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Message-Id: <02861d0a05c2d48db4e9ee9093e2e2598093c372.1577111366.git.christophe.leroy@c-s.fr>
In-Reply-To: <cover.1577111363.git.christophe.leroy@c-s.fr>
References: <cover.1577111363.git.christophe.leroy@c-s.fr>
From:   Christophe Leroy <christophe.leroy@c-s.fr>
Subject: [RFC PATCH v2 04/10] lib: vdso: get pointer to vdso data from the
 arch
To:     Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>, arnd@arndb.de,
        tglx@linutronix.de, vincenzo.frascino@arm.com, luto@kernel.org
Cc:     linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org,
        x86@kernel.org
Date:   Mon, 23 Dec 2019 14:31:05 +0000 (UTC)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On powerpc, __arch_get_vdso_data() clobbers the link register,
requiring the caller to set a stack frame in order to save it.

As the parent function already has to set a stack frame and save
the link register to call the C vdso function, retriving the
vdso data pointer there is lighter.

Give arches the opportunity to hand the vdso data pointer
to C vdso functions.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/arm/vdso/vgettimeofday.c            | 12 ++++++++----
 arch/arm64/kernel/vdso/vgettimeofday.c   |  9 ++++++---
 arch/arm64/kernel/vdso32/vgettimeofday.c | 12 ++++++++----
 arch/mips/vdso/vgettimeofday.c           | 21 ++++++++++++++-------
 arch/x86/entry/vdso/vclock_gettime.c     | 22 +++++++++++++++-------
 lib/vdso/gettimeofday.c                  | 28 ++++++++++++++--------------
 6 files changed, 65 insertions(+), 39 deletions(-)

diff --git a/arch/arm/vdso/vgettimeofday.c b/arch/arm/vdso/vgettimeofday.c
index 5451afb715e6..efad7d508d06 100644
--- a/arch/arm/vdso/vgettimeofday.c
+++ b/arch/arm/vdso/vgettimeofday.c
@@ -10,7 +10,8 @@
 int __vdso_clock_gettime(clockid_t clock,
 			 struct old_timespec32 *ts)
 {
-	int ret = __cvdso_clock_gettime32(clock, ts);
+	const struct vdso_data *vd = __arch_get_vdso_data();
+	int ret = __cvdso_clock_gettime32(vd, clock, ts);
 
 	if (likely(!ret))
 		return ret;
@@ -21,7 +22,8 @@ int __vdso_clock_gettime(clockid_t clock,
 int __vdso_clock_gettime64(clockid_t clock,
 			   struct __kernel_timespec *ts)
 {
-	int ret = __cvdso_clock_gettime(clock, ts);
+	const struct vdso_data *vd = __arch_get_vdso_data();
+	int ret = __cvdso_clock_gettime(vd, clock, ts);
 
 	if (likely(!ret))
 		return ret;
@@ -32,7 +34,8 @@ int __vdso_clock_gettime64(clockid_t clock,
 int __vdso_gettimeofday(struct __kernel_old_timeval *tv,
 			struct timezone *tz)
 {
-	int ret = __cvdso_gettimeofday(tv, tz);
+	const struct vdso_data *vd = __arch_get_vdso_data();
+	int ret = __cvdso_gettimeofday(vd, tv, tz);
 
 	if (likely(!ret))
 		return ret;
@@ -43,7 +46,8 @@ int __vdso_gettimeofday(struct __kernel_old_timeval *tv,
 int __vdso_clock_getres(clockid_t clock_id,
 			struct old_timespec32 *res)
 {
-	int ret = __cvdso_clock_getres_time32(clock_id, res);
+	const struct vdso_data *vd = __arch_get_vdso_data();
+	int ret = __cvdso_clock_getres_time32(vd, clock_id, res);
 
 	if (likely(!ret))
 		return ret;
diff --git a/arch/arm64/kernel/vdso/vgettimeofday.c b/arch/arm64/kernel/vdso/vgettimeofday.c
index 62694876b216..9a7122ec6d17 100644
--- a/arch/arm64/kernel/vdso/vgettimeofday.c
+++ b/arch/arm64/kernel/vdso/vgettimeofday.c
@@ -11,7 +11,8 @@
 int __kernel_clock_gettime(clockid_t clock,
 			   struct __kernel_timespec *ts)
 {
-	int ret = __cvdso_clock_gettime(clock, ts);
+	const struct vdso_data *vd = __arch_get_vdso_data();
+	int ret = __cvdso_clock_gettime(vd, clock, ts);
 
