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mips: Fix gettimeofday() in the vdso library 

[ Upstream commit 7d2aa4bb90 ]

The libc provides a discovery mechanism for vDSO library and its
symbols. When a symbol is not exposed by the vDSOs the libc falls back
on the system calls.

With the introduction of the unified vDSO library on mips this behavior
is not honored anymore by the kernel in the case of gettimeofday().

The issue has been noticed and reported due to a dhclient failure on the
CI20 board:

root@letux:~# dhclient
../../../../lib/isc/unix/time.c:200: Operation not permitted
root@letux:~#

Restore the original behavior fixing gettimeofday() in the vDSO library.

Reported-by: H. Nikolaus Schaller <hns@goldelico.com>
Tested-by: H. Nikolaus Schaller <hns@goldelico.com> # CI20 with JZ4780
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Paul Burton <paulburton@kernel.org>
Cc: mips-creator-ci20-dev@googlegroups.com
Cc: letux-kernel@openphoenux.org
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
5.4-rM2-2.2.x-imx-squashed
Vincenzo Frascino 2019-11-29 14:36:58 +00:00 committed by Greg Kroah-Hartman
parent 7acc6f949d
commit 520e3bd3de
2 changed files with 20 additions and 13 deletions
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13
arch/mips/include/asm/vdso/gettimeofday.h
View File

@ -26,8 +26,6 @@
#define __VDSO_USE_SYSCALL ULLONG_MAX
#ifdef CONFIG_MIPS_CLOCK_VSYSCALL
static __always_inline long gettimeofday_fallback(
struct __kernel_old_timeval *_tv,
struct timezone *_tz)
@ -48,17 +46,6 @@ static __always_inline long gettimeofday_fallback(
return error ? -ret : ret;
}
#else
static __always_inline long gettimeofday_fallback(
struct __kernel_old_timeval *_tv,
struct timezone *_tz)
{
return -1;
}
#endif
static __always_inline long clock_gettime_fallback(
clockid_t _clkid,
struct __kernel_timespec *_ts)

20
arch/mips/vdso/vgettimeofday.c
View File

@ -17,12 +17,22 @@ int __vdso_clock_gettime(clockid_t clock,
return __cvdso_clock_gettime32(clock, ts);
}
#ifdef CONFIG_MIPS_CLOCK_VSYSCALL
/*
* This is behind the ifdef so that we don't provide the symbol when there's no
* possibility of there being a usable clocksource, because there's nothing we
* can do without it. When libc fails the symbol lookup it should fall back on
* the standard syscall path.
*/
int __vdso_gettimeofday(struct __kernel_old_timeval *tv,
struct timezone *tz)
{
return __cvdso_gettimeofday(tv, tz);
}
#endif /* CONFIG_MIPS_CLOCK_VSYSCALL */
int __vdso_clock_getres(clockid_t clock_id,
struct old_timespec32 *res)
{
@ -43,12 +53,22 @@ int __vdso_clock_gettime(clockid_t clock,
return __cvdso_clock_gettime(clock, ts);
}
#ifdef CONFIG_MIPS_CLOCK_VSYSCALL
/*
* This is behind the ifdef so that we don't provide the symbol when there's no
* possibility of there being a usable clocksource, because there's nothing we
* can do without it. When libc fails the symbol lookup it should fall back on
* the standard syscall path.
*/
int __vdso_gettimeofday(struct __kernel_old_timeval *tv,
struct timezone *tz)
{
return __cvdso_gettimeofday(tv, tz);
}
#endif /* CONFIG_MIPS_CLOCK_VSYSCALL */
int __vdso_clock_getres(clockid_t clock_id,
struct __kernel_timespec *res)
{