On 12/17/25 7:59 PM, Yury Norov wrote:
> 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.
There are some problems with using __builtin_mem{cpy,set} -- don't
know about __builtin_str{whatever}. See
commit 4ce97317f41d
Author: Nick Desaulniers <[email protected]>
Date: Wed Aug 7 15:15:32 2019 -0700
x86/purgatory: Do not use __builtin_memcpy and __builtin_memset
We should drop the header from kernel.h soon anyway, whether now or
in a few weeks/months. IMHO.
--
~Randy
