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x86/entry: Simplify entry_INT80_compat()

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Instead of playing silly games with rdi, use rax for simpler and more
consistent code.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220506121631.221072885@infradead.org
This commit is contained in:
Linus Torvalds 2022-05-06 14:14:33 +02:00 committed by Borislav Petkov
parent a1e2c031ec
commit d205222eb6
1 changed files with 9 additions and 10 deletions
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19
arch/x86/entry/entry_64_compat.S
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@ -362,26 +362,25 @@ SYM_CODE_START(entry_INT80_compat)
/* switch to thread stack expects orig_ax and rdi to be pushed */
pushq %rax /* pt_regs->orig_ax */
pushq %rdi /* pt_regs->di */
/* Need to switch before accessing the thread stack. */
SWITCH_TO_KERNEL_CR3 scratch_reg=%rdi
SWITCH_TO_KERNEL_CR3 scratch_reg=%rax
/* In the Xen PV case we already run on the thread stack. */
ALTERNATIVE "", "jmp .Lint80_keep_stack", X86_FEATURE_XENPV
movq %rsp, %rdi
movq %rsp, %rax
movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp
pushq 6*8(%rdi) /* regs->ss */
pushq 5*8(%rdi) /* regs->rsp */
pushq 4*8(%rdi) /* regs->eflags */
pushq 3*8(%rdi) /* regs->cs */
pushq 2*8(%rdi) /* regs->ip */
pushq 1*8(%rdi) /* regs->orig_ax */
pushq (%rdi) /* pt_regs->di */
pushq 5*8(%rax) /* regs->ss */
pushq 4*8(%rax) /* regs->rsp */
pushq 3*8(%rax) /* regs->eflags */
pushq 2*8(%rax) /* regs->cs */
pushq 1*8(%rax) /* regs->ip */
pushq 0*8(%rax) /* regs->orig_ax */
.Lint80_keep_stack:
pushq %rdi /* pt_regs->di */
pushq %rsi /* pt_regs->si */
xorl %esi, %esi /* nospec si */
pushq %rdx /* pt_regs->dx */