From: Peter Zijlstra <peterz@infradead.org>
To: tglx@linutronix.de, jpoimboe@redhat.com
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
peterz@infradead.org, mhiramat@kernel.org, mbenes@suse.cz,
jthierry@redhat.com, alexandre.chartre@oracle.com
Subject: [PATCH v5 06/17] x86,ftrace: Shrink ftrace_regs_caller() by one byte
Date: Thu, 16 Apr 2020 13:47:12 +0200 [thread overview]
Message-ID: <20200416115118.867411350@infradead.org> (raw)
In-Reply-To: <20200416114706.625340212@infradead.org>
'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>
---
arch/x86/kernel/ftrace_64.S | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- 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_
* 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
next prev parent reply other threads:[~2020-04-16 11:54 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 ` Peter Zijlstra [this message]
2020-04-22 22:24 ` [tip: objtool/core] x86,ftrace: Shrink ftrace_regs_caller() by one byte tip-bot2 for Peter Zijlstra
2020-04-23 7:49 ` 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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