diff options
| author | Ingo Molnar <mingo@kernel.org> | 2015-03-04 06:33:49 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-03-04 06:36:15 +0100 |
| commit | f8e92fb4b0ffc4d62279ab39f34e798e37e90b0b (patch) | |
| tree | 9caa8df664792e64ddcb4ea03fd418a8a529c82e /arch/x86/lib/memmove_64.S | |
| parent | d2c032e3dc58137a7261a7824d3acce435db1d66 (diff) | |
| parent | dfecb95cdfeaf7872d83a96bec3a606e9cd95c8d (diff) | |
Merge tag 'alternatives_padding' of git://git.kernel.org/pub/scm/linux/kernel/git/bp/bp into x86/asm
Pull alternative instructions framework improvements from Borislav Petkov:
"A more involved rework of the alternatives framework to be able to
pad instructions and thus make using the alternatives macros more
straightforward and without having to figure out old and new instruction
sizes but have the toolchain figure that out for us.
Furthermore, it optimizes JMPs used so that fetch and decode can be
relieved with smaller versions of the JMPs, where possible.
Some stats:
x86_64 defconfig:
Alternatives sites total: 2478
Total padding added (in Bytes): 6051
The padding is currently done for:
X86_FEATURE_ALWAYS
X86_FEATURE_ERMS
X86_FEATURE_LFENCE_RDTSC
X86_FEATURE_MFENCE_RDTSC
X86_FEATURE_SMAP
This is with the latest version of the patchset. Of course, on each
machine the alternatives sites actually being patched are a proper
subset of the total number."
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/lib/memmove_64.S')
| -rw-r--r-- | arch/x86/lib/memmove_64.S | 19 |
1 files changed, 2 insertions, 17 deletions
diff --git a/arch/x86/lib/memmove_64.S b/arch/x86/lib/memmove_64.S index 9c4b530575da..0f8a0d0331b9 100644 --- a/arch/x86/lib/memmove_64.S +++ b/arch/x86/lib/memmove_64.S @@ -5,7 +5,6 @@ * This assembly file is re-written from memmove_64.c file. * - Copyright 2011 Fenghua Yu <fenghua.yu@intel.com> */ -#define _STRING_C #include <linux/linkage.h> #include <asm/dwarf2.h> #include <asm/cpufeature.h> @@ -44,6 +43,8 @@ ENTRY(__memmove) jg 2f .Lmemmove_begin_forward: + ALTERNATIVE "", "movq %rdx, %rcx; rep movsb; retq", X86_FEATURE_ERMS + /* * movsq instruction have many startup latency * so we handle small size by general register. @@ -207,21 +208,5 @@ ENTRY(__memmove) 13: retq CFI_ENDPROC - - .section .altinstr_replacement,"ax" -.Lmemmove_begin_forward_efs: - /* Forward moving data. */ - movq %rdx, %rcx - rep movsb - retq -.Lmemmove_end_forward_efs: - .previous - - .section .altinstructions,"a" - altinstruction_entry .Lmemmove_begin_forward, \ - .Lmemmove_begin_forward_efs,X86_FEATURE_ERMS, \ - .Lmemmove_end_forward-.Lmemmove_begin_forward, \ - .Lmemmove_end_forward_efs-.Lmemmove_begin_forward_efs - .previous ENDPROC(__memmove) ENDPROC(memmove) |