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Commit 0b523a85 authored by Goran Ferenc's avatar Goran Ferenc Committed by Ralf Baechle
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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: default avatarGoran Ferenc <goran.ferenc@imgtec.com>
Signed-off-by: default avatarMiodrag Dinic <miodrag.dinic@imgtec.com>
Signed-off-by: default avatarAleksandar 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: default avatarRalf Baechle <ralf@linux-mips.org>
parent 180902e0

arch/mips/vdso/gettimeofday.c

+23 −1
Original line number Diff line number Diff line
@@ -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;