On 2015-05-11 18:38, Josh Poimboeuf wrote:
> Frame pointer based stack traces aren't always reliable. One big reason
> is that most asm functions don't set up the frame pointer.
>
> Fix that by enforcing that all asm functions honor CONFIG_FRAME_POINTER.
> This is done with a new stackvalidate host tool which is automatically
> run for every compiled .S file and which validates that every asm
> function does the proper frame pointer setup.
>
> Also, to make sure somebody didn't forget to annotate their callable asm code
> as a function, flag an error for any return instructions which are hiding
> outside of a function. In almost all cases, return instructions are part of
> callable functions and should be annotated as such so that we can validate
> their frame pointer usage. A whitelist mechanism exists for those few return
> instructions which are not actually in callable code.
>
> It currently only supports x86_64. It *almost* supports x86_32, but the
> stackvalidate code doesn't yet know how to deal with 32-bit REL
> relocations for the return whitelists. I tried to make the code generic
> so that support for other architectures can be plugged in pretty easily.
>
> As a first step, all reported non-compliances result in warnings. Right
> now I'm seeing 200+ warnings. Once we get them all cleaned up, we can
> change the warnings to build errors so the asm code can stay clean.
>
> Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> ---
> MAINTAINERS | 6 +
> arch/Kconfig | 4 +
> arch/x86/Kconfig | 1 +
> arch/x86/Makefile | 6 +-
> lib/Kconfig.debug | 11 ++
> scripts/Makefile | 1 +
> scripts/Makefile.build | 22 ++-
For the kbuild parts: Acked-by: Michal Marek <mmarek@xxxxxxx>
> +int main(int argc, char *argv[])
> +{
> + struct args args;
> + struct elf *elf;
> + struct section *sec;
> + int ret, warnings = 0;
> +
> + argp_parse(&argp, argc, argv, 0, 0, &args);
> +
> + elf = elf_open(args.args[0]);
> + if (!elf) {
> + fprintf(stderr, "error reading elf file %s\n", args.args[0]);
> + return 1;
> + }
> +
> + if (is_file_whitelisted(elf))
> + return 0;
> +
> + list_for_each_entry(sec, &elf->sections, list) {
> + ret = validate_section(elf, sec);
> + if (ret < 0)
> + return -1;
return 1? Since this is the exit status of the program.
Michal
--
To unsubscribe from this list: send the line "unsubscribe live-patching" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
