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Fri Sep 23 19:00:06 2005 Søren Sandmann <sandmann@redhat.com> 

Apply patch from Ronald Wahl to make sure that the stack pointer is not
    modified at points where we access external variables. (Bug 4269).
This commit is contained in:
Søren Sandmann Pedersen 2005-09-23 23:04:04 +00:00
parent 7554e1bf29
commit 2ba865b3f5
1 changed files with 16 additions and 7 deletions
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23
fb/fbmmx.c
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@ -2304,28 +2304,37 @@ static unsigned int detectCPUFeatures(void) {
vendor[0] = 0;
vendor[12] = 0;
/* see p. 118 of amd64 instruction set manual Vol3 */
__asm__ ("push %%ebx\n"
"pushf\n"
/* We need to be careful about the handling of %ebx and
* %esp here. We can't declare either one as clobbered
* since they are special registers (%ebx is the "PIC
* register" holding an offset to global data, %esp the
* stack pointer), so we need to make sure they have their+ * original values when we access the output operands.
*/
__asm__ ("pushf\n"
"pop %%eax\n"
"mov %%eax, %%ebx\n"
"mov %%eax, %%ecx\n"
"xor $0x00200000, %%eax\n"
"push %%eax\n"
"popf\n"
"pushf\n"
"pop %%eax\n"
"mov $0x0, %%edx\n"
"xor %%ebx, %%eax\n"
"xor %%ecx, %%eax\n"
"jz 1\n"
"mov $0x00000000, %%eax\n"
"push %%ebx\n"
"cpuid\n"
"mov %%ebx, %1\n"
"mov %%ebx, %%eax\n"
"pop %%ebx\n"
"mov %%eax, %1\n"
"mov %%edx, %2\n"
"mov %%ecx, %3\n"
"mov $0x00000001, %%eax\n"
"push %%ebx\n"
"cpuid\n"
"pop %%ebx\n"
"1:\n"
"pop %%ebx\n"
"mov %%edx, %0\n"
: "=r" (result),
"=m" (vendor[0]),
@ -2359,8 +2368,8 @@ static unsigned int detectCPUFeatures(void) {
"mov $0x80000001, %%eax\n"
"cpuid\n"
"2:\n"
"mov %%edx, %0\n"
"pop %%ebx\n"
"mov %%edx, %0\n"
: "=r" (result)
:
: "%eax", "%ecx", "%edx"