On Tue, Dec 16, 2025 at 09:24:55PM -0800, Randy Dunlap wrote:
> [adding Kees]
>
> On 12/16/25 4:13 PM, Andrew Morton wrote:
> > On Fri, 5 Dec 2025 12:52:35 -0500 "Yury Norov (NVIDIA)"
> > <[email protected]> wrote:
> >
> >> Tracing is a half of the kernel.h in terms of LOCs, although it's
> >> a self-consistent part. It is intended for quick debugging purposes
> >> and isn't used by the normal tracing utilities.
> >>
> >> Move it to a separate header. If someone needs to just throw a
> >> trace_printk() in their driver, they will not have to pull all
> >> the heavy tracing machinery.
> >>
> >> This is a pure move, except for removing a few 'extern's.
> >>
>
> Hm, for a pure move, this shouldn't be necessary. Anyway, not using
> FORTIFY in purgatory.o fixes this build error.
> Or maybe there's a better answer.
>
> ---
> arch/x86/purgatory/Makefile | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- a/arch/x86/purgatory/Makefile
> +++ b/arch/x86/purgatory/Makefile
> @@ -62,7 +62,7 @@ PURGATORY_CFLAGS_REMOVE += $(CC_FLAGS_C
> endif
>
> CFLAGS_REMOVE_purgatory.o += $(PURGATORY_CFLAGS_REMOVE)
> -CFLAGS_purgatory.o += $(PURGATORY_CFLAGS)
> +CFLAGS_purgatory.o += $(PURGATORY_CFLAGS) -D__NO_FORTIFY
>
> CFLAGS_REMOVE_sha256.o += $(PURGATORY_CFLAGS_REMOVE)
> CFLAGS_sha256.o += $(PURGATORY_CFLAGS)
That happened because the new trace_printk.h includes string.h for
strlen(), so all kernel.h users now indirectly include it, and it
causes, seemingly, a circular dependency if FORTIFY is enabled.
A fix would be dropping trace_printk.h from kernel.h, or switching the
only user of string.h, trace_puts(), to __builtin_strlen().
Notice, Andy has concerned about this on the previous round, and also
suggested __builtin_strlen():
https://lkml.org/lkml/2025/12/3/910
I deem to drop trace_printk.h from kernel.h - it is more aligned with
the idea of unloading the header. The original motivation to keep
trace_printk.h in kernel.h was just because a similar printk.h is living
there. But after all, this is a purely debugging header, so no need for
almost every C file to bear debugging stuff.
I can actually do both - switch to an intrinsic and drop the header.
Guys, please let me know what do you thing.
Thanks,
Yury
