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-rw-r--r--arch/x86/lib/copy_user_64.S447
1 files changed, 64 insertions, 383 deletions
diff --git a/arch/x86/lib/copy_user_64.S b/arch/x86/lib/copy_user_64.S
index 9dec1b38a98f..fc9fb5d06174 100644
--- a/arch/x86/lib/copy_user_64.S
+++ b/arch/x86/lib/copy_user_64.S
@@ -6,405 +6,86 @@
* Functions to copy from and to user space.
*/
+#include <linux/export.h>
#include <linux/linkage.h>
-#include <asm/current.h>
-#include <asm/asm-offsets.h>
-#include <asm/thread_info.h>
#include <asm/cpufeatures.h>
#include <asm/alternative.h>
#include <asm/asm.h>
-#include <asm/smap.h>
-#include <asm/export.h>
-#include <asm/trapnr.h>
-
-.macro ALIGN_DESTINATION
- /* 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:
-
- _ASM_EXTABLE_CPY(100b, .Lcopy_user_handle_align)
- _ASM_EXTABLE_CPY(101b, .Lcopy_user_handle_align)
-.endm
-
-/*
- * 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.
- */
-SYM_FUNC_START(copy_user_generic_unrolled)
- ASM_STAC
- cmpl $8,%edx
- jb .Lcopy_user_short_string_bytes
- ALIGN_DESTINATION
- movl %edx,%ecx
- andl $63,%edx
- shrl $6,%ecx
- jz copy_user_short_string
-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
- jmp copy_user_short_string
-
-30: shll $6,%ecx
- addl %ecx,%edx
- jmp .Lcopy_user_handle_tail
-
- _ASM_EXTABLE_CPY(1b, 30b)
- _ASM_EXTABLE_CPY(2b, 30b)
- _ASM_EXTABLE_CPY(3b, 30b)
- _ASM_EXTABLE_CPY(4b, 30b)
- _ASM_EXTABLE_CPY(5b, 30b)
- _ASM_EXTABLE_CPY(6b, 30b)
- _ASM_EXTABLE_CPY(7b, 30b)
- _ASM_EXTABLE_CPY(8b, 30b)
- _ASM_EXTABLE_CPY(9b, 30b)
- _ASM_EXTABLE_CPY(10b, 30b)
- _ASM_EXTABLE_CPY(11b, 30b)
- _ASM_EXTABLE_CPY(12b, 30b)
- _ASM_EXTABLE_CPY(13b, 30b)
- _ASM_EXTABLE_CPY(14b, 30b)
- _ASM_EXTABLE_CPY(15b, 30b)
- _ASM_EXTABLE_CPY(16b, 30b)
-SYM_FUNC_END(copy_user_generic_unrolled)
-EXPORT_SYMBOL(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.
- *
- * Input:
- * rdi destination
- * rsi source
- * rdx count
- *
- * Output:
- * eax uncopied bytes or 0 if successful.
- */
-SYM_FUNC_START(copy_user_generic_string)
- ASM_STAC
- 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
- xorl %eax,%eax
- ASM_CLAC
- RET
-
-11: leal (%rdx,%rcx,8),%ecx
-12: movl %ecx,%edx /* ecx is zerorest also */
- jmp .Lcopy_user_handle_tail
-
- _ASM_EXTABLE_CPY(1b, 11b)
- _ASM_EXTABLE_CPY(3b, 12b)
-SYM_FUNC_END(copy_user_generic_string)
-EXPORT_SYMBOL(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
- *
- * Output:
- * eax uncopied bytes or 0 if successful.
- */
-SYM_FUNC_START(copy_user_enhanced_fast_string)
- ASM_STAC
- /* CPUs without FSRM should avoid rep movsb for short copies */
- ALTERNATIVE "cmpl $64, %edx; jb copy_user_short_string", "", X86_FEATURE_FSRM
- movl %edx,%ecx
-1: rep movsb
- xorl %eax,%eax
- ASM_CLAC
- RET
-
-12: movl %ecx,%edx /* ecx is zerorest also */
- jmp .Lcopy_user_handle_tail
-
- _ASM_EXTABLE_CPY(1b, 12b)
-SYM_FUNC_END(copy_user_enhanced_fast_string)
-EXPORT_SYMBOL(copy_user_enhanced_fast_string)
/*
- * Try to copy last bytes and clear the rest if needed.
- * Since protection fault in copy_from/to_user is not a normal situation,
- * it is not necessary to optimize tail handling.
- * Don't try to copy the tail if machine check happened
+ * rep_movs_alternative - memory copy with exception handling.
