Re: [PATCH 04/18] arm: implement nospec_ptr()

[Laura Abbott]

On 01/09/2018 11:40 PM, Hanjun Guo wrote:
> On 2018/1/10 10:04, Laura Abbott wrote:
> > On 01/05/2018 05:10 PM, Dan Williams wrote:
> > > From: Mark Rutland <mark.rutland@xxxxxxx>
> > >
> > > This patch implements nospec_ptr() for arm, following the recommended
> > > architectural sequences for the arm and thumb instruction sets.
> > Fedora picked up the series and it fails on arm:
> >
> > In file included from ./include/linux/compiler.h:242:0,
> >  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ from ./include/uapi/linux/swab.h:6,
> >  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ from ./include/linux/swab.h:5,
> >  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ from ./arch/arm/include/asm/opcodes.h:89,
> >  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ from ./arch/arm/include/asm/bug.h:7,
> >  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ from ./include/linux/bug.h:5,
> >  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ from ./include/linux/mmdebug.h:5,
> >  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ from ./include/linux/gfp.h:5,
> >  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ from ./include/linux/slab.h:15,
> >  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ from kernel/fork.c:14:
> > ./include/linux/fdtable.h: In function '__fcheck_files':
> > ./arch/arm/include/asm/barrier.h:112:41: error: expected declaration specifiers or '...' before numeric constant
> >  Â __load_no_speculate(&__np_ptr, lo, hi, 0, __np_ptr);Â \
> >  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ ^
> > ./arch/arm/include/asm/barrier.h:68:32: note: in definition of macro '__load_no_speculate_n'
> >  ÂÂ (typeof(*ptr)(unsigned long)(failval));Â \
> >  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ ^~~~~~~
> > ./arch/arm/include/asm/barrier.h:112:2: note: in expansion of macro '__load_no_speculate'
> >  Â __load_no_speculate(&__np_ptr, lo, hi, 0, __np_ptr);Â \
> >  Â ^~~~~~~~~~~~~~~~~~~
> > ./include/asm-generic/barrier.h:122:2: note: in expansion of macro 'nospec_ptr'
> >  Â nospec_ptr(__arr + __idx, __arr, __arr + __sz);ÂÂ \
> >  Â ^~~~~~~~~~
> > ./include/linux/fdtable.h:86:13: note: in expansion of macro 'nospec_array_ptr'
> >  Â if ((fdp = nospec_array_ptr(fdt->fd, fd, fdt->max_fds)))
> >  ÂÂÂÂÂÂÂÂÂÂÂÂ ^~~~~~~~~~~~~~~~
> > ./arch/arm/include/asm/barrier.h:112:41: error: expected declaration specifiers or '...' before numeric constant
> >  Â __load_no_speculate(&__np_ptr, lo, hi, 0, __np_ptr);Â \
> >  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ ^
> > ./arch/arm/include/asm/barrier.h:68:32: note: in definition of macro '__load_no_speculate_n'
> >  ÂÂ (typeof(*ptr)(unsigned long)(failval));Â \
> >  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ ^~~~~~~
> > ./arch/arm/include/asm/barrier.h:112:2: note: in expansion of macro '__load_no_speculate'
> >  Â __load_no_speculate(&__np_ptr, lo, hi, 0, __np_ptr);Â \
> >  Â ^~~~~~~~~~~~~~~~~~~
> > ./include/asm-generic/barrier.h:122:2: note: in expansion of macro 'nospec_ptr'
> >  Â nospec_ptr(__arr + __idx, __arr, __arr + __sz);ÂÂ \
> >  Â ^~~~~~~~~~
> > ./include/linux/fdtable.h:86:13: note: in expansion of macro 'nospec_array_ptr'
> >  Â if ((fdp = nospec_array_ptr(fdt->fd, fd, fdt->max_fds)))
> >  ÂÂÂÂÂÂÂÂÂÂÂÂ ^~~~~~~~~~~~~~~~
> > ./arch/arm/include/asm/barrier.h:112:41: error: expected declaration specifiers or '...' before numeric constant
> >  Â __load_no_speculate(&__np_ptr, lo, hi, 0, __np_ptr);Â \
> >  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ ^
> > ./arch/arm/include/asm/barrier.h:68:32: note: in definition of macro '__load_no_speculate_n'
> >  ÂÂ (typeof(*ptr)(unsigned long)(failval));Â \
> >  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ ^~~~~~~
> > ./arch/arm/include/asm/barrier.h:112:2: note: in expansion of macro '__load_no_speculate'
> >  Â __load_no_speculate(&__np_ptr, lo, hi, 0, __np_ptr);Â \
> >  Â ^~~~~~~~~~~~~~~~~~~
> > ./include/asm-generic/barrier.h:122:2: note: in expansion of macro 'nospec_ptr'
> >  Â nospec_ptr(__arr + __idx, __arr, __arr + __sz);ÂÂ \
> >  Â ^~~~~~~~~~
> > ./include/linux/fdtable.h:86:13: note: in expansion of macro 'nospec_array_ptr'
> >  Â if ((fdp = nospec_array_ptr(fdt->fd, fd, fdt->max_fds)))
> >
> > I can't puzzle out what exactly is the problem here, except that it really
> > does not seem to like that failval. Does the arm compiler not like doing
> > the typeof with the __arr + __idx?
>
> > > +#define __load_no_speculate_n(ptr, lo, hi, failval, cmpptr, sz)ÂÂÂ \
> > > +({ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ \
> > > +ÂÂÂ typeof(*ptr) __nln_val;ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ \
> > > +ÂÂÂ typeof(*ptr) __failval =ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ \
> > > +ÂÂÂÂÂÂÂ (typeof(*ptr)(unsigned long)(failval));ÂÂÂÂÂÂÂ \
>
> Just typo,
>
> -         (typeof(*ptr)(unsigned long)(failval));         \
> +         (typeof(*ptr))(unsigned long)(failval);             \
>
> Please try it.
>
> Thanks
> Hanjun

Ah yeah, that's exactly it. I really missed the obvious.

Thanks,
Laura