Merge tag 'ras_updates_for_v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull RAS updates from Borislav Petkov:

 - Extend the recovery from MCE in kernel space also to processes which
   encounter an MCE in kernel space but while copying from user memory
   by sending them a SIGBUS on return to user space and umapping the
   faulty memory, by Tony Luck and Youquan Song.

 - memcpy_mcsafe() rework by splitting the functionality into
   copy_mc_to_user() and copy_mc_to_kernel(). This, as a result, enables
   support for new hardware which can recover from a machine check
   encountered during a fast string copy and makes that the default and
   lets the older hardware which does not support that advance recovery,
   opt in to use the old, fragile, slow variant, by Dan Williams.

 - New AMD hw enablement, by Yazen Ghannam and Akshay Gupta.

 - Do not use MSR-tracing accessors in #MC context and flag any fault
   while accessing MCA architectural MSRs as an architectural violation
   with the hope that such hw/fw misdesigns are caught early during the
   hw eval phase and they don't make it into production.

 - Misc fixes, improvements and cleanups, as always.

* tag 'ras_updates_for_v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mce: Allow for copy_mc_fragile symbol checksum to be generated
  x86/mce: Decode a kernel instruction to determine if it is copying from user
  x86/mce: Recover from poison found while copying from user space
  x86/mce: Avoid tail copy when machine check terminated a copy from user
  x86/mce: Add _ASM_EXTABLE_CPY for copy user access
  x86/mce: Provide method to find out the type of an exception handler
  x86/mce: Pass pointer to saved pt_regs to severity calculation routines
  x86/copy_mc: Introduce copy_mc_enhanced_fast_string()
  x86, powerpc: Rename memcpy_mcsafe() to copy_mc_to_{user, kernel}()
  x86/mce: Drop AMD-specific "DEFERRED" case from Intel severity rule list
  x86/mce: Add Skylake quirk for patrol scrub reported errors
  RAS/CEC: Convert to DEFINE_SHOW_ATTRIBUTE()
  x86/mce: Annotate mce_rd/wrmsrl() with noinstr
  x86/mce/dev-mcelog: Do not update kflags on AMD systems
  x86/mce: Stop mce_reign() from re-computing severity for every CPU
  x86/mce: Make mce_rdmsrl() panic on an inaccessible MSR
  x86/mce: Increase maximum number of banks to 64
  x86/mce: Delay clearing IA32_MCG_STATUS to the end of do_machine_check()
  x86/MCE/AMD, EDAC/mce_amd: Remove struct smca_hwid.xec_bitmap
  RAS/CEC: Fix cec_init() prototype