 	if (likely(!ret))
 		return ret;
@@ -22,7 +23,8 @@ int __kernel_clock_gettime(clockid_t clock,
 int __kernel_gettimeofday(struct __kernel_old_timeval *tv,
 			  struct timezone *tz)
 {
-	int ret = __cvdso_gettimeofday(tv, tz);
+	const struct vdso_data *vd = __arch_get_vdso_data();
+	int ret = __cvdso_gettimeofday(vd, tv, tz);
 
 	if (likely(!ret))
 		return ret;
@@ -33,7 +35,8 @@ int __kernel_gettimeofday(struct __kernel_old_timeval *tv,
 int __kernel_clock_getres(clockid_t clock_id,
 			  struct __kernel_timespec *res)
 {
-	int ret =  __cvdso_clock_getres(clock_id, res);
+	const struct vdso_data *vd = __arch_get_vdso_data();
+	int ret =  __cvdso_clock_getres(vd, clock_id, res);
 
 	if (likely(!ret))
 		return ret;
diff --git a/arch/arm64/kernel/vdso32/vgettimeofday.c b/arch/arm64/kernel/vdso32/vgettimeofday.c
index 6770d2bedd1f..3eb6a82c1c25 100644
--- a/arch/arm64/kernel/vdso32/vgettimeofday.c
+++ b/arch/arm64/kernel/vdso32/vgettimeofday.c
@@ -11,13 +11,14 @@
 int __vdso_clock_gettime(clockid_t clock,
 			 struct old_timespec32 *ts)
 {
+	const struct vdso_data *vd = __arch_get_vdso_data();
 	int ret;
 
 	/* The checks below are required for ABI consistency with arm */
 	if ((u32)ts >= TASK_SIZE_32)
 		return -EFAULT;
 
-	ret = __cvdso_clock_gettime32(clock, ts);
+	ret = __cvdso_clock_gettime32(vd, clock, ts);
 
 	if (likely(!ret))
 		return ret;
@@ -28,13 +29,14 @@ int __vdso_clock_gettime(clockid_t clock,
 int __vdso_clock_gettime64(clockid_t clock,
 			   struct __kernel_timespec *ts)
 {
+	const struct vdso_data *vd = __arch_get_vdso_data();
 	int ret;
 
 	/* The checks below are required for ABI consistency with arm */
 	if ((u32)ts >= TASK_SIZE_32)
 		return -EFAULT;
 
-	ret = __cvdso_clock_gettime(clock, ts);
+	ret = __cvdso_clock_gettime(vd, clock, ts);
 
 	if (likely(!ret))
 		return ret;
@@ -45,7 +47,8 @@ int __vdso_clock_gettime64(clockid_t clock,
 int __vdso_gettimeofday(struct __kernel_old_timeval *tv,
 			struct timezone *tz)
 {
-	int ret = __cvdso_gettimeofday(tv, tz);
+	const struct vdso_data *vd = __arch_get_vdso_data();
+	int ret = __cvdso_gettimeofday(vd, tv, tz);
 
 	if (likely(!ret))
 		return ret;
@@ -56,6 +59,7 @@ int __vdso_gettimeofday(struct __kernel_old_timeval *tv,
 int __vdso_clock_getres(clockid_t clock_id,
 			struct old_timespec32 *res)
 {
+	const struct vdso_data *vd = __arch_get_vdso_data();
 	int ret;
 	struct __kernel_timespec ts;
 
@@ -63,7 +67,7 @@ int __vdso_clock_getres(clockid_t clock_id,
 	if ((u32)res >= TASK_SIZE_32)
 		return -EFAULT;
 
-	ret = __cvdso_clock_getres_time32(clock_id, res);
+	ret = __cvdso_clock_getres_time32(vd, clock_id, res);
 
 	if (likely(!ret))
 		return ret;
diff --git a/arch/mips/vdso/vgettimeofday.c b/arch/mips/vdso/vgettimeofday.c
index 02758c58454c..65d79d4695da 100644
--- a/arch/mips/vdso/vgettimeofday.c
+++ b/arch/mips/vdso/vgettimeofday.c
@@ -14,7 +14,8 @@
 int __vdso_clock_gettime(clockid_t clock,
 			 struct old_timespec32 *ts)
 {
-	int ret = __cvdso_clock_gettime32(clock, ts);
+	const struct vdso_data *vd = __arch_get_vdso_data();
+	int ret = __cvdso_clock_gettime32(vd, clock, ts);
 
 	if (likely(!ret))
 		return ret;
@@ -25,7 +26,8 @@ int __vdso_clock_gettime(clockid_t clock,
 int __vdso_gettimeofday(struct __kernel_old_timeval *tv,
 			struct timezone *tz)
 {
-	int ret = __cvdso_gettimeofday(tv, tz);
+	const struct vdso_data *vd = __arch_get_vdso_data();
+	int ret = __cvdso_gettimeofday(vd, tv, tz);
 
