From: Uros Bizjak <ubizjak@gmail.com>
To: x86@kernel.org, linux-kernel@vger.kernel.org
Cc: Uros Bizjak <ubizjak@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: [PATCH 1/2] x86/vdso: Fix output operand size of RDPID insn
Date: Mon, 16 Jun 2025 11:52:57 +0200 [thread overview]
Message-ID: <20250616095315.230620-1-ubizjak@gmail.com> (raw)
RDPID instruction outputs to a word-sized register (64-bit on
x86_64 and 32-bit on x86_32). Use unsigned long variable to use
the correct size.
LSL outputs to 32-bit register, use %k operand prefix
to always print 32-bit name of the register.
Fixes: ffebbaedc861 ("x86/vdso: Introduce helper functions for CPU and node number")
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
---
arch/x86/include/asm/segment.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/segment.h b/arch/x86/include/asm/segment.h
index 77d8f49b92bd..93fcf0daba01 100644
--- a/arch/x86/include/asm/segment.h
+++ b/arch/x86/include/asm/segment.h
@@ -244,7 +244,7 @@ static inline unsigned long vdso_encode_cpunode(int cpu, unsigned long node)
static inline void vdso_read_cpunode(unsigned *cpu, unsigned *node)
{
- unsigned int p;
+ unsigned long p;
/*
* Load CPU and node number from the GDT. LSL is faster than RDTSCP
@@ -254,7 +254,7 @@ static inline void vdso_read_cpunode(unsigned *cpu, unsigned *node)
*
* If RDPID is available, use it.
*/
- alternative_io ("lsl %[seg],%[p]",
+ alternative_io ("lsl %[seg],%k[p]",
".byte 0xf3,0x0f,0xc7,0xf8", /* RDPID %eax/rax */
X86_FEATURE_RDPID,
[p] "=a" (p), [seg] "r" (__CPUNODE_SEG));
--
2.49.0
next reply other threads:[~2025-06-16 9:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-16 9:52 Uros Bizjak [this message]
2025-06-16 9:52 ` [PATCH 2/2] x86/vdso: Use RDPID mnemonic in vdso_red_cpunode() Uros Bizjak
2025-08-27 6:45 ` [tip: x86/asm] x86/vdso: Fix output operand size of RDPID tip-bot2 for Uros Bizjak
2025-08-27 7:53 ` Uros Bizjak
2025-08-27 8:19 ` Borislav Petkov
2025-08-27 8:28 ` Uros Bizjak
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