From 7bcd3f34e262bbebffa954d80eab3a84f053da31 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Fri, 3 Feb 2006 21:51:02 +0100 Subject: [PATCH] [PATCH] x86_64: Undo the earlier changes to remove unrolled copy/memset functions 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 Signed-off-by: Linus Torvalds --- arch/x86_64/kernel/setup.c | 6 + arch/x86_64/lib/clear_page.S | 38 +++++++ arch/x86_64/lib/copy_page.S | 87 ++++++++++++++ arch/x86_64/lib/copy_user.S | 247 ++++++++++++++++++++++++++++++++++++---- arch/x86_64/lib/memcpy.S | 93 ++++++++++++++- arch/x86_64/lib/memset.S | 94 +++++++++++++++ include/asm-x86_64/cpufeature.h | 2 +- 7 files changed, 543 insertions(+), 24 deletions(-) diff --git a/arch/x86_64/kernel/setup.c b/arch/x86_64/kernel/setup.c index 28895c0..506f152 100644 --- a/arch/x86_64/kernel/setup.c +++ b/arch/x86_64/kernel/setup.c @@ -877,6 +877,7 @@ static void __init amd_detect_cmp(struct cpuinfo_x86 *c) static int __init init_amd(struct cpuinfo_x86 *c) { int r; + unsigned level; #ifdef CONFIG_SMP unsigned long value; @@ -899,6 +900,11 @@ static int __init init_amd(struct cpuinfo_x86 *c) 3DNow is IDd by bit 31 in extended CPUID (1*32+31) anyway */ clear_bit(0*32+31, &c->x86_capability); + /* On C+ stepping K8 rep microcode works well for copy/memset */ + level = cpuid_eax(1); + if (c->x86 == 15 && ((level >= 0x0f48 && level < 0x0f50) || level >= 0x0f58)) + set_bit(X86_FEATURE_REP_GOOD, &c->x86_capability); + r = get_model_name(c); if (!r) { switch (c->x86) { diff --git a/arch/x86_64/lib/clear_page.S b/arch/x86_64/lib/clear_page.S index 43d9fa1..1f81b79 100644 --- a/arch/x86_64/lib/clear_page.S +++ b/arch/x86_64/lib/clear_page.S @@ -5,8 +5,46 @@ .globl clear_page .p2align 4 clear_page: + xorl %eax,%eax + movl $4096/64,%ecx + .p2align 4 +.Lloop: + decl %ecx +#define PUT(x) movq %rax,x*8(%rdi) + movq %rax,(%rdi) + PUT(1) + PUT(2) + PUT(3) + PUT(4) + PUT(5) + PUT(6) + PUT(7) + leaq 64(%rdi),%rdi + jnz .Lloop + nop + ret +clear_page_end: + + /* Some CPUs run faster using the string instructions. + It is also a lot simpler. Use this when possible */ + +#include + + .section .altinstructions,"a" + .align 8 + .quad clear_page + .quad clear_page_c + .byte X86_FEATURE_REP_GOOD + .byte clear_page_end-clear_page + .byte clear_page_c_end-clear_page_c + .previous + + .section .altinstr_replacement,"ax" +clear_page_c: movl $4096/8,%ecx xorl %eax,%eax rep stosq ret +clear_page_c_end: + .previous diff --git a/arch/x86_64/lib/copy_page.S b/arch/x86_64/lib/copy_page.S index 621a197..8fa19d9 100644 --- a/arch/x86_64/lib/copy_page.S +++ b/arch/x86_64/lib/copy_page.S @@ -8,7 +8,94 @@ .globl copy_page .p2align 4 copy_page: + subq $3*8,%rsp + movq %rbx,(%rsp) + movq %r12,1*8(%rsp) + movq %r13,2*8(%rsp) + + movl $(4096/64)-5,%ecx + .p2align 4 +.Loop64: + dec %rcx + + movq (%rsi), %rax + movq 8 (%rsi), %rbx + movq 16 (%rsi), %rdx + movq 24 (%rsi), %r8 + movq 32 (%rsi), %r9 + movq 40 (%rsi), %r10 + movq 