FAILED: patch "[PATCH] timekeeping/vsyscall: Update VDSO data unconditionally" failed to apply to 5.3-stable tree

PATCH [email protected] 2 participants 2 messages Nov 11, 2019

Subsystems (5)

Stable branch MIPS arm64 Generic include/asm header files +1 more subsystems

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[email protected]

author maintainer

2019-11-11 06:30 UTC #0 lore raw

The patch below does not apply to the 5.3-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 52338415cf4d4064ae6b8dd972dadbda841da4fa Mon Sep 17 00:00:00 2001
From: Huacai Chen <[email protected]>
Date: Thu, 24 Oct 2019 11:28:29 +0800
Subject: [PATCH] timekeeping/vsyscall: Update VDSO data unconditionally

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 <[email protected]>

Signed-off-by Thomas Gleixner <[email protected]>

Cc Andy Lutomirski <[email protected]>

Cc Vincenzo Frascino <[email protected]>

Cc Arnd Bergmann <[email protected]>

Cc Paul Burton <[email protected]>

Cc [email protected]

Link https://lkml.kernel.org/r/[email protected] open here

arch/arm64/include/asm/vdso/vsyscall.h +0 -7

index 0c731bfc7c8c..0c20a7c1bee5 100644
@@ -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)
 {

arch/mips/include/asm/vdso/vsyscall.h +0 -7

index 195314732233..00d41b94ba31 100644
@@ -28,13 +28,6 @@ int __mips_get_clock_mode(struct timekeeper *tk)
 }
 #define __arch_get_clock_mode __mips_get_clock_mode
 
-static __always_inline
-int __mips_use_vsyscall(struct vdso_data *vdata)
-{
-	return (vdata[CS_HRES_COARSE].clock_mode != VDSO_CLOCK_NONE);
-}
-#define __arch_use_vsyscall __mips_use_vsyscall
-
 /* The asm-generic header needs to be included after the definitions above */
 #include <asm-generic/vdso/vsyscall.h>

include/asm-generic/vdso/vsyscall.h +0 -7

index e94b19782c92..ce4103208619 100644
@@ -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)

kernel/time/vsyscall.c +3 -6

index 4bc37ac3bb05..5ee0f7709410 100644
@@ -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);
 }

Sasha Levin

maintainer

2019-11-11 14:19 UTC #1 lore raw

Quoted 40 lines · On Mon, Nov 11, 2019 at 07:30:37AM +0100, [email protected] wrote:

The patch below does not apply to the 5.3-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 52338415cf4d4064ae6b8dd972dadbda841da4fa Mon Sep 17 00:00:00 2001
From: Huacai Chen <[email protected]>
Date: Thu, 24 Oct 2019 11:28:29 +0800
Subject: [PATCH] timekeeping/vsyscall: Update VDSO data unconditionally
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 ]

Quoted 11 lines

Fixes 44f57d788e7deecb50 ("timekeeping: Provide a generic update_vsyscall() implementation")
Signed-off-by Huacai Chen <[email protected]>
Signed-off-by Thomas Gleixner <[email protected]>
Cc Andy Lutomirski <[email protected]>
Cc Vincenzo Frascino <[email protected]>
Cc Arnd Bergmann <[email protected]>
Cc Paul Burton <[email protected]>
Cc [email protected]
Cc [email protected]
Cc [email protected]
Link https://lkml.kernel.org/r/[email protected] open here

I've dropped the mips bits because we don't have 24640f233b46 ("mips:
Add support for generic vDSO") on 5.3 and queued it up.

Signature · 2 lines

Thanks,
Sasha