Re: [PATCH 1/8] unwind: build kernel with sframe info

Josh Poimboeuf
2025-02-07T18:01:59Z

On Tue, Feb 04, 2025 at 04:22:27PM -0800, Indu Bhagat wrote:
> > +++ b/arch/Kconfig
> > @@ -1736,4 +1736,12 @@ config ARCH_WANTS_PRE_LINK_VMLINUX
> > An architecture can select this if it provides arch/<arch>/tools/Makefile
> > with .arch.vmlinux.o target to be linked into vmlinux.
> > +config AS_HAS_SFRAME_SUPPORT
> > + # Detect availability of the AS option -Wa,--gsframe for generating
> > + # sframe unwind table.
> > + def_bool $(cc-option,-Wa$(comma)--gsframe)
> > +
>
> Since the version of an admissible SFrame section needs to be atleast
> SFRAME_VERSION_2, it will make sense to include SFrame version check when
> detecting compatible toolchain.

Also, Jens pointed out that checking for '-Wa,--gsframe' isn't
sufficient, as it still succeeds for architectures that aren't yet
supported:

https://lore.kernel.org/b89bcb68-d010-4041-aacf-15b934675705@linux.ibm.com

so in my patches I have:

config AS_SFRAME
def_bool $(as-instr,.cfi_sections .sframe\n.cfi_startproc\n.cfi_endproc)

Though I'm not sure how you would add an SFrame version check to that.

--
Josh