Linus Walleij <linus.wall...@linaro.org> writes:
> On Tue, Nov 7, 2023 at 6:57 AM Michael Ellerman <m...@ellerman.id.au> wrote:
>
>> I'm struggling to connect the removal of const with those bug reports.
>> It looks like all those warnings are about 0xc000000000000000 being
>> outside the range of unsigned long when building 32-bit.
>
> Aha right. I wonder what actually causes that.
It is the 32-bit VDSO being built:
VDSO32C arch/powerpc/kernel/vdso/vgettimeofday-32.o
In file included from <built-in>:4:
In file included from /home/michael/linux/lib/vdso/gettimeofday.c:5:
In file included from ../include/vdso/datapage.h:137:
In file included from ../arch/powerpc/include/asm/vdso/gettimeofday.h:7:
../arch/powerpc/include/asm/page.h:230:9: warning: result of comparison of
constant 13835058055282163712 with expression of type 'unsigned long' is always
true [-Wtautological-constant-out-of-range-compare]
230 | return __pa(kaddr) >> PAGE_SHIFT;
| ^~~~~~~~~~~
../arch/powerpc/include/asm/page.h:217:37: note: expanded from macro '__pa'
217 | VIRTUAL_WARN_ON((unsigned long)(x) < PAGE_OFFSET);
\
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~
../arch/powerpc/include/asm/page.h:202:73: note: expanded from macro
'VIRTUAL_WARN_ON'
202 | #define VIRTUAL_WARN_ON(x)
WARN_ON(IS_ENABLED(CONFIG_DEBUG_VIRTUAL) && (x))
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
../arch/powerpc/include/asm/bug.h:88:25: note: expanded from macro 'WARN_ON'
88 | int __ret_warn_on = !!(x); \
| ^
Which is a bit of a frankenstein, because we're building 32-bit VDSO
code for a 64-bit kernel, and using some of the kernel headers for that.
So the warning is correct, we are doing a tautological comparison.
Except that we're not actually using that code in the VDSO, it's just
included in the VDSO because it needs PAGE_SHIFT.
Anyway none of that is your fault, you just had the misfortune of
touching page.h :)
I think I see a way to clean it up. Will send a patch.
cheers