48 (%rsi), %r11 + movq 56 (%rsi), %r12 + + prefetcht0 5*64(%rsi) + + movq %rax, (%rdi) + movq %rbx, 8 (%rdi) + movq %rdx, 16 (%rdi) + movq %r8, 24 (%rdi) + movq %r9, 32 (%rdi) + movq %r10, 40 (%rdi) + movq %r11, 48 (%rdi) + movq %r12, 56 (%rdi) + + leaq 64 (%rsi), %rsi + leaq 64 (%rdi), %rdi + + jnz .Loop64 + + movl $5,%ecx + .p2align 4 +.Loop2: + decl %ecx + + movq (%rsi), %rax + movq 8 (%rsi), %rbx + movq 16 (%rsi), %rdx + movq 24 (%rsi), %r8 + movq 32 (%rsi), %r9 + movq 40 (%rsi), %r10 + movq 48 (%rsi), %r11 + movq 56 (%rsi), %r12 + + movq %rax, (%rdi) + movq %rbx, 8 (%rdi) + movq %rdx, 16 (%rdi) + movq %r8, 24 (%rdi) + movq %r9, 32 (%rdi) + movq %r10, 40 (%rdi) + movq %r11, 48 (%rdi) + movq %r12, 56 (%rdi) + + leaq 64(%rdi),%rdi + leaq 64(%rsi),%rsi + + jnz .Loop2 + + movq (%rsp),%rbx + movq 1*8(%rsp),%r12 + movq 2*8(%rsp),%r13 + addq $3*8,%rsp + ret + + /* Some CPUs run faster using the string copy instructions. + It is also a lot simpler. Use this when possible */ + +#include + + .section .altinstructions,"a" + .align 8 + .quad copy_page + .quad copy_page_c + .byte X86_FEATURE_REP_GOOD + .byte copy_page_c_end-copy_page_c + .byte copy_page_c_end-copy_page_c + .previous + + .section .altinstr_replacement,"ax" +copy_page_c: movl $4096/8,%ecx rep movsq ret +copy_page_c_end: + .previous diff --git a/arch/x86_64/lib/copy_user.S b/arch/x86_64/lib/copy_user.S index 79422b6..f64569b 100644 --- a/arch/x86_64/lib/copy_user.S +++ b/arch/x86_64/lib/copy_user.S @@ -4,9 +4,12 @@ * Functions to copy from and to user space. */ +#define FIX_ALIGNMENT 1 + #include #include #include + #include /* Standard copy_to_user with segment limit checking */ .globl copy_to_user @@ -18,7 +21,23 @@ copy_to_user: jc bad_to_user cmpq threadinfo_addr_limit(%rax),%rcx jae bad_to_user - jmp copy_user_generic +2: + .byte 0xe9 /* 32bit jump */ + .long .Lcug-1f +1: + + .section .altinstr_replacement,"ax" +3: .byte 0xe9 /* replacement jmp with 8 bit immediate */ + .long copy_user_generic_c-1b /* offset */ + .previous + .section .altinstructions,"a" + .align 8 + .quad 2b + .quad 3b + .byte X86_FEATURE_REP_GOOD + .byte 5 + .byte 5 + .previous /* Standard copy_from_user with segment limit checking */ .globl copy_from_user @@ -53,44 +72,230 @@ bad_to_user: * rsi source * rdx count * - * Only 4GB of copy is supported. This shouldn't be a problem - * because the kernel normally only writes from/to page sized chunks - * even if user space passed a longer buffer. - * And more would be dangerous because both Intel and AMD have - * errata with rep movsq > 4GB. If someone feels the need to fix - * this please consider this. - * * Output: * eax uncopied bytes or 0 if successful. */ - .globl copy_user_generic + .p2align 4 copy_user_generic: + .byte 0x66,0x66,0x90 /* 5 byte nop for replacement jump */ + .byte 0x66,0x90 +1: + .section .altinstr_replacement,"ax" +2: .byte 0xe9 /* near jump with 32bit immediate */ + .long copy_user_generic_c-1b /* offset */ + .previous + .section .altinstructions,"a" + .align 8 + .quad copy_user_generic + .quad 2b + .byte X86_FEATURE_REP_GOOD + .byte 5 + .byte 5 + .previous +.Lcug: + pushq %rbx + xorl %eax,%eax /*zero for the exception handler */ + +#ifdef FIX_ALIGNMENT + /* check for bad alignment of destination */ + movl %edi,%ecx + andl $7,%ecx + jnz .Lbad_alignment +.Lafter_bad_alignment: +#endif + + movq %rdx,%rcx + + movl $64,%ebx + shrq $6,%rdx + decq %rdx + js .Lhandle_tail + + .p2align 4 +.Lloop: +.Ls1: movq (%rsi),%r11 +.Ls2: movq 1*8(%rsi),%r8 +.Ls3: movq 2*8(%rsi),%r9 +.Ls4: movq 3*8(%rsi),%r10 +.Ld1: movq %r11,(%rdi) +.Ld2: movq %r8,1*8(%rdi) +.Ld3: movq %r9,2*8(%rdi) +.Ld4: movq %r10,3*8(%rdi) + +.Ls5: movq 4*8(%rsi),%r11 +.Ls6: movq 5*8(%rsi),%r8 +.Ls7: movq 6*8(%rsi),%r9 +.Ls8: movq 7*8(%rsi),%r10 +.Ld5: movq %r11,4*8(%rdi) +.Ld6: movq %r8,5*8(%rdi) +.Ld7: movq %r9,6*8(%rdi) +.Ld8: movq %r10,7*8(%rdi) + + decq %rdx + + leaq 64(%rsi),%rsi + leaq 64(%rdi),%rdi + + jns .Lloop + + .p2align 4 +.Lhandle_tail: + movl %ecx,%edx + andl $63,%ecx + shrl $3,%ecx + jz .Lhandle_7 + movl $8,%ebx + .p2align 4 +.Lloop_8: +.Ls9: movq (%rsi),%r8 +.Ld9: movq %r8,(%rdi) + decl %ecx + leaq 8(%rdi),%rdi + leaq 8(%rsi),%rsi + jnz .Lloop_8 + +.Lhandle_7: + movl %edx,%ecx + andl $7,%ecx + jz .Lende + .p2align 4 +.Lloop_1: +.Ls10: movb (%rsi),%bl +.Ld10: movb %bl,(%rdi) + incq %rdi + incq %rsi + decl %ecx + jnz .Lloop_1 + +.Lende: + popq %rbx + ret + +#ifdef FIX_ALIGNMENT + /* align destination */ + .p2align 4 +.Lbad_alignment: + movl $8,%r9d + subl %ecx,%r9d + movl %r9d,%ecx + cmpq %r9,%rdx + jz .Lhandle_7 + js .Lhandle_7 +.Lalign_1: +.Ls11: movb (%rsi),%bl +.Ld11: movb %bl,(%rdi) + incq %rsi + incq %rdi + decl %ecx + jnz .Lalign_1 + subq %r9,%rdx + jmp .Lafter_bad_alignment +#endif + + /* table sorted by exception address */ + .section __ex_table,"a" + .align 8 + .quad .Ls1,.Ls1e + .quad .Ls2,.Ls2e + .quad .Ls3,.Ls3e + .quad .Ls4,.Ls4e + .quad .Ld1,.Ls1e + .quad .Ld2,.Ls2e + .quad .Ld3,.Ls3e + .quad .Ld4,.Ls4e + .quad .Ls5,.Ls5e + .quad .Ls6,.Ls6e + .quad .Ls7,.Ls7e + .quad .Ls8,.Ls8e + .quad .Ld5,.Ls5e + .quad .Ld6,.Ls6e + .quad .Ld7,.Ls7e + .quad .Ld8,.Ls8e + .quad .Ls9,.Le_quad + .quad .Ld9,.Le_quad + .quad .Ls10,.Le_byte + .quad .Ld10,.Le_byte +#ifdef FIX_ALIGNMENT + .quad .Ls11,.Lzero_rest + .quad .Ld11,.Lzero_rest +#endif + .quad .Le5,.Le_zero + .previous + + /* compute 64-offset for main loop. 8 bytes accuracy with error on the + pessimistic side. this is gross. it would be better to fix the + interface. */ + /* eax: zero, ebx: 64 */ +.Ls1e: addl $8,%eax +.Ls2e: addl $8,%eax +.Ls3e: addl $8,%eax +.Ls4e: addl $8,%eax +.Ls5e: addl $8,%eax +.Ls6e: addl $8,%eax +.Ls7e: addl $8,%eax +.Ls8e: addl $8,%eax + addq %rbx,%rdi /* +64 */ + subq %rax,%rdi /* correct destination with computed offset */ + + shlq $6,%rdx /* loop counter * 64 (stride length) */ + addq %rax,%rdx /* add offset to loopcnt */ + andl $63,%ecx /* remaining