diff options
Diffstat (limited to 'arch/x86/lib/copy_user_64.S')
| -rw-r--r-- | arch/x86/lib/copy_user_64.S | 354 |
1 files changed, 354 insertions, 0 deletions
diff --git a/arch/x86/lib/copy_user_64.S b/arch/x86/lib/copy_user_64.S new file mode 100644 index 000000000000..70bebd310408 --- /dev/null +++ b/arch/x86/lib/copy_user_64.S @@ -0,0 +1,354 @@ +/* Copyright 2002 Andi Kleen, SuSE Labs. + * Subject to the GNU Public License v2. + * + * 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> + + .macro ALTERNATIVE_JUMP feature,orig,alt +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 \alt-1b /* offset */ /* or alternatively to alt */ + .previous + .section .altinstructions,"a" + .align 8 + .quad 0b + .quad 2b + .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 */ +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 + 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 + stosb +bad_to_user: + movl %edx,%eax + ret + CFI_ENDPROC +END(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 + * ecx zero flag -- if true zero destination on error + * + * Output: + * eax uncopied bytes or 0 if successful. + */ +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 + /* 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 + + 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 */ + .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: + cmpl $0,(%rsp) + jz .Le_zero + 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 + 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. + 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 + * ecx zero flag + * + * 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. + */ +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 +9: movl %ecx,%eax + ret + + /* 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,5b + .quad 8b,11b + .quad 10b,3b + .previous |