[PATCH v2 0/9] vDSO: Respect COMPAT_32BIT_TIME

[PATCH v2 0/9] vDSO: Respect COMPAT_32BIT_TIME

[Thomas Weißschuh]

If CONFIG_COMPAT_32BIT_TIME is disabled then the vDSO should not
provide any 32-bit time related functionality. This is the intended
effect of the kconfig option and also the fallback system calls would
also not be implemented.

Currently the kconfig option does not affect the gettimeofday() syscall,
so also keep that in the vDSO.

I also tried to introduce some helpers to avoid much of the ifdeffery,
but due to the high variance in the architecture-specific glue code
these would need to handle they ended up being worse than the current
proposal.

As a side-effect this will make the self-tests more reliable,
as there is now always a matching syscall available for each vDSO function.

clock_gettime_time64() was only introduced in v6.19, so libc implementations
are likely not using it yet.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
---
Changes in v2:
- Also handle SPARC.
- Drop MIPS cleanup patches.
- Also handle gettimeofday().
- Add more static validations.
- Rebase on v7.2-rc1.
- Link to v1: https://lore.kernel.org/r/20260227-vdso-compat_32bit_time-v1-0-3f0286a7bac3@linutronix.de

To: Andy Lutomirski <luto@kernel.org>
To: Thomas Gleixner <tglx@kernel.org>
To: Ingo Molnar <mingo@redhat.com>
To: Borislav Petkov <bp@alien8.de>
To: Dave Hansen <dave.hansen@linux.intel.com>
To: x86@kernel.org
To: H. Peter Anvin <hpa@zytor.com>
To: Russell King <linux@armlinux.org.uk>
To: Catalin Marinas <catalin.marinas@arm.com>
To: Will Deacon <will@kernel.org>
To: Madhavan Srinivasan <maddy@linux.ibm.com>
To: Michael Ellerman <mpe@ellerman.id.au>
To: Nicholas Piggin <npiggin@gmail.com>
To: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
To: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
To: Vincenzo Frascino <vincenzo.frascino@arm.com>
To: John Stultz <jstultz@google.com>
To: Stephen Boyd <sboyd@kernel.org>
To: "David S. Miller" <davem@davemloft.net>
To: Andreas Larsson <andreas@gaisler.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-mips@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: linux-api@vger.kernel.org
Cc: sparclinux@vger.kernel.org

---
Thomas Weißschuh (9):
      time: Respect COMPAT_32BIT_TIME for old time type functions
      vdso/gettimeofday: Validate system call existence for time() and gettimeofday()
      x86/vdso: Respect COMPAT_32BIT_TIME
      arm64: vdso32: Respect COMPAT_32BIT_TIME
      ARM: VDSO: Respect COMPAT_32BIT_TIME
      powerpc/vdso: Respect COMPAT_32BIT_TIME
      MIPS: VDSO: Respect COMPAT_32BIT_TIME
      sparc: vdso: Respect COMPAT_32BIT_TIME
      vdso/gettimeofday: Verify COMPAT_32BIT_TIME interactions

 arch/arm/vdso/vdso.lds.S                    |  2 ++
 arch/arm/vdso/vgettimeofday.c               | 14 ++++++++------
 arch/arm64/kernel/vdso32/vdso.lds.S         |  2 ++
 arch/arm64/kernel/vdso32/vgettimeofday.c    | 14 ++++++++------
 arch/mips/vdso/vdso.lds.S                   |  2 ++
 arch/mips/vdso/vgettimeofday.c              |  3 +++
 arch/powerpc/kernel/vdso/gettimeofday.S     |  8 ++++++++
 arch/powerpc/kernel/vdso/vdso32.lds.S       | 10 ++++++----
 arch/powerpc/kernel/vdso/vgettimeofday.c    | 16 ++++++++++------
 arch/sparc/vdso/vclock_gettime.c            |  4 ++++
 arch/sparc/vdso/vdso32/vdso32.lds.S         |  6 ++++--
 arch/x86/entry/vdso/common/vclock_gettime.c | 20 ++++++++++++--------
 arch/x86/entry/vdso/vdso32/vdso32.lds.S     |  2 ++
 kernel/sys_ni.c                             |  4 ++++
 kernel/time/time.c                          | 24 ++++++++++++++++++++----
 lib/vdso/gettimeofday.c                     | 20 ++++++++++++++++++++
 16 files changed, 115 insertions(+), 36 deletions(-)
---
base-commit: e6da2429169af9b33f3629b69905d89bb5ee9e64
change-id: 20260113-vdso-compat_32bit_time-e808763e976a

Best regards,
--  
Thomas Weißschuh (Schneider Electric) <thomas.weissschuh@linutronix.de>

[PATCH v2 1/9] time: Respect COMPAT_32BIT_TIME for old time type functions

[Thomas Weißschuh]

The "old" time types use 32-bit seconds which are not y2038-safe.
Respect COMPAT_32BIT_TIME for functions using those types.
time(), stime() and gettimeofday() are disabled completely.

settimeofday() is kept as it is required to do the initial timewarping
after boot. However the 'tv' argument will be rejected.