6 files changed, 323 insertions, 184 deletions

diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index aa067859a70b..bad4dee4f0e4 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -44,6 +44,7 @@ obj-$(CONFIG_SMP) += msr-smp.o cache-smp.o
 lib-y := delay.o misc.o cmdline.o cpu.o
 lib-y += usercopy_$(BITS).o usercopy.o getuser.o putuser.o
 lib-y += memcpy_$(BITS).o
+lib-$(CONFIG_ARCH_HAS_COPY_MC) += copy_mc.o copy_mc_64.o
 lib-$(CONFIG_INSTRUCTION_DECODER) += insn.o inat.o insn-eval.o
 lib-$(CONFIG_RANDOMIZE_BASE) += kaslr.o
 lib-$(CONFIG_FUNCTION_ERROR_INJECTION)	+= error-inject.o
diff --git a/arch/x86/lib/copy_mc.c b/arch/x86/lib/copy_mc.c
new file mode 100644
index 000000000000..c13e8c9ee926
--- /dev/null
+++ b/arch/x86/lib/copy_mc.c
@@ -0,0 +1,96 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright(c) 2016-2020 Intel Corporation. All rights reserved. */
+
+#include <linux/jump_label.h>
+#include <linux/uaccess.h>
+#include <linux/export.h>
+#include <linux/string.h>
+#include <linux/types.h>
+
+#include <asm/mce.h>
+
+#ifdef CONFIG_X86_MCE
+/*
+ * See COPY_MC_TEST for self-test of the copy_mc_fragile()
+ * implementation.
+ */
+static DEFINE_STATIC_KEY_FALSE(copy_mc_fragile_key);
+
+void enable_copy_mc_fragile(void)
+{
+	static_branch_inc(&copy_mc_fragile_key);
+}
+#define copy_mc_fragile_enabled (static_branch_unlikely(&copy_mc_fragile_key))
+
+/*
+ * Similar to copy_user_handle_tail, probe for the write fault point, or
+ * source exception point.
+ */
+__visible notrace unsigned long
+copy_mc_fragile_handle_tail(char *to, char *from, unsigned len)
+{
+	for (; len; --len, to++, from++)
+		if (copy_mc_fragile(to, from, 1))
+			break;
+	return len;
+}
+#else
+/*
+ * No point in doing careful copying, or consulting a static key when
+ * there is no #MC handler in the CONFIG_X86_MCE=n case.
+ */
+void enable_copy_mc_fragile(void)
+{
+}
+#define copy_mc_fragile_enabled (0)
+#endif
+
+unsigned long copy_mc_enhanced_fast_string(void *dst, const void *src, unsigned len);
+
+/**
+ * copy_mc_to_kernel - memory copy that handles source exceptions
+ *
+ * @dst:	destination address
+ * @src:	source address
+ * @len:	number of bytes to copy
+ *
+ * Call into the 'fragile' version on systems that benefit from avoiding
+ * corner case poison consumption scenarios, For example, accessing
+ * poison across 2 cachelines with a single instruction. Almost all
+ * other uses case can use copy_mc_enhanced_fast_string() for a fast
+ * recoverable copy, or fallback to plain memcpy.
+ *
+ * Return 0 for success, or number of bytes not copied if there was an
+ * exception.
+ */
+unsigned long __must_check copy_mc_to_kernel(void *dst, const void *src, unsigned len)
+{
+	if (copy_mc_fragile_enabled)
+		return copy_mc_fragile(dst, src, len);
+	if (static_cpu_has(X86_FEATURE_ERMS))
+		return copy_mc_enhanced_fast_string(dst, src, len);
+	memcpy(dst, src, len);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(copy_mc_to_kernel);
+
+unsigned long __must_check copy_mc_to_user(void *dst, const void *src, unsigned len)
+{
+	unsigned long ret;
+
+	if (copy_mc_fragile_enabled) {
+		__uaccess_begin();
+		ret = copy_mc_fragile(dst, src, len);
+		__uaccess_end();
+		return ret;
+	}
+
+	if (static_cpu_has(X86_FEATURE_ERMS)) {
+		__uaccess_begin();
+		ret = copy_mc_enhanced_fast_string(dst, src, len);
+		__uaccess_end();
+		return ret;
+	}
+
+	return copy_user_generic(dst, src, len);
+}
diff --git a/arch/x86/lib/copy_mc_64.S b/arch/x86/lib/copy_mc_64.S
new file mode 100644
index 000000000000..892d8915f609
--- /dev/null
+++ b/arch/x86/lib/copy_mc_64.S
@@ -0,0 +1,163 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Copyright(c) 2016-2020 Intel Corporation. All rights reserved. */
+
+#include <linux/linkage.h>
+#include <asm/copy_mc_test.h>
+#include <asm/export.h>
+#include <asm/asm.h>
+
+#ifndef CONFIG_UML
+
+#ifdef CONFIG_X86_MCE
+COPY_MC_TEST_CTL
+
+/*
+ * copy_mc_fragile - copy memory with indication if an exception / fault happened
