[PATCH V2 2/4] perf/x86/amd: AMD implementation for hardware breakpoint address mask

[Jacob Shin <jacob.shin@amd.com>]

Implement hardware breakpoint address mask for AMD Family 16h (and
any other future) processors. CPUID feature bit indicates the hardware
support for DRn_ADDR_MASK MSRs.

Signed-off-by: Jacob Shin <jacob.shin@amd.com>
---
 arch/x86/include/asm/cpufeature.h     |    2 ++
 arch/x86/include/asm/debugreg.h       |    5 +++++
 arch/x86/include/asm/hw_breakpoint.h  |    1 +
 arch/x86/include/uapi/asm/msr-index.h |    6 ++++++
 arch/x86/kernel/cpu/amd.c             |   19 +++++++++++++++++++
 arch/x86/kernel/hw_breakpoint.c       |   16 ++++++++++++++++
 6 files changed, 49 insertions(+)

diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index ac10df7..bee6994 100644
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -168,6 +168,7 @@
 #define X86_FEATURE_TOPOEXT	(6*32+22) /* topology extensions CPUID leafs */
 #define X86_FEATURE_PERFCTR_CORE (6*32+23) /* core performance counter extensions */
 #define X86_FEATURE_PERFCTR_NB  (6*32+24) /* NB performance counter extensions */
+#define X86_FEATURE_BPEXT	(6*32+26) /* data breakpoint extension */
 #define X86_FEATURE_PERFCTR_L2	(6*32+28) /* L2 performance counter extensions */
 
 /*
@@ -317,6 +318,7 @@ extern const char * const x86_power_flags[32];
 #define cpu_has_cx16		boot_cpu_has(X86_FEATURE_CX16)
 #define cpu_has_eager_fpu	boot_cpu_has(X86_FEATURE_EAGER_FPU)
 #define cpu_has_topoext		boot_cpu_has(X86_FEATURE_TOPOEXT)
+#define cpu_has_bpext		boot_cpu_has(X86_FEATURE_BPEXT)
 
 #ifdef CONFIG_X86_64
 
diff --git a/arch/x86/include/asm/debugreg.h b/arch/x86/include/asm/debugreg.h
index 4b528a9..9b38750 100644
--- a/arch/x86/include/asm/debugreg.h
+++ b/arch/x86/include/asm/debugreg.h
@@ -114,5 +114,10 @@ static inline void debug_stack_usage_inc(void) { }
 static inline void debug_stack_usage_dec(void) { }
 #endif /* X86_64 */
 
+#ifdef CONFIG_CPU_SUP_AMD
+extern void set_dr_addr_mask(u32 mask, int dr);
+#else
+static inline void set_dr_addr_mask(u32 mask, int dr) { }
+#endif
 
 #endif /* _ASM_X86_DEBUGREG_H */
diff --git a/arch/x86/include/asm/hw_breakpoint.h b/arch/x86/include/asm/hw_breakpoint.h
index ef1c4d2..c0b89d8 100644
--- a/arch/x86/include/asm/hw_breakpoint.h
+++ b/arch/x86/include/asm/hw_breakpoint.h
@@ -14,6 +14,7 @@ struct arch_hw_breakpoint {
 	unsigned long	address;
 	u8		len;
 	u8		type;
+	u32		mask;
 };
 
 #include <linux/kdebug.h>
diff --git a/arch/x86/include/uapi/asm/msr-index.h b/arch/x86/include/uapi/asm/msr-index.h
index b575788..ea7c98f 100644
--- a/arch/x86/include/uapi/asm/msr-index.h
+++ b/arch/x86/include/uapi/asm/msr-index.h
@@ -200,6 +200,12 @@
 #define MSR_F16H_L2I_PERF_CTL		0xc0010230
 #define MSR_F16H_L2I_PERF_CTR		0xc0010231
 
+/* Fam 16h MSRs */
+#define MSR_F16H_DR0_ADDR_MASK		0xc0011027
+#define MSR_F16H_DR1_ADDR_MASK		0xc0011019
+#define MSR_F16H_DR2_ADDR_MASK		0xc001101a
+#define MSR_F16H_DR3_ADDR_MASK		0xc001101b
+
 /* Fam 15h MSRs */
 #define MSR_F15H_PERF_CTL		0xc0010200
 #define MSR_F15H_PERF_CTR		0xc0010201
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index fa96eb0..aadc499 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -910,3 +910,22 @@ bool cpu_has_amd_erratum(const int *erratum)
 }
 
 EXPORT_SYMBOL_GPL(cpu_has_amd_erratum);
+
+void set_dr_addr_mask(u32 mask, int dr)
+{
+	if (!cpu_has_bpext)
+		return;
+
+	switch (dr) {
+	case 0:
+		wrmsr(MSR_F16H_DR0_ADDR_MASK, mask, 0);
+		break;
+	case 1:
+	case 2:
+	case 3:
+		wrmsr(MSR_F16H_DR1_ADDR_MASK - 1 + dr, mask, 0);
+		break;
+	default:
+		break;
+	}
+}
diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c
index 02f0763..58a1b80 100644
--- a/arch/x86/kernel/hw_breakpoint.c
+++ b/arch/x86/kernel/hw_breakpoint.c
@@ -121,6 +121,8 @@ int arch_install_hw_breakpoint(struct perf_event *bp)
 	if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot"))
 		return -EBUSY;
 
+	set_dr_addr_mask(info->mask, i);
+
 	set_debugreg(info->address, i);
 	__this_cpu_write(cpu_debugreg[i], info->address);
 
@@ -163,6 +165,8 @@ void arch_uninstall_hw_breakpoint(struct perf_event *bp)
 	*dr7 &= ~__encode_dr7(i, info->len, info->type);
 
 	set_debugreg(*dr7, 7);
+
+	set_dr_addr_mask(0, i);
 }
 
 static int get_hbp_len(u8 hbp_len)
@@ -254,6 +258,7 @@ static int arch_build_bp_info(struct perf_event *bp)
 	struct arch_hw_breakpoint *info = counter_arch_bp(bp);
 
 	info->address = bp->attr.bp_addr;
+	info->mask = bp->attr.bp_addr_mask;
 
 	/* Type */
 	switch (bp->attr.bp_type) {
@@ -345,6 +350,17 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp)
 	return 0;
 }
 
+int arch_validate_hwbkpt_addr_mask(struct perf_event *bp)
+{
+	if (!cpu_has_bpext)
+		return -EOPNOTSUPP;
+
+	if (bp->attr.bp_addr & bp->attr.bp_addr_mask)
+		return -EINVAL;
+
+	return 0;
+}
+
 /*
  * Dump the debug register contents to the user.
  * We can't dump our per cpu values because it
-- 
1.7.9.5