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| author |  Peter Zijlstra <peterz@infradead.org>
| 2020-04-01 16:51:11 +0200 |
|---|---|---|
| committer |  Ingo Molnar <mingo@kernel.org>
| 2020-04-22 10:53:50 +0200 |
| commit | 9f2dfd61dd022d4559d42a832fb03e76aad36c5f (patch) | |
| tree | 911e5d0f266368063710de91316e4fef732d84c5 /arch/x86/kernel/ftrace_64.S | |
| parent | x86,ftrace: Use SIZEOF_PTREGS (diff) | |
| download | linux-9f2dfd61dd022d4559d42a832fb03e76aad36c5f.tar.gz linux-9f2dfd61dd022d4559d42a832fb03e76aad36c5f.tar.bz2 linux-9f2dfd61dd022d4559d42a832fb03e76aad36c5f.zip | |
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>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115118.867411350@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/ftrace_64.S')
| -rw-r--r-- | arch/x86/kernel/ftrace_64.S | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S index be9aff20dd5f..9738ed23964e 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 |