[PATCH v7 23/25] x86: Add clock_getres entry point

Vincenzo Frascino
2019-06-21T09:54:17Z

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

Add clock_getres() entry point on x86.

Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Vincenzo Frascino <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 | 30 ++++++++++++++++++++++++
4 files changed, 50 insertions(+)

diff --git a/arch/x86/entry/vdso/vclock_gettime.c b/arch/x86/entry/vdso/vclock_gettime.c
index 4a7ef4ca4f52..de9212a4833e 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)
#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)
{
@@ -44,9 +45,18 @@ 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)
{
@@ -55,4 +65,11 @@ 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 a274d4fea7a5..df8c8dfadfa7 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")));
@@ -57,6 +59,17 @@ static __always_inline long gettimeofday_fallback(
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 long clock_gettime_fallback(
@@ -92,6 +105,23 @@ static __always_inline long gettimeofday_fallback(
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
--
2.21.0