+ *
+ * The 'fragile' version is opted into by platform quirks and takes
+ * pains to avoid unrecoverable corner cases like 'fast-string'
+ * instruction sequences, and consuming poison across a cacheline
+ * boundary. The non-fragile version is equivalent to memcpy()
+ * regardless of CPU machine-check-recovery capability.
+ */
+SYM_FUNC_START(copy_mc_fragile)
+	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_read_leading_bytes:
+	movb (%rsi), %al
+	COPY_MC_TEST_SRC %rsi 1 .E_leading_bytes
+	COPY_MC_TEST_DST %rdi 1 .E_leading_bytes
+.L_write_leading_bytes:
+	movb %al, (%rdi)
+	incq %rsi
+	incq %rdi
+	decl %ecx
+	jnz .L_read_leading_bytes
+
+.L_8byte_aligned:
+	movl %edx, %ecx
+	andl $7, %edx
+	shrl $3, %ecx
+	jz .L_no_whole_words
+
+.L_read_words:
+	movq (%rsi), %r8
+	COPY_MC_TEST_SRC %rsi 8 .E_read_words
+	COPY_MC_TEST_DST %rdi 8 .E_write_words
+.L_write_words:
+	movq %r8, (%rdi)
+	addq $8, %rsi
+	addq $8, %rdi
+	decl %ecx
+	jnz .L_read_words
+
+	/* Any trailing bytes? */
+.L_no_whole_words:
+	andl %edx, %edx
+	jz .L_done_memcpy_trap
+
+	/* Copy trailing bytes */
+	movl %edx, %ecx
+.L_read_trailing_bytes:
+	movb (%rsi), %al
+	COPY_MC_TEST_SRC %rsi 1 .E_trailing_bytes
+	COPY_MC_TEST_DST %rdi 1 .E_trailing_bytes
+.L_write_trailing_bytes:
+	movb %al, (%rdi)
+	incq %rsi
+	incq %rdi
+	decl %ecx
+	jnz .L_read_trailing_bytes
+
+	/* Copy successful. Return zero */
+.L_done_memcpy_trap:
+	xorl %eax, %eax
+.L_done:
+	ret
+SYM_FUNC_END(copy_mc_fragile)
+EXPORT_SYMBOL_GPL(copy_mc_fragile)
+
+	.section .fixup, "ax"
+	/*
+	 * Return number of bytes not copied for any failure. Note that
+	 * there is no "tail" handling since the source buffer is 8-byte
+	 * aligned and poison is cacheline aligned.
+	 */
+.E_read_words:
+	shll	$3, %ecx
+.E_leading_bytes:
+	addl	%edx, %ecx
+.E_trailing_bytes:
+	mov	%ecx, %eax
+	jmp	.L_done
+
+	/*
+	 * For write fault handling, given the destination is unaligned,
+	 * we handle faults on multi-byte writes with a byte-by-byte
+	 * copy up to the write-protected page.
+	 */
+.E_write_words:
+	shll	$3, %ecx
+	addl	%edx, %ecx
+	movl	%ecx, %edx
+	jmp copy_mc_fragile_handle_tail
+
+	.previous
+
+	_ASM_EXTABLE_FAULT(.L_read_leading_bytes, .E_leading_bytes)
+	_ASM_EXTABLE_FAULT(.L_read_words, .E_read_words)
+	_ASM_EXTABLE_FAULT(.L_read_trailing_bytes, .E_trailing_bytes)
+	_ASM_EXTABLE(.L_write_leading_bytes, .E_leading_bytes)
+	_ASM_EXTABLE(.L_write_words, .E_write_words)
+	_ASM_EXTABLE(.L_write_trailing_bytes, .E_trailing_bytes)
+#endif /* CONFIG_X86_MCE */
+
+/*
+ * copy_mc_enhanced_fast_string - memory copy with exception handling
+ *
+ * Fast string copy + fault / exception handling. If the CPU does
+ * support machine check exception recovery, but does not support
+ * recovering from fast-string exceptions then this CPU needs to be
+ * added to the copy_mc_fragile_key set of quirks. Otherwise, absent any
+ * machine check recovery support this version should be no slower than
+ * standard memcpy.
+ */
+SYM_FUNC_START(copy_mc_enhanced_fast_string)
+	movq %rdi, %rax
+	movq %rdx, %rcx
+.L_copy:
+	rep movsb
+	/* Copy successful. Return zero */
+	xorl %eax, %eax
+	ret
+SYM_FUNC_END(copy_mc_enhanced_fast_string)
+
+	.section .fixup, "ax"
+.E_copy:
+	/*
+	 * On fault %rcx is updated such that the copy instruction could
+	 * optionally be restarted at the fault position, i.e. it
+	 * contains 'bytes remaining'. A non-zero return indicates error
+	 * to copy_mc_generic() users, or indicate short transfers to
+	 * user-copy routines.
+	 */
+	movq %rcx, %rax
+	ret
+
+	.previous
+
+	_ASM_EXTABLE_FAULT(.L_copy, .E_copy)
+#endif /* !CONFIG_UML */
diff --git a/arch/x86/lib/copy_user_64.S b/arch/x86/lib/copy_user_64.S
index 816f128a6d52..77b9b2a3b5c8 100644
--- a/arch/x86/lib/copy_user_64.S
+++ b/arch/x86/lib/copy_user_64.S
@@ -15,6 +15,7 @@
 #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 */
@@ -36,8 +37,8 @@
 	jmp .Lcopy_user_handle_tail
 	.previous
 