+ * This version is for CPUs that don't have FSRM (Fast Short Rep Movs)
*
* Input:
- * eax trap number written by ex_handler_copy()
* rdi destination
* rsi source
- * rdx count
+ * rcx count
*
* Output:
- * eax uncopied bytes or 0 if successful.
- */
-SYM_CODE_START_LOCAL(.Lcopy_user_handle_tail)
- cmp $X86_TRAP_MC,%eax
- je 3f
-
- movl %edx,%ecx
-1: rep movsb
-2: mov %ecx,%eax
- ASM_CLAC
- RET
-
-3:
- movl %edx,%eax
- ASM_CLAC
- RET
-
- _ASM_EXTABLE_CPY(1b, 2b)
-
-.Lcopy_user_handle_align:
- addl %ecx,%edx /* ecx is zerorest also */
- jmp .Lcopy_user_handle_tail
-
-SYM_CODE_END(.Lcopy_user_handle_tail)
-
-/*
- * Finish memcpy of less than 64 bytes. #AC should already be set.
+ * rcx uncopied bytes or 0 if successful.
*
- * Input:
- * rdi destination
- * rsi source
- * rdx count (< 64)
- *
- * 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.
*/
-SYM_CODE_START_LOCAL(copy_user_short_string)
- movl %edx,%ecx
- andl $7,%edx
- shrl $3,%ecx
- jz .Lcopy_user_short_string_bytes
-18: movq (%rsi),%r8
-19: movq %r8,(%rdi)
- leaq 8(%rsi),%rsi
- leaq 8(%rdi),%rdi
- decl %ecx
- jnz 18b
-.Lcopy_user_short_string_bytes:
- 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
+SYM_FUNC_START(rep_movs_alternative)
+ 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
-40: leal (%rdx,%rcx,8),%edx
- jmp 60f
-50: movl %ecx,%edx /* ecx is zerorest also */
-60: jmp .Lcopy_user_handle_tail
-
- _ASM_EXTABLE_CPY(18b, 40b)
- _ASM_EXTABLE_CPY(19b, 40b)
- _ASM_EXTABLE_CPY(21b, 50b)
- _ASM_EXTABLE_CPY(22b, 50b)
-SYM_CODE_END(copy_user_short_string)
-
-/*
- * copy_user_nocache - Uncached memory copy with exception handling
- * This will force destination out of cache for more performance.
- *
- * Note: Cached memory copy is used when destination or size is not
- * naturally aligned. That is:
- * - Require 8-byte alignment when size is 8 bytes or larger.
- * - Require 4-byte alignment when size is 4 bytes.
- */
-SYM_FUNC_START(__copy_user_nocache)
- ASM_STAC
-
- /* If size is less than 8 bytes, go to 4-byte copy */
- cmpl $8,%edx
- jb .L_4b_nocache_copy_entry
-
- /* If destination is not 8-byte aligned, "cache" copy to align it */
- ALIGN_DESTINATION
-
- /* Set 4x8-byte copy count and remainder */
- movl %edx,%ecx
- andl $63,%edx
- shrl $6,%ecx
- jz .L_8b_nocache_copy_entry /* jump if count is 0 */
-
- /* Perform 4x8-byte nocache loop-copy */
-.L_4x8b_nocache_copy_loop:
-1: movq (%rsi),%r8
-2: movq 1*8(%rsi),%r9
-3: movq 2*8(%rsi),%r10
-4: movq 3*8(%rsi),%r11
-5: movnti %r8,(%rdi)
-6: movnti %r9,1*8(%rdi)
-7: movnti %r10,2*8(%rdi)
-8: movnti %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: movnti %r8,4*8(%rdi)
-14: movnti %r9,5*8(%rdi)
-15: movnti %r10,6*8(%rdi)
-16: movnti %r11,7*8(%rdi)
- leaq 64(%rsi),%rsi
- leaq 64(%rdi),%rdi
- decl %ecx
- jnz .L_4x8b_nocache_copy_loop
-
- /* Set 8-byte copy count and remainder */
-.L_8b_nocache_copy_entry:
