Fix register corruption during Intel Microcode update
Another bug in the Intel microcode update code that existed since we switched to LinuxBIOSv2 in 2004: The inline assembly code that reads the CPU revision from an MSR after running cpuid(1) trashes registers EBX and ECX. Only ECX was mentioned in the clobber list. C code running after this function could silently access completely wrong data, which resulted in the wrong date being printed on microcode updates (and potentially other issues happening until the C code writes to EBX again) Change-Id: Ida733fa1747565ec9824d3a37d08b1a73cd8355f Signed-off-by: Stefan Reinauer <reinauer@google.com> Reviewed-on: http://review.coreboot.org/996 Tested-by: build bot (Jenkins) Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>
This commit is contained in:
parent
8bec7fbc0f
commit
3b5a9edcb2
|
@ -63,7 +63,7 @@ static inline u32 read_microcode_rev(void)
|
|||
"=a" (msr.lo), "=d" (msr.hi)
|
||||
: /* inputs */
|
||||
: /* trashed */
|
||||
"ecx"
|
||||
"ebx", "ecx"
|
||||
);
|
||||
return msr.hi;
|
||||
}
|
||||
|
|
Loading…
Reference in New Issue