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: Wed, 24 Nov 2021 12:50:40 -0300 [thread overview]
Message-ID: <b790b9fc-32ac-c7fe-50ac-3006e7076240@linaro.org> (raw)
In-Reply-To: <YZ1feHQWeHus91SV@antec>
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:
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
next prev parent reply other threads:[~2021-11-24 15:50 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 [this message]
2021-11-24 21:29 ` Stafford Horne
2021-11-25 12:53 ` Adhemerval Zanella
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