lib/vdso: Allow architectures to provide the vdso data pointer

On powerpc, __arch_get_vdso_data() clobbers the link register, requiring
the caller to save it.

As the parent function already has to set a stack frame and saves the link
register before calling the C vdso function, retrieving the vdso data
pointer there is less overhead.

Split out the functional code from the __cvdso.*() interfaces into new
static functions which can either be called from the existing interfaces
with the vdso data pointer supplied via __arch_get_vdso_data() or directly
from ASM code.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://lore.kernel.org/r/abf97996602ef07223fec30c005df78e5ed41b2e.1580399657.git.christophe.leroy@c-s.fr
Link: https://lkml.kernel.org/r/20200207124403.965789141@linutronix.de

diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index b95aef97501e7889a31385e6a27caa43aa1672f8..72d282ffd1564454b73e71537feb7ef3b74d00b8 100644 (file)
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -233,9 +233,9 @@ static __always_inline int do_coarse(const struct vdso_data *vd, clockid_t clk,
 }
 
 static __maybe_unused int
-__cvdso_clock_gettime_common(clockid_t clock, struct __kernel_timespec *ts)
+__cvdso_clock_gettime_common(const struct vdso_data *vd, clockid_t clock,
+                            struct __kernel_timespec *ts)
 {
-       const struct vdso_data *vd = __arch_get_vdso_data();
        u32 msk;
 
        /* Check for negative values or invalid clocks */
@@ -260,23 +260,31 @@ __cvdso_clock_gettime_common(clockid_t clock, struct __kernel_timespec *ts)
 }
 
 static __maybe_unused int
-__cvdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
+__cvdso_clock_gettime_data(const struct vdso_data *vd, clockid_t clock,
+                          struct __kernel_timespec *ts)
 {
-       int ret = __cvdso_clock_gettime_common(clock, ts);
+       int ret = __cvdso_clock_gettime_common(vd, clock, ts);
 
        if (unlikely(ret))
                return clock_gettime_fallback(clock, ts);
        return 0;
 }
 
+static __maybe_unused int
+__cvdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
+{
+       return __cvdso_clock_gettime_data(__arch_get_vdso_data(), clock, ts);
+}
+
 #ifdef BUILD_VDSO32
 static __maybe_unused int
-__cvdso_clock_gettime32(clockid_t clock, struct old_timespec32 *res)
+__cvdso_clock_gettime32_data(const struct vdso_data *vd, clockid_t clock,
+                            struct old_timespec32 *res)
 {
        struct __kernel_timespec ts;
        int ret;
 
-       ret = __cvdso_clock_gettime_common(clock, &ts);
+       ret = __cvdso_clock_gettime_common(vd, clock, &ts);
 
        if (unlikely(ret))
                return clock_gettime32_fallback(clock, res);
@@ -287,12 +295,18 @@ __cvdso_clock_gettime32(clockid_t clock, struct old_timespec32 *res)
 
        return ret;
 }
+
+static __maybe_unused int
+__cvdso_clock_gettime32(clockid_t clock, struct old_timespec32 *res)
+{
+       return __cvdso_clock_gettime32_data(__arch_get_vdso_data(), clock, res);
+}
 #endif /* BUILD_VDSO32 */
 
 static __maybe_unused int
-__cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
+__cvdso_gettimeofday_data(const struct vdso_data *vd,
+                         struct __kernel_old_timeval *tv, struct timezone *tz)
 {
-       const struct vdso_data *vd = __arch_get_vdso_data();
 
        if (likely(tv != NULL)) {
                struct __kernel_timespec ts;
@@ -316,10 +330,16 @@ __cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
        return 0;
 }
 
+static __maybe_unused int
+__cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
+{
+       return __cvdso_gettimeofday_data(__arch_get_vdso_data(), tv, tz);
+}
+
 #ifdef VDSO_HAS_TIME
-static __maybe_unused __kernel_old_time_t __cvdso_time(__kernel_old_time_t *time)
+static __maybe_unused __kernel_old_time_t
+__cvdso_time_data(const struct vdso_data *vd, __kernel_old_time_t *time)
 {
-       const struct vdso_data *vd = __arch_get_vdso_data();
        __kernel_old_time_t t;
 
        if (IS_ENABLED(CONFIG_TIME_NS) &&
@@ -333,13 +353,18 @@ static __maybe_unused __kernel_old_time_t __cvdso_time(__kernel_old_time_t *time
 
        return t;
 }
+
+static __maybe_unused __kernel_old_time_t __cvdso_time(__kernel_old_time_t *time)
+{
+       return __cvdso_time_data(__arch_get_vdso_data(), time);
+}
 #endif /* VDSO_HAS_TIME */
 
 #ifdef VDSO_HAS_CLOCK_GETRES
 static __maybe_unused
-int __cvdso_clock_getres_common(clockid_t clock, struct __kernel_timespec *res)
+int __cvdso_clock_getres_common(const struct vdso_data *vd, clockid_t clock,
+                               struct __kernel_timespec *res)
 {
-       const struct vdso_data *vd = __arch_get_vdso_data();
        u32 msk;
        u64 ns;
 
@@ -378,23 +403,31 @@ int __cvdso_clock_getres_common(clockid_t clock, struct __kernel_timespec *res)
 }
 
 static __maybe_unused
-int __cvdso_clock_getres(clockid_t clock, struct __kernel_timespec *res)
+int __cvdso_clock_getres_data(const struct vdso_data *vd, clockid_t clock,
+                             struct __kernel_timespec *res)
 {
-       int ret = __cvdso_clock_getres_common(clock, res);
+       int ret = __cvdso_clock_getres_common(vd, clock, res);
 
        if (unlikely(ret))
                return clock_getres_fallback(clock, res);
        return 0;
 }
 
+static __maybe_unused
+int __cvdso_clock_getres(clockid_t clock, struct __kernel_timespec *res)
+{
+       return __cvdso_clock_getres_data(__arch_get_vdso_data(), clock, res);
+}
+
 #ifdef BUILD_VDSO32
 static __maybe_unused int
-__cvdso_clock_getres_time32(clockid_t clock, struct old_timespec32 *res)
+__cvdso_clock_getres_time32_data(const struct vdso_data *vd, clockid_t clock,
+                                struct old_timespec32 *res)
 {
        struct __kernel_timespec ts;
        int ret;
 
-       ret = __cvdso_clock_getres_common(clock, &ts);
+       ret = __cvdso_clock_getres_common(vd, clock, &ts);
 
        if (unlikely(ret))
                return clock_getres32_fallback(clock, res);
@@ -405,5 +438,12 @@ __cvdso_clock_getres_time32(clockid_t clock, struct old_timespec32 *res)
        }
        return ret;
 }
+
+static __maybe_unused int
+__cvdso_clock_getres_time32(clockid_t clock, struct old_timespec32 *res)
+{
+       return __cvdso_clock_getres_time32_data(__arch_get_vdso_data(),
+                                               clock, res);
+}
 #endif /* BUILD_VDSO32 */
 #endif /* VDSO_HAS_CLOCK_GETRES */