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-rw-r--r--arch/x86/include/asm/string_64.h13
-rw-r--r--arch/x86/kernel/x8664_ksyms_64.c2
-rw-r--r--arch/x86/lib/memcpy_64.S117
3 files changed, 132 insertions, 0 deletions
diff --git a/arch/x86/include/asm/string_64.h b/arch/x86/include/asm/string_64.h
index ff8b9a17dc4b..ca6ba3607705 100644
--- a/arch/x86/include/asm/string_64.h
+++ b/arch/x86/include/asm/string_64.h
@@ -78,6 +78,19 @@ int strcmp(const char *cs, const char *ct);
#define memset(s, c, n) __memset(s, c, n)
#endif
+/**
+ * memcpy_mcsafe - copy memory with indication if a machine check happened
+ *
+ * @dst: destination address
+ * @src: source address
+ * @cnt: number of bytes to copy
+ *
+ * Low level memory copy function that catches machine checks
+ *
+ * Return true for success, false for fail
+ */
+bool memcpy_mcsafe(void *dst, const void *src, size_t cnt);
+
#endif /* __KERNEL__ */
#endif /* _ASM_X86_STRING_64_H */
diff --git a/arch/x86/kernel/x8664_ksyms_64.c b/arch/x86/kernel/x8664_ksyms_64.c
index a0695be19864..cd05942bc918 100644
--- a/arch/x86/kernel/x8664_ksyms_64.c
+++ b/arch/x86/kernel/x8664_ksyms_64.c
@@ -37,6 +37,8 @@ EXPORT_SYMBOL(__copy_user_nocache);
EXPORT_SYMBOL(_copy_from_user);
EXPORT_SYMBOL(_copy_to_user);
+EXPORT_SYMBOL_GPL(memcpy_mcsafe);
+
EXPORT_SYMBOL(copy_page);
EXPORT_SYMBOL(clear_page);
diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S
index 16698bba87de..7d37641ada5b 100644
--- a/arch/x86/lib/memcpy_64.S
+++ b/arch/x86/lib/memcpy_64.S
@@ -177,3 +177,120 @@ ENTRY(memcpy_orig)
.Lend:
retq
ENDPROC(memcpy_orig)
+
+#ifndef CONFIG_UML
+/*
+ * memcpy_mcsafe - memory copy with machine check exception handling
+ * Note that we only catch machine checks when reading the source addresses.
+ * Writes to target are posted and don't generate machine checks.
+ */
+ENTRY(memcpy_mcsafe)
+ cmpl $8, %edx
+ /* Less than 8 bytes? Go to byte copy loop */
+ jb .L_no_whole_words
+
+ /* Check for bad alignment of source */
+ testl $7, %esi
+ /* Already aligned */
+ jz .L_8byte_aligned
+
+ /* Copy one byte at a time until source is 8-byte aligned */
+ movl %esi, %ecx
+ andl $7, %ecx
+ subl $8, %ecx
+ negl %ecx
+ subl %ecx, %edx
+.L_copy_leading_bytes:
+ movb (%rsi), %al
+ movb %al, (%rdi)
+ incq %rsi
+ incq %rdi
+ decl %ecx
+ jnz .L_copy_leading_bytes
+
+.L_8byte_aligned:
+ /* Figure out how many whole cache lines (64-bytes) to copy */
+ movl %edx, %ecx
+ andl $63, %edx
+ shrl $6, %ecx
+ jz .L_no_whole_cache_lines
+
+ /* Loop copying whole cache lines */
+.L_cache_w0: movq (%rsi), %r8
+.L_cache_w1: movq 1*8(%rsi), %r9
+.L_cache_w2: movq 2*8(%rsi), %r10
+.L_cache_w3: movq 3*8(%rsi), %r11
+ movq %r8, (%rdi)
+ movq %r9, 1*8(%rdi)
+ movq %r10, 2*8(%rdi)
+ movq %r11, 3*8(%rdi)
+.L_cache_w4: movq 4*8(%rsi), %r8
+.L_cache_w5: movq 5*8(%rsi), %r9
+.L_cache_w6: movq 6*8(%rsi), %r10
+.L_cache_w7: movq 7*8(%rsi), %r11
+ movq %r8, 4*8(%rdi)
+ movq %r9, 5*8(%rdi)
+ movq %r10, 6*8(%rdi)
+ movq %r11, 7*8(%rdi)
+ leaq 64(%rsi), %rsi
+ leaq 64(%rdi), %rdi
+ decl %ecx
+ jnz .L_cache_w0
+
+ /* Are there any trailing 8-byte words? */
+.L_no_whole_cache_lines:
+ movl %edx, %ecx
+ andl $7, %edx
+ shrl $3, %ecx
+ jz .L_no_whole_words
+
+ /* Copy trailing words */
+.L_copy_trailing_words:
+ movq (%rsi), %r8
+ mov %r8, (%rdi)
+ leaq 8(%rsi), %rsi
+ leaq 8(%rdi), %rdi
+ decl %ecx
+ jnz .L_copy_trailing_words
+
+ /* Any trailing bytes? */
+.L_no_whole_words:
+ andl %edx, %edx
+ jz .L_done_memcpy_trap
+
+ /* Copy trailing bytes */
+ movl %edx, %ecx
+.L_copy_trailing_bytes:
+ movb (%rsi), %al
+ movb %al, (%rdi)
+ incq %rsi
+ incq %rdi
+ decl %ecx
+ jnz .L_copy_trailing_bytes
+
+ /* Copy successful. Return true */
+.L_done_memcpy_trap:
+ xorq %rax, %rax
+ ret
+ENDPROC(memcpy_mcsafe)
+
+ .section .fixup, "ax"
+ /* Return false for any failure */
+.L_memcpy_mcsafe_fail:
+ mov $1, %rax
+ ret
+
+ .previous
+
+ _ASM_EXTABLE_FAULT(.L_copy_leading_bytes, .L_memcpy_mcsafe_fail)
+ _ASM_EXTABLE_FAULT(.L_cache_w0, .L_memcpy_mcsafe_fail)
+ _ASM_EXTABLE_FAULT(.L_cache_w1, .L_memcpy_mcsafe_fail)
+ _ASM_EXTABLE_FAULT(.L_cache_w3, .L_memcpy_mcsafe_fail)
+ _ASM_EXTABLE_FAULT(.L_cache_w3, .L_memcpy_mcsafe_fail)
+ _ASM_EXTABLE_FAULT(.L_cache_w4, .L_memcpy_mcsafe_fail)
+ _ASM_EXTABLE_FAULT(.L_cache_w5, .L_memcpy_mcsafe_fail)
+ _ASM_EXTABLE_FAULT(.L_cache_w6, .L_memcpy_mcsafe_fail)
+ _ASM_EXTABLE_FAULT(.L_cache_w7, .L_memcpy_mcsafe_fail)
+ _ASM_EXTABLE_FAULT(.L_copy_trailing_words, .L_memcpy_mcsafe_fail)
+ _ASM_EXTABLE_FAULT(.L_copy_trailing_bytes, .L_memcpy_mcsafe_fail)
+#endif