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| author | Denys Vlasenko <dvlasenk@redhat.com> | 2017-01-20 00:33:04 +0300 |
|---|---|---|
| committer | Herbert Xu <herbert@gondor.apana.org.au> | 2017-01-23 17:50:29 +0300 |
| commit | e183914af00e15eb41ae666d44e323bfa154be13 (patch) | |
| tree | 177ded54a5bd45ec1ae6c544d28b0a45a31118f1 /arch/x86/crypto/sha256-ssse3-asm.S | |
| parent | 587d531b8f67ebe62f8326849a7a685a03cbc904 (diff) | |
| download | linux-e183914af00e15eb41ae666d44e323bfa154be13.tar.xz | |
crypto: x86 - make constants readonly, allow linker to merge them
A lot of asm-optimized routines in arch/x86/crypto/ keep its
constants in .data. This is wrong, they should be on .rodata.
Mnay of these constants are the same in different modules.
For example, 128-bit shuffle mask 0x000102030405060708090A0B0C0D0E0F
exists in at least half a dozen places.
There is a way to let linker merge them and use just one copy.
The rules are as follows: mergeable objects of different sizes
should not share sections. You can't put them all in one .rodata
section, they will lose "mergeability".
GCC puts its mergeable constants in ".rodata.cstSIZE" sections,
or ".rodata.cstSIZE.<object_name>" if -fdata-sections is used.
This patch does the same:
.section .rodata.cst16.SHUF_MASK, "aM", @progbits, 16
It is important that all data in such section consists of
16-byte elements, not larger ones, and there are no implicit
use of one element from another.
When this is not the case, use non-mergeable section:
.section .rodata[.VAR_NAME], "a", @progbits
This reduces .data by ~15 kbytes:
text data bss dec hex filename
11097415 2705840 2630712 16433967 fac32f vmlinux-prev.o
11112095 2690672 2630712 16433479 fac147 vmlinux.o
Merged objects are visible in System.map:
ffffffff81a28810 r POLY
ffffffff81a28810 r POLY
ffffffff81a28820 r TWOONE
ffffffff81a28820 r TWOONE
ffffffff81a28830 r PSHUFFLE_BYTE_FLIP_MASK <- merged regardless of
ffffffff81a28830 r SHUF_MASK <------------- the name difference
ffffffff81a28830 r SHUF_MASK
ffffffff81a28830 r SHUF_MASK
..
ffffffff81a28d00 r K512 <- merged three identical 640-byte tables
ffffffff81a28d00 r K512
ffffffff81a28d00 r K512
Use of object names in section name suffixes is not strictly necessary,
but might help if someday link stage will use garbage collection
to eliminate unused sections (ld --gc-sections).
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
CC: Herbert Xu <herbert@gondor.apana.org.au>
CC: Josh Poimboeuf <jpoimboe@redhat.com>
CC: Xiaodong Liu <xiaodong.liu@intel.com>
CC: Megha Dey <megha.dey@intel.com>
CC: linux-crypto@vger.kernel.org
CC: x86@kernel.org
CC: linux-kernel@vger.kernel.org
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'arch/x86/crypto/sha256-ssse3-asm.S')
| -rw-r--r-- | arch/x86/crypto/sha256-ssse3-asm.S | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/arch/x86/crypto/sha256-ssse3-asm.S b/arch/x86/crypto/sha256-ssse3-asm.S index 2cedc44e8121..39b83c93e7fd 100644 --- a/arch/x86/crypto/sha256-ssse3-asm.S +++ b/arch/x86/crypto/sha256-ssse3-asm.S @@ -474,7 +474,7 @@ done_hash: ret ENDPROC(sha256_transform_ssse3) -.data +.section .rodata.cst256.K256, "aM", @progbits, 256 .align 64 K256: .long 0x428a2f98,0x71374491,0xb5c0fbcf,0xe9b5dba5 @@ -494,13 +494,19 @@ K256: .long 0x748f82ee,0x78a5636f,0x84c87814,0x8cc70208 .long 0x90befffa,0xa4506ceb,0xbef9a3f7,0xc67178f2 +.section .rodata.cst16.PSHUFFLE_BYTE_FLIP_MASK, "aM", @progbits, 16 +.align 16 PSHUFFLE_BYTE_FLIP_MASK: .octa 0x0c0d0e0f08090a0b0405060700010203 +.section .rodata.cst16._SHUF_00BA, "aM", @progbits, 16 +.align 16 # shuffle xBxA -> 00BA _SHUF_00BA: .octa 0xFFFFFFFFFFFFFFFF0b0a090803020100 +.section .rodata.cst16._SHUF_DC00, "aM", @progbits, 16 +.align 16 # shuffle xDxC -> DC00 _SHUF_DC00: .octa 0x0b0a090803020100FFFFFFFFFFFFFFFF |