On Tue, 6 Aug 2019 11:39:04 -0300 Jason Gunthorpe <jgg@xxxxxxxx> wrote:
> On Fri, Aug 02, 2019 at 03:41:22PM -0400, Qian Cai wrote:
> > GCC throws a warning on an arm64 system since the commit 9849a5697d3d
> > ("arch, mm: convert all architectures to use 5level-fixup.h"),
> >
> > mm/kasan/init.c: In function 'kasan_free_p4d':
> > mm/kasan/init.c:344:9: warning: variable 'p4d' set but not used
> > [-Wunused-but-set-variable]
> > p4d_t *p4d;
> > ^~~
> >
> > because p4d_none() in "5level-fixup.h" is compiled away while it is a
> > static inline function in "pgtable-nopud.h". However, if converted
> > p4d_none() to a static inline there, powerpc would be unhappy as it
> > reads those in assembler language in
> > "arch/powerpc/include/asm/book3s/64/pgtable.h",
> >
> > ./include/asm-generic/5level-fixup.h: Assembler messages:
> > ./include/asm-generic/5level-fixup.h:20: Error: unrecognized opcode:
> > `static'
> > ./include/asm-generic/5level-fixup.h:21: Error: junk at end of line,
> > first unrecognized character is `{'
> > ./include/asm-generic/5level-fixup.h:22: Error: unrecognized opcode:
> > `return'
> > ./include/asm-generic/5level-fixup.h:23: Error: junk at end of line,
> > first unrecognized character is `}'
> > ./include/asm-generic/5level-fixup.h:25: Error: unrecognized opcode:
> > `static'
> > ./include/asm-generic/5level-fixup.h:26: Error: junk at end of line,
> > first unrecognized character is `{'
> > ./include/asm-generic/5level-fixup.h:27: Error: unrecognized opcode:
> > `return'
> > ./include/asm-generic/5level-fixup.h:28: Error: junk at end of line,
> > first unrecognized character is `}'
> > ./include/asm-generic/5level-fixup.h:30: Error: unrecognized opcode:
> > `static'
> > ./include/asm-generic/5level-fixup.h:31: Error: junk at end of line,
> > first unrecognized character is `{'
> > ./include/asm-generic/5level-fixup.h:32: Error: unrecognized opcode:
> > `return'
> > ./include/asm-generic/5level-fixup.h:33: Error: junk at end of line,
> > first unrecognized character is `}'
> > make[2]: *** [scripts/Makefile.build:375:
> > arch/powerpc/kvm/book3s_hv_rmhandlers.o] Error 1
> >
> > Fix it by reference the variable in the macro instead.
> >
> > Signed-off-by: Qian Cai <cai@xxxxxx>
> > include/asm-generic/5level-fixup.h | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/include/asm-generic/5level-fixup.h b/include/asm-generic/5level-fixup.h
> > index bb6cb347018c..2c3e14c924b6 100644
> > +++ b/include/asm-generic/5level-fixup.h
> > @@ -19,7 +19,7 @@
> >
> > #define p4d_alloc(mm, pgd, address) (pgd)
> > #define p4d_offset(pgd, start) (pgd)
> > -#define p4d_none(p4d) 0
> > +#define p4d_none(p4d) ((void)p4d, 0)
>
> Yuk, how about a static inline instead?
Yes. With the appropriate `#ifndef __ASSEMBLY__' to avoid powerpc
build errors?
