On Wed, Oct 14, 2020 at 12:29 AM Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote: > > On Mon, 12 Oct 2020 10:39:49 -0500 > Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote: > > > On Mon, Oct 12, 2020 at 09:12:36AM +0900, Masami Hiramatsu wrote: > > > On Sat, 10 Oct 2020 12:44:15 -0500 > > > Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote: > > > > > > > On Fri, Oct 09, 2020 at 10:49:21PM +0200, Borislav Petkov wrote: > > > > > On Fri, Oct 09, 2020 at 10:38:22PM +0200, Peter Zijlstra wrote: > > > > > > On Wed, Oct 07, 2020 at 04:20:19PM -0000, tip-bot2 for Martin Schwidefsky wrote: > > > > > > > The following commit has been merged into the objtool/core branch of tip: > > > > > > > > > > > > > > Commit-ID: 2a522b53c47051d3bf98748418f4f8e5f20d2c04 > > > > > > > Gitweb: https://git.kernel.org/tip/2a522b53c47051d3bf98748418f4f8e5f20d2c04 > > > > > > > Author: Martin Schwidefsky <schwidefsky@xxxxxxxxxx> > > > > > > > AuthorDate: Mon, 05 Oct 2020 17:50:31 +02:00 > > > > > > > Committer: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> > > > > > > > CommitterDate: Tue, 06 Oct 2020 09:32:29 -05:00 > > > > > > > > > > > > > > x86/insn: Support big endian cross-compiles > > > > > > > > > > > > > > x86 instruction decoder code is shared across the kernel source and the > > > > > > > tools. Currently objtool seems to be the only tool from build tools needed > > > > > > > which breaks x86 cross compilation on big endian systems. Make the x86 > > > > > > > instruction decoder build host endianness agnostic to support x86 cross > > > > > > > compilation and enable objtool to implement endianness awareness for > > > > > > > big endian architectures support. > > > > > > > > > > > > > > Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx> > > > > > > > Co-developed-by: Vasily Gorbik <gor@xxxxxxxxxxxxx> > > > > > > > Signed-off-by: Vasily Gorbik <gor@xxxxxxxxxxxxx> > > > > > > > Acked-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx> > > > > > > > Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> > > > > > > > > > > > > This commit breaks the x86 build with CONFIG_X86_DECODER_SELFTEST=y. > > > > > > > > > > > > I've asked Boris to truncate tip/objtool/core. > > > > > > > > > > Yeah, top 4 are gone until this is resolved. > > > > > > > > Masami, I wonder if we even need these selftests anymore? Objtool > > > > already decodes the entire kernel. > > > > > > No, they have different roles. The selftest checks if the decoder > > > works correctly by comparing with the output of objdump. > > > > > > As far as I can see, the objtool relies on the sanity of the decoder > > > (it trusts the output of the decoder). > > > > Ok. I wonder if we should move the decoder selftest to the 'tools' > > subdirectory. > > It is in the arch/x86/tools, so it is already in a kind of tools :) > But yeah, it was considered to be used only on x86. But if someone > start trying to run it on non-x86, cross compiling, we need to > reconsider that. > > Thank you, > > -- > Masami Hiramatsu <mhiramat@xxxxxxxxxx> There is undefined behavior that is present in the x86 insn.c code as described in: https://lore.kernel.org/lkml/20190724184512.162887-4-nums@xxxxxxxxxx/ I resent this patch fixing other potential undefined behavior: https://lore.kernel.org/lkml/20201015062148.1437894-1-irogers@xxxxxxxxxx/T/#t The misaligned loads will likely break on anything non-x86. Thanks, Ian
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