On Thu, Sep 28, 2017 at 01:42:31PM +0100, Dave Martin wrote: > On Thu, Sep 28, 2017 at 11:55:47AM +0100, Will Deacon wrote: > > 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. > > Any idea why this doesn't affect other arches too ... or does it?
I'm not sure, although I don't know how .inst works for architectures with variable-length instructions and I *guess* the disassembly is less fussy about data vs text for those targets. > > 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. > > > > Signed-off-by: Will Deacon <[email protected]> > > > > --- > > scripts/decodecode | 8 ++++++++ > > 1 file changed, 8 insertions(+) > > > > diff --git a/scripts/decodecode b/scripts/decodecode > > index d8824f37acce..67214ec5b2cb 100755 > > --- a/scripts/decodecode > > +++ b/scripts/decodecode > > @@ -58,6 +58,14 @@ disas() { > > ${CROSS_COMPILE}strip $1.o > > fi > > > > + if [ "$ARCH" = "arm64" ]; then > > + if [ $width -eq 4 ]; then > > + type=inst > > Can we merge with arm here, or does arm still support toolchains that > don't have .inst? Anyway, no big deal. I thought we still supported those, so I'd be reluctant to merge the clauses unless it's broken (the script works as-is for me with arm). I'm also not sure what we should do for 16-bit Thumb-2 encodings, where we have inst.n and inst.w to contend with. > > + fi > > + > > + ${CROSS_COMPILE}strip $1.o > > + fi > > + > > ${CROSS_COMPILE}objdump $OBJDUMPFLAGS -S $1.o | \ > > grep -v "/tmp\|Disassembly\|\.text\|^$" > $1.dis 2>&1 > > FWIW, > > Reviewed-by: Dave Martin <[email protected]> Thanks! Will
