From 426932909093e4e7729777a0e2beed4b54911361 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Thu, 5 Jan 2012 16:12:25 +0000 Subject: x86-64: Slightly shorten copy_page() %r13 got saved and restored without ever getting touched, so there's no need to do so. Signed-off-by: Jan Beulich Cc: Linus Torvalds Cc: Andrew Morton Link: http://lkml.kernel.org/r/4F05D9F9020000780006AA0D@nat28.tlf.novell.com Signed-off-by: Ingo Molnar --- arch/x86/lib/copy_page_64.S | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) (limited to 'arch/x86/lib') diff --git a/arch/x86/lib/copy_page_64.S b/arch/x86/lib/copy_page_64.S index 01c805b..6b34d04 100644 --- a/arch/x86/lib/copy_page_64.S +++ b/arch/x86/lib/copy_page_64.S @@ -20,14 +20,12 @@ ENDPROC(copy_page_c) ENTRY(copy_page) CFI_STARTPROC - subq $3*8,%rsp - CFI_ADJUST_CFA_OFFSET 3*8 + subq $2*8,%rsp + CFI_ADJUST_CFA_OFFSET 2*8 movq %rbx,(%rsp) CFI_REL_OFFSET rbx, 0 movq %r12,1*8(%rsp) CFI_REL_OFFSET r12, 1*8 - movq %r13,2*8(%rsp) - CFI_REL_OFFSET r13, 2*8 movl $(4096/64)-5,%ecx .p2align 4 @@ -91,10 +89,8 @@ ENTRY(copy_page) CFI_RESTORE rbx movq 1*8(%rsp),%r12 CFI_RESTORE r12 - movq 2*8(%rsp),%r13 - CFI_RESTORE r13 - addq $3*8,%rsp - CFI_ADJUST_CFA_OFFSET -3*8 + addq $2*8,%rsp + CFI_ADJUST_CFA_OFFSET -2*8 ret .Lcopy_page_end: CFI_ENDPROC -- cgit v1.1 From 5d7244e7c984cecead412bde6395ce18618a4a37 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Thu, 5 Jan 2012 16:10:42 +0000 Subject: x86-64: Fix memset() to support sizes of 4Gb and above While currently there doesn't appear to be any reachable in-tree case where such large memory blocks may be passed to memset() (alloc_bootmem() being the primary non-reachable one, as it gets called with suitably large sizes in FLATMEM configurations), we have recently hit the problem a second time in our Xen kernels. Rather than working around it a second time, prevent others from falling into the same trap by fixing this long standing limitation. Signed-off-by: Jan Beulich Cc: Linus Torvalds Cc: Andrew Morton Link: http://lkml.kernel.org/r/4F05D992020000780006AA09@nat28.tlf.novell.com Signed-off-by: Ingo Molnar --- arch/x86/lib/memset_64.S | 33 +++++++++++++++------------------ 1 file changed, 15 insertions(+), 18 deletions(-) (limited to 'arch/x86/lib') diff --git a/arch/x86/lib/memset_64.S b/arch/x86/lib/memset_64.S index 79bd454..2dcb380 100644 --- a/arch/x86/lib/memset_64.S +++ b/arch/x86/lib/memset_64.S @@ -19,16 +19,15 @@ .section .altinstr_replacement, "ax", @progbits .Lmemset_c: movq %rdi,%r9 - movl %edx,%r8d - andl $7,%r8d - movl %edx,%ecx - shrl $3,%ecx + movq %rdx,%rcx + andl $7,%edx + shrq $3,%rcx /* expand byte value */ movzbl %sil,%esi movabs $0x0101010101010101,%rax - mulq %rsi /* with rax, clobbers rdx */ + imulq %rsi,%rax rep stosq - movl %r8d,%ecx + movl %edx,%ecx rep stosb movq %r9,%rax ret @@ -50,7 +49,7 @@ .Lmemset_c_e: movq %rdi,%r9 movb %sil,%al - movl %edx,%ecx + movq %rdx,%rcx rep stosb movq %r9,%rax ret @@ -61,12 +60,11 @@ ENTRY(memset) ENTRY(__memset) CFI_STARTPROC movq %rdi,%r10 - movq %rdx,%r11 /* expand byte value */ movzbl %sil,%ecx movabs $0x0101010101010101,%rax - mul %rcx /* with rax, clobbers rdx */ + imulq %rcx,%rax /* align dst */ movl %edi,%r9d @@ -75,13 +73,13 @@ ENTRY(__memset) CFI_REMEMBER_STATE .Lafter_bad_alignment: - movl %r11d,%ecx - shrl $6,%ecx + movq %rdx,%rcx + shrq $6,%rcx jz .Lhandle_tail .p2align 4 .Lloop_64: - decl %ecx + decq %rcx movq %rax,(%rdi) movq %rax,8(%rdi) movq %rax,16(%rdi) @@ -97,7 +95,7 @@ ENTRY(__memset) to predict jump tables. */ .p2align 4 .Lhandle_tail: - movl %r11d,%ecx + movl %edx,%ecx andl $63&(~7),%ecx jz .Lhandle_7 shrl $3,%ecx @@ -109,12 +107,11 @@ ENTRY(__memset) jnz .Lloop_8 .Lhandle_7: - movl %r11d,%ecx - andl $7,%ecx + andl $7,%edx jz .Lende .p2align 4 .Lloop_1: - decl %ecx + decl %edx movb %al,(%rdi) leaq 1(%rdi),%rdi jnz .Lloop_1 @@ -125,13 +122,13 @@ ENTRY(__memset) CFI_RESTORE_STATE .Lbad_alignment: - cmpq $7,%r11 + cmpq $7,%rdx jbe .Lhandle_7 movq %rax,(%rdi) /* unaligned store */ movq $8,%r8 subq %r9,%r8 addq %r8,%rdi - subq %r8,%r11 + subq %r8,%rdx jmp .Lafter_bad_alignment .Lfinal: CFI_ENDPROC -- cgit v1.1 From 2ab560911a427fdc73bfd3a7d2944d8ee0ca6db8 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Thu, 26 Jan 2012 15:50:55 +0000 Subject: x86-64: Fix memcpy() to support sizes of 4Gb and above While currently there doesn't appear to be any reachable in-tree case where such large memory blocks may be passed to memcpy(), we already had hit the problem in our Xen kernels. Just like done recently for mmeset(), rather than working around it, prevent others from falling into the same trap by fixing this long standing limitation. Signed-off-by: Jan Beulich Cc: Linus Torvalds Link: http://lkml.kernel.org/r/4F21846F020000780006F3FA@nat28.tlf.novell.com Signed-off-by: Ingo Molnar --- arch/x86/lib/memcpy_64.S | 25 ++++++++++--------------- 1 file changed, 10 insertions(+), 15 deletions(-) (limited to 'arch/x86/lib') diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S index efbf2a0..1235b04 100644 --- a/arch/x86/lib/memcpy_64.S +++ b/arch/x86/lib/memcpy_64.S @@ -27,9 +27,8 @@ .section .altinstr_replacement, "ax", @progbits .Lmemcpy_c: movq %rdi, %rax - - movl %edx, %ecx - shrl $3, %ecx + movq %rdx, %rcx + shrq $3, %rcx andl $7, %edx rep movsq movl %edx, %ecx @@ -48,8 +47,7 @@ .section .altinstr_replacement, "ax", @progbits .Lmemcpy_c_e: movq %rdi, %rax - - movl %edx, %ecx + movq %rdx, %rcx rep movsb ret .Lmemcpy_e_e: @@ -60,10 +58,7 @@ ENTRY(memcpy) CFI_STARTPROC movq %rdi, %rax - /* - * Use 32bit CMP here to avoid long NOP padding. - */ - cmp $0x20, %edx + cmpq $0x20, %rdx jb .Lhandle_tail /* @@ -72,7 +67,7 @@ ENTRY(memcpy) */ cmp %dil, %sil jl .Lcopy_backward - subl $0x20, %edx + subq $0x20, %rdx .Lcopy_forward_loop: subq $0x20, %rdx @@ -91,7 +86,7 @@ ENTRY(memcpy) movq %r11, 3*8(%rdi) leaq 4*8(%rdi), %rdi jae .Lcopy_forward_loop - addq $0x20, %rdx + addl $0x20, %edx jmp .Lhandle_tail .Lcopy_backward: @@ -123,11 +118,11 @@ ENTRY(memcpy) /* * Calculate copy position to head. */ - addq $0x20, %rdx + addl $0x20, %edx subq %rdx, %rsi subq %rdx, %rdi .Lhandle_tail: - cmpq $16, %rdx + cmpl $16, %edx jb .Lless_16bytes /* @@ -144,7 +139,7 @@ ENTRY(memcpy) retq .p2align 4 .Lless_16bytes: - cmpq $8, %rdx + cmpl $8, %edx jb .Lless_8bytes /* * Move data from 8 bytes to 15 bytes. @@ -156,7 +151,7 @@ ENTRY(memcpy) retq .p2align 4 .Lless_8bytes: - cmpq $4, %rdx + cmpl $4, %edx jb .Lless_3bytes /* -- cgit v1.1 From 9d8e22777e66f420e46490e9fc6f8cb7e0e2222b Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Thu, 26 Jan 2012 15:55:32 +0000 Subject: x86-64: Handle byte-wise tail copying in memcpy() without a loop While hard to measure, reducing the number of possibly/likely mis-predicted branches can generally be expected to be slightly better. Other than apparent at the first glance, this also doesn't grow the function size (the alignment gap to the next function just gets smaller). Signed-off-by: Jan Beulich Cc: Linus Torvalds Link: http://lkml.kernel.org/r/4F218584020000780006F422@nat28.tlf.novell.com Signed-off-by: Ingo Molnar --- arch/x86/lib/memcpy_64.S | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) (limited to 'arch/x86/lib') diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S index 1235b04..1c273be 100644 --- a/arch/x86/lib/memcpy_64.S +++ b/arch/x86/lib/memcpy_64.S @@ -164,18 +164,19 @@ ENTRY(memcpy) retq .p2align 4 .Lless_3bytes: - cmpl $0, %edx - je .Lend + subl $1, %edx + jb .Lend /* * Move data from 1 bytes to 3 bytes. */ -.Lloop_1: - movb (%rsi), %r8b - movb %r8b, (%rdi) - incq %rdi - incq %rsi - decl %edx - jnz .Lloop_1 + movzbl (%rsi), %ecx + jz .Lstore_1byte + movzbq 1(%rsi), %r8 + movzbq (%rsi, %rdx), %r9 + movb %r8b, 1(%rdi) + movb %r9b, (%rdi, %rdx) +.Lstore_1byte: + movb %cl, (%rdi) .Lend: retq -- cgit v1.1