Commit d205222e authored by Linus Torvalds's avatar Linus Torvalds Committed by Borislav Petkov
Browse files

x86/entry: Simplify entry_INT80_compat() 



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

Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220506121631.221072885@infradead.org
parent a1e2c031

arch/x86/entry/entry_64_compat.S

+9 −10
Original line number Diff line number Diff line
@@ -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 */