RESEND [PATCH v6 05/12] arm: vdso: Add support for CLOCK_MONOTONIC_RAW

Mark Salyzyn
2018-10-01T18:01:00Z

Take an effort to recode the arm64 vdso code from assembler to C
previously submitted by Andrew Pinski <apinski@cavium.com>, 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 a case for CLOCK_MONOTONIC_RAW to match up with support that
is available in arm64's vdso.

Signed-off-by: Mark Salyzyn <salyzyn@android.com>
Tested-by: Mark Salyzyn <salyzyn@android.com>
Cc: James Morse <james.morse@arm.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Andy Gross <andy.gross@linaro.org>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Andrew Pinski <apinski@cavium.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: Jeremy Linton <Jeremy.Linton@arm.com>
Cc: android-kernel@android.com

v2:
- split first CL into 6 of 7 pieces

v4:
- Move out ARCH_CLOCK_FIXED_MASK to later adjustment.
- update commit message to reflect overall reasoning.
- replace typeof() with type vdso_raw_time_sec_t.

v5:
- replace erroneous tk->raw_time.shift with tk->tkr_raw.shift

v6:
- fixup raw_time_sec and raw_time_nsec in vdso.c
---
arch/arm/include/asm/vdso_datapage.h | 11 +++++++
arch/arm/kernel/vdso.c | 3 ++
arch/arm/vdso/vgettimeofday.c | 44 ++++++++++++++++++++++++++++
3 files changed, 58 insertions(+)

diff --git a/arch/arm/include/asm/vdso_datapage.h b/arch/arm/include/asm/vdso_datapage.h
index 8dd7303db4ec..1c6e6a5d5d9d 100644
--- a/arch/arm/include/asm/vdso_datapage.h
+++ b/arch/arm/include/asm/vdso_datapage.h
@@ -34,6 +34,11 @@ typedef u32 vdso_wtm_clock_nsec_t;
typedef u32 vdso_xtime_clock_sec_t;
#endif

+#ifndef _VDSO_RAW_TIME_SEC_T
+#define _VDSO_RAW_TIME_SEC_T
+typedef u32 vdso_raw_time_sec_t;
+#endif
+
/* Try to be cache-friendly on systems that don't implement the
* generic timer: fit the unconditionally updated fields in the first
* 32 bytes.
@@ -58,6 +63,12 @@ struct vdso_data {
u64 xtime_clock_snsec; /* CLOCK_REALTIME sub-ns base */
u32 tz_minuteswest; /* timezone info for gettimeofday(2) */
u32 tz_dsttime;
+
+ /* Raw clocksource multipler */
+ u32 cs_raw_mult;
+ /* Raw time */
+ vdso_raw_time_sec_t raw_time_sec;
+ u32 raw_time_nsec;
};

union vdso_data_store {
diff --git a/arch/arm/kernel/vdso.c b/arch/arm/kernel/vdso.c
index c2c57f6b8c60..9c13a32fa5f0 100644
--- a/arch/arm/kernel/vdso.c
+++ b/arch/arm/kernel/vdso.c
@@ -337,9 +337,12 @@ void update_vsyscall(struct timekeeper *tk)

if (!vdso_data->use_syscall) {
vdso_data->cs_cycle_last = tk->tkr_mono.cycle_last;
+ vdso_data->raw_time_sec = tk->raw_sec;
+ vdso_data->raw_time_nsec = tk->tkr_raw.xtime_nsec;
vdso_data->xtime_clock_sec = tk->xtime_sec;
vdso_data->xtime_clock_snsec = tk->tkr_mono.xtime_nsec;
vdso_data->cs_mono_mult = tk->tkr_mono.mult;
+ vdso_data->cs_raw_mult = tk->tkr_raw.mult;
/* tkr_mono.shift == tkr_raw.shift */
vdso_data->cs_shift = tk->tkr_mono.shift;
vdso_data->cs_mask = tk->tkr_mono.mask;
diff --git a/arch/arm/vdso/vgettimeofday.c b/arch/arm/vdso/vgettimeofday.c
index 59893fca03b3..a2c4db83edc4 100644
--- a/arch/arm/vdso/vgettimeofday.c
+++ b/arch/arm/vdso/vgettimeofday.c
@@ -194,6 +194,40 @@ static notrace int do_monotonic(const struct vdso_data *vd, struct timespec *ts)
return 0;
}

+static notrace int do_monotonic_raw(const struct vdso_data *vd,
+ struct timespec *ts)
+{
+ u32 seq, mult, shift;
+ u64 nsec, cycle_last;
+ u64 mask;
+ vdso_raw_time_sec_t sec;
+
+ do {
+ seq = vdso_read_begin(vd);
+
+ if (vd->use_syscall)
+ return -1;
+
+ cycle_last = vd->cs_cycle_last;
+
+ mult = vd->cs_raw_mult;
+ shift = vd->cs_shift;
+ mask = vd->cs_mask;
+
+ sec = vd->raw_time_sec;
+ nsec = vd->raw_time_nsec;
+
+ } while (unlikely(vdso_read_retry(vd, seq)));
+
+ nsec += get_clock_shifted_nsec(cycle_last, mult, mask);
+ nsec >>= shift;
+ /* open coding timespec_add_ns to save a ts->tv_nsec = 0 */
+ ts->tv_sec = sec + __iter_div_u64_rem(nsec, NSEC_PER_SEC, &nsec);
+ ts->tv_nsec = nsec;
+
+ return 0;
+}
+
#else /* CONFIG_ARM_ARCH_TIMER */

static notrace int do_realtime(const struct vdso_data *vd, struct timespec *ts)
@@ -206,6 +240,12 @@ 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;
+}
+
#endif /* CONFIG_ARM_ARCH_TIMER */

notrace int __vdso_clock_gettime(clockid_t clock, struct timespec *ts)
@@ -227,6 +267,10 @@ notrace int __vdso_clock_gettime(clockid_t clock, struct timespec *ts)
if (do_monotonic(vd, ts))
goto fallback;
break;
+ case CLOCK_MONOTONIC_RAW:
+ if (do_monotonic_raw(vd, ts))
+ goto fallback;
+ break;
default:
goto fallback;
}
--
2.19.0.605.g01d371f741-goog