From bd131544aa7e318a5735cbcbad46c4a5ee6b9d42 Mon Sep 17 00:00:00 2001
From: Dan Williams <dan.j.williams@intel.com>
Date: Thu, 3 May 2018 17:06:16 -0700
Subject: [PATCH] x86/asm/memcpy_mcsafe: Add labels for __memcpy_mcsafe() write
 fault handling
Git-commit: bd131544aa7e318a5735cbcbad46c4a5ee6b9d42
Patch-mainline: v4.18-rc1
References: bsc#1098782

The memcpy_mcsafe() implementation handles CPU exceptions when reading
from the source address. Before it can be used for user copies it needs
to grow support for handling write faults. In preparation for adding
that exception handling update the labels for the read cache word X case
(.L_cache_rX) and write cache word X case (.L_cache_wX).

Reported-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: hch@lst.de
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-nvdimm@lists.01.org
Link: http://lkml.kernel.org/r/152539237606.31796.6719743548991782264.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Jan Kara <jack@suse.cz>

---
 arch/x86/lib/memcpy_64.S | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S
index 54c971892db5..5709f3ec22a4 100644
--- a/arch/x86/lib/memcpy_64.S
+++ b/arch/x86/lib/memcpy_64.S
@@ -204,13 +204,14 @@ ENTRY(__memcpy_mcsafe)
 	subl $8, %ecx
 	negl %ecx
 	subl %ecx, %edx
-.L_copy_leading_bytes:
+.L_read_leading_bytes:
 	movb (%rsi), %al
+.L_write_leading_bytes:
 	movb %al, (%rdi)
 	incq %rsi
 	incq %rdi
 	decl %ecx
-	jnz .L_copy_leading_bytes
+	jnz .L_read_leading_bytes
 
 .L_8byte_aligned:
 	movl %edx, %ecx
@@ -218,13 +219,14 @@ ENTRY(__memcpy_mcsafe)
 	shrl $3, %ecx
 	jz .L_no_whole_words
 
-.L_copy_words:
+.L_read_words:
 	movq (%rsi), %r8
+.L_write_words:
 	movq %r8, (%rdi)
 	addq $8, %rsi
 	addq $8, %rdi
 	decl %ecx
-	jnz .L_copy_words
+	jnz .L_read_words
 
 	/* Any trailing bytes? */
 .L_no_whole_words:
@@ -233,13 +235,14 @@ ENTRY(__memcpy_mcsafe)
 
 	/* Copy trailing bytes */
 	movl %edx, %ecx
-.L_copy_trailing_bytes:
+.L_read_trailing_bytes:
 	movb (%rsi), %al
+.L_write_trailing_bytes:
 	movb %al, (%rdi)
 	incq %rsi
 	incq %rdi
 	decl %ecx
-	jnz .L_copy_trailing_bytes
+	jnz .L_read_trailing_bytes
 
 	/* Copy successful. Return zero */
 .L_done_memcpy_trap:
@@ -256,7 +259,7 @@ EXPORT_SYMBOL_GPL(__memcpy_mcsafe)
 
 	.previous
 
-	_ASM_EXTABLE_FAULT(.L_copy_leading_bytes, .L_memcpy_mcsafe_fail)
-	_ASM_EXTABLE_FAULT(.L_copy_words, .L_memcpy_mcsafe_fail)
-	_ASM_EXTABLE_FAULT(.L_copy_trailing_bytes, .L_memcpy_mcsafe_fail)
+	_ASM_EXTABLE_FAULT(.L_read_leading_bytes, .L_memcpy_mcsafe_fail)
+	_ASM_EXTABLE_FAULT(.L_read_words, .L_memcpy_mcsafe_fail)
+	_ASM_EXTABLE_FAULT(.L_read_trailing_bytes, .L_memcpy_mcsafe_fail)
 #endif
-- 
2.16.4