Commit 487472bc authored by Andi Kleen's avatar Andi Kleen Committed by Linus Torvalds
Browse files

[PATCH] i386: Replace broken serialize_cpu in microcode driver with correct sync_core



Passing random input values in eax to cpuid is not a good idea
because the CPU will GPF for unknown ones.
Use the correct x86-64 version that exists for a longer time too.
This also adds a memory barrier to prevent the optimizer from
reordering.

Cc: tigran@veritas.com
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent c818a181
......@@ -166,7 +166,7 @@ static void collect_cpu_info (void *unused)
wrmsr(MSR_IA32_UCODE_REV, 0, 0);
/* see notes above for revision 1.07. Apparent chip bug */
serialize_cpu();
sync_core();
/* get the current revision from MSR 0x8B */
rdmsr(MSR_IA32_UCODE_REV, val[0], uci->rev);
pr_debug("microcode: collect_cpu_info : sig=0x%x, pf=0x%x, rev=0x%x\n",
......@@ -380,7 +380,7 @@ static void do_update_one (void * unused)
wrmsr(MSR_IA32_UCODE_REV, 0, 0);
/* see notes above for revision 1.07. Apparent chip bug */
serialize_cpu();
sync_core();
/* get the current revision from MSR 0x8B */
rdmsr(MSR_IA32_UCODE_REV, val[0], val[1]);
......
......@@ -281,9 +281,11 @@ static inline void clear_in_cr4 (unsigned long mask)
outb((data), 0x23); \
} while (0)
static inline void serialize_cpu(void)
/* Stop speculative execution */
static inline void sync_core(void)
{
__asm__ __volatile__ ("cpuid" : : : "ax", "bx", "cx", "dx");
int tmp;
asm volatile("cpuid" : "=a" (tmp) : "0" (1) : "ebx","ecx","edx","memory");
}
static inline void __monitor(const void *eax, unsigned long ecx,
......
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