RESEND [PATCH v5 06/12] arm: vdso: add support for clock_getres

Commit Message

Mark Salyzyn Oct. 1, 2018, 5:58 p.m. UTC

Take an effort to recode the arm64 vdso code from assembler to C
previously submitted by Andrew Pinski <[e-mail]>, 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 <[e-mail]>
Tested-by: Mark Salyzyn <[e-mail]>
Cc: James Morse <[e-mail]>
Cc: Russell King <[e-mail]>
Cc: Catalin Marinas <[e-mail]>
Cc: Will Deacon <[e-mail]>
Cc: Andy Lutomirski <[e-mail]>
Cc: Dmitry Safonov <[e-mail]>
Cc: John Stultz <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Laura Abbott <[e-mail]>
Cc: Kees Cook <[e-mail]>
Cc: Ard Biesheuvel <[e-mail]>
Cc: Andy Gross <[e-mail]>
Cc: Kevin Brodsky <[e-mail]>
Cc: Andrew Pinski <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Cc: Jeremy Linton <[e-mail]>
Cc: [e-mail]

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(+)

Patch

diff --git a/arch/arm/kernel/vdso.c b/arch/arm/kernel/vdso.c
index 9c13a32fa5f0..c299967df63c 100644
--- a/arch/arm/kernel/vdso.c
+++ b/arch/arm/kernel/vdso.c
@@ -191,6 +191,7 @@  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");
 	}
 }
 
diff --git a/arch/arm/vdso/compiler.h b/arch/arm/vdso/compiler.h
index 3edddb705a1b..c7751019246a 100644
--- a/arch/arm/vdso/compiler.h
+++ b/arch/arm/vdso/compiler.h
@@ -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
diff --git a/arch/arm/vdso/vdso.lds.S b/arch/arm/vdso/vdso.lds.S
index 89ca89f12d23..1d81e8c3acf6 100644
--- a/arch/arm/vdso/vdso.lds.S
+++ b/arch/arm/vdso/vdso.lds.S
@@ -82,6 +82,7 @@  VERSION
 	global:
 		__vdso_clock_gettime;
 		__vdso_gettimeofday;
+		__vdso_clock_getres;
 	local: *;
 	};
 }
diff --git a/arch/arm/vdso/vgettimeofday.c b/arch/arm/vdso/vgettimeofday.c
index a2c4db83edc4..a354586f8a65 100644
--- a/arch/arm/vdso/vgettimeofday.c
+++ b/arch/arm/vdso/vgettimeofday.c
@@ -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;
+}