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KVM: SVM: Let gcc to choose which registers to save (i386) 

This patch lets GCC to determine which registers to save when we
switch to/from a VCPU in the case of AMD i386

* Original code saves following registers:

    ebx, ecx, edx, esi, edi, ebp

* Patched code:

  - informs GCC that we modify following registers
    using the clobber description:

    ebx, ecx, edx, esi, edi

  - rbp is saved (pop/push) because GCC seems to ignore its use in the clobber
    description.

Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Laurent Vivier 2007-10-25 14:18:54 +02:00 committed by Avi Kivity
parent 54a08c0449
commit fe7935d49f
1 changed files with 4 additions and 4 deletions
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8
drivers/kvm/svm.c
View File

@ -1501,8 +1501,7 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
#ifdef CONFIG_X86_64
"push %%rbp; \n\t"
#else
"push %%ebx; push %%ecx; push %%edx;"
"push %%esi; push %%edi; push %%ebp;"
"push %%ebp; \n\t"
#endif
#ifdef CONFIG_X86_64
@ -1573,8 +1572,7 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
"mov %%edi, %c[rdi](%[svm]) \n\t"
"mov %%ebp, %c[rbp](%[svm]) \n\t"
"pop %%ebp; pop %%edi; pop %%esi;"
"pop %%edx; pop %%ecx; pop %%ebx; \n\t"
"pop %%ebp; \n\t"
#endif
:
: [svm]"a"(svm),
@ -1599,6 +1597,8 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
#ifdef CONFIG_X86_64
, "rbx", "rcx", "rdx", "rsi", "rdi"
, "r8", "r9", "r10", "r11" , "r12", "r13", "r14", "r15"
#else
, "ebx", "ecx", "edx" , "esi", "edi"
#endif
);