- movl %edx,%ecx
- andl $7,%edx
- shrl $3,%ecx
- jz .L_4b_nocache_copy_entry /* jump if count is 0 */
-
- /* Perform 8-byte nocache loop-copy */
-.L_8b_nocache_copy_loop:
-20: movq (%rsi),%r8
-21: movnti %r8,(%rdi)
- leaq 8(%rsi),%rsi
- leaq 8(%rdi),%rdi
- decl %ecx
- jnz .L_8b_nocache_copy_loop
-
- /* If no byte left, we're done */
-.L_4b_nocache_copy_entry:
- andl %edx,%edx
- jz .L_finish_copy
-
- /* If destination is not 4-byte aligned, go to byte copy: */
- movl %edi,%ecx
- andl $3,%ecx
- jnz .L_1b_cache_copy_entry
-
- /* Set 4-byte copy count (1 or 0) and remainder */
- movl %edx,%ecx
- andl $3,%edx
- shrl $2,%ecx
- jz .L_1b_cache_copy_entry /* jump if count is 0 */
-
- /* Perform 4-byte nocache copy: */
-30: movl (%rsi),%r8d
-31: movnti %r8d,(%rdi)
- leaq 4(%rsi),%rsi
- leaq 4(%rdi),%rdi
-
- /* If no bytes left, we're done: */
- andl %edx,%edx
- jz .L_finish_copy
-
- /* Perform byte "cache" loop-copy for the remainder */
-.L_1b_cache_copy_entry:
- movl %edx,%ecx
-.L_1b_cache_copy_loop:
-40: movb (%rsi),%al
-41: movb %al,(%rdi)
- incq %rsi
- incq %rdi
- decl %ecx
- jnz .L_1b_cache_copy_loop
-
- /* Finished copying; fence the prior stores */
-.L_finish_copy:
- xorl %eax,%eax
- ASM_CLAC
- sfence
+ _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:
+ movq %rcx,%rax
+ shrq $3,%rcx
+ andl $7,%eax
+0: rep movsq
+ movl %eax,%ecx
+ testl %ecx,%ecx
+ jne .Lcopy_user_tail
RET
-.L_fixup_4x8b_copy:
- shll $6,%ecx
- addl %ecx,%edx
- jmp .L_fixup_handle_tail
-.L_fixup_8b_copy:
- lea (%rdx,%rcx,8),%rdx
- jmp .L_fixup_handle_tail
-.L_fixup_4b_copy:
- lea (%rdx,%rcx,4),%rdx
- jmp .L_fixup_handle_tail
-.L_fixup_1b_copy:
- movl %ecx,%edx
-.L_fixup_handle_tail:
- sfence
- jmp .Lcopy_user_handle_tail
+1: leaq (%rax,%rcx,8),%rcx
+ jmp .Lcopy_user_tail
- _ASM_EXTABLE_CPY(1b, .L_fixup_4x8b_copy)
- _ASM_EXTABLE_CPY(2b, .L_fixup_4x8b_copy)
- _ASM_EXTABLE_CPY(3b, .L_fixup_4x8b_copy)
- _ASM_EXTABLE_CPY(4b, .L_fixup_4x8b_copy)
- _ASM_EXTABLE_CPY(5b, .L_fixup_4x8b_copy)
- _ASM_EXTABLE_CPY(6b, .L_fixup_4x8b_copy)
- _ASM_EXTABLE_CPY(7b, .L_fixup_4x8b_copy)
- _ASM_EXTABLE_CPY(8b, .L_fixup_4x8b_copy)
- _ASM_EXTABLE_CPY(9b, .L_fixup_4x8b_copy)
- _ASM_EXTABLE_CPY(10b, .L_fixup_4x8b_copy)
- _ASM_EXTABLE_CPY(11b, .L_fixup_4x8b_copy)
- _ASM_EXTABLE_CPY(12b, .L_fixup_4x8b_copy)
- _ASM_EXTABLE_CPY(13b, .L_fixup_4x8b_copy)
- _ASM_EXTABLE_CPY(14b, .L_fixup_4x8b_copy)
- _ASM_EXTABLE_CPY(15b, .L_fixup_4x8b_copy)
- _ASM_EXTABLE_CPY(16b, .L_fixup_4x8b_copy)
- _ASM_EXTABLE_CPY(20b, .L_fixup_8b_copy)
- _ASM_EXTABLE_CPY(21b, .L_fixup_8b_copy)
- _ASM_EXTABLE_CPY(30b, .L_fixup_4b_copy)
- _ASM_EXTABLE_CPY(31b, .L_fixup_4b_copy)
- _ASM_EXTABLE_CPY(40b, .L_fixup_1b_copy)
- _ASM_EXTABLE_CPY(41b, .L_fixup_1b_copy)
-SYM_FUNC_END(__copy_user_nocache)
-EXPORT_SYMBOL(__copy_user_nocache)
+ _ASM_EXTABLE_UA( 0b, 1b)
+SYM_FUNC_END(rep_movs_alternative)
+EXPORT_SYMBOL(rep_movs_alternative)