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>

diff --git a/arch/x86/crypto/crc32-pclmul_asm.S b/arch/x86/crypto/crc32-pclmul_asm.S
index f247304299a28b1f3245563b2437ab54a8a82889..1c099dc08cc33151ec97c0a250813783c9bf9c4c 100644 (file)
--- 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