bytes */ + addq %rcx,%rdx /* add them */ + jmp .Lzero_rest + + /* exception on quad word loop in tail handling */ + /* ecx: loopcnt/8, %edx: length, rdi: correct */ +.Le_quad: + shll $3,%ecx + andl $7,%edx + addl %ecx,%edx + /* edx: bytes to zero, rdi: dest, eax:zero */ +.Lzero_rest: + movq %rdx,%rcx +.Le_byte: + xorl %eax,%eax +.Le5: rep + stosb + /* when there is another exception while zeroing the rest just return */ +.Le_zero: + movq %rdx,%rax + jmp .Lende + + /* Some CPUs run faster using the string copy instructions. + This is also a lot simpler. Use them when possible. + Patch in jmps to this code instead of copying it fully + to avoid unwanted aliasing in the exception tables. */ + + /* rdi destination + * rsi source + * rdx count + * + * Output: + * eax uncopied bytes or 0 if successfull. + * + * Only 4GB of copy is supported. This shouldn't be a problem + * because the kernel normally only writes from/to page sized chunks + * even if user space passed a longer buffer. + * And more would be dangerous because both Intel and AMD have + * errata with rep movsq > 4GB. If someone feels the need to fix + * this please consider this. + */ +copy_user_generic_c: movl %edx,%ecx shrl $3,%ecx andl $7,%edx - jz 5f 1: rep movsq movl %edx,%ecx - xor %eax,%eax 2: rep movsb +4: movl %ecx,%eax ret - /* align here? */ -5: xorl %eax,%eax -6: rep movsq - ret - - .section .fixup,"ax" 3: lea (%rdx,%rcx,8),%rax ret -4: movl %ecx,%eax - ret - .previous .section __ex_table,"a" .quad 1b,3b .quad 2b,4b - .quad 6b,4b .previous diff --git a/arch/x86_64/lib/memcpy.S b/arch/x86_64/lib/memcpy.S index 92dd805..5554948 100644 --- a/arch/x86_64/lib/memcpy.S +++ b/arch/x86_64/lib/memcpy.S @@ -11,8 +11,6 @@ * * Output: * rax original destination - * - * TODO: check best memcpy for PSC */ .globl __memcpy @@ -20,6 +18,95 @@ .p2align 4 __memcpy: memcpy: + pushq %rbx + movq %rdi,%rax + + movl %edx,%ecx + shrl $6,%ecx + jz .Lhandle_tail + + .p2align 4 +.Lloop_64: + decl %ecx + + movq (%rsi),%r11 + movq 8(%rsi),%r8 + + movq %r11,(%rdi) + movq %r8,1*8(%rdi) + + movq 2*8(%rsi),%r9 + movq 3*8(%rsi),%r10 + + movq %r9,2*8(%rdi) + movq %r10,3*8(%rdi) + + movq 4*8(%rsi),%r11 + movq 5*8(%rsi),%r8 + + movq %r11,4*8(%rdi) + movq %r8,5*8(%rdi) + + movq 6*8(%rsi),%r9 + movq 7*8(%rsi),%r10 + + movq %r9,6*8(%rdi) + movq %r10,7*8(%rdi) + + leaq 64(%rsi),%rsi + leaq 64(%rdi),%rdi + jnz .Lloop_64 + +.Lhandle_tail: + movl %edx,%ecx + andl $63,%ecx + shrl $3,%ecx + jz .Lhandle_7 + .p2align 4 +.Lloop_8: + decl %ecx + movq (%rsi),%r8 + movq %r8,(%rdi) + leaq 8(%rdi),%rdi + leaq 8(%rsi),%rsi + jnz .Lloop_8 + +.Lhandle_7: + movl %edx,%ecx + andl $7,%ecx + jz .Lende + .p2align 4 +.Lloop_1: + movb (%rsi),%r8b + movb %r8b,(%rdi) + incq %rdi + incq %rsi + decl %ecx + jnz .Lloop_1 + +.Lende: + popq %rbx + ret +.Lfinal: + + /* Some CPUs run faster using the string copy instructions. + It is also a lot simpler. Use this when possible */ + + .section .altinstructions,"a" + .align 8 + .quad memcpy + .quad memcpy_c + .byte X86_FEATURE_REP_GOOD + .byte .Lfinal-memcpy + .byte memcpy_c_end-memcpy_c + .previous + + .section .altinstr_replacement,"ax" + /* rdi destination + * rsi source + * rdx count + */ +memcpy_c: movq %rdi,%rax movl %edx,%ecx shrl $3,%ecx @@ -30,3 +117,5 @@ memcpy: rep movsb ret +memcpy_c_end: + .previous diff --git a/arch/x86_64/lib/memset.S b/arch/x86_64/lib/memset.S index 2aa48f2..ad397f2 100644 --- a/arch/x86_64/lib/memset.S +++ b/arch/x86_64/lib/memset.S @@ -13,6 +13,98 @@ .p2align 4 memset: __memset: + movq %rdi,%r10 + movq %rdx,%r11 + + /* expand byte value */ + movzbl %sil,%ecx + movabs $0x0101010101010101,%rax + mul %rcx /* with rax, clobbers rdx */ + + /* align dst */ + movl %edi,%r9d + andl $7,%r9d + jnz .Lbad_alignment +.Lafter_bad_alignment: + + movl %r11d,%ecx + shrl $6,%ecx + jz .Lhandle_tail + + .p2align 4 +.Lloop_64: + decl %ecx + movq %rax,(%rdi) + movq %rax,8(%rdi) + movq %rax,16(%rdi) + movq %rax,24(%rdi) + movq %rax,32(%rdi) + movq %rax,40(%rdi) + movq %rax,48(%rdi) + movq %rax,56(%rdi) + leaq 64(%rdi),%rdi + jnz .Lloop_64 + + /* Handle tail in loops. The loops should be faster than hard + to predict jump tables. */ + .p2align 4 +.Lhandle_tail: + movl %r11d,%ecx + andl $63&(~7),%ecx + jz .Lhandle_7 + shrl $3,%ecx + .p2align 4 +.Lloop_8: + decl %ecx + movq %rax,(%rdi) + leaq 8(%rdi),%rdi + jnz .Lloop_8 + +.Lhandle_7: + movl %r11d,%ecx + andl $7,%ecx + jz .Lende + .p2align 4 +.Lloop_1: + decl %ecx + movb %al,(%rdi) + leaq 1(%rdi),%rdi + jnz .Lloop_1 + +.Lende: + movq %r10,%rax + ret + +.Lbad_alignment: + cmpq $7,%r11 + jbe .Lhandle_7 + movq %rax,(%rdi) /* unaligned store */ + movq $8,%r8 + subq %r9,%r8 + addq %r8,%rdi + subq %r8,%r11 + jmp .Lafter_bad_alignment + + /* Some CPUs run faster using the string instructions. + It is also a lot simpler. Use this when possible */ + +#include + + .section .altinstructions,"a" + .align 8 + .quad memset + .quad memset_c + .byte X86_FEATURE_REP_GOOD + .byte memset_c_end-memset_c + .byte memset_c_end-memset_c + .previous + + .section .altinstr_replacement,"ax" + /* rdi destination + * rsi value + * rdx count + */ +memset_c: movq %rdi,%r9 movl %edx,%r8d andl $7,%r8d @@ -29,3 +121,5 @@ __memset: stosb movq %r9,%rax ret +memset_c_end: + .previous diff --git a/include/asm-x86_64/cpufeature.h b/include/asm-x86_64/cpufeature.h index 41c0ac8..76bb619 100644 --- a/include/asm-x86_64/cpufeature.h +++ b/include/asm-x86_64/cpufeature.h @@ -61,7 +61,7 @@ #define X86_FEATURE_K6_MTRR (3*32+ 1) /* AMD K6 nonstandard MTRRs */ #define X86_FEATURE_CYRIX_ARR (3*32+ 2) /* Cyrix ARRs (= MTRRs) */ #define X86_FEATURE_CENTAUR_MCR (3*32+ 3) /* Centaur MCRs (= MTRRs) */ -/* 4 free */ +#define X86_FEATURE_REP_GOOD (3*32+ 4) /* rep microcode works well on this CPU */ #define X86_FEATURE_CONSTANT_TSC (3*32+5) /* TSC runs at constant rate */ #define X86_FEATURE_SYNC_RDTSC (3*32+6) /* RDTSC syncs CPU core */ -- 2.7.4