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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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7bcd3f34e2
They cause quite bad performance regressions on Netburst This is temporary until we can get new optimized functions for these CPUs. This undoes changes that were done in 2.6.15 and in 2.6.16-rc1, essentially bringing the code back to 2.6.14 level. Only change is I renamed the X86_FEATURE_K8_C flag to X86_FEATURE_REP_GOOD and fixed the check for the flag and also fixed some comments. Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
126 lines
2.1 KiB
ArmAsm
126 lines
2.1 KiB
ArmAsm
/* Copyright 2002 Andi Kleen, SuSE Labs */
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/*
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* ISO C memset - set a memory block to a byte value.
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*
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* rdi destination
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* rsi value (char)
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* rdx count (bytes)
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*
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* rax original destination
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*/
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.globl __memset
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.globl memset
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.p2align 4
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memset:
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__memset:
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movq %rdi,%r10
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movq %rdx,%r11
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/* expand byte value */
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movzbl %sil,%ecx
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movabs $0x0101010101010101,%rax
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mul %rcx /* with rax, clobbers rdx */
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/* align dst */
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movl %edi,%r9d
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andl $7,%r9d
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jnz .Lbad_alignment
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.Lafter_bad_alignment:
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movl %r11d,%ecx
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shrl $6,%ecx
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jz .Lhandle_tail
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.p2align 4
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.Lloop_64:
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decl %ecx
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movq %rax,(%rdi)
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movq %rax,8(%rdi)
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movq %rax,16(%rdi)
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movq %rax,24(%rdi)
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movq %rax,32(%rdi)
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movq %rax,40(%rdi)
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movq %rax,48(%rdi)
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movq %rax,56(%rdi)
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leaq 64(%rdi),%rdi
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jnz .Lloop_64
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/* Handle tail in loops. The loops should be faster than hard
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to predict jump tables. */
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.p2align 4
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.Lhandle_tail:
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movl %r11d,%ecx
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andl $63&(~7),%ecx
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jz .Lhandle_7
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shrl $3,%ecx
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.p2align 4
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.Lloop_8:
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decl %ecx
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movq %rax,(%rdi)
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leaq 8(%rdi),%rdi
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jnz .Lloop_8
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.Lhandle_7:
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movl %r11d,%ecx
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andl $7,%ecx
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jz .Lende
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.p2align 4
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.Lloop_1:
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decl %ecx
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movb %al,(%rdi)
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leaq 1(%rdi),%rdi
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jnz .Lloop_1
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.Lende:
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movq %r10,%rax
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ret
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.Lbad_alignment:
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cmpq $7,%r11
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jbe .Lhandle_7
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movq %rax,(%rdi) /* unaligned store */
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movq $8,%r8
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subq %r9,%r8
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addq %r8,%rdi
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subq %r8,%r11
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jmp .Lafter_bad_alignment
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/* Some CPUs run faster using the string instructions.
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It is also a lot simpler. Use this when possible */
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#include <asm/cpufeature.h>
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.section .altinstructions,"a"
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.align 8
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.quad memset
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.quad memset_c
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.byte X86_FEATURE_REP_GOOD
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.byte memset_c_end-memset_c
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.byte memset_c_end-memset_c
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.previous
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.section .altinstr_replacement,"ax"
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/* rdi destination
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* rsi value
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* rdx count
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*/
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memset_c:
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movq %rdi,%r9
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movl %edx,%r8d
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andl $7,%r8d
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movl %edx,%ecx
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shrl $3,%ecx
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/* expand byte value */
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movzbl %sil,%esi
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movabs $0x0101010101010101,%rax
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mulq %rsi /* with rax, clobbers rdx */
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rep
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stosq
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movl %r8d,%ecx
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rep
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stosb
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movq %r9,%rax
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ret
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memset_c_end:
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.previous
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