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Re: PowerPC: Add time vDSO support
- From: Adhemerval Zanella <azanella at linux dot vnet dot ibm dot com>
- To: Roland McGrath <roland at hack dot frob dot com>
- Cc: "GNU C. Library" <libc-alpha at sourceware dot org>
- Date: Tue, 30 Apr 2013 12:06:29 -0300
- Subject: Re: PowerPC: Add time vDSO support
- References: <517EB999 dot 5000504 at linux dot vnet dot ibm dot com> <20130429182738 dot 7563D2C069 at topped-with-meat dot com>
Thanks for the review Roland, I have fixed all your comments.
Ok to apply now?
---
2013-04-30 Adhemerval Zanella <azanella@linux.vnet.ibm.com>
* sysdeps/unix/sysv/linux/powerpc/Versions: Add __vdso_time symbol.
* sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h: Add __vdso_time
definition.
(VDSO_IFUNC_RET): Cast to void * to silence compiler warning.
* sysdeps/unix/sysv/linux/powerpc/init-first.c
(_libc_vdso_platform_setup): Add __vdso_time initialization.
* sysdeps/unix/sysv/linux/powerpc/time.c: New file: time implementation
for PowerPC using vDSO where is avaliable or gettimeofday as a fallback.
--
diff --git a/sysdeps/unix/sysv/linux/powerpc/Versions b/sysdeps/unix/sysv/linux/powerpc/Versions
index 396a423..289c4fe 100644
--- a/sysdeps/unix/sysv/linux/powerpc/Versions
+++ b/sysdeps/unix/sysv/linux/powerpc/Versions
@@ -4,5 +4,6 @@ libc {
__vdso_clock_gettime;
__vdso_clock_getres;
__vdso_getcpu;
+ __vdso_time;
}
}
diff --git a/sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h b/sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h
index 5f5fc1e..8b195db 100644
--- a/sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h
+++ b/sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h
@@ -32,14 +32,16 @@ extern void *__vdso_get_tbfreq;
extern void *__vdso_getcpu;
+extern void *__vdso_time;
+
/* This macro is needed for PPC64 to return a skeleton OPD entry of a vDSO
symbol. This works because _dl_vdso_vsym always return the function
address, and no vDSO symbols use the TOC or chain pointers from the OPD
so we can allow them to be garbage. */
#if defined(__PPC64__) || defined(__powerpc64__)
-#define VDSO_IFUNC_RET(value) &value
+#define VDSO_IFUNC_RET(value) ((void *) &(value))
#else
-#define VDSO_IFUNC_RET(value) value
+#define VDSO_IFUNC_RET(value) ((void *) (value))
#endif
#endif
diff --git a/sysdeps/unix/sysv/linux/powerpc/init-first.c b/sysdeps/unix/sysv/linux/powerpc/init-first.c
index 204c0c6..f6f05f0 100644
--- a/sysdeps/unix/sysv/linux/powerpc/init-first.c
+++ b/sysdeps/unix/sysv/linux/powerpc/init-first.c
@@ -28,7 +28,7 @@ void *__vdso_clock_gettime;
void *__vdso_clock_getres;
void *__vdso_get_tbfreq;
void *__vdso_getcpu;
-
+void *__vdso_time;
static inline void
_libc_vdso_platform_setup (void)
@@ -44,6 +44,8 @@ _libc_vdso_platform_setup (void)
__vdso_get_tbfreq = _dl_vdso_vsym ("__kernel_get_tbfreq", &linux2615);
__vdso_getcpu = _dl_vdso_vsym ("__kernel_getcpu", &linux2615);
+
+ __vdso_time = _dl_vdso_vsym ("__kernel_time", &linux2615);
}
# define VDSO_SETUP _libc_vdso_platform_setup
diff --git a/sysdeps/unix/sysv/linux/powerpc/time.c b/sysdeps/unix/sysv/linux/powerpc/time.c
new file mode 100644
index 0000000..66b4eb3
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/powerpc/time.c
@@ -0,0 +1,62 @@
+/* time system call for Linux/PowerPC.
+ Copyright (C) 2013 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#ifdef SHARED
+
+# include <time.h>
+# include <sysdep.h>
+# include <bits/libc-vdso.h>
+
+void *time_ifunc (void) asm ("time");
+
+static time_t
+time_syscall (time_t *t)
+{
+ struct timeval tv;
+ time_t result;
+
+ if (INLINE_VSYSCALL (gettimeofday, 2, &tv, NULL) < 0)
+ result = (time_t) -1;
+ else
+ result = (time_t) tv.tv_sec;
+
+ if (t != NULL)
+ *t = result;
+ return result;
+}
+
+void *
+time_ifunc (void)
+{
+ /* If the vDSO is not available we fall back to the syscall. */
+ return (__vdso_time ? VDSO_IFUNC_RET (__vdso_time)
+ : time_syscall);
+}
+asm (".type time, %gnu_indirect_function");
+
+/* This is doing "libc_hidden_def (time)" but the compiler won't
+ * let us do it in C because it doesn't know we're defining time
+ * here in this file. */
+asm (".globl __GI_time\n"
+ "__GI_time = time");
+
+#else
+
+#include <sysdeps/posix/time.c>
+
+#endif
--
1.7.1
On 29-04-2013 15:27, Roland McGrath wrote:
>> (VDSO_IFUNC_RET): Fix compiler warning on cast.
> "Cast to void *" is what you're doing here, so say that.
> You can say, "Cast to void * to silence compiler warning."
>
>> #if defined(__PPC64__) || defined(__powerpc64__)
>> -#define VDSO_IFUNC_RET(value) &value
>> +#define VDSO_IFUNC_RET(value) (void*)(&value)
> Should be: ((void *) &(value))
>
>> #else
>> -#define VDSO_IFUNC_RET(value) value
>> +#define VDSO_IFUNC_RET(value) (void*)(value)
> Should be: ((void *) (value))
>
>> +++ b/sysdeps/unix/sysv/linux/powerpc/time.c
>> @@ -0,0 +1,63 @@
>> +/* Copyright (C) 2013 Free Software Foundation, Inc.
> Top line of each new file is a descriptive comment.
>
>> +#ifdef SHARED
>> +
>> +# include <time.h>
>> +# include <sysdep.h>
>> +# include <bits/libc-vdso.h>
>> +
>> +void *time_ifunc (void) __asm__ ("time");
> No need for __ flavors in libc source code.
>
>> +static time_t
>> +__time_syscall (time_t *t)
> No need for __ prefix on a static.
>
>> + if (INLINE_VSYSCALL (gettimeofday, 2, &tv, NULL))
> Canonical failure test would be "< 0".
>
>> +void *
>> +time_ifunc (void)
>> +{
>> + /* If the vDSO is not available we fall back syscall. */
> "fall back to the syscall"
>