Re: [PATCH] Coresight: tpda/tpdm: remove incorrect __exit annotation

[Suzuki K Poulose]

On 27/01/2023 17:00, Arnd Bergmann wrote:
> On Fri, Jan 27, 2023, at 17:46, Suzuki K Poulose wrote:
> > On 26/01/2023 20:37, Arnd Bergmann wrote:
> > > On Thu, Jan 26, 2023, at 19:02, Suzuki K Poulose wrote:
> > > > On 26/01/2023 16:35, Arnd Bergmann wrote:
> > > > > From: Arnd Bergmann <arnd@xxxxxxxx>
> > > > Thanks for the fix, I will queue this. Btw, I did try to
> > > > reproduce it locally, but couldn't trigger the warnings,
> > > > even with
> > > >
> > > > CONFIG_WERROR=y
> > > >
> > > > and all CORESIGHT configs builtin. I see other drivers doing the
> > > > same outside coresight too. Just curious to know why is this
> > > > any different. Is it specific to "bus" driver (e.g. AMBA) ?
> > >
> > > The warning comes from postprocessing the object file, it's got
> > > nothing to do with the bus type, only with a symbol in .data
> > > referencing a symbol in .init.text. Maybe there are some
> > > config options that keep the section from getting discarded?
> > > Or possibly you only built the files in this directory, but did
> > > not get to the final link?
> >
> > I did a full kernel build. Also, I see a similar issue with the
> > coresight-etm4x (by code inspection) driver. Did you not hit that ?
> >
> > May be there is a config option that is masking it on my end. But
> > the case of etm4x driver is puzzling.
> >
> > $ git grep etm4_remove_amba
> > drivers/hwtracing/coresight/coresight-etm4x-core.c
> > drivers/hwtracing/coresight/coresight-etm4x-core.c:static void __exit
> > etm4_remove_amba(struct amba_device *adev)
> > drivers/hwtracing/coresight/coresight-etm4x-core.c:     .remove
> > = etm4_remove_amba,
>
> Indeed, that one clearly has the same but, but I have never
> observed a warning for it.
>
> I checked one more thing and found that I only get the warning
> for 32-bit Arm builds, but not arm64. Since the etm4x driver
> 'depends on ARM64' for its use of asm/sysreg.h,
> I never test-built it on 32-bit arm.
>
>  From the git history of arch/arm64/kernel/vmlinux.lds.S,
> I can see that arm64 never discards the .exit section, see
> commit 07c802bd7c39 ("arm64: vmlinux.lds.S: don't discard
> .exit.* sections at link-time").

That makes sense, thanks for getting to the bottom of this. I
have pushed it to coresight next.

https://git.kernel.org/coresight/c/0c1ccc158bbc

Kind regards
Suzuki



>       Arnd