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-rw-r--r--kernel/arch/x86/lib/memcpy_64.S182
1 files changed, 182 insertions, 0 deletions
diff --git a/kernel/arch/x86/lib/memcpy_64.S b/kernel/arch/x86/lib/memcpy_64.S
new file mode 100644
index 000000000..b046664f5
--- /dev/null
+++ b/kernel/arch/x86/lib/memcpy_64.S
@@ -0,0 +1,182 @@
+/* Copyright 2002 Andi Kleen */
+
+#include <linux/linkage.h>
+#include <asm/cpufeature.h>
+#include <asm/dwarf2.h>
+#include <asm/alternative-asm.h>
+
+/*
+ * We build a jump to memcpy_orig by default which gets NOPped out on
+ * the majority of x86 CPUs which set REP_GOOD. In addition, CPUs which
+ * have the enhanced REP MOVSB/STOSB feature (ERMS), change those NOPs
+ * to a jmp to memcpy_erms which does the REP; MOVSB mem copy.
+ */
+
+.weak memcpy
+
+/*
+ * memcpy - Copy a memory block.
+ *
+ * Input:
+ * rdi destination
+ * rsi source
+ * rdx count
+ *
+ * Output:
+ * rax original destination
+ */
+ENTRY(__memcpy)
+ENTRY(memcpy)
+ ALTERNATIVE_2 "jmp memcpy_orig", "", X86_FEATURE_REP_GOOD, \
+ "jmp memcpy_erms", X86_FEATURE_ERMS
+
+ movq %rdi, %rax
+ movq %rdx, %rcx
+ shrq $3, %rcx
+ andl $7, %edx
+ rep movsq
+ movl %edx, %ecx
+ rep movsb
+ ret
+ENDPROC(memcpy)
+ENDPROC(__memcpy)
+
+/*
+ * memcpy_erms() - enhanced fast string memcpy. This is faster and
+ * simpler than memcpy. Use memcpy_erms when possible.
+ */
+ENTRY(memcpy_erms)
+ movq %rdi, %rax
+ movq %rdx, %rcx
+ rep movsb
+ ret
+ENDPROC(memcpy_erms)
+
+ENTRY(memcpy_orig)
+ CFI_STARTPROC
+ movq %rdi, %rax
+
+ cmpq $0x20, %rdx
+ jb .Lhandle_tail
+
+ /*
+ * We check whether memory false dependence could occur,
+ * then jump to corresponding copy mode.
+ */
+ cmp %dil, %sil
+ jl .Lcopy_backward
+ subq $0x20, %rdx
+.Lcopy_forward_loop:
+ subq $0x20, %rdx
+
+ /*
+ * Move in blocks of 4x8 bytes:
+ */
+ movq 0*8(%rsi), %r8
+ movq 1*8(%rsi), %r9
+ movq 2*8(%rsi), %r10
+ movq 3*8(%rsi), %r11
+ leaq 4*8(%rsi), %rsi
+
+ movq %r8, 0*8(%rdi)
+ movq %r9, 1*8(%rdi)
+ movq %r10, 2*8(%rdi)
+ movq %r11, 3*8(%rdi)
+ leaq 4*8(%rdi), %rdi
+ jae .Lcopy_forward_loop
+ addl $0x20, %edx
+ jmp .Lhandle_tail
+
+.Lcopy_backward:
+ /*
+ * Calculate copy position to tail.
+ */
+ addq %rdx, %rsi
+ addq %rdx, %rdi
+ subq $0x20, %rdx
+ /*
+ * At most 3 ALU operations in one cycle,
+ * so append NOPS in the same 16 bytes trunk.
+ */
+ .p2align 4
+.Lcopy_backward_loop:
+ subq $0x20, %rdx
+ movq -1*8(%rsi), %r8
+ movq -2*8(%rsi), %r9
+ movq -3*8(%rsi), %r10
+ movq -4*8(%rsi), %r11
+ leaq -4*8(%rsi), %rsi
+ movq %r8, -1*8(%rdi)
+ movq %r9, -2*8(%rdi)
+ movq %r10, -3*8(%rdi)
+ movq %r11, -4*8(%rdi)
+ leaq -4*8(%rdi), %rdi
+ jae .Lcopy_backward_loop
+
+ /*
+ * Calculate copy position to head.
+ */
+ addl $0x20, %edx
+ subq %rdx, %rsi
+ subq %rdx, %rdi
+.Lhandle_tail:
+ cmpl $16, %edx
+ jb .Lless_16bytes
+
+ /*
+ * Move data from 16 bytes to 31 bytes.
+ */
+ movq 0*8(%rsi), %r8
+ movq 1*8(%rsi), %r9
+ movq -2*8(%rsi, %rdx), %r10
+ movq -1*8(%rsi, %rdx), %r11
+ movq %r8, 0*8(%rdi)
+ movq %r9, 1*8(%rdi)
+ movq %r10, -2*8(%rdi, %rdx)
+ movq %r11, -1*8(%rdi, %rdx)
+ retq
+ .p2align 4
+.Lless_16bytes:
+ cmpl $8, %edx
+ jb .Lless_8bytes
+ /*
+ * Move data from 8 bytes to 15 bytes.
+ */
+ movq 0*8(%rsi), %r8
+ movq -1*8(%rsi, %rdx), %r9
+ movq %r8, 0*8(%rdi)
+ movq %r9, -1*8(%rdi, %rdx)
+ retq
+ .p2align 4
+.Lless_8bytes:
+ cmpl $4, %edx
+ jb .Lless_3bytes
+
+ /*
+ * Move data from 4 bytes to 7 bytes.
+ */
+ movl (%rsi), %ecx
+ movl -4(%rsi, %rdx), %r8d
+ movl %ecx, (%rdi)
+ movl %r8d, -4(%rdi, %rdx)
+ retq
+ .p2align 4
+.Lless_3bytes:
+ subl $1, %edx
+ jb .Lend
+ /*
+ * Move data from 1 bytes to 3 bytes.
+ */
+ movzbl (%rsi), %ecx
+ jz .Lstore_1byte
+ movzbq 1(%rsi), %r8
+ movzbq (%rsi, %rdx), %r9
+ movb %r8b, 1(%rdi)
+ movb %r9b, (%rdi, %rdx)
+.Lstore_1byte:
+ movb %cl, (%rdi)
+
+.Lend:
+ retq
+ CFI_ENDPROC
+ENDPROC(memcpy_orig)