Link: https://lore.kernel.org/lkml/e9487ebe-3730-438a-9c23-e45f75986ecc@app.fastmail.com/
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
---
 kernel/sys_ni.c    |  4 ++++
 kernel/time/time.c | 24 ++++++++++++++++++++----
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index add3032da16f..c8be0abaa407 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -351,6 +351,10 @@ COND_SYSCALL(ppoll_time32);
 COND_SYSCALL_COMPAT(ppoll_time32);
 COND_SYSCALL(utimensat_time32);
 COND_SYSCALL(clock_adjtime32);
+COND_SYSCALL(gettimeofday);
+COND_SYSCALL_COMPAT(gettimeofday);
+COND_SYSCALL(time);
+COND_SYSCALL(stime);
 
 /*
  * The syscalls below are not found in include/uapi/asm-generic/unistd.h
diff --git a/kernel/time/time.c b/kernel/time/time.c
index 0dd63a91e7c5..0b7aa432bc76 100644
--- a/kernel/time/time.c
+++ b/kernel/time/time.c
@@ -43,6 +43,12 @@
 #include <generated/timeconst.h>
 #include "timekeeping.h"
 
+#if defined(CONFIG_64BIT) || defined(CONFIG_COMPAT_32BIT_TIME)
+#define __WANT_OLD_TIME_TYPE_SYSCALL 1
+#endif
+
+static_assert(sizeof(__kernel_old_time_t) == 8 ? IS_ENABLED(__WANT_OLD_TIME_TYPE_SYSCALL) : true);
+
 /*
  * The timezone where the local system is located.  Used as a default by some
  * programs who obtain this value by using gettimeofday.
@@ -51,7 +57,7 @@ struct timezone sys_tz;
 
 EXPORT_SYMBOL(sys_tz);
 
-#ifdef __ARCH_WANT_SYS_TIME
+#if defined(__ARCH_WANT_SYS_TIME) && defined(__WANT_OLD_TIME_TYPE_SYSCALL)
 
 /*
  * sys_time() can be implemented in user-level using
@@ -96,7 +102,7 @@ SYSCALL_DEFINE1(stime, __kernel_old_time_t __user *, tptr)
 	return 0;
 }
 
-#endif /* __ARCH_WANT_SYS_TIME */
+#endif /* __ARCH_WANT_SYS_TIME && __WANT_OLD_TIME_TYPE_SYSCALL */
 
 #ifdef CONFIG_COMPAT_32BIT_TIME
 #ifdef __ARCH_WANT_SYS_TIME32
@@ -137,6 +143,7 @@ SYSCALL_DEFINE1(stime32, old_time32_t __user *, tptr)
 #endif /* __ARCH_WANT_SYS_TIME32 */
 #endif
 
+#ifdef __WANT_OLD_TIME_TYPE_SYSCALL
 SYSCALL_DEFINE2(gettimeofday, struct __kernel_old_timeval __user *, tv,
 		struct timezone __user *, tz)
 {
@@ -154,6 +161,7 @@ SYSCALL_DEFINE2(gettimeofday, struct __kernel_old_timeval __user *, tv,
 	}
 	return 0;
 }
+#endif /* __WANT_OLD_TIME_TYPE_SYSCALL */
 
 /*
  * In case for some reason the CMOS clock has not already been running
@@ -203,6 +211,9 @@ SYSCALL_DEFINE2(settimeofday, struct __kernel_old_timeval __user *, tv,
 	struct timezone new_tz;
 
 	if (tv) {
+		if (!IS_ENABLED(__WANT_OLD_TIME_TYPE_SYSCALL))
+			return -EINVAL;
+
 		if (get_user(new_ts.tv_sec, &tv->tv_sec) ||
 		    get_user(new_ts.tv_nsec, &tv->tv_usec))
 			return -EFAULT;
@@ -220,7 +231,7 @@ SYSCALL_DEFINE2(settimeofday, struct __kernel_old_timeval __user *, tv,
 	return do_sys_settimeofday64(tv ? &new_ts : NULL, tz ? &new_tz : NULL);
 }
 
-#ifdef CONFIG_COMPAT
+#ifdef CONFIG_COMPAT_32BIT_TIME
 COMPAT_SYSCALL_DEFINE2(gettimeofday, struct old_timeval32 __user *, tv,
 		       struct timezone __user *, tz)
 {
@@ -239,7 +250,9 @@ COMPAT_SYSCALL_DEFINE2(gettimeofday, struct old_timeval32 __user *, tv,
 
 	return 0;
 }
+#endif /* CONFIG_COMPAT_32BIT_TIME */
 
+#ifdef CONFIG_COMPAT
 COMPAT_SYSCALL_DEFINE2(settimeofday, struct old_timeval32 __user *, tv,
 		       struct timezone __user *, tz)
 {
@@ -247,6 +260,9 @@ COMPAT_SYSCALL_DEFINE2(settimeofday, struct old_timeval32 __user *, tv,
 	struct timezone new_tz;
 
 	if (tv) {
+		if (!IS_ENABLED(__WANT_OLD_TIME_TYPE_SYSCALL))
+			return -EINVAL;
+
 		if (get_user(new_ts.tv_sec, &tv->tv_sec) ||
 		    get_user(new_ts.tv_nsec, &tv->tv_usec))
 			return -EFAULT;
@@ -263,7 +279,7 @@ COMPAT_SYSCALL_DEFINE2(settimeofday, struct old_timeval32 __user *, tv,
 
 	return do_sys_settimeofday64(tv ? &new_ts : NULL, tz ? &new_tz : NULL);
 }
-#endif
+#endif /* CONFIG_COMPAT */
 
