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

arch/i386/kernel/microcode.c

+2 −2
Original line number Diff line number Diff line
@@ -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]);

include/asm-i386/processor.h

+4 −2
Original line number Diff line number Diff line
@@ -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,