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Subject[tip:timers/vdso] x86/vdso: Add clock_getres() entry point
Commit-ID:  f66501dc53e72079045a6a17e023b41316ede220
Gitweb: https://git.kernel.org/tip/f66501dc53e72079045a6a17e023b41316ede220
Author: Vincenzo Frascino <vincenzo.frascino@arm.com>
AuthorDate: Fri, 21 Jun 2019 10:52:50 +0100
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Sat, 22 Jun 2019 21:21:10 +0200

x86/vdso: Add clock_getres() entry point

The generic vDSO library provides an implementation of clock_getres()
that can be leveraged by each architecture.

Add the clock_getres() VDSO entry point on x86.

[ tglx: Massaged changelog and cleaned up the function signature formatting ]

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mips@vger.kernel.org
Cc: linux-kselftest@vger.kernel.org
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Mark Salyzyn <salyzyn@android.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Huw Davies <huw@codeweavers.com>
Cc: Shijith Thotton <sthotton@marvell.com>
Cc: Andre Przywara <andre.przywara@arm.com>
Link: https://lkml.kernel.org/r/20190621095252.32307-24-vincenzo.frascino@arm.com

---
arch/x86/entry/vdso/vclock_gettime.c | 17 +++++++++++++++++
arch/x86/entry/vdso/vdso.lds.S | 2 ++
arch/x86/entry/vdso/vdso32/vdso32.lds.S | 1 +
arch/x86/include/asm/vdso/gettimeofday.h | 31 +++++++++++++++++++++++++++++++
4 files changed, 51 insertions(+)

diff --git a/arch/x86/entry/vdso/vclock_gettime.c b/arch/x86/entry/vdso/vclock_gettime.c
index f01a3f0787ca..1a648b509d46 100644
--- a/arch/x86/entry/vdso/vclock_gettime.c
+++ b/arch/x86/entry/vdso/vclock_gettime.c
@@ -36,6 +36,7 @@ time_t time(time_t *t) __attribute__((weak, alias("__vdso_time")));
#if defined(CONFIG_X86_64) && !defined(BUILD_VDSO32_64)
/* both 64-bit and x32 use these */
extern int __vdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts);
+extern int __vdso_clock_getres(clockid_t clock, struct __kernel_timespec *res);

int __vdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
{
@@ -45,9 +46,18 @@ int __vdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
int clock_gettime(clockid_t, struct __kernel_timespec *)
__attribute__((weak, alias("__vdso_clock_gettime")));

+int __vdso_clock_getres(clockid_t clock,
+ struct __kernel_timespec *res)
+{
+ return __cvdso_clock_getres(clock, res);
+}
+int clock_getres(clockid_t, struct __kernel_timespec *)
+ __attribute__((weak, alias("__vdso_clock_getres")));
+
#else
/* i386 only */
extern int __vdso_clock_gettime(clockid_t clock, struct old_timespec32 *ts);
+extern int __vdso_clock_getres(clockid_t clock, struct old_timespec32 *res);

int __vdso_clock_gettime(clockid_t clock, struct old_timespec32 *ts)
{
@@ -57,4 +67,11 @@ int __vdso_clock_gettime(clockid_t clock, struct old_timespec32 *ts)
int clock_gettime(clockid_t, struct old_timespec32 *)
__attribute__((weak, alias("__vdso_clock_gettime")));

+int __vdso_clock_getres(clockid_t clock, struct old_timespec32 *res)
+{
+ return __cvdso_clock_getres_time32(clock, res);
+}
+
+int clock_getres(clockid_t, struct old_timespec32 *)
+ __attribute__((weak, alias("__vdso_clock_getres")));
#endif
diff --git a/arch/x86/entry/vdso/vdso.lds.S b/arch/x86/entry/vdso/vdso.lds.S
index d3a2dce4cfa9..36b644e16272 100644
--- a/arch/x86/entry/vdso/vdso.lds.S
+++ b/arch/x86/entry/vdso/vdso.lds.S
@@ -25,6 +25,8 @@ VERSION {
__vdso_getcpu;
time;
__vdso_time;
+ clock_getres;
+ __vdso_clock_getres;
local: *;
};
}
diff --git a/arch/x86/entry/vdso/vdso32/vdso32.lds.S b/arch/x86/entry/vdso/vdso32/vdso32.lds.S
index 422764a81d32..991b26cc855b 100644
--- a/arch/x86/entry/vdso/vdso32/vdso32.lds.S
+++ b/arch/x86/entry/vdso/vdso32/vdso32.lds.S
@@ -26,6 +26,7 @@ VERSION
__vdso_clock_gettime;
__vdso_gettimeofday;
__vdso_time;
+ __vdso_clock_getres;
};

LINUX_2.5 {
diff --git a/arch/x86/include/asm/vdso/gettimeofday.h b/arch/x86/include/asm/vdso/gettimeofday.h
index 0e2650fc191b..f92752d6cbcf 100644
--- a/arch/x86/include/asm/vdso/gettimeofday.h
+++ b/arch/x86/include/asm/vdso/gettimeofday.h
@@ -24,6 +24,8 @@

#define VDSO_HAS_TIME 1

+#define VDSO_HAS_CLOCK_GETRES 1
+
#ifdef CONFIG_PARAVIRT_CLOCK
extern u8 pvclock_page[PAGE_SIZE]
__attribute__((visibility("hidden")));
@@ -60,6 +62,18 @@ long gettimeofday_fallback(struct __kernel_old_timeval *_tv,
return ret;
}

+static __always_inline
+long clock_getres_fallback(clockid_t _clkid, struct __kernel_timespec *_ts)
+{
+ long ret;
+
+ asm ("syscall" : "=a" (ret), "=m" (*_ts) :
+ "0" (__NR_clock_getres), "D" (_clkid), "S" (_ts) :
+ "rcx", "r11");
+
+ return ret;
+}
+
#else

static __always_inline
@@ -97,6 +111,23 @@ long gettimeofday_fallback(struct __kernel_old_timeval *_tv,
return ret;
}

+static __always_inline long
+clock_getres_fallback(clockid_t _clkid, struct __kernel_timespec *_ts)
+{
+ long ret;
+
+ asm (
+ "mov %%ebx, %%edx \n"
+ "mov %[clock], %%ebx \n"
+ "call __kernel_vsyscall \n"
+ "mov %%edx, %%ebx \n"
+ : "=a" (ret), "=m" (*_ts)
+ : "0" (__NR_clock_getres_time64), [clock] "g" (_clkid), "c" (_ts)
+ : "edx");
+
+ return ret;
+}
+
#endif

#ifdef CONFIG_PARAVIRT_CLOCK
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