 #ifdef CONFIG_64BIT
 SYSCALL_DEFINE1(adjtimex, struct __kernel_timex __user *, txc_p)

-- 
2.55.0

Re: [PATCH v2 1/9] time: Respect COMPAT_32BIT_TIME for old time type functions

[Arnd Bergmann]

On Tue, Jun 30, 2026, at 09:38, Thomas Weißschuh wrote:
> The "old" time types use 32-bit seconds which are not y2038-safe.
> Respect COMPAT_32BIT_TIME for functions using those types.
> time(), stime() and gettimeofday() are disabled completely.

Looks good, yes

> settimeofday() is kept as it is required to do the initial timewarping
> after boot. However the 'tv' argument will be rejected.

Not sure about this part, did we already discuss this last time?

I can see how keeping the timewarping functionality is the easy way
out, but completely disabling the settimeofday syscall the same
way we do on new architectures seems so much more consistent.

Note how scripts/syscall.tbl blocks sys_settimeofday on
architectures that don't set the time32 flag, which ideally
should match the COMPAT_32BIT_TIME option here.

     Arnd

Re: [PATCH v2 1/9] time: Respect COMPAT_32BIT_TIME for old time type functions

[Thomas Weißschuh]

On Tue, Jun 30, 2026 at 03:00:37PM +0200, Arnd Bergmann wrote:
> On Tue, Jun 30, 2026, at 09:38, Thomas Weißschuh wrote:
> > The "old" time types use 32-bit seconds which are not y2038-safe.
> > Respect COMPAT_32BIT_TIME for functions using those types.
> > time(), stime() and gettimeofday() are disabled completely.
> 
> Looks good, yes

Sashiko found an issue [0], which I think is valid. I'll change that for v3.

> > settimeofday() is kept as it is required to do the initial timewarping
> > after boot. However the 'tv' argument will be rejected.
> 
> Not sure about this part, did we already discuss this last time?

This is my interpretation of [1].

> I can see how keeping the timewarping functionality is the easy way
> out, but completely disabling the settimeofday syscall the same
> way we do on new architectures seems so much more consistent.

Shouldn't we then do this completely? Irrespective of COMPAT_32BIT_TIME?
And then remove all of the timewarping and kernel timezone bits.

It would be nice however if this series, and my other ones blocked behind it,
are not blocked on that larger rework.

(...)

[0] https://sashiko.dev/#/patchset/20260630-vdso-compat_32bit_time-v2-0-520d194640dd%40linutronix.de?part=1
[1] https://lore.kernel.org/all/e9487ebe-3730-438a-9c23-e45f75986ecc@app.fastmail.com/


Thomas

Re: [PATCH v2 1/9] time: Respect COMPAT_32BIT_TIME for old time type functions

[Arnd Bergmann]

On Wed, Jul 1, 2026, at 10:40, Thomas Weißschuh wrote:
> On Tue, Jun 30, 2026 at 03:00:37PM +0200, Arnd Bergmann wrote:
>> On Tue, Jun 30, 2026, at 09:38, Thomas Weißschuh wrote:
>> > The "old" time types use 32-bit seconds which are not y2038-safe.
>> > Respect COMPAT_32BIT_TIME for functions using those types.
>> > time(), stime() and gettimeofday() are disabled completely.
>> 
>> Looks good, yes
>
> Sashiko found an issue [0], which I think is valid. I'll change that for v3.

Ok

>> > settimeofday() is kept as it is required to do the initial timewarping
>> > after boot. However the 'tv' argument will be rejected.
>> 
>> Not sure about this part, did we already discuss this last time?
>
> This is my interpretation of [1].

Indeed, we did.

>> I can see how keeping the timewarping functionality is the easy way
>> out, but completely disabling the settimeofday syscall the same
>> way we do on new architectures seems so much more consistent.
>
> Shouldn't we then do this completely? Irrespective of COMPAT_32BIT_TIME?
> And then remove all of the timewarping and kernel timezone bits.

I don't think we can simply kill the timewarping code since that
likely has users on architectures including on x86-64.

COMPAT_32BIT_TIME=n is somewhat special because this is an
intentional (and optional) ABI break already and requires
updated userspace that avoids the time32 syscalls. Having the
timewarp still in settimeofday() or dropping it entirely is not
that different for userspace.

