x86/entry: Simplify entry_INT80_compat()

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

diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index c5aeb0819707f06693de947e7cf1aaae36f1c637..d743eaa19d9b3a42c3c71370931d7f0d2274e39b 100644 (file)
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -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 */