-	_ASM_EXTABLE_UA(100b, 103b)
-	_ASM_EXTABLE_UA(101b, 103b)
+	_ASM_EXTABLE_CPY(100b, 103b)
+	_ASM_EXTABLE_CPY(101b, 103b)
 	.endm
 
 /*
@@ -116,26 +117,26 @@ SYM_FUNC_START(copy_user_generic_unrolled)
 60:	jmp .Lcopy_user_handle_tail /* ecx is zerorest also */
 	.previous
 
-	_ASM_EXTABLE_UA(1b, 30b)
-	_ASM_EXTABLE_UA(2b, 30b)
-	_ASM_EXTABLE_UA(3b, 30b)
-	_ASM_EXTABLE_UA(4b, 30b)
-	_ASM_EXTABLE_UA(5b, 30b)
-	_ASM_EXTABLE_UA(6b, 30b)
-	_ASM_EXTABLE_UA(7b, 30b)
-	_ASM_EXTABLE_UA(8b, 30b)
-	_ASM_EXTABLE_UA(9b, 30b)
-	_ASM_EXTABLE_UA(10b, 30b)
-	_ASM_EXTABLE_UA(11b, 30b)
-	_ASM_EXTABLE_UA(12b, 30b)
-	_ASM_EXTABLE_UA(13b, 30b)
-	_ASM_EXTABLE_UA(14b, 30b)
-	_ASM_EXTABLE_UA(15b, 30b)
-	_ASM_EXTABLE_UA(16b, 30b)
-	_ASM_EXTABLE_UA(18b, 40b)
-	_ASM_EXTABLE_UA(19b, 40b)
-	_ASM_EXTABLE_UA(21b, 50b)
-	_ASM_EXTABLE_UA(22b, 50b)
+	_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)
+	_ASM_EXTABLE_CPY(18b, 40b)
+	_ASM_EXTABLE_CPY(19b, 40b)
+	_ASM_EXTABLE_CPY(21b, 50b)
+	_ASM_EXTABLE_CPY(22b, 50b)
 SYM_FUNC_END(copy_user_generic_unrolled)
 EXPORT_SYMBOL(copy_user_generic_unrolled)
 
@@ -180,8 +181,8 @@ SYM_FUNC_START(copy_user_generic_string)
 	jmp .Lcopy_user_handle_tail
 	.previous
 
-	_ASM_EXTABLE_UA(1b, 11b)
-	_ASM_EXTABLE_UA(3b, 12b)
+	_ASM_EXTABLE_CPY(1b, 11b)
+	_ASM_EXTABLE_CPY(3b, 12b)
 SYM_FUNC_END(copy_user_generic_string)
 EXPORT_SYMBOL(copy_user_generic_string)
 
@@ -213,7 +214,7 @@ SYM_FUNC_START(copy_user_enhanced_fast_string)
 	jmp .Lcopy_user_handle_tail
 	.previous
 
-	_ASM_EXTABLE_UA(1b, 12b)
+	_ASM_EXTABLE_CPY(1b, 12b)
 SYM_FUNC_END(copy_user_enhanced_fast_string)
 EXPORT_SYMBOL(copy_user_enhanced_fast_string)
 
