--- /dev/null
+/*
+ * 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/linkage.h>
+#include <asm/dwarf2.h>
+#include <asm/current.h>
+#include <asm/asm-offsets.h>
+#include <asm/thread_info.h>
+#include <asm/cpufeature.h>
+#include <asm/alternative-asm.h>
+#include <asm/asm.h>
+#include <asm/smap.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:
+ .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)
+ .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_2 "jmp copy_user_generic_unrolled", \
+ "jmp copy_user_generic_string", \
+ X86_FEATURE_REP_GOOD, \
+ "jmp copy_user_enhanced_fast_string", \
+ X86_FEATURE_ERMS
+ 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_2 "jmp copy_user_generic_unrolled", \
+ "jmp copy_user_generic_string", \
+ X86_FEATURE_REP_GOOD, \
+ "jmp copy_user_enhanced_fast_string", \
+ X86_FEATURE_ERMS
+ 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: leal (%rdx,%rcx,8),%edx
+ 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.
+ *
+ * Input:
+ * rdi destination
+ * rsi source
+ * rdx count
+ *
+ * Output:
+ * eax uncopied bytes or 0 if successful.
+ */
+ENTRY(copy_user_generic_string)
+ CFI_STARTPROC
+ 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
+
+ .section .fixup,"ax"
+11: leal (%rdx,%rcx,8),%ecx
+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
+ *
+ * Output:
+ * eax uncopied bytes or 0 if successful.
+ */
+ENTRY(copy_user_enhanced_fast_string)
+ CFI_STARTPROC
+ ASM_STAC
+ movl %edx,%ecx
+1: rep
+ movsb
+ 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)
Code Review / kvmfornfv.git / blobdiff