep missing this one. It's really too late again for
> the merge window, so it won't be in 6.17 either, but I've applied
> it locally in my asm-generic branch that I'm planning for 6.18
> so I hope I won't miss it again.
>
Can I follow this along somewhere? (I don't see it on arnd/asm-generic.git atm.)
The unnecessary log_*_mmio() calls are showing up on enough Pixel devices
as a CPU cycles wastage, and I'm sure other Androids see it too.
Thanks,
Varad
> I currently have nothing queued up for 6.17 at all, but I already
> have some of my own patches that I plan to submit for review after
> the merge window and merge through the asm-generic tree.
>
> Arnd
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH] asm-generic/io.h: Skip trace helpers if rwmmio events are disabled
2025-09-23 11:07 ` Varad Gautam
@ 2025-09-24 14:25 ` Arnd Bergmann
0 siblings, 0 replies; 8+ messages in thread
From: Arnd Bergmann @ 2025-09-24 14:25 UTC (permalink / raw)
To: Varad Gautam; +Cc: Linux-Arch, Sai Prakash Ranjan, linux-kernel, stable
On Tue, Sep 23, 2025, at 13:07, Varad Gautam wrote:
>
> Can I follow this along somewhere? (I don't see it on arnd/asm-generic.git atm.)
>
> The unnecessary log_*_mmio() calls are showing up on enough Pixel devices
> as a CPU cycles wastage, and I'm sure other Androids see it too.
Pushed out now. I still had it in my local branch, but did not
have any other asm-generic changes, so I ended up missing it again...
Arnd
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2025-09-24 14:25 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2025-03-30 16:42 [PATCH] asm-generic/io.h: Skip trace helpers if rwmmio events are disabled Varad Gautam
2025-04-07 16:13 ` Varad Gautam
2025-04-28 19:41 ` Varad Gautam
2025-05-28 11:58 ` Varad Gautam
2025-07-24 11:49 ` Varad Gautam
2025-07-26 16:22 ` Arnd Bergmann
2025-09-23 11:07 ` Varad Gautam
2025-09-24 14:25 ` Arnd Bergmann
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