@@ -221,6 +222,7 @@ 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
  *
  * Input:
  * rdi destination
@@ -232,12 +234,25 @@ EXPORT_SYMBOL(copy_user_enhanced_fast_string)
  */
 SYM_CODE_START_LOCAL(.Lcopy_user_handle_tail)
 	movl %edx,%ecx
+	cmp $X86_TRAP_MC,%eax		/* check if X86_TRAP_MC */
+	je 3f
 1:	rep movsb
 2:	mov %ecx,%eax
 	ASM_CLAC
 	ret
 
-	_ASM_EXTABLE_UA(1b, 2b)
+	/*
+	 * Return zero to pretend that this copy succeeded. This
+	 * is counter-intuitive, but needed to prevent the code
+	 * in lib/iov_iter.c from retrying and running back into
+	 * the poison cache line again. The machine check handler
+	 * will ensure that a SIGBUS is sent to the task.
+	 */
+3:	xorl %eax,%eax
+	ASM_CLAC
+	ret
+
+	_ASM_EXTABLE_CPY(1b, 2b)
 SYM_CODE_END(.Lcopy_user_handle_tail)
 
 /*
@@ -366,27 +381,27 @@ SYM_FUNC_START(__copy_user_nocache)
 	jmp .Lcopy_user_handle_tail
 	.previous
 
-	_ASM_EXTABLE_UA(1b, .L_fixup_4x8b_copy)
-	_ASM_EXTABLE_UA(2b, .L_fixup_4x8b_copy)
-	_ASM_EXTABLE_UA(3b, .L_fixup_4x8b_copy)
-	_ASM_EXTABLE_UA(4b, .L_fixup_4x8b_copy)
-	_ASM_EXTABLE_UA(5b, .L_fixup_4x8b_copy)
-	_ASM_EXTABLE_UA(6b, .L_fixup_4x8b_copy)
-	_ASM_EXTABLE_UA(7b, .L_fixup_4x8b_copy)
-	_ASM_EXTABLE_UA(8b, .L_fixup_4x8b_copy)
-	_ASM_EXTABLE_UA(9b, .L_fixup_4x8b_copy)
-	_ASM_EXTABLE_UA(10b, .L_fixup_4x8b_copy)
-	_ASM_EXTABLE_UA(11b, .L_fixup_4x8b_copy)
-	_ASM_EXTABLE_UA(12b, .L_fixup_4x8b_copy)
-	_ASM_EXTABLE_UA(13b, .L_fixup_4x8b_copy)
-	_ASM_EXTABLE_UA(14b, .L_fixup_4x8b_copy)
-	_ASM_EXTABLE_UA(15b, .L_fixup_4x8b_copy)
-	_ASM_EXTABLE_UA(16b, .L_fixup_4x8b_copy)
-	_ASM_EXTABLE_UA(20b, .L_fixup_8b_copy)
-	_ASM_EXTABLE_UA(21b, .L_fixup_8b_copy)
-	_ASM_EXTABLE_UA(30b, .L_fixup_4b_copy)
-	_ASM_EXTABLE_UA(31b, .L_fixup_4b_copy)
-	_ASM_EXTABLE_UA(40b, .L_fixup_1b_copy)
-	_ASM_EXTABLE_UA(41b, .L_fixup_1b_copy)
+	_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)
diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S
index bbcc05bcefad..037faac46b0c 100644
--- a/arch/x86/lib/memcpy_64.S
+++ b/arch/x86/lib/memcpy_64.S
@@ -4,7 +4,6 @@
 #include <linux/linkage.h>
 #include <asm/errno.h>
 #include <asm/cpufeatures.h>
-#include <asm/mcsafe_test.h>
 #include <asm/alternative-asm.h>
 #include <asm/export.h>
 
@@ -187,117 +186,3 @@ SYM_FUNC_START_LOCAL(memcpy_orig)
 SYM_FUNC_END(memcpy_orig)
 
