* Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote:
> Add a new objtool ignore macro, STACK_FRAME_NON_STANDARD, which can be
> used to tell objtool to skip validation of a function.
>
> Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> ---
> MAINTAINERS | 1 +
> arch/x86/kernel/vmlinux.lds.S | 5 ++++-
> include/linux/objtool.h | 22 ++++++++++++++++++++++
> 3 files changed, 27 insertions(+), 1 deletion(-)
> create mode 100644 include/linux/objtool.h
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 7c7cebd..43a940e 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -7782,6 +7782,7 @@ OBJTOOL
> M: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> S: Supported
> F: tools/objtool/
> +F: include/linux/objtool.h
>
> OMAP SUPPORT
> M: Tony Lindgren <tony@xxxxxxxxxxx>
> diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
> index 92dc211..6038fe0 100644
> --- a/arch/x86/kernel/vmlinux.lds.S
> +++ b/arch/x86/kernel/vmlinux.lds.S
> @@ -343,7 +343,10 @@ SECTIONS
>
> /* Sections to be discarded */
> DISCARDS
> - /DISCARD/ : { *(.eh_frame) }
> + /DISCARD/ : {
> + *(.eh_frame)
> + *(__objtool_ignore_*)
> + }
> }
>
>
> diff --git a/include/linux/objtool.h b/include/linux/objtool.h
> new file mode 100644
> index 0000000..cce9d67
> --- /dev/null
> +++ b/include/linux/objtool.h
So I think this should really be in asm/frame.h, not in an objtool specific
header.
> @@ -0,0 +1,22 @@
> +#ifndef _LINUX_OBJTOOL_H
> +#define _LINUX_OBJTOOL_H
> +
> +#ifdef CONFIG_STACK_VALIDATION
> +/*
> + * This C macro tells objtool to ignore the function when doing stack metadata
> + * validation. It should only be used in special cases where you're 100% sure
> + * it won't affect the reliability of frame pointers and kernel stack traces.
> + *
> + * For more information, see tools/objtool/Documentation/stack-validation.txt.
> + */
> +#define STACK_FRAME_NON_STANDARD(_func) \
> + static void __used __section(__objtool_ignore_func) \
> + *__objtool_ignore_func_##_func = _func
Likewise, this section should be named __func_non_standard_stack_frame or so, with
objtool one (but not the only possible) consumer of it.
> +#else /* !CONFIG_STACK_VALIDATION */
> +
> +#define STACK_FRAME_NON_STANDARD(_func)
> +
> +#endif /* CONFIG_STACK_VALIDATION */
> +
> +#endif /* _LINUX_OBJTOOL_H */
The CONFIG_STACK_VALIDATION dependency can be kept.
Thanks,
Ingo
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