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From: "tip-bot2 for Peter Zijlstra" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Miroslav Benes <mbenes@suse.cz>,
	Alexandre Chartre <alexandre.chartre@oracle.com>,
	"Steven Rostedt (VMware)" <rostedt@goodmis.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>, x86 <x86@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: [tip: objtool/core] x86,ftrace: Shrink ftrace_regs_caller() by one byte
Date: Wed, 22 Apr 2020 22:24:36 -0000	[thread overview]
Message-ID: <158759427624.28353.12057979900259706863.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20200416115118.867411350@infradead.org>

The following commit has been merged into the objtool/core branch of tip:

Commit-ID:     fdf6101cab968605564f211ab03f396dde67785b
Gitweb:        https://git.kernel.org/tip/fdf6101cab968605564f211ab03f396dde67785b
Author:        Peter Zijlstra <peterz@infradead.org>
AuthorDate:    Wed, 01 Apr 2020 16:51:11 +02:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 22 Apr 2020 23:10:06 +02:00

x86,ftrace: Shrink ftrace_regs_caller() by one byte

'Optimize' ftrace_regs_caller. Instead of comparing against an
immediate, the more natural way to test for zero on x86 is: 'test
%r,%r'.

  48 83 f8 00             cmp    $0x0,%rax
  74 49                   je     226 <ftrace_regs_call+0xa3>

  48 85 c0                test   %rax,%rax
  74 49                   je     225 <ftrace_regs_call+0xa2>

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115118.867411350@infradead.org
---
 arch/x86/kernel/ftrace_64.S | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S
index be9aff2..9738ed2 100644
--- a/arch/x86/kernel/ftrace_64.S
+++ b/arch/x86/kernel/ftrace_64.S
@@ -240,8 +240,8 @@ SYM_INNER_LABEL(ftrace_regs_call, SYM_L_GLOBAL)
 	 * See arch_ftrace_set_direct_caller().
 	 */
 	movq ORIG_RAX(%rsp), %rax
-	cmpq	$0, %rax
-	je	1f
+	testq	%rax, %rax
+	jz	1f
 
 	/* Swap the flags with orig_rax */
 	movq MCOUNT_REG_SIZE(%rsp), %rdi

  reply	other threads:[~2020-04-22 22:26 UTC|newest]

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-16 11:47 [PATCH v5 00/17] objtool: vmlinux.o and noinstr validation Peter Zijlstra
2020-04-16 11:47 ` [PATCH v5 01/17] objtool: Support multiple stack_op per instruction Peter Zijlstra
2020-04-16 11:47 ` [PATCH v5 02/17] objtool: Better handle IRET Peter Zijlstra
2020-04-17 11:29   ` Miroslav Benes
2020-04-17 12:25     ` Peter Zijlstra
2020-04-17 12:35       ` Miroslav Benes
2020-04-17 17:37   ` Alexandre Chartre
2020-04-17 18:23     ` Peter Zijlstra
2020-04-17 23:53       ` Andy Lutomirski
2020-04-18 17:18         ` Josh Poimboeuf
2020-04-22 22:24   ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2020-04-23  7:49   ` tip-bot2 for Peter Zijlstra
2020-04-16 11:47 ` [PATCH v5 03/17] objtool: Introduce HINT_RET_OFFSET Peter Zijlstra
2020-04-22 22:24   ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2020-04-23  7:49   ` tip-bot2 for Peter Zijlstra
2020-04-16 11:47 ` [PATCH v5 04/17] x86,ftrace: Fix ftrace_regs_caller() unwind Peter Zijlstra
2020-04-17 19:24   ` Alexandre Chartre
2020-04-22  0:33   ` Steven Rostedt
2020-04-22  9:44     ` Peter Zijlstra
2020-04-22 13:33       ` Steven Rostedt
2020-04-22 20:20       ` Steven Rostedt
2020-04-22 22:24   ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2020-04-23  7:49   ` tip-bot2 for Peter Zijlstra
2020-04-16 11:47 ` [PATCH v5 05/17] x86,ftrace: Use SIZEOF_PTREGS Peter Zijlstra
2020-04-22 22:24   ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2020-04-23  7:49   ` tip-bot2 for Peter Zijlstra
2020-04-16 11:47 ` [PATCH v5 06/17] x86,ftrace: Shrink ftrace_regs_caller() by one byte Peter Zijlstra
2020-04-22 22:24   ` tip-bot2 for Peter Zijlstra [this message]
2020-04-23  7:49   ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2020-04-16 11:47 ` [PATCH v5 07/17] objtool: Remove SAVE/RESTORE hints Peter Zijlstra
2020-04-22 22:24   ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2020-04-23  7:49   ` tip-bot2 for Peter Zijlstra
2020-04-16 11:47 ` [PATCH v5 08/17] objtool: Rename struct cfi_state Peter Zijlstra
2020-04-22 22:24   ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2020-04-23  7:49   ` tip-bot2 for Peter Zijlstra
2020-04-16 11:47 ` [PATCH v5 09/17] objtool: Fix !CFI insn_state propagation Peter Zijlstra
2020-04-22 22:24   ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2020-04-23  7:49   ` tip-bot2 for Peter Zijlstra
2020-04-16 11:47 ` [PATCH v5 10/17] objtool: Implement noinstr validation Peter Zijlstra
2020-04-22 22:24   ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2020-04-23  7:49   ` tip-bot2 for Peter Zijlstra
2020-04-16 11:47 ` [PATCH v5 11/17] objtool: Optimize !vmlinux.o again Peter Zijlstra
2020-04-22 22:24   ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2020-04-23  7:49   ` tip-bot2 for Peter Zijlstra
2020-04-16 11:47 ` [PATCH v5 12/17] objtool: Use sec_offset_hash() for insn_hash Peter Zijlstra
2020-04-22 22:24   ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2020-04-23  7:49   ` tip-bot2 for Peter Zijlstra
2020-04-16 11:47 ` [PATCH v5 13/17] kbuild/objtool: Add objtool-vmlinux.o pass Peter Zijlstra
2020-04-22 22:24   ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2020-04-23  7:49   ` tip-bot2 for Peter Zijlstra
2020-04-16 11:47 ` [PATCH v5 14/17] objtool: Avoid iterating !text section symbols Peter Zijlstra
2020-04-22 22:24   ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2020-04-23  7:49   ` tip-bot2 for Peter Zijlstra
2020-04-16 11:47 ` [PATCH v5 15/17] objtool: Rearrange validate_section() Peter Zijlstra
2020-04-22 22:24   ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2020-04-23  7:49   ` tip-bot2 for Peter Zijlstra
2020-04-16 11:47 ` [PATCH v5 16/17] objtool: Add STT_NOTYPE noinstr validation Peter Zijlstra
2020-04-22 22:24   ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2020-04-23  7:49   ` tip-bot2 for Peter Zijlstra
2020-04-16 11:47 ` [PATCH v5 17/17] objtool: Also consider .entry.text as noinstr Peter Zijlstra
2020-04-22 22:24   ` [tip: objtool/core] " tip-bot2 for Thomas Gleixner
2020-04-23  7:49   ` tip-bot2 for Thomas Gleixner
2020-04-17 12:33 ` [PATCH v5 00/17] objtool: vmlinux.o and noinstr validation Miroslav Benes
2020-04-17 20:22 ` Alexandre Chartre

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