Skip to contentSkip to conversation

arm: vdso: add support for clock_getres

PATCH New Mark Salyzyn 1 participant 1 message Nov 6, 2017 Arm (32-bit)

lore
Share & tools
lore

Mark Salyzyn

author
#0 lore raw

PATCH v5 6/12 arm: vdso: add support for clock_getres

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.

Add clock_getres vdso support to match up with existing support in the arm64's vdso.

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

v2:
- split first CL into 7 of 7 pieces

v4:
- update commit message to reflect overall reasoning.
- replace typeof() with long for nsec
- replace clock_id with clock to match usage elsewhere.

v5:
- add linux/hrtimer.h to compiler.h to supply for LOW_RES_NSEC and MONOTONIC_RES_NSEC.

---
 arch/arm/kernel/vdso.c        |  1 +
 arch/arm/vdso/compiler.h      |  1 +
 arch/arm/vdso/vdso.lds.S      |  1 +
 arch/arm/vdso/vgettimeofday.c | 23 +++++++++++++++++++++++
 4 files changed, 26 insertions(+)
arch/arm/kernel/vdso.c +1 -0
index b7c93fce2f59..a80c58805699 100644
@@ -189,6 +189,7 @@ static void __init patch_vdso(void *ehdr)
 	if (!cntvct_ok) {
 		vdso_nullpatch_one(&einfo, "__vdso_gettimeofday");
 		vdso_nullpatch_one(&einfo, "__vdso_clock_gettime");
+		vdso_nullpatch_one(&einfo, "__vdso_clock_getres");
 	}
 }
arch/arm/vdso/compiler.h +1 -0
index 3edddb705a1b..c7751019246a 100644
@@ -27,6 +27,7 @@
 #include <asm/processor.h>	/* for cpu_relax()			*/
 #include <asm/unistd.h>
 #include <linux/compiler.h>
+#include <linux/hrtimer.h>	/* for LOW_RES_NSEC and MONOTONIC_RES_NSEC */
 #include <linux/time.h>		/* for NSEC_PER_SEC			*/
 
 #ifndef CONFIG_AEABI
arch/arm/vdso/vdso.lds.S +1 -0
index 89ca89f12d23..1d81e8c3acf6 100644
@@ -82,6 +82,7 @@ VERSION
 	global:
 		__vdso_clock_gettime;
 		__vdso_gettimeofday;
+		__vdso_clock_getres;
 	local: *;
 	};
 }
arch/arm/vdso/vgettimeofday.c +23 -0
index a2c4db83edc4..a354586f8a65 100644
@@ -32,6 +32,7 @@
 
 DEFINE_FALLBACK(gettimeofday, struct timeval *, tv, struct timezone *, tz)
 DEFINE_FALLBACK(clock_gettime, clockid_t, clock, struct timespec *, ts)
+DEFINE_FALLBACK(clock_getres, clockid_t, clock, struct timespec *, ts)
 
 static notrace u32 vdso_read_begin(const struct vdso_data *vd)
 {

@@ -301,3 +302,25 @@ notrace int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
 
 	return 0;
 }
+
+int __vdso_clock_getres(clockid_t clock, struct timespec *res)
+{
+	long nsec;
+
+	if (clock == CLOCK_REALTIME ||
+	    clock == CLOCK_MONOTONIC ||
+	    clock == CLOCK_MONOTONIC_RAW)
+		nsec = MONOTONIC_RES_NSEC;
+	else if (clock == CLOCK_REALTIME_COARSE ||
+		 clock == CLOCK_MONOTONIC_COARSE)
+		nsec = LOW_RES_NSEC;
+	else
+		return clock_getres_fallback(clock, res);
+
+	if (likely(res != NULL)) {
+		res->tv_sec = 0;
+		res->tv_nsec = nsec;
+	}
+
+	return 0;
+}
Signature · 1 line
2.15.0.403.gc27cc4dac6-goog