 .popsection
-
-#ifndef CONFIG_UML
-
-MCSAFE_TEST_CTL
-
-/*
- * __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.
- */
-SYM_FUNC_START(__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_read_leading_bytes:
-	movb (%rsi), %al
-	MCSAFE_TEST_SRC %rsi 1 .E_leading_bytes
-	MCSAFE_TEST_DST %rdi 1 .E_leading_bytes
-.L_write_leading_bytes:
-	movb %al, (%rdi)
-	incq %rsi
-	incq %rdi
-	decl %ecx
-	jnz .L_read_leading_bytes
-
-.L_8byte_aligned:
-	movl %edx, %ecx
-	andl $7, %edx
-	shrl $3, %ecx
-	jz .L_no_whole_words
-
-.L_read_words:
-	movq (%rsi), %r8
-	MCSAFE_TEST_SRC %rsi 8 .E_read_words
-	MCSAFE_TEST_DST %rdi 8 .E_write_words
-.L_write_words:
-	movq %r8, (%rdi)
-	addq $8, %rsi
-	addq $8, %rdi
-	decl %ecx
-	jnz .L_read_words
-
-	/* Any trailing bytes? */
-.L_no_whole_words:
-	andl %edx, %edx
-	jz .L_done_memcpy_trap
-
-	/* Copy trailing bytes */
-	movl %edx, %ecx
-.L_read_trailing_bytes:
-	movb (%rsi), %al
-	MCSAFE_TEST_SRC %rsi 1 .E_trailing_bytes
-	MCSAFE_TEST_DST %rdi 1 .E_trailing_bytes
-.L_write_trailing_bytes:
-	movb %al, (%rdi)
-	incq %rsi
-	incq %rdi
-	decl %ecx
-	jnz .L_read_trailing_bytes
-
-	/* Copy successful. Return zero */
-.L_done_memcpy_trap:
-	xorl %eax, %eax
-.L_done:
-	ret
-SYM_FUNC_END(__memcpy_mcsafe)
-EXPORT_SYMBOL_GPL(__memcpy_mcsafe)
-
-	.section .fixup, "ax"
-	/*
-	 * Return number of bytes not copied for any failure. Note that
-	 * there is no "tail" handling since the source buffer is 8-byte
-	 * aligned and poison is cacheline aligned.
-	 */
-.E_read_words:
-	shll	$3, %ecx
-.E_leading_bytes:
-	addl	%edx, %ecx
-.E_trailing_bytes:
-	mov	%ecx, %eax
-	jmp	.L_done
-
-	/*
-	 * For write fault handling, given the destination is unaligned,
-	 * we handle faults on multi-byte writes with a byte-by-byte
-	 * copy up to the write-protected page.
-	 */
-.E_write_words:
-	shll	$3, %ecx
-	addl	%edx, %ecx
-	movl	%ecx, %edx
-	jmp mcsafe_handle_tail
-
-	.previous
-
-	_ASM_EXTABLE_FAULT(.L_read_leading_bytes, .E_leading_bytes)
-	_ASM_EXTABLE_FAULT(.L_read_words, .E_read_words)
-	_ASM_EXTABLE_FAULT(.L_read_trailing_bytes, .E_trailing_bytes)
-	_ASM_EXTABLE(.L_write_leading_bytes, .E_leading_bytes)
-	_ASM_EXTABLE(.L_write_words, .E_write_words)
-	_ASM_EXTABLE(.L_write_trailing_bytes, .E_trailing_bytes)
-#endif
diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c
index 1847e993ac63..508c81e97ab1 100644
--- a/arch/x86/lib/usercopy_64.c
+++ b/arch/x86/lib/usercopy_64.c
@@ -56,27 +56,6 @@ unsigned long clear_user(void __user *to, unsigned long n)
 }
 EXPORT_SYMBOL(clear_user);
 
-/*
- * Similar to copy_user_handle_tail, probe for the write fault point,
- * but reuse __memcpy_mcsafe in case a new read error is encountered.
- * clac() is handled in _copy_to_iter_mcsafe().
- */
-__visible notrace unsigned long
-mcsafe_handle_tail(char *to, char *from, unsigned len)
-{
-	for (; len; --len, to++, from++) {
-		/*
-		 * Call the assembly routine back directly since
-		 * memcpy_mcsafe() may silently fallback to memcpy.
-		 */
-		unsigned long rem = __memcpy_mcsafe(to, from, 1);
-
-		if (rem)
-			break;
-	}
-	return len;
-}
-
 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
 /**
  * clean_cache_range - write back a cache range with CLWB