 	if (likely(!ret))
 		return ret;
@@ -36,7 +38,8 @@ int __vdso_gettimeofday(struct __kernel_old_timeval *tv,
 int __vdso_clock_getres(clockid_t clock_id,
 			struct old_timespec32 *res)
 {
-	int ret = __cvdso_clock_getres_time32(clock_id, res);
+	const struct vdso_data *vd = __arch_get_vdso_data();
+	int ret = __cvdso_clock_getres_time32(vd, clock_id, res);
 
 	if (likely(!ret))
 		return ret;
@@ -47,7 +50,8 @@ int __vdso_clock_getres(clockid_t clock_id,
 int __vdso_clock_gettime64(clockid_t clock,
 			   struct __kernel_timespec *ts)
 {
-	int ret = __cvdso_clock_gettime(clock, ts);
+	const struct vdso_data *vd = __arch_get_vdso_data();
+	int ret = __cvdso_clock_gettime(vd, clock, ts);
 
 	if (likely(!ret))
 		return ret;
@@ -60,7 +64,8 @@ int __vdso_clock_gettime64(clockid_t clock,
 int __vdso_clock_gettime(clockid_t clock,
 			 struct __kernel_timespec *ts)
 {
-	int ret = __cvdso_clock_gettime(clock, ts);
+	const struct vdso_data *vd = __arch_get_vdso_data();
+	int ret = __cvdso_clock_gettime(vd, clock, ts);
 
 	if (likely(!ret))
 		return ret;
@@ -71,7 +76,8 @@ int __vdso_clock_gettime(clockid_t clock,
 int __vdso_gettimeofday(struct __kernel_old_timeval *tv,
 			struct timezone *tz)
 {
-	int ret = __cvdso_gettimeofday(tv, tz);
+	const struct vdso_data *vd = __arch_get_vdso_data();
+	int ret = __cvdso_gettimeofday(vd, tv, tz);
 
 	if (likely(!ret))
 		return ret;
@@ -82,7 +88,8 @@ int __vdso_gettimeofday(struct __kernel_old_timeval *tv,
 int __vdso_clock_getres(clockid_t clock_id,
 			struct __kernel_timespec *res)
 {
-	int ret =  __cvdso_clock_getres(clock_id, res);
+	const struct vdso_data *vd = __arch_get_vdso_data();
+	int ret =  __cvdso_clock_getres(vd, clock_id, res);
 
 	if (likely(!ret))
 		return ret;
diff --git a/arch/x86/entry/vdso/vclock_gettime.c b/arch/x86/entry/vdso/vclock_gettime.c
index fde511cfe284..b87847b660dd 100644
--- a/arch/x86/entry/vdso/vclock_gettime.c
+++ b/arch/x86/entry/vdso/vclock_gettime.c
@@ -19,7 +19,8 @@ extern __kernel_old_time_t __vdso_time(__kernel_old_time_t *t);
 
 int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
 {
-	int ret = __cvdso_gettimeofday(tv, tz);
+	const struct vdso_data *vd = __arch_get_vdso_data();
+	int ret = __cvdso_gettimeofday(vd, tv, tz);
 
 	if (likely(!ret))
 		return ret;
@@ -32,7 +33,9 @@ int gettimeofday(struct __kernel_old_timeval *, struct timezone *)
 
 __kernel_old_time_t __vdso_time(__kernel_old_time_t *t)
 {
-	return __cvdso_time(t);
+	const struct vdso_data *vd = __arch_get_vdso_data();
+
+	return __cvdso_time(vd, t);
 }
 
 __kernel_old_time_t time(__kernel_old_time_t *t)	__attribute__((weak, alias("__vdso_time")));
@@ -45,7 +48,8 @@ extern int __vdso_clock_getres(clockid_t clock, struct __kernel_timespec *res);
 
 int __vdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
 {
-	int ret = __cvdso_clock_gettime(clock, ts);
+	const struct vdso_data *vd = __arch_get_vdso_data();
+	int ret = __cvdso_clock_gettime(vd, clock, ts);
 
 	if (likely(!ret))
 		return ret;
@@ -59,7 +63,8 @@ int clock_gettime(clockid_t, struct __kernel_timespec *)
 int __vdso_clock_getres(clockid_t clock,
 			struct __kernel_timespec *res)
 {
-	int ret =  __cvdso_clock_getres(clock_id, res);
+	const struct vdso_data *vd = __arch_get_vdso_data();
+	int ret =  __cvdso_clock_getres(vd, clock_id, res);
 