I was slightly worried about whether returning -EINVAL or -ENOSYS
is the better option here, but I think your choice is the correct
one after seeing that this is what glibc does other invalid
cases, and that in all of codesearch.debian.net, I could not
find a single caller that would care about the difference.

> It would be nice however if this series, and my other ones blocked behind it,
> are not blocked on that larger rework.

Sure.

I think you can go ahead with this version. I would prefer
to not have any settimeofday() for the COMPAT_32BIT_TIME=n
case, but if nobody else has a strong opinion on the matter,
let's do it your way.

Reviewed-by: Arnd Bergmann <arnd@arndb.de>

[PATCH v2 2/9] vdso/gettimeofday: Validate system call existence for time() and gettimeofday()

[Thomas Weißschuh]

Not all architectures have the system calls for time() and
gettimeofday(). When the system call is missing, the vDSO function
should also not be present.

Validate that.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
---
 lib/vdso/gettimeofday.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index e0f289d3d110..b8c1fc85eb74 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -12,6 +12,8 @@
 #include <vdso/time32.h>
 #include <vdso/time64.h>
 
+#include <uapi/linux/unistd.h>
+
 /*
  * The generic vDSO implementation requires that gettimeofday.h
  * provides:
@@ -348,6 +350,10 @@ __cvdso_gettimeofday_data(const struct vdso_time_data *vd,
 {
 	const struct vdso_clock *vc = vd->clock_data;
 
+#ifndef __NR_gettimeofday
+	BUILD_BUG();
+#endif
+
 	if (likely(tv != NULL)) {
 		struct __kernel_timespec ts;
 
@@ -382,6 +388,10 @@ __cvdso_time_data(const struct vdso_time_data *vd, __kernel_old_time_t *time)
 	const struct vdso_clock *vc = vd->clock_data;
 	__kernel_old_time_t t;
 
+#ifndef __NR_time
+	BUILD_BUG();
+#endif
+
 	if (vdso_is_timens_clock(vc)) {
 		vd = vdso_timens_data(vd);
 		vc = vd->clock_data;

-- 
2.55.0

Re: [PATCH v2 2/9] vdso/gettimeofday: Validate system call existence for time() and gettimeofday()

[Philippe Mathieu-Daudé]

On 30/6/26 09:38, Thomas WeiÃschuh wrote:
> Not all architectures have the system calls for time() and
> gettimeofday(). When the system call is missing, the vDSO function
> should also not be present.
> 
> Validate that.
> 
> Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
> ---
>   lib/vdso/gettimeofday.c | 10 ++++++++++
>   1 file changed, 10 insertions(+)

Reviewed-by: Philippe Mathieu-Daudé <philmd@oss.qualcomm.com>

[PATCH v2 3/9] x86/vdso: Respect COMPAT_32BIT_TIME

[Thomas Weißschuh]

If CONFIG_COMPAT_32BIT_TIME is disabled then the vDSO should not
provide any 32-bit time related functionality. This is the intended
effect of the kconfig option and also the fallback system calls would
also not be implemented.

Currently the kconfig option does not affect the gettimeofday() syscall,
so also keep that in the vDSO.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
---
 arch/x86/entry/vdso/common/vclock_gettime.c | 20 ++++++++++++--------
 arch/x86/entry/vdso/vdso32/vdso32.lds.S     |  2 ++
 2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/arch/x86/entry/vdso/common/vclock_gettime.c b/arch/x86/entry/vdso/common/vclock_gettime.c
index 57066f346b3f..304dbd1f9db4 100644
--- a/arch/x86/entry/vdso/common/vclock_gettime.c
+++ b/arch/x86/entry/vdso/common/vclock_gettime.c
@@ -15,6 +15,7 @@
 
 #include "lib/vdso/gettimeofday.c"
 
+#if defined(__x86_64__) || defined(CONFIG_COMPAT_32BIT_TIME)
 int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
 {
 	return __cvdso_gettimeofday(tv, tz);
@@ -29,6 +30,7 @@ __kernel_old_time_t __vdso_time(__kernel_old_time_t *t)
 }
 
 __kernel_old_time_t time(__kernel_old_time_t *t)	__attribute__((weak, alias("__vdso_time")));
+#endif /* CONFIG_COMPAT_32BIT_TIME */
 
 
 #if defined(CONFIG_X86_64) && !defined(BUILD_VDSO32_64)
@@ -51,6 +53,7 @@ int clock_getres(clockid_t, struct __kernel_timespec *)
 
