timekeeping/vsyscall: Update VDSO data unconditionally

BugLink: https://bugs.launchpad.net/bugs/1852338
[ Upstream commit 52338415cf4d4064ae6b8dd972dadbda841da4fa ]

The update of the VDSO data is depending on __arch_use_vsyscall() returning
True. This is a leftover from the attempt to map the features of various
architectures 1:1 into generic code.

The usage of __arch_use_vsyscall() in the actual vsyscall implementations
got dropped and replaced by the requirement for the architecture code to
return U64_MAX if the global clocksource is not usable in the VDSO.

But the __arch_use_vsyscall() check in the update code stayed which causes
the VDSO data to be stale or invalid when an architecture actually
implements that function and returns False when the current clocksource is
not usable in the VDSO.

As a consequence the VDSO implementations of clock_getres(), time(),
clock_gettime(CLOCK_.*_COARSE) operate on invalid data and return bogus
information.

Remove the __arch_use_vsyscall() check from the VDSO update function and
update the VDSO data unconditionally.

[ tglx: Massaged changelog and removed the now useless implementations in
  	asm-generic/ARM64/MIPS ]

Fixes: 44f57d788e7deecb50 ("timekeeping: Provide a generic update_vsyscall() implementation")
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/1571887709-11447-1-git-send-email-chenhc@lemote.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/arch/arm64/include/asm/vdso/vsyscall.h b/arch/arm64/include/asm/vdso/vsyscall.h
index 0c731bfc7c8c763a1644c98d291be3454b63f760..0c20a7c1bee506d453c7635dedf887a5b0c77e33 100644 (file)
--- a/arch/arm64/include/asm/vdso/vsyscall.h
+++ b/arch/arm64/include/asm/vdso/vsyscall.h
@@ -30,13 +30,6 @@ int __arm64_get_clock_mode(struct timekeeper *tk)
 }
 #define __arch_get_clock_mode __arm64_get_clock_mode
 
-static __always_inline
-int __arm64_use_vsyscall(struct vdso_data *vdata)
-{
-       return !vdata[CS_HRES_COARSE].clock_mode;
-}
-#define __arch_use_vsyscall __arm64_use_vsyscall
-
 static __always_inline
 void __arm64_update_vsyscall(struct vdso_data *vdata, struct timekeeper *tk)
 {

diff --git a/include/asm-generic/vdso/vsyscall.h b/include/asm-generic/vdso/vsyscall.h
index e94b19782c92ff4f79ff75964a61b3b207fdda94..ce41032086193dfb98e9ad1b444624d0dee7a207 100644 (file)
--- a/include/asm-generic/vdso/vsyscall.h
+++ b/include/asm-generic/vdso/vsyscall.h
@@ -25,13 +25,6 @@ static __always_inline int __arch_get_clock_mode(struct timekeeper *tk)
 }
 #endif /* __arch_get_clock_mode */
 
-#ifndef __arch_use_vsyscall
-static __always_inline int __arch_use_vsyscall(struct vdso_data *vdata)
-{
-       return 1;
-}
-#endif /* __arch_use_vsyscall */
-
 #ifndef __arch_update_vsyscall
 static __always_inline void __arch_update_vsyscall(struct vdso_data *vdata,
                                                   struct timekeeper *tk)

diff --git a/kernel/time/vsyscall.c b/kernel/time/vsyscall.c
index 4bc37ac3bb0526994e2dcacd20369e6f2e98f8d3..5ee0f77094107486752338021a7e22210bdbec1d 100644 (file)
--- a/kernel/time/vsyscall.c
+++ b/kernel/time/vsyscall.c
@@ -110,8 +110,7 @@ void update_vsyscall(struct timekeeper *tk)
        nsec            = nsec + tk->wall_to_monotonic.tv_nsec;
        vdso_ts->sec    += __iter_div_u64_rem(nsec, NSEC_PER_SEC, &vdso_ts->nsec);
 
-       if (__arch_use_vsyscall(vdata))
-               update_vdso_data(vdata, tk);
+       update_vdso_data(vdata, tk);
 
        __arch_update_vsyscall(vdata, tk);
 
@@ -124,10 +123,8 @@ void update_vsyscall_tz(void)
 {
        struct vdso_data *vdata = __arch_get_k_vdso_data();
 
-       if (__arch_use_vsyscall(vdata)) {
-               vdata[CS_HRES_COARSE].tz_minuteswest = sys_tz.tz_minuteswest;
-               vdata[CS_HRES_COARSE].tz_dsttime = sys_tz.tz_dsttime;
-       }
+       vdata[CS_HRES_COARSE].tz_minuteswest = sys_tz.tz_minuteswest;
+       vdata[CS_HRES_COARSE].tz_dsttime = sys_tz.tz_dsttime;
 
        __arch_sync_vdso_data(vdata);
 }