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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Peter Zijlstra (Intel)" <peterz@infradead.org>,
        Borislav Petkov <bp@suse.de>,
        Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Subject: [PATCH 5.4 11/51] x86/entry: Remove skip_r11rcx
Date:   Wed,  5 Oct 2022 13:31:59 +0200
Message-Id: <20221005113210.784576725@linuxfoundation.org>
In-Reply-To: <20221005113210.255710920@linuxfoundation.org>
References: <20221005113210.255710920@linuxfoundation.org>
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From: Peter Zijlstra <peterz@infradead.org>

commit 1b331eeea7b8676fc5dbdf80d0a07e41be226177 upstream.

Yes, r11 and rcx have been restored previously, but since they're being
popped anyway (into rsi) might as well pop them into their own regs --
setting them to the value they already are.

Less magical code.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220506121631.365070674@infradead.org
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/entry/calling.h  |   10 +---------
 arch/x86/entry/entry_64.S |    3 +--
 2 files changed, 2 insertions(+), 11 deletions(-)

--- a/arch/x86/entry/calling.h
+++ b/arch/x86/entry/calling.h
@@ -146,27 +146,19 @@ For 32-bit we have the following convent
 
 .endm
 
-.macro POP_REGS pop_rdi=1 skip_r11rcx=0
+.macro POP_REGS pop_rdi=1
 	popq %r15
 	popq %r14
 	popq %r13
 	popq %r12
 	popq %rbp
 	popq %rbx
-	.if \skip_r11rcx
-	popq %rsi
-	.else
 	popq %r11
-	.endif
 	popq %r10
 	popq %r9
 	popq %r8
 	popq %rax
-	.if \skip_r11rcx
-	popq %rsi
-	.else
 	popq %rcx
-	.endif
 	popq %rdx
 	popq %rsi
 	.if \pop_rdi
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -248,8 +248,7 @@ GLOBAL(entry_SYSCALL_64_after_hwframe)
 	 * perf profiles. Nothing jumps here.
 	 */
 syscall_return_via_sysret:
-	/* rcx and r11 are already restored (see code above) */
-	POP_REGS pop_rdi=0 skip_r11rcx=1
+	POP_REGS pop_rdi=0
 
 	/*
 	 * Now all regs are restored except RSP and RDI.