 #else
 /* i386 only */
+#ifdef CONFIG_COMPAT_32BIT_TIME
 int __vdso_clock_gettime(clockid_t clock, struct old_timespec32 *ts)
 {
 	return __cvdso_clock_gettime32(clock, ts);
@@ -59,14 +62,6 @@ 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_gettime64(clockid_t clock, struct __kernel_timespec *ts)
-{
-	return __cvdso_clock_gettime(clock, ts);
-}
-
-int clock_gettime64(clockid_t, struct __kernel_timespec *)
-	__attribute__((weak, alias("__vdso_clock_gettime64")));
-
 int __vdso_clock_getres(clockid_t clock, struct old_timespec32 *res)
 {
 	return __cvdso_clock_getres_time32(clock, res);
@@ -74,6 +69,15 @@ int __vdso_clock_getres(clockid_t clock, struct old_timespec32 *res)
 
 int clock_getres(clockid_t, struct old_timespec32 *)
 	__attribute__((weak, alias("__vdso_clock_getres")));
+#endif /* CONFIG_COMPAT_32BIT_TIME */
+
+int __vdso_clock_gettime64(clockid_t clock, struct __kernel_timespec *ts)
+{
+	return __cvdso_clock_gettime(clock, ts);
+}
+
+int clock_gettime64(clockid_t, struct __kernel_timespec *)
+	__attribute__((weak, alias("__vdso_clock_gettime64")));
 
 int __vdso_clock_getres_time64(clockid_t clock, struct __kernel_timespec *ts)
 {
diff --git a/arch/x86/entry/vdso/vdso32/vdso32.lds.S b/arch/x86/entry/vdso/vdso32/vdso32.lds.S
index cee8f7f9fe80..00629192db56 100644
--- a/arch/x86/entry/vdso/vdso32/vdso32.lds.S
+++ b/arch/x86/entry/vdso/vdso32/vdso32.lds.S
@@ -23,10 +23,12 @@ VERSION
 {
 	LINUX_2.6 {
 	global:
+#ifdef CONFIG_COMPAT_32BIT_TIME
 		__vdso_clock_gettime;
 		__vdso_gettimeofday;
 		__vdso_time;
 		__vdso_clock_getres;
+#endif /* CONFIG_COMPAT_32BIT_TIME */
 		__vdso_clock_gettime64;
 		__vdso_clock_getres_time64;
 		__vdso_getcpu;

-- 
2.55.0

[PATCH v2 4/9] arm64: vdso32: Respect COMPAT_32BIT_TIME

[Thomas Weißschuh]

If CONFIG_COMPAT_32BIT_TIME is disabled then the vDSO should not
provide any 32-bit time related functionality. This is the intended
effect of the kconfig option and also the fallback system calls would
also not be implemented.

Currently the kconfig option does not affect the gettimeofday() syscall,
so also keep that in the vDSO.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
---
 arch/arm64/kernel/vdso32/vdso.lds.S      |  2 ++
 arch/arm64/kernel/vdso32/vgettimeofday.c | 14 ++++++++------
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/kernel/vdso32/vdso.lds.S b/arch/arm64/kernel/vdso32/vdso.lds.S
index c374fb0146f3..12bfc39e8aab 100644
--- a/arch/arm64/kernel/vdso32/vdso.lds.S
+++ b/arch/arm64/kernel/vdso32/vdso.lds.S
@@ -82,9 +82,11 @@ VERSION
 {
 	LINUX_2.6 {
 	global:
+#ifdef CONFIG_COMPAT_32BIT_TIME
 		__vdso_clock_gettime;
 		__vdso_gettimeofday;
 		__vdso_clock_getres;
+#endif /* CONFIG_COMPAT_32BIT_TIME */
 		__vdso_clock_gettime64;
 		__vdso_clock_getres_time64;
 	local: *;
diff --git a/arch/arm64/kernel/vdso32/vgettimeofday.c b/arch/arm64/kernel/vdso32/vgettimeofday.c
index 0c6998ebe491..12d0255cc2cf 100644
--- a/arch/arm64/kernel/vdso32/vgettimeofday.c
+++ b/arch/arm64/kernel/vdso32/vgettimeofday.c
@@ -8,16 +8,17 @@
 #define BUILD_VDSO32_64
 #include <vdso/gettime.h>
 
+#ifdef CONFIG_COMPAT_32BIT_TIME
 int __vdso_clock_gettime(clockid_t clock,
 			 struct old_timespec32 *ts)
 {
 	return __cvdso_clock_gettime32(clock, ts);
 }
 
-int __vdso_clock_gettime64(clockid_t clock,
-			   struct __kernel_timespec *ts)
+int __vdso_clock_getres(clockid_t clock_id,
+			struct old_timespec32 *res)
 {
-	return __cvdso_clock_gettime(clock, ts);
+	return __cvdso_clock_getres_time32(clock_id, res);
 }
 
 int __vdso_gettimeofday(struct __kernel_old_timeval *tv,
@@ -25,11 +26,12 @@ int __vdso_gettimeofday(struct __kernel_old_timeval *tv,
 {
 	return __cvdso_gettimeofday(tv, tz);
 }
+#endif /* CONFIG_COMPAT_32BIT_TIME */
 
-int __vdso_clock_getres(clockid_t clock_id,
-			struct old_timespec32 *res)
+int __vdso_clock_gettime64(clockid_t clock,
+			   struct __kernel_timespec *ts)
 {
-	return __cvdso_clock_getres_time32(clock_id, res);
+	return __cvdso_clock_gettime(clock, ts);
 }
 
 int __vdso_clock_getres_time64(clockid_t clock_id, struct __kernel_timespec *res)

