linux-kernel - [tip: x86/asm] x86/entry: Simplify entry_INT80

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Date:   Fri, 06 May 2022 15:09:02 -0000
From:   "tip-bot2 for Linus Torvalds" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Borislav Petkov <bp@...e.de>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/asm] x86/entry: Simplify entry_INT80_compat()

The following commit has been merged into the x86/asm branch of tip:

Commit-ID:     d205222eb6a8e5e70c21200beb81c6e19ec211d6
Gitweb:        https://git.kernel.org/tip/d205222eb6a8e5e70c21200beb81c6e19ec211d6
Author:        Linus Torvalds <torvalds@...ux-foundation.org>
AuthorDate:    Fri, 06 May 2022 14:14:33 +02:00
Committer:     Borislav Petkov <bp@...e.de>
CommitterDate: Fri, 06 May 2022 15:49:51 +02:00

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@...ux-foundation.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Borislav Petkov <bp@...e.de>
Reviewed-by: Borislav Petkov <bp@...e.de>
Link: https://lore.kernel.org/r/20220506121631.221072885@infradead.org
---
 arch/x86/entry/entry_64_compat.S | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index c5aeb08..d743eaa 100644
--- 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 */