From 60d903fbb7653bc9754228bdab4c6933fcda1e72 Mon Sep 17 00:00:00 2001 From: "Richard W.M. Jones" Date: Tue, 13 Apr 2021 09:35:07 +0100 Subject: [PATCH] Simplify and fix invocation of cpuid. Fixes a crash on some platforms identified by Yongkui Guo in https://bugzilla.redhat.com/show_bug.cgi?id=1756381#c15 --- virt-what-cpuid-helper.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-) diff --git a/virt-what-cpuid-helper.c b/virt-what-cpuid-helper.c index 9c6cdb2..fdceb62 100644 --- a/virt-what-cpuid-helper.c +++ b/virt-what-cpuid-helper.c @@ -47,17 +47,25 @@ known_signature (const char *sig) 0; } +/* Copied from the Linux kernel definition in + * arch/x86/include/asm/processor.h + */ +static inline void +cpuid (uint32_t *eax, uint32_t *ebx, uint32_t *ecx, uint32_t *edx) +{ + asm volatile ("cpuid" + : "=a" (*eax), "=b" (*ebx), "=c" (*ecx), "=d" (*edx) + : "0" (*eax), "2" (*ecx) + : "memory"); +} + static uint32_t -cpuid (uint32_t eax, char *sig) +cpuid_leaf (uint32_t eax, char *sig) { uint32_t *sig32 = (uint32_t *) sig; - asm volatile ( - "xchgl %%ebx,%1; xor %%ebx,%%ebx; cpuid; xchgl %%ebx,%1" - : "=a" (eax), "+r" (sig32[0]), "=c" (sig32[1]), "=d" (sig32[2]) - : "0" (eax)); - sig[12] = 0; - + cpuid (&eax, &sig32[0], &sig32[1], &sig32[2]); + sig[12] = 0; /* \0-terminate the string to make string comparison possible */ return eax; } @@ -87,7 +95,7 @@ cpu_sig (void) */ for (leaf = base + 0xff00; leaf >= base; leaf -= 0x100) { memset (sig, 0, sizeof sig); - cpuid (leaf, sig); + cpuid_leaf (leaf, sig); if (known_signature (sig)) { puts (sig); break; -- 1.8.3.1