-- 
2.55.0

Re: [PATCH v2 4/9] arm64: vdso32: Respect COMPAT_32BIT_TIME

[Philippe Mathieu-Daudé]

On 30/6/26 09:38, Thomas WeiÃschuh wrote:
> If CONFIG_COMPAT_32BIT_TIME is disabled then the vDSO should not
> provide any 32-bit time related functionality. This is the intended
> effect of the kconfig option and also the fallback system calls would
> also not be implemented.
> 
> Currently the kconfig option does not affect the gettimeofday() syscall,
> so also keep that in the vDSO.
> 
> Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
> ---
>   arch/arm64/kernel/vdso32/vdso.lds.S      |  2 ++
>   arch/arm64/kernel/vdso32/vgettimeofday.c | 14 ++++++++------
>   2 files changed, 10 insertions(+), 6 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <philmd@oss.qualcomm.com>

[PATCH v2 5/9] ARM: VDSO: Respect COMPAT_32BIT_TIME

[Thomas Weißschuh]

If CONFIG_COMPAT_32BIT_TIME is disabled then the vDSO should not
provide any 32-bit time related functionality. This is the intended
effect of the kconfig option and also the fallback system calls would
also not be implemented.

Currently the kconfig option does not affect the gettimeofday() syscall,
so also keep that in the vDSO.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
---
 arch/arm/vdso/vdso.lds.S      |  2 ++
 arch/arm/vdso/vgettimeofday.c | 14 ++++++++------
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/arch/arm/vdso/vdso.lds.S b/arch/arm/vdso/vdso.lds.S
index 74d8d8bc8a40..e61038c0195a 100644
--- a/arch/arm/vdso/vdso.lds.S
+++ b/arch/arm/vdso/vdso.lds.S
@@ -70,9 +70,11 @@ VERSION
 {
 	LINUX_2.6 {
 	global:
+#ifdef CONFIG_COMPAT_32BIT_TIME
 		__vdso_clock_gettime;
 		__vdso_gettimeofday;
 		__vdso_clock_getres;
+#endif /* CONFIG_COMPAT_32BIT_TIME */
 		__vdso_clock_gettime64;
 		__vdso_clock_getres_time64;
 	local: *;
diff --git a/arch/arm/vdso/vgettimeofday.c b/arch/arm/vdso/vgettimeofday.c
index f7a2f5dc2fdc..3eebeddbfd18 100644
--- a/arch/arm/vdso/vgettimeofday.c
+++ b/arch/arm/vdso/vgettimeofday.c
@@ -10,16 +10,17 @@
 #include <asm/unwind.h>
 #include <vdso/gettime.h>
 
+#ifdef CONFIG_COMPAT_32BIT_TIME
 int __vdso_clock_gettime(clockid_t clock,
 			 struct old_timespec32 *ts)
 {
 	return __cvdso_clock_gettime32(clock, ts);
 }
 
-int __vdso_clock_gettime64(clockid_t clock,
-			   struct __kernel_timespec *ts)
+int __vdso_clock_getres(clockid_t clock_id,
+			struct old_timespec32 *res)
 {
-	return __cvdso_clock_gettime(clock, ts);
+	return __cvdso_clock_getres_time32(clock_id, res);
 }
 
 int __vdso_gettimeofday(struct __kernel_old_timeval *tv,
@@ -27,11 +28,12 @@ int __vdso_gettimeofday(struct __kernel_old_timeval *tv,
 {
 	return __cvdso_gettimeofday(tv, tz);
 }
+#endif /* CONFIG_COMPAT_32BIT_TIME */
 
-int __vdso_clock_getres(clockid_t clock_id,
-			struct old_timespec32 *res)
+int __vdso_clock_gettime64(clockid_t clock,
+			   struct __kernel_timespec *ts)
 {
-	return __cvdso_clock_getres_time32(clock_id, res);
+	return __cvdso_clock_gettime(clock, ts);
 }
 
 int __vdso_clock_getres_time64(clockid_t clock_id, struct __kernel_timespec *res)

-- 
2.55.0

Re: [PATCH v2 5/9] ARM: VDSO: Respect COMPAT_32BIT_TIME

[Philippe Mathieu-Daudé]

On 30/6/26 09:38, Thomas WeiÃschuh wrote:
> If CONFIG_COMPAT_32BIT_TIME is disabled then the vDSO should not
> provide any 32-bit time related functionality. This is the intended
> effect of the kconfig option and also the fallback system calls would
> also not be implemented.
> 
> Currently the kconfig option does not affect the gettimeofday() syscall,
> so also keep that in the vDSO.
> 
> Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
> ---
>   arch/arm/vdso/vdso.lds.S      |  2 ++
>   arch/arm/vdso/vgettimeofday.c | 14 ++++++++------
>   2 files changed, 10 insertions(+), 6 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <philmd@oss.qualcomm.com>

[PATCH v2 6/9] powerpc/vdso: Respect COMPAT_32BIT_TIME

[Thomas Weißschuh]

If CONFIG_COMPAT_32BIT_TIME is disabled then the vDSO should not
provide any 32-bit time related functionality. This is the intended
effect of the kconfig option and also the fallback system calls would
also not be implemented.

