From: Goran Ferenc goran.ferenc@imgtec.com
[ Upstream commit 0b523a85e134d41f57ddd8c5193bd9f0a5e20b0d ]
This patch adds gettimeofday_fallback() function that wraps assembly invocation of gettimeofday() syscall using __NR_gettimeofday.
This function is used if pure VDSO implementation gettimeofday() does not succeed for any reason. Its imeplementation is enclosed in "#ifdef CONFIG_MIPS_CLOCK_VSYSCALL" to be in sync with the similar arrangement for __vdso_gettimeofday().
If syscall invocation via __NR_gettimeofday fails, register a3 will be set. So, after the syscall, register a3 is tested and the return valuem 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/16640/ Signed-off-by: Ralf Baechle ralf@linux-mips.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- arch/mips/vdso/gettimeofday.c | 24 +++++++++++++++++++++++- 1 file changed, 23 insertions(+), 1 deletion(-)
diff --git a/arch/mips/vdso/gettimeofday.c b/arch/mips/vdso/gettimeofday.c index 5f6337545ee2..23305bf6c7a2 100644 --- a/arch/mips/vdso/gettimeofday.c +++ b/arch/mips/vdso/gettimeofday.c @@ -20,6 +20,28 @@ #include <asm/unistd.h> #include <asm/vdso.h>
+#ifdef CONFIG_MIPS_CLOCK_VSYSCALL + +static __always_inline long gettimeofday_fallback(struct timeval *_tv, + struct timezone *_tz) +{ + register struct timezone *tz asm("a1") = _tz; + register struct timeval *tv asm("a0") = _tv; + register long ret asm("v0"); + register long nr asm("v0") = __NR_gettimeofday; + register long error asm("a3"); + + asm volatile( + " syscall\n" + : "=r" (ret), "=r" (error) + : "r" (tv), "r" (tz), "r" (nr) + : "memory"); + + return error ? -ret : ret; +} + +#endif + static __always_inline long clock_gettime_fallback(clockid_t _clkid, struct timespec *_ts) { @@ -205,7 +227,7 @@ int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
ret = do_realtime(&ts, data); if (ret) - return ret; + return gettimeofday_fallback(tv, tz);
if (tv) { tv->tv_sec = ts.tv_sec;