diff options
Diffstat (limited to 'arch/x86/lib/copy_user_64.S')
| -rw-r--r-- | arch/x86/lib/copy_user_64.S | 372 |
1 files changed, 93 insertions, 279 deletions
diff --git a/arch/x86/lib/copy_user_64.S b/arch/x86/lib/copy_user_64.S index a30ca15be21c..06296eb69fd4 100644 --- a/arch/x86/lib/copy_user_64.S +++ b/arch/x86/lib/copy_user_64.S @@ -1,298 +1,112 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ /* * Copyright 2008 Vitaly Mayatskikh <vmayatsk@redhat.com> * Copyright 2002 Andi Kleen, SuSE Labs. - * Subject to the GNU Public License v2. * * Functions to copy from and to user space. */ +#include <linux/export.h> #include <linux/linkage.h> -#include <asm/dwarf2.h> - -#define FIX_ALIGNMENT 1 - -#include <asm/current.h> -#include <asm/asm-offsets.h> -#include <asm/thread_info.h> -#include <asm/cpufeature.h> -#include <asm/alternative-asm.h> +#include <linux/cfi_types.h> +#include <linux/objtool.h> +#include <asm/cpufeatures.h> +#include <asm/alternative.h> #include <asm/asm.h> -#include <asm/smap.h> /* - * By placing feature2 after feature1 in altinstructions section, we logically - * implement: - * If CPU has feature2, jmp to alt2 is used - * else if CPU has feature1, jmp to alt1 is used - * else jmp to orig is used. - */ - .macro ALTERNATIVE_JUMP feature1,feature2,orig,alt1,alt2 -0: - .byte 0xe9 /* 32bit jump */ - .long \orig-1f /* by default jump to orig */ -1: - .section .altinstr_replacement,"ax" -2: .byte 0xe9 /* near jump with 32bit immediate */ - .long \alt1-1b /* offset */ /* or alternatively to alt1 */ -3: .byte 0xe9 /* near jump with 32bit immediate */ - .long \alt2-1b /* offset */ /* or alternatively to alt2 */ - .previous - - .section .altinstructions,"a" - altinstruction_entry 0b,2b,\feature1,5,5 - altinstruction_entry 0b,3b,\feature2,5,5 - .previous - .endm - - .macro ALIGN_DESTINATION -#ifdef FIX_ALIGNMENT - /* check for bad alignment of destination */ - movl %edi,%ecx - andl $7,%ecx - jz 102f /* already aligned */ - subl $8,%ecx - negl %ecx - subl %ecx,%edx -100: movb (%rsi),%al -101: movb %al,(%rdi) - incq %rsi - incq %rdi - decl %ecx - jnz 100b -102: - .section .fixup,"ax" -103: addl %ecx,%edx /* ecx is zerorest also */ - jmp copy_user_handle_tail - .previous - - _ASM_EXTABLE(100b,103b) - _ASM_EXTABLE(101b,103b) -#endif - .endm - -/* Standard copy_to_user with segment limit checking */ -ENTRY(_copy_to_user) - CFI_STARTPROC - GET_THREAD_INFO(%rax) - movq %rdi,%rcx - addq %rdx,%rcx - jc bad_to_user - cmpq TI_addr_limit(%rax),%rcx - ja bad_to_user - ALTERNATIVE_JUMP X86_FEATURE_REP_GOOD,X86_FEATURE_ERMS, \ - copy_user_generic_unrolled,copy_user_generic_string, \ - copy_user_enhanced_fast_string - CFI_ENDPROC -ENDPROC(_copy_to_user) - -/* Standard copy_from_user with segment limit checking */ -ENTRY(_copy_from_user) - CFI_STARTPROC - GET_THREAD_INFO(%rax) - movq %rsi,%rcx - addq %rdx,%rcx - jc bad_from_user - cmpq TI_addr_limit(%rax),%rcx - ja