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authorGoran Ferenc <goran.ferenc@imgtec.com>2017-06-28 17:55:30 +0200
committerRalf Baechle <ralf@linux-mips.org>2017-06-29 02:42:30 +0200
commit0b523a85e134d41f57ddd8c5193bd9f0a5e20b0d (patch)
tree53df5cfb90329d12fd3fe83641a261dbaaf07d9f /arch/mips/vdso
parent180902e08f051f72c89ffa366f4e4f7a8e9c753e (diff)
MIPS: VDSO: Add implementation of gettimeofday() fallback
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>
Diffstat (limited to 'arch/mips/vdso')
-rw-r--r--arch/mips/vdso/gettimeofday.c24
1 files changed, 23 insertions, 1 deletions
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;