[PATCH] linux: Define STAT64_IS_KERNEL_STAT64 by default

[Stafford Horne]

On Mon, Nov 22, 2021 at 10:00:31AM -0300, Adhemerval Zanella wrote:
> 
> 
> On 20/11/2021 18:09, Stafford Horne via Libc-alpha wrote:
> > In commit 36260d5035 ("linux: Set default kernel_stat.h to LFS") the
> > default for STAT64_IS_KERNEL_STAT64 was removed.  This patch adds it
> > back.
> > 
> > For architectures that want to used the default kernel_stat.h and do not
> > have __NR_newfstatat, STAT64_IS_KERNEL_STAT64 needs to be defined.  Set
> > the default as 1 as modern port's stat64 struct should match the kernel
> > stat64 layout.
> > 
> > I tested this on the OpenRISC port and it seems to work fine.  Currently,
> > all archs that use the default kernel_stat.h define __NR_newfstatat so
> > they will not use the STAT64_IS_KERNEL_STAT64 macro.  However, arc seems
> > to be an outlier it uses the default kernel_stat.h, but does not define
> > __NR_newfstatat or __NR_fstatat64 I am not clear how arc works here.
> 
> arc and usually newer 32-bit ports will only use __NR_statx:
> 
> 138 #if (__WORDSIZE == 32 \
> 139      && (!defined __SYSCALL_WORDSIZE || __SYSCALL_WORDSIZE == 32)) \
> 140      || defined STAT_HAS_TIME32
> 141 # define FSTATAT_USE_STATX 1
> 142 #else
> 143 # define FSTATAT_USE_STATX 0
> 144 #endif
> 
> The patch looks ok, but it seems strange that ork1 requires it since it
> setting minimum required kernel to 5.10. I would expect that __ASSUME_STATX
> would be defined and only fstatat64_time64_statx would be used.

Right,

In that case maybe another ifdef is needed in fstatat64.c?  I don't see
fstatat64_time64_stat is actually getting compiled into the libc.so binary.  But
if I don't define STAT64_IS_KERNEL_STAT64 I get the below compile error.

I added a pragma to output the value of FSTATAT_USE_STATX and __ASSUME_STATX in
the compile unit and I get the below which looks right:

  * __ASSUME_STATX: 1
  * FSTATAT_USE_STATX: 1

Error:

or1k-glibc-linux-gnu-gcc ../sysdeps/unix/sysv/linux/fstatat64.c -c -std=gnu11 -fgnu89-inline  -g -O2 -Wall -Wwrite-strings -Wundef -Werror -fmerge-all-constants -frounding-math -fno-stack-protector -fno-common -Wstrict-prototypes -Wold-style-definition -fmath-errno      -ftls-model=initial-exec      -I../include -I/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/io  -I/home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc  -I../sysdeps/unix/sysv/linux/or1k  -I../sysdeps/or1k/nptl  -I../sysdeps/unix/sysv/linux/generic/wordsize-32  -I../sysdeps/unix/sysv/linux/generic  -I../sysdeps/unix/sysv/linux/include -I../sysdeps/unix/sysv/linux  -I../sysdeps/nptl  -I../sysdeps/pthread  -I../sysdeps/gnu  -I../sysdeps/unix/inet  -I../sysdeps/unix/sysv  -I../sysdeps/unix  -I../sysdeps/posix  -I../sysdeps/or1k/nofpu  -I../sysdeps/ieee754/soft-fp  -I../sysdeps/or1k  -I../sysdeps/wordsize-32  -I../sysdeps/ieee754/dbl-64  -I../sysdeps/ieee754/flt-32  -I../sysdeps/ieee754  -I../sysdeps/generic  -I.. -I../libio -I.  -D_LIBC_REENTRANT -include /home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/libc-modules.h -DMODULE_NAME=libc -include ../include/libc-symbols.h       -DTOP_NAMESPACE=glibc -o /home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/io/fstatat64.o -MD -MP -MF /home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/io/fstatat64.o.dt -MT /home/shorne/work/gnu-toolchain/build-many/build/glibcs/or1k-linux-gnu-soft/glibc/io/fstatat64.o
../sysdeps/unix/sysv/linux/fstatat64.c: In function ‘fstatat64_time64_stat’:
../sysdeps/unix/sysv/linux/fstatat64.c:89:7: error: "STAT64_IS_KERNEL_STAT64" is not defined, evaluates to 0 [-Werror=undef]
   89 | #  if STAT64_IS_KERNEL_STAT64
      |       ^~~~~~~~~~~~~~~~~~~~~~~
../sysdeps/unix/sysv/linux/fstatat64.c:94:24: error: storage size of ‘kst64’ isn’t known
   94 |   struct kernel_stat64 kst64;
      |                        ^~~~~
../sysdeps/unix/sysv/linux/fstatat64.c:97:5: error: implicit declaration of function ‘__cp_stat64_kstat64’ [-Werror=implicit-function-declaration]
   97 |     __cp_stat64_kstat64 (buf, &kst64);
      |     ^~~~~~~~~~~~~~~~~~~
../sysdeps/unix/sysv/linux/fstatat64.c:94:24: error: unused variable ‘kst64’ [-Werror=unused-variable]
   94 |   struct kernel_stat64 kst64;
      |                        ^~~~~
../sysdeps/unix/sysv/linux/fstatat64.c: At top level:
../sysdeps/unix/sysv/linux/fstatat64.c:149:9: note: ‘#pragma message: The value of FSTATAT_USE_STATX: 1’
  149 | #pragma message "The value of FSTATAT_USE_STATX: " XSTR(FSTATAT_USE_STATX)
      |         ^~~~~~~
../sysdeps/unix/sysv/linux/fstatat64.c:150:9: note: ‘#pragma message: The value of __ASSUME_STATX: 1’
  150 | #pragma message "The value of __ASSUME_STATX: " XSTR(__ASSUME_STATX)
      |         ^~~~~~~

Again I am not sure how arc avoids this error I shall try to compile it too.

-Stafford

> > ---
> >  sysdeps/unix/sysv/linux/kernel_stat.h | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/sysdeps/unix/sysv/linux/kernel_stat.h b/sysdeps/unix/sysv/linux/kernel_stat.h
> > index 6c1b175cb4..b8c376f41e 100644
> > --- a/sysdeps/unix/sysv/linux/kernel_stat.h
> > +++ b/sysdeps/unix/sysv/linux/kernel_stat.h
> > @@ -20,3 +20,4 @@
> >  #define XSTAT_IS_XSTAT64     1
> >  #define STATFS_IS_STATFS64   __STATFS_MATCHES_STATFS64
> >  #define STAT_IS_KERNEL_STAT  1
> > +#define STAT64_IS_KERNEL_STAT64 1
> > 
>