scripts/decodecode: fix decoding for AArch64 (arm64) instructions

There are a couple of problems with the decodecode script and arm64:

1. AArch64 objdump refuses to disassemble .4byte directives as instructions,
   insisting that they are data values and displaying them as:

	a94153f3	.word	0xa94153f3		<-- trapping instruction

   This is resolved by using the .inst directive instead.

2. Disassembly of branch instructions attempts to provide the target as
   an offset from a symbol, e.g.:

   0:	34000082	cbz	w2, 10 <.text+0x10>

  however this falls foul of the grep -v, which matches lines containing
  ".text" and ends up removing all branch instructions from the dump.

This patch resolves both issues by using the .inst directive for 4-byte
quantities on arm64 and stripping the resulting binaries (as is done on
arm already) to remove the mapping symbols.

Link: http://lkml.kernel.org/r/1506596147-23630-1-git-send-email-will.deacon@arm.com
Signed-off-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Cc: Michal Marek <mmarek@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/scripts/decodecode b/scripts/decodecode
index 438120da1361002833a2014b1ca3fb02cc0aa539..5ea07109933043888b802c9252205c7da3b7705c 100755 (executable)
--- a/scripts/decodecode
+++ b/scripts/decodecode
@@ -59,6 +59,14 @@ disas() {
                ${CROSS_COMPILE}strip $1.o
        fi
 
+       if [ "$ARCH" = "arm64" ]; then
+               if [ $width -eq 4 ]; then
+                       type=inst
+               fi
+
+               ${CROSS_COMPILE}strip $1.o
+       fi
+
        ${CROSS_COMPILE}objdump $OBJDUMPFLAGS -S $1.o | \
                grep -v "/tmp\|Disassembly\|\.text\|^$" > $1.dis 2>&1
 }