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| author | Mikulas Patocka <mpatocka@redhat.com> | 2017-09-06 22:41:21 -0400 |
|---|---|---|
| committer | Herbert Xu <herbert@gondor.apana.org.au> | 2017-10-07 12:10:30 +0800 |
| commit | 5e1a646204deb0efd0e0bbc1730ac11dcb39f8fb (patch) | |
| tree | f9a8400f86d11aca28a00e501da6e4cab4b26d2b /arch | |
| parent | c07f7c29d1c6a7c62b66299d50acd6ffd171f612 (diff) | |
| download | linux-0-day-5e1a646204deb0efd0e0bbc1730ac11dcb39f8fb.tar.gz linux-0-day-5e1a646204deb0efd0e0bbc1730ac11dcb39f8fb.tar.xz | |
crypto: crc32-pclmul - remove useless relative addressing
In 32-bit mode, the x86 architecture can hold full 32-bit pointers.
Therefore, the code that copies the current address to the %ecx register
and uses %ecx-relative addressing is useless, we could just use absolute
addressing.
The processors have a stack of return addresses for branch prediction. If
we use a call instruction and pop the return address, it desynchronizes
the return stack and causes branch prediction misses.
This patch also moves the data to the .rodata section.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/crypto/crc32-pclmul_asm.S | 17 |
1 files changed, 6 insertions, 11 deletions
diff --git a/arch/x86/crypto/crc32-pclmul_asm.S b/arch/x86/crypto/crc32-pclmul_asm.S index f247304299a28..1c099dc08cc33 100644 --- a/arch/x86/crypto/crc32-pclmul_asm.S +++ b/arch/x86/crypto/crc32-pclmul_asm.S @@ -41,6 +41,7 @@ #include <asm/inst.h> +.section .rodata .align 16 /* * [x4*128+32 mod P(x) << 32)]' << 1 = 0x154442bd4 @@ -111,19 +112,13 @@ ENTRY(crc32_pclmul_le_16) /* buffer and buffer size are 16 bytes aligned */ pxor CONSTANT, %xmm1 sub $0x40, LEN add $0x40, BUF -#ifndef __x86_64__ - /* This is for position independent code(-fPIC) support for 32bit */ - call delta -delta: - pop %ecx -#endif cmp $0x40, LEN jb less_64 #ifdef __x86_64__ movdqa .Lconstant_R2R1(%rip), CONSTANT #else - movdqa .Lconstant_R2R1 - delta(%ecx), CONSTANT + movdqa .Lconstant_R2R1, CONSTANT #endif loop_64:/* 64 bytes Full cache line folding */ @@ -172,7 +167,7 @@ less_64:/* Folding cache line into 128bit */ #ifdef __x86_64__ movdqa .Lconstant_R4R3(%rip), CONSTANT #else - movdqa .Lconstant_R4R3 - delta(%ecx), CONSTANT + movdqa .Lconstant_R4R3, CONSTANT #endif prefetchnta (BUF) @@ -220,8 +215,8 @@ fold_64: movdqa .Lconstant_R5(%rip), CONSTANT movdqa .Lconstant_mask32(%rip), %xmm3 #else - movdqa .Lconstant_R5 - delta(%ecx), CONSTANT - movdqa .Lconstant_mask32 - delta(%ecx), %xmm3 + movdqa .Lconstant_R5, CONSTANT + movdqa .Lconstant_mask32, %xmm3 #endif psrldq $0x04, %xmm2 pand %xmm3, %xmm1 @@ -232,7 +227,7 @@ fold_64: #ifdef __x86_64__ movdqa .Lconstant_RUpoly(%rip), CONSTANT #else - movdqa .Lconstant_RUpoly - delta(%ecx), CONSTANT + movdqa .Lconstant_RUpoly, CONSTANT #endif movdqa %xmm1, %xmm2 pand %xmm3, %xmm1 |