linux-kernel - [tip: x86/asm] x86/entry: Remove skip

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 06 May 2022 15:09:00 -0000
From:   "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     "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: Remove skip_r11rcx

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

Commit-ID:     1b331eeea7b8676fc5dbdf80d0a07e41be226177
Gitweb:        https://git.kernel.org/tip/1b331eeea7b8676fc5dbdf80d0a07e41be226177
Author:        Peter Zijlstra <peterz@...radead.org>
AuthorDate:    Fri, 06 May 2022 14:14:35 +02:00
Committer:     Borislav Petkov <bp@...e.de>
CommitterDate: Fri, 06 May 2022 15:58:19 +02:00

x86/entry: Remove skip_r11rcx

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@...radead.org>
Signed-off-by: Borislav Petkov <bp@...e.de>
Link: https://lore.kernel.org/r/20220506121631.365070674@infradead.org
---
 arch/x86/entry/calling.h  | 10 +---------
 arch/x86/entry/entry_64.S |  3 +--
 2 files changed, 2 insertions(+), 11 deletions(-)

diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h
index debbe94..a97cc78 100644
--- a/arch/x86/entry/calling.h
+++ b/arch/x86/entry/calling.h
@@ -120,27 +120,19 @@ For 32-bit we have the following conventions - kernel is built with
 	CLEAR_REGS
 .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
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 3121866..3a1e3f2 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -191,8 +191,7 @@ SYM_INNER_LABEL(entry_SYSCALL_64_after_hwframe, SYM_L_GLOBAL)
 	 * 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.