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lib: vdso: do not expose gettimeofday, if no arch supported timer

PATCH New Mark Salyzyn 1 participant 1 message Nov 6, 2017 Generic VDSO library

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Mark Salyzyn

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PATCH v5 12/12 lib: vdso: do not expose gettimeofday, if no arch supported timer

Take an effort to recode the arm64 vdso code from assembler to C previously submitted by Andrew Pinski <[email protected]>, rework it for use in both arm and arm64, overlapping any optimizations for each architecture. But instead of landing it in arm64, land the result into lib/vdso and unify both implementations to simplify future maintenance.

If ARCH_PROVIDES_TIMER is not defined, do not expose gettimeofday. libc will default directly to syscall. Also ifdef clock_gettime switch cases and stubs if not supported and other unused components.

Signed-off-by Mark Salyzyn <[email protected]>
Cc James Morse <[email protected]>
Cc Russell King <[email protected]>
Cc Catalin Marinas <[email protected]>
Cc Will Deacon <[email protected]>
Cc Andy Lutomirski <[email protected]>
Cc Dmitry Safonov <[email protected]>
Cc John Stultz <[email protected]>
Cc Mark Rutland <[email protected]>
Cc Laura Abbott <[email protected]>
Cc Kees Cook <[email protected]>
Cc Ard Biesheuvel <[email protected]>
Cc Andy Gross <[email protected]>
Cc Kevin Brodsky <[email protected]>
Cc Andrew Pinski <[email protected]>
Cc Thomas Gleixner <[email protected]>
Cc linux-kernel at vger.kernel.org
Cc linux-arm-kernel at lists.infradead.org

v3:
- do not expose gettimeofday if arch does not support user space timer.

v4:
- update commit message to reflect overall reasoning of patch series.

v5:
- rebase

---
 lib/vdso/vgettimeofday.c | 52 +++++++++++++++++++-----------------------------
 1 file changed, 20 insertions(+), 32 deletions(-)
lib/vdso/vgettimeofday.c +20 -32
index d64f60010bb2..079955162be8 100644
@@ -30,7 +30,9 @@
 #include "compiler.h"
 #include "datapage.h"
 
+#ifdef ARCH_PROVIDES_TIMER
 DEFINE_FALLBACK(gettimeofday, struct timeval *, tv, struct timezone *, tz)
+#endif
 DEFINE_FALLBACK(clock_gettime, clockid_t, clock, struct timespec *, ts)
 DEFINE_FALLBACK(clock_getres, clockid_t, clock, struct timespec *, ts)
 

@@ -291,30 +293,6 @@ static notrace int do_boottime(const struct vdso_data *vd, struct timespec *ts)
 	return 0;
 }
 
-#else /* ARCH_PROVIDES_TIMER */
-
-static notrace int do_realtime(const struct vdso_data *vd, struct timespec *ts)
-{
-	return -1;
-}
-
-static notrace int do_monotonic(const struct vdso_data *vd, struct timespec *ts)
-{
-	return -1;
-}
-
-static notrace int do_monotonic_raw(const struct vdso_data *vd,
-				    struct timespec *ts)
-{
-	return -1;
-}
-
-static notrace int do_boottime(const struct vdso_data *vd,
-			       struct timespec *ts)
-{
-	return -1;
-}
-
 #endif /* ARCH_PROVIDES_TIMER */
 
 notrace int __vdso_clock_gettime(clockid_t clock, struct timespec *ts)

@@ -328,6 +306,7 @@ notrace int __vdso_clock_gettime(clockid_t clock, struct timespec *ts)
 	case CLOCK_MONOTONIC_COARSE:
 		do_monotonic_coarse(vd, ts);
 		break;
+#ifdef ARCH_PROVIDES_TIMER
 	case CLOCK_REALTIME:
 		if (do_realtime(vd, ts))
 			goto fallback;

@@ -344,6 +323,7 @@ notrace int __vdso_clock_gettime(clockid_t clock, struct timespec *ts)
 		if (do_boottime(vd, ts))
 			goto fallback;
 		break;
+#endif
 	default:
 		goto fallback;
 	}

@@ -353,6 +333,7 @@ notrace int __vdso_clock_gettime(clockid_t clock, struct timespec *ts)
 	return clock_gettime_fallback(clock, ts);
 }
 
+#ifdef ARCH_PROVIDES_TIMER
 notrace int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
 {
 	const struct vdso_data *vd = __get_datapage();

@@ -374,21 +355,28 @@ notrace int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
 
 	return 0;
 }
+#endif
 
 int __vdso_clock_getres(clockid_t clock, struct timespec *res)
 {
 	long nsec;
 
-	if (clock == CLOCK_REALTIME ||
-	    clock == CLOCK_BOOTTIME ||
-	    clock == CLOCK_MONOTONIC ||
-	    clock == CLOCK_MONOTONIC_RAW)
-		nsec = MONOTONIC_RES_NSEC;
-	else if (clock == CLOCK_REALTIME_COARSE ||
-		 clock == CLOCK_MONOTONIC_COARSE)
+	switch (clock) {
+	case CLOCK_REALTIME_COARSE:
+	case CLOCK_MONOTONIC_COARSE:
 		nsec = LOW_RES_NSEC;
-	else
+		break;
+#ifdef ARCH_PROVIDES_TIMER
+	case CLOCK_REALTIME:
+	case CLOCK_MONOTONIC:
+	case CLOCK_MONOTONIC_RAW:
+	case CLOCK_BOOTTIME:
+		nsec = MONOTONIC_RES_NSEC;
+		break;
+#endif
+	default:
 		return clock_getres_fallback(clock, res);
+	}
 
 	if (likely(res != NULL)) {
 		res->tv_sec = 0;
Signature · 1 line
2.15.0.403.gc27cc4dac6-goog