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| author | jdp <jdp@FreeBSD.org> | 2001-10-12 16:49:28 +0000 |
|---|---|---|
| committer | jdp <jdp@FreeBSD.org> | 2001-10-12 16:49:28 +0000 |
| commit | b5831c25304dd586fa1a1d4d5bc6dbc7dc70b061 (patch) | |
| tree | bc9ff09a10a97e71eee89536515d6d92ddffb328 /sys/amd64 | |
| parent | 369a58f711ffd453dbb3553b998262364eb584d6 (diff) | |
| download | FreeBSD-src-b5831c25304dd586fa1a1d4d5bc6dbc7dc70b061.zip FreeBSD-src-b5831c25304dd586fa1a1d4d5bc6dbc7dc70b061.tar.gz | |
Correct the input/output/clobber specifications for the cpuid
instruction. Stefan Keller <dres@earth.serd.org> noticed that CPU
identification was broken when compiled with -O2, and tracked it
down to the asm statement, which was storing values into memory
without specifying that memory was modified. He submitted a patch
which added "memory" as a clobber, but I refined it further to
arrive at this version.
MFC after: 3 days
Diffstat (limited to 'sys/amd64')
| -rw-r--r-- | sys/amd64/amd64/identcpu.c | 11 |
1 files changed, 3 insertions, 8 deletions
diff --git a/sys/amd64/amd64/identcpu.c b/sys/amd64/amd64/identcpu.c index 949c05f..d81b7ed 100644 --- a/sys/amd64/amd64/identcpu.c +++ b/sys/amd64/amd64/identcpu.c @@ -116,14 +116,9 @@ static void do_cpuid(u_int ax, u_int *p) { __asm __volatile( - "cpuid;" - "movl %%eax, (%2);" - "movl %%ebx, 4(%2);" - "movl %%ecx, 8(%2);" - "movl %%edx, 12(%2);" - : "=a" (ax) - : "0" (ax), "S" (p) - : "bx", "cx", "dx" + "cpuid" + : "=a" (p[0]), "=b" (p[1]), "=c" (p[2]), "=d" (p[3]) + : "0" (ax) ); } |
