x86/asm/memcpy_mcsafe: Add labels for __memcpy_mcsafe() write fault handling

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>

diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S
index 54c9718..5709f3e 100644 (file)
--- 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