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author | Denys Vlasenko <dvlasenk@redhat.com> | 2015-06-03 16:58:50 +0300 |
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committer | Ingo Molnar <mingo@kernel.org> | 2015-06-05 14:41:28 +0300 |
commit | 7a5a9824c18f93415944c997dc6bb8eecfddd2e7 (patch) | |
tree | c5035a0440a4182ad18e3953bf0fe323a91e566d /arch/x86/kernel/asm-offsets_64.c | |
parent | 5cdc683b7d8b3341a3d18e0c5498bc1e4f3fb990 (diff) | |
download | linux-7a5a9824c18f93415944c997dc6bb8eecfddd2e7.tar.xz |
x86/asm/entry/32: Remove unnecessary optimization in stub32_clone
Really swap arguments #4 and #5 in stub32_clone instead of
"optimizing" it into a move.
Yes, tls_val is currently unused. Yes, on some CPUs XCHG is a
little bit more expensive than MOV. But a cycle or two on an
expensive syscall like clone() is way below noise floor, and
this optimization is simply not worth the obfuscation of logic.
[ There's also ongoing work on the clone() ABI by Josh Triplett
that will depend on this change later on. ]
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1433339930-20880-2-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/asm-offsets_64.c')
0 files changed, 0 insertions, 0 deletions