bad_from_user - ALTERNATIVE_JUMP X86_FEATURE_REP_GOOD,X86_FEATURE_ERMS, \ - copy_user_generic_unrolled,copy_user_generic_string, \ - copy_user_enhanced_fast_string - CFI_ENDPROC -ENDPROC(_copy_from_user) - - .section .fixup,"ax" - /* must zero dest */ -ENTRY(bad_from_user) -bad_from_user: - CFI_STARTPROC - movl %edx,%ecx - xorl %eax,%eax - rep - stosb -bad_to_user: - movl %edx,%eax - ret - CFI_ENDPROC -ENDPROC(bad_from_user) - .previous - -/* - * copy_user_generic_unrolled - memory copy with exception handling. - * This version is for CPUs like P4 that don't have efficient micro - * code for rep movsq - * - * Input: - * rdi destination - * rsi source - * rdx count - * - * Output: - * eax uncopied bytes or 0 if successful. - */ -ENTRY(copy_user_generic_unrolled) - CFI_STARTPROC - ASM_STAC - cmpl $8,%edx - jb 20f /* less then 8 bytes, go to byte copy loop */ - ALIGN_DESTINATION - movl %edx,%ecx - andl $63,%edx - shrl $6,%ecx - jz 17f -1: movq (%rsi),%r8 -2: movq 1*8(%rsi),%r9 -3: movq 2*8(%rsi),%r10 -4: movq 3*8(%rsi),%r11 -5: movq %r8,(%rdi) -6: movq %r9,1*8(%rdi) -7: movq %r10,2*8(%rdi) -8: movq %r11,3*8(%rdi) -9: movq 4*8(%rsi),%r8 -10: movq 5*8(%rsi),%r9 -11: movq 6*8(%rsi),%r10 -12: movq 7*8(%rsi),%r11 -13: movq %r8,4*8(%rdi) -14: movq %r9,5*8(%rdi) -15: movq %r10,6*8(%rdi) -16: movq %r11,7*8(%rdi) - leaq 64(%rsi),%rsi - leaq 64(%rdi),%rdi - decl %ecx - jnz 1b -17: movl %edx,%ecx - andl $7,%edx - shrl $3,%ecx - jz 20f -18: movq (%rsi),%r8 -19: movq %r8,(%rdi) - leaq 8(%rsi),%rsi - leaq 8(%rdi),%rdi - decl %ecx - jnz 18b -20: andl %edx,%edx - jz 23f - movl %edx,%ecx -21: movb (%rsi),%al -22: movb %al,(%rdi) - incq %rsi - incq %rdi - decl %ecx - jnz 21b -23: xor %eax,%eax - ASM_CLAC - ret - - .section .fixup,"ax" -30: shll $6,%ecx - addl %ecx,%edx - jmp 60f -40: lea (%rdx,%rcx,8),%rdx - jmp 60f -50: movl %ecx,%edx -60: jmp copy_user_handle_tail /* ecx is zerorest also */ - .previous - - _ASM_EXTABLE(1b,30b) - _ASM_EXTABLE(2b,30b) - _ASM_EXTABLE(3b,30b) - _ASM_EXTABLE(4b,30b) - _ASM_EXTABLE(5b,30b) - _ASM_EXTABLE(6b,30b) - _ASM_EXTABLE(7b,30b) - _ASM_EXTABLE(8b,30b) - _ASM_EXTABLE(9b,30b) - _ASM_EXTABLE(10b,30b) - _ASM_EXTABLE(11b,30b) - _ASM_EXTABLE(12b,30b) - _ASM_EXTABLE(13b,30b) - _ASM_EXTABLE(14b,30b) - _ASM_EXTABLE(15b,30b) - _ASM_EXTABLE(16b,30b) - _ASM_EXTABLE(18b,40b) - _ASM_EXTABLE(19b,40b) - _ASM_EXTABLE(21b,50b) - _ASM_EXTABLE(22b,50b) - CFI_ENDPROC -ENDPROC(copy_user_generic_unrolled) - -/* Some CPUs run faster using the string copy instructions. - * This is also a lot simpler. Use them when possible. - * - * 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. + * rep_movs_alternative - memory copy with exception handling. + * This version is for CPUs that don't have FSRM (Fast Short Rep Movs) * * Input: * rdi destination * rsi source - * rdx count + * rcx count * * Output: - * eax uncopied bytes or 0 if successful. - */ -ENTRY(copy_user_generic_string) - CFI_STARTPROC - ASM_STAC - andl %edx,%edx - jz 4f - cmpl $8,%edx - jb 2f /* less than 8 bytes, go to byte copy loop */ - ALIGN_DESTINATION - movl %edx,%ecx - shrl $3,%ecx - andl $7,%edx -1: rep - movsq -2: movl %edx,%ecx -3: rep - movsb -4: xorl %eax,%eax - ASM_CLAC - ret - - .section .fixup,"ax" -11: lea (%rdx,%rcx,8),%rcx -12: movl %ecx,%edx /* ecx is zerorest also */ - jmp copy_user_handle_tail - .previous - - _ASM_EXTABLE(1b,11b) - _ASM_EXTABLE(3b,12b) - CFI_ENDPROC -ENDPROC(copy_user_generic_string) - -/* - * Some CPUs are adding enhanced REP MOVSB/STOSB instructions. - * It's recommended to use enhanced REP MOVSB/STOSB if it's enabled. - * - * Input: - * rdi destination - * rsi source - * rdx count + * rcx uncopied bytes or 0 if successful. * - * Output: - * eax uncopied bytes or 0 if successful. + * NOTE! The calling convention is very intentionally the same as + * for 'rep movs', so that we can rewrite the function call with + * just a plain 'rep movs' on machines that have FSRM. But to make + * it simpler for us, we can clobber rsi/rdi and rax freely. */ -ENTRY(copy_user_enhanced_fast_string) - CFI_STARTPROC - ASM_STAC - andl %edx,%edx - jz 2f - movl %edx,%ecx -1: rep - movsb -2: xorl %eax,%eax - ASM_CLAC - ret - - .section .fixup,"ax" -12: movl %ecx,%edx /* ecx is zerorest also */ - jmp copy_user_handle_tail - .previous - - _ASM_EXTABLE(1b,12b) - CFI_ENDPROC -ENDPROC(copy_user_enhanced_fast_string) +SYM_FUNC_START(rep_movs_alternative) + ANNOTATE_NOENDBR + cmpq $64,%rcx + jae .Llarge + + cmp $8,%ecx + jae .Lword + + testl %ecx,%ecx + je .Lexit + +.Lcopy_user_tail: +0: movb (%rsi),%al +1: movb %al,(%rdi) + inc %rdi + inc %rsi + dec %rcx + jne .Lcopy_user_tail +.Lexit: + RET + + _ASM_EXTABLE_UA( 0b, .Lexit) + _ASM_EXTABLE_UA( 1b, .Lexit) + + .p2align 4 +.Lword: +2: movq (%rsi),%rax +3: movq %rax,(%rdi) + addq $8,%rsi + addq $8,%rdi + sub $8,%ecx + je .Lexit + cmp $8,%ecx + jae .Lword + jmp .Lcopy_user_tail + + _ASM_EXTABLE_UA( 2b, .Lcopy_user_tail) + _ASM_EXTABLE_UA( 3b, .Lcopy_user_tail) + +.Llarge: +0: ALTERNATIVE "jmp .Llarge_movsq", "rep movsb", X86_FEATURE_ERMS +1: RET + + _ASM_EXTABLE_UA( 0b, 1b) + +.Llarge_movsq: + /* Do the first possibly unaligned word */ +0: movq (%rsi),%rax +1: movq %rax,(%rdi) + + _ASM_EXTABLE_UA( 0b, .Lcopy_user_tail) + _ASM_EXTABLE_UA( 1b, .Lcopy_user_tail) + + /* What would be the offset to the aligned destination? */ + leaq 8(%rdi),%rax + andq $-8,%rax + subq %rdi,%rax + + /* .. and update pointers and count to match */ + addq %rax,%rdi + addq %rax,%rsi + subq %rax,%rcx + + /* make %rcx contain the number of words, %rax the remainder */ + movq %rcx,%rax + shrq $3,%rcx + andl $7,%eax +0: rep movsq + movl %eax,%ecx + testl %ecx,%ecx + jne .Lcopy_user_tail + RET + +1: leaq (%rax,%rcx,8),%rcx + jmp .Lcopy_user_tail + + _ASM_EXTABLE_UA( 0b, 1b) +SYM_FUNC_END(rep_movs_alternative) +EXPORT_SYMBOL(rep_movs_alternative) |