* Functions to copy from and to user space.
*/
+#define FIX_ALIGNMENT 1
+
#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
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
* 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
projects / powerpc.git / blobdiff