diff options
Diffstat (limited to 'arch/x86_64/lib/copy_user.S')
| -rw-r--r-- | arch/x86_64/lib/copy_user.S | 153 |
1 files changed, 103 insertions, 50 deletions
diff --git a/arch/x86_64/lib/copy_user.S b/arch/x86_64/lib/copy_user.S index f64569b83b54..70bebd310408 100644 --- a/arch/x86_64/lib/copy_user.S +++ b/arch/x86_64/lib/copy_user.S @@ -4,56 +4,78 @@ * Functions to copy from and to user space. */ +#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/current.h> +#include <asm/asm-offsets.h> +#include <asm/thread_info.h> +#include <asm/cpufeature.h> -/* Standard copy_to_user with segment limit checking */ - .globl copy_to_user - .p2align 4 -copy_to_user: - GET_THREAD_INFO(%rax) - movq %rdi,%rcx - addq %rdx,%rcx - jc bad_to_user - cmpq threadinfo_addr_limit(%rax),%rcx - jae bad_to_user -2: + .macro ALTERNATIVE_JUMP feature,orig,alt +0: .byte 0xe9 /* 32bit jump */ - .long .Lcug-1f + .long \orig-1f /* by default jump to orig */ 1: - .section .altinstr_replacement,"ax" -3: .byte 0xe9 /* replacement jmp with 8 bit immediate */ - .long copy_user_generic_c-1b /* offset */ +2: .byte 0xe9 /* near jump with 32bit immediate */ + .long \alt-1b /* offset */ /* or alternatively to alt */ .previous .section .altinstructions,"a" .align 8 + .quad 0b .quad 2b - .quad 3b - .byte X86_FEATURE_REP_GOOD + .byte \feature /* when feature is set */ .byte 5 .byte 5 .previous + .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 threadinfo_addr_limit(%rax),%rcx + jae bad_to_user + xorl %eax,%eax /* clear zero flag */ + ALTERNATIVE_JUMP X86_FEATURE_REP_GOOD,copy_user_generic_unrolled,copy_user_generic_string + CFI_ENDPROC + +ENTRY(copy_user_generic) + CFI_STARTPROC + movl $1,%ecx /* set zero flag */ + ALTERNATIVE_JUMP X86_FEATURE_REP_GOOD,copy_user_generic_unrolled,copy_user_generic_string + CFI_ENDPROC + +ENTRY(__copy_from_user_inatomic) + CFI_STARTPROC + xorl %ecx,%ecx /* clear zero flag */ + ALTERNATIVE_JUMP X86_FEATURE_REP_GOOD,copy_user_generic_unrolled,copy_user_generic_string + CFI_ENDPROC /* Standard copy_from_user with segment limit checking */ - .globl copy_from_user - .p2align 4 -copy_from_user: +ENTRY(copy_from_user) + CFI_STARTPROC GET_THREAD_INFO(%rax) movq %rsi,%rcx addq %rdx,%rcx jc bad_from_user cmpq threadinfo_addr_limit(%rax),%rcx jae bad_from_user - /* FALL THROUGH to copy_user_generic */ + movl $1,%ecx /* set zero flag */ + ALTERNATIVE_JUMP X86_FEATURE_REP_GOOD,copy_user_generic_unrolled,copy_user_generic_string + CFI_ENDPROC +ENDPROC(copy_from_user) .section .fixup,"ax" /* must zero dest */ bad_from_user: + CFI_STARTPROC movl %edx,%ecx xorl %eax,%eax rep @@ -61,40 +83,32 @@ bad_from_user: bad_to_user: movl %edx,%eax ret + CFI_ENDPROC +END(bad_from_user) .previous /* - * copy_user_generic - memory copy with exception handling. + * 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 + * ecx zero flag -- if true zero destination on error * * 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: +ENTRY(copy_user_generic_unrolled) + CFI_STARTPROC pushq %rbx + CFI_ADJUST_CFA_OFFSET 8 + CFI_REL_OFFSET rbx, 0 + pushq %rcx + CFI_ADJUST_CFA_OFFSET 8 + CFI_REL_OFFSET rcx, 0 xorl %eax,%eax /*zero for the exception handler */ #ifdef FIX_ALIGNMENT @@ -168,9 +182,16 @@ copy_user_generic: decl %ecx jnz .Lloop_1 + CFI_REMEMBER_STATE .Lende: + popq %rcx + CFI_ADJUST_CFA_OFFSET -8 + CFI_RESTORE rcx popq %rbx + CFI_ADJUST_CFA_OFFSET -8 + CFI_RESTORE rbx ret + CFI_RESTORE_STATE #ifdef FIX_ALIGNMENT /* align destination */ @@ -252,6 +273,8 @@ copy_user_generic: addl %ecx,%edx /* edx: bytes to zero, rdi: dest, eax:zero */ .Lzero_rest: + cmpl $0,(%rsp) + jz .Le_zero movq %rdx,%rcx .Le_byte: xorl %eax,%eax @@ -261,6 +284,9 @@ copy_user_generic: .Le_zero: movq %rdx,%rax jmp .Lende + CFI_ENDPROC +ENDPROC(copy_user_generic) + /* Some CPUs run faster using the string copy instructions. This is also a lot simpler. Use them when possible. @@ -270,6 +296,7 @@ copy_user_generic: /* rdi destination * rsi source * rdx count + * ecx zero flag * * Output: * eax uncopied bytes or 0 if successfull. @@ -280,22 +307,48 @@ copy_user_generic: * 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: + */ +ENTRY(copy_user_generic_string) + CFI_STARTPROC + movl %ecx,%r8d /* save zero flag */ movl %edx,%ecx shrl $3,%ecx andl $7,%edx + jz 10f 1: rep movsq movl %edx,%ecx 2: rep movsb -4: movl %ecx,%eax +9: movl %ecx,%eax ret -3: lea (%rdx,%rcx,8),%rax + + /* multiple of 8 byte */ +10: rep + movsq + xor %eax,%eax ret + /* exception handling */ +3: lea (%rdx,%rcx,8),%rax /* exception on quad loop */ + jmp 6f +5: movl %ecx,%eax /* exception on byte loop */ + /* eax: left over bytes */ +6: testl %r8d,%r8d /* zero flag set? */ + jz 7f + movl %eax,%ecx /* initialize x86 loop counter */ + push %rax + xorl %eax,%eax +8: rep + stosb /* zero the rest */ +11: pop %rax +7: ret + CFI_ENDPROC +END(copy_user_generic_c) + .section __ex_table,"a" .quad 1b,3b - .quad 2b,4b + .quad 2b,5b + .quad 8b,11b + .quad 10b,3b .previous |