 	if (likely(!ret))
 		return ret;
@@ -76,7 +81,8 @@ extern int __vdso_clock_getres(clockid_t clock, struct old_timespec32 *res);
 
 int __vdso_clock_gettime(clockid_t clock, struct old_timespec32 *ts)
 {
-	int ret = __cvdso_clock_gettime32(clock, ts);
+	const struct vdso_data *vd = __arch_get_vdso_data();
+	int ret = __cvdso_clock_gettime32(vd, clock, ts);
 
 	if (likely(!ret))
 		return ret;
@@ -89,7 +95,8 @@ int clock_gettime(clockid_t, struct old_timespec32 *)
 
 int __vdso_clock_gettime64(clockid_t clock, struct __kernel_timespec *ts)
 {
-	int ret = __cvdso_clock_gettime(clock, ts);
+	const struct vdso_data *vd = __arch_get_vdso_data();
+	int ret = __cvdso_clock_gettime(vd, clock, ts);
 
 	if (likely(!ret))
 		return ret;
@@ -102,7 +109,8 @@ int clock_gettime64(clockid_t, struct __kernel_timespec *)
 
 int __vdso_clock_getres(clockid_t clock, struct old_timespec32 *res)
 {
-	int ret = __cvdso_clock_getres_time32(clock, res);
+	const struct vdso_data *vd = __arch_get_vdso_data();
+	int ret = __cvdso_clock_getres_time32(vd, clock, res);
 
 	if (likely(!ret))
 		return ret;
diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index c6eeeb47f446..24e1ba838260 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -13,7 +13,6 @@
 /*
  * The generic vDSO implementation requires that gettimeofday.h
  * provides:
- * - __arch_get_vdso_data(): to get the vdso datapage.
  * - __arch_get_hw_counter(): to get the hw counter based on the
  *   clock_mode.
  */
@@ -79,9 +78,9 @@ static void do_coarse(const struct vdso_data *vd, clockid_t clk,
 }
 
 static __maybe_unused int
-__cvdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
+__cvdso_clock_gettime(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 */
@@ -105,10 +104,11 @@ __cvdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
 }
 
 static __maybe_unused int
-__cvdso_clock_gettime32(clockid_t clock, struct old_timespec32 *res)
+__cvdso_clock_gettime32(const struct vdso_data *vd, clockid_t clock,
+			struct old_timespec32 *res)
 {
 	struct __kernel_timespec ts;
-	int ret = __cvdso_clock_gettime(clock, &ts);
+	int ret = __cvdso_clock_gettime(vd, clock, &ts);
 
 	if (likely(!ret)) {
 		res->tv_sec = ts.tv_sec;
@@ -118,10 +118,9 @@ __cvdso_clock_gettime32(clockid_t clock, struct old_timespec32 *res)
 }
 
 static __maybe_unused int
-__cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
+__cvdso_gettimeofday(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;
 
@@ -141,9 +140,9 @@ __cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *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(const struct vdso_data *vd, __kernel_old_time_t *time)
 {
-	const struct vdso_data *vd = __arch_get_vdso_data();
 	__kernel_old_time_t t = READ_ONCE(vd[CS_HRES_COARSE].basetime[CLOCK_REALTIME].sec);
 
 	if (time)
@@ -155,9 +154,9 @@ static __maybe_unused __kernel_old_time_t __cvdso_time(__kernel_old_time_t *time
 
 #ifdef VDSO_HAS_CLOCK_GETRES
 static __maybe_unused
-int __cvdso_clock_getres(clockid_t clock, struct __kernel_timespec *res)
+int __cvdso_clock_getres(const struct vdso_data *vd, clockid_t clock,
+			 struct __kernel_timespec *res)
 {
-	const struct vdso_data *vd = __arch_get_vdso_data();
 	u64 hrtimer_res;
 	u32 msk;
 	u64 ns;
@@ -199,10 +198,11 @@ int __cvdso_clock_getres(clockid_t clock, struct __kernel_timespec *res)
 }
 
 static __maybe_unused int
-__cvdso_clock_getres_time32(clockid_t clock, struct old_timespec32 *res)
+__cvdso_clock_getres_time32(const struct vdso_data *vd, clockid_t clock,
+			    struct old_timespec32 *res)
 {
 	struct __kernel_timespec ts;
-	int ret = __cvdso_clock_getres(clock, &ts);
+	int ret = __cvdso_clock_getres(vd, clock, &ts);
 
 	if (likely(!ret && res)) {
 		res->tv_sec = ts.tv_sec;
-- 
2.13.3