From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: Stafford Horne <shorne@gmail.com>
Cc: GLIBC patches <libc-alpha@sourceware.org>
Subject: Re: [PATCH] linux: Define STAT64_IS_KERNEL_STAT64 by default
Date: Thu, 25 Nov 2021 09:53:17 -0300 [thread overview]
Message-ID: <7d151797-11b2-1b3f-9f31-f8c150165d17@linaro.org> (raw)
In-Reply-To: <YZ6uq0APvPHZT1LL@antec>
On 24/11/2021 18:29, Stafford Horne wrote:
> On Wed, Nov 24, 2021 at 12:50:40PM -0300, Adhemerval Zanella wrote:
>>
>>
>> On 23/11/2021 18:39, Stafford Horne wrote:
>>> 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.
>>
>> The problem is 'fstatat64_time64_stat' should not be build for 32-bit architectures
>> with __ASSUME_STATX (since only statx provides 64-bit timestamps). Other architecture
>> might get an improved codegen using older syscalls (specially 64-bit ones), so statx
>> should be used only when really required.
>>
>> The patch below fixes it:
>
> Right, this was what I was thinking too. However, I am still not sure why or1k
> needs it and arc does not. I tested the arc build and confirmed with the same
> version of GCC the arc build passes but or1k fails with the above error. So as
> you said, maybe there is better codegen somewhere.
ARC has:
sysdeps/unix/sysv/linux/arc/fixup-asm-unistd.h:24:#undef __NR_fstatat64
Which leads fstatat64_time64_stat to be an empty function:
static inline int
fstatat64_time64_stat (int fd, const char *file, struct stat64 *buf,
int flag)
{
int r;
# 135 "../sysdeps/unix/sysv/linux/fstatat64.c"
return r;
}
>
>> diff --git a/sysdeps/unix/sysv/linux/fstatat64.c b/sysdeps/unix/sysv/linux/fstatat64.c
>> index f968e4ef05..50ae5ad748 100644
>> --- a/sysdeps/unix/sysv/linux/fstatat64.c
>> +++ b/sysdeps/unix/sysv/linux/fstatat64.c
>> @@ -74,6 +74,17 @@ fstatat64_time64_statx (int fd, const char *file, struct __stat64_t64 *buf,
>> return r;
>> }
>>
>> +#if (__WORDSIZE == 32 \
>> + && (!defined __SYSCALL_WORDSIZE || __SYSCALL_WORDSIZE == 32)) \
>> + || defined STAT_HAS_TIME32
>> +# define FSTATAT_USE_STATX 1
>> +#else
>> +# define FSTATAT_USE_STATX 0
>> +#endif
>> +
>> +/* Only statx supports 64-bit timestamps for 32-bit architectures with
>> + __ASSUME_STATX, so there is no point in building the fallback. */
>> +#if !FSTATAT_USE_STATX || (FSTATAT_USE_STATX && !defined __ASSUME_STATX)
>> static inline int
>> fstatat64_time64_stat (int fd, const char *file, struct __stat64_t64 *buf,
>> int flag)
>> @@ -134,13 +145,6 @@ fstatat64_time64_stat (int fd, const char *file, struct __stat64_t64 *buf,
>>
>> return r;
>> }
>> -
>> -#if (__WORDSIZE == 32 \
>> - && (!defined __SYSCALL_WORDSIZE || __SYSCALL_WORDSIZE == 32)) \
>> - || defined STAT_HAS_TIME32
>> -# define FSTATAT_USE_STATX 1
>> -#else
>> -# define FSTATAT_USE_STATX 0
>> #endif
>>
>> int
>
> I tested this patch and it works.
Thanks, I will push it upstream.
prev parent reply other threads:[~2021-11-25 12:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-20 21:09 Stafford Horne
2021-11-22 13:00 ` Adhemerval Zanella
2021-11-23 21:39 ` Stafford Horne
2021-11-24 15:50 ` Adhemerval Zanella
2021-11-24 21:29 ` Stafford Horne
2021-11-25 12:53 ` Adhemerval Zanella [this message]
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