diff options
| author | Goran Ferenc <goran.ferenc@imgtec.com> | 2017-06-28 17:55:29 +0200 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 2017-06-29 02:42:29 +0200 |
| commit | 180902e08f051f72c89ffa366f4e4f7a8e9c753e (patch) | |
| tree | 2230db590022baf0071409ed226b2934ec78fb5f /arch/mips/vdso | |
| parent | 8ec7f15b8cca4f790df5cdf33f26e2926d4ee2fd (diff) | |
MIPS: VDSO: Add implementation of clock_gettime() fallback
This patch adds clock_gettime_fallback() function that wraps assembly
invocation of clock_gettime() syscall using __NR_clock_gettime.
This function is used if pure VDSO implementation of clock_gettime()
does not succeed for any reason. For example, it is called if the
clkid parameter of clock_gettime() is not one of the clkids listed
in the switch-case block of the function __vdso_clock_gettime()
(one such case for clkid is CLOCK_BOOTIME).
If syscall invocation via __NR_clock_gettime fails, register a3 will
be set. So, after the syscall, register a3 is tested and the return
value is negated if it's set.
Signed-off-by: Goran Ferenc <goran.ferenc@imgtec.com>
Signed-off-by: Miodrag Dinic <miodrag.dinic@imgtec.com>
Signed-off-by: Aleksandar Markovic <aleksandar.markovic@imgtec.com>
Cc: Douglas Leung <douglas.leung@imgtec.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Petar Jovanovic <petar.jovanovic@imgtec.com>
Cc: Raghu Gandham <raghu.gandham@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/16639/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/vdso')
| -rw-r--r-- | arch/mips/vdso/gettimeofday.c | 25 |
1 files changed, 22 insertions, 3 deletions
diff --git a/arch/mips/vdso/gettimeofday.c b/arch/mips/vdso/gettimeofday.c index fd7d433970bf..5f6337545ee2 100644 --- a/arch/mips/vdso/gettimeofday.c +++ b/arch/mips/vdso/gettimeofday.c @@ -20,6 +20,24 @@ #include <asm/unistd.h> #include <asm/vdso.h> +static __always_inline long clock_gettime_fallback(clockid_t _clkid, + struct timespec *_ts) +{ + register struct timespec *ts asm("a1") = _ts; + register clockid_t clkid asm("a0") = _clkid; + register long ret asm("v0"); + register long nr asm("v0") = __NR_clock_gettime; + register long error asm("a3"); + + asm volatile( + " syscall\n" + : "=r" (ret), "=r" (error) + : "r" (clkid), "r" (ts), "r" (nr) + : "memory"); + + return error ? -ret : ret; +} + static __always_inline int do_realtime_coarse(struct timespec *ts, const union mips_vdso_data *data) { @@ -207,7 +225,7 @@ int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz) int __vdso_clock_gettime(clockid_t clkid, struct timespec *ts) { const union mips_vdso_data *data = get_vdso_data(); - int ret; + int ret = -1; switch (clkid) { case CLOCK_REALTIME_COARSE: @@ -223,10 +241,11 @@ int __vdso_clock_gettime(clockid_t clkid, struct timespec *ts) ret = do_monotonic(ts, data); break; default: - ret = -ENOSYS; break; } - /* If we return -ENOSYS libc should fall back to a syscall. */ + if (ret) + ret = clock_gettime_fallback(clkid, ts); + return ret; } |