Currently the kconfig option does not affect the gettimeofday() syscall,
so also keep that in the vDSO.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
---
 arch/powerpc/kernel/vdso/gettimeofday.S  |  8 ++++++++
 arch/powerpc/kernel/vdso/vdso32.lds.S    | 10 ++++++----
 arch/powerpc/kernel/vdso/vgettimeofday.c | 16 ++++++++++------
 3 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/kernel/vdso/gettimeofday.S b/arch/powerpc/kernel/vdso/gettimeofday.S
index 1c8e51691bf8..c635cd1e77be 100644
--- a/arch/powerpc/kernel/vdso/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso/gettimeofday.S
@@ -67,9 +67,11 @@
  * int __kernel_gettimeofday(struct timeval *tv, struct timezone *tz);
  *
  */
+#if defined(__powerpc64__) || defined(CONFIG_COMPAT_32BIT_TIME)
 V_FUNCTION_BEGIN(__kernel_gettimeofday)
 	cvdso_call __c_kernel_gettimeofday
 V_FUNCTION_END(__kernel_gettimeofday)
+#endif
 
 /*
  * Exact prototype of clock_gettime()
@@ -77,9 +79,11 @@ V_FUNCTION_END(__kernel_gettimeofday)
  * int __kernel_clock_gettime(clockid_t clock_id, struct timespec *tp);
  *
  */
+#if defined(__powerpc64__) || defined(CONFIG_COMPAT_32BIT_TIME)
 V_FUNCTION_BEGIN(__kernel_clock_gettime)
 	cvdso_call __c_kernel_clock_gettime
 V_FUNCTION_END(__kernel_clock_gettime)
+#endif
 
 /*
  * Exact prototype of clock_gettime64()
@@ -99,9 +103,11 @@ V_FUNCTION_END(__kernel_clock_gettime64)
  * int __kernel_clock_getres(clockid_t clock_id, struct timespec *res);
  *
  */
+#if defined(__powerpc64__) || defined(CONFIG_COMPAT_32BIT_TIME)
 V_FUNCTION_BEGIN(__kernel_clock_getres)
 	cvdso_call __c_kernel_clock_getres
 V_FUNCTION_END(__kernel_clock_getres)
+#endif
 
 /*
  * Exact prototype of clock_getres_time64()
@@ -122,6 +128,8 @@ V_FUNCTION_END(__kernel_clock_getres_time64)
  * time_t time(time *t);
  *
  */
+#if defined(__powerpc64__) || defined(CONFIG_COMPAT_32BIT_TIME)
 V_FUNCTION_BEGIN(__kernel_time)
 	cvdso_call __c_kernel_time call_time=1
 V_FUNCTION_END(__kernel_time)
+#endif
diff --git a/arch/powerpc/kernel/vdso/vdso32.lds.S b/arch/powerpc/kernel/vdso/vdso32.lds.S
index 3f384a2526ae..876c965b827d 100644
--- a/arch/powerpc/kernel/vdso/vdso32.lds.S
+++ b/arch/powerpc/kernel/vdso/vdso32.lds.S
@@ -119,13 +119,15 @@ VERSION
 {
 	VDSO_VERSION_STRING {
 	global:
-		__kernel_get_syscall_map;
-		__kernel_gettimeofday;
+#ifdef CONFIG_COMPAT_32BIT_TIME
 		__kernel_clock_gettime;
-		__kernel_clock_gettime64;
 		__kernel_clock_getres;
-		__kernel_clock_getres_time64;
+		__kernel_gettimeofday;
 		__kernel_time;
+#endif /* CONFIG_COMPAT_32BIT_TIME */
+		__kernel_get_syscall_map;
+		__kernel_clock_gettime64;
+		__kernel_clock_getres_time64;
 		__kernel_get_tbfreq;
 		__kernel_sync_dicache;
 		__kernel_sigtramp32;
diff --git a/arch/powerpc/kernel/vdso/vgettimeofday.c b/arch/powerpc/kernel/vdso/vgettimeofday.c
index 3c194e1ab562..4b712fb01a3f 100644
--- a/arch/powerpc/kernel/vdso/vgettimeofday.c
+++ b/arch/powerpc/kernel/vdso/vgettimeofday.c
@@ -18,23 +18,25 @@ int __c_kernel_clock_getres(clockid_t clock_id, struct __kernel_timespec *res,
 	return __cvdso_clock_getres_data(vd, clock_id, res);
 }
 #else
+#ifdef CONFIG_COMPAT_32BIT_TIME
 int __c_kernel_clock_gettime(clockid_t clock, struct old_timespec32 *ts,
 			     const struct vdso_time_data *vd)
 {
 	return __cvdso_clock_gettime32_data(vd, clock, ts);
 }
 
-int __c_kernel_clock_gettime64(clockid_t clock, struct __kernel_timespec *ts,
-			       const struct vdso_time_data *vd)
-{
-	return __cvdso_clock_gettime_data(vd, clock, ts);
-}
-
 int __c_kernel_clock_getres(clockid_t clock_id, struct old_timespec32 *res,
 			    const struct vdso_time_data *vd)
 {
 	return __cvdso_clock_getres_time32_data(vd, clock_id, res);
 }
+#endif /* CONFIG_COMPAT_32BIT_TIME */
+
+int __c_kernel_clock_gettime64(clockid_t clock, struct __kernel_timespec *ts,
+			       const struct vdso_time_data *vd)
+{
+	return __cvdso_clock_gettime_data(vd, clock, ts);
+}
 
 int __c_kernel_clock_getres_time64(clockid_t clock_id, struct __kernel_timespec *res,
 				   const struct vdso_time_data *vd)
@@ -43,6 +45,7 @@ int __c_kernel_clock_getres_time64(clockid_t clock_id, struct __kernel_timespec
 }
 #endif
 
+#if defined(__powerpc64__) || defined(CONFIG_COMPAT_32BIT_TIME)
 int __c_kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz,
 			    const struct vdso_time_data *vd)
 {
@@ -53,3 +56,4 @@ __kernel_old_time_t __c_kernel_time(__kernel_old_time_t *time, const struct vdso
 {
 	return __cvdso_time_data(vd, time);
 }
+#endif

-- 
2.55.0

[PATCH v2 7/9] MIPS: VDSO: Respect COMPAT_32BIT_TIME

[Thomas Weißschuh]

If CONFIG_COMPAT_32BIT_TIME is disabled then the vDSO should not
provide any 32-bit time related functionality. This is the intended
effect of the kconfig option and also the fallback system calls would
also not be implemented.

Currently the kconfig option does not affect the gettimeofday() syscall,
so also keep that in the vDSO.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
---
 arch/mips/vdso/vdso.lds.S      | 2 ++
 arch/mips/vdso/vgettimeofday.c | 3 +++
 2 files changed, 5 insertions(+)

diff --git a/arch/mips/vdso/vdso.lds.S b/arch/mips/vdso/vdso.lds.S
index 278ab6444e98..b11ee493c67f 100644
--- a/arch/mips/vdso/vdso.lds.S
+++ b/arch/mips/vdso/vdso.lds.S
@@ -97,9 +97,11 @@ VERSION
 	LINUX_2.6 {
 #ifdef CONFIG_GENERIC_GETTIMEOFDAY
 	global:
+#if _MIPS_SIM == _MIPS_SIM_ABI64 || defined(CONFIG_COMPAT_32BIT_TIME)
 		__vdso_clock_gettime;
 		__vdso_gettimeofday;
 		__vdso_clock_getres;
+#endif
 #if _MIPS_SIM != _MIPS_SIM_ABI64
 		__vdso_clock_gettime64;
 		__vdso_clock_getres_time64;
diff --git a/arch/mips/vdso/vgettimeofday.c b/arch/mips/vdso/vgettimeofday.c
index 00f9fcfc327e..a1fb06b8973e 100644
--- a/arch/mips/vdso/vgettimeofday.c
+++ b/arch/mips/vdso/vgettimeofday.c
@@ -12,6 +12,8 @@
 #include <vdso/gettime.h>
 
 #if _MIPS_SIM != _MIPS_SIM_ABI64
+
+#ifdef CONFIG_COMPAT_32BIT_TIME
 int __vdso_clock_gettime(clockid_t clock,
 			 struct old_timespec32 *ts)
 {
@@ -29,6 +31,7 @@ int __vdso_clock_getres(clockid_t clock_id,
 {
 	return __cvdso_clock_getres_time32(clock_id, res);
 }
+#endif /* CONFIG_COMPAT_32BIT_TIME */
 
 int __vdso_clock_gettime64(clockid_t clock,
 			   struct __kernel_timespec *ts)

-- 
2.55.0

[PATCH v2 8/9] sparc: vdso: Respect COMPAT_32BIT_TIME

[Thomas Weißschuh]

If CONFIG_COMPAT_32BIT_TIME is disabled then the vDSO should not
provide any 32-bit time related functionality. This is the intended
effect of the kconfig option and also the fallback system calls would
also not be implemented.

Currently the kconfig option does not affect the gettimeofday() syscall,
so also keep that in the vDSO.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
---
 arch/sparc/vdso/vclock_gettime.c    | 4 ++++
 arch/sparc/vdso/vdso32/vdso32.lds.S | 6 ++++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/sparc/vdso/vclock_gettime.c b/arch/sparc/vdso/vclock_gettime.c
index 1d9859392e4c..221bd4ed19f5 100644
--- a/arch/sparc/vdso/vclock_gettime.c
+++ b/arch/sparc/vdso/vclock_gettime.c
@@ -21,6 +21,7 @@
 
 #include "../../../../lib/vdso/gettimeofday.c"
 
+#if defined(CONFIG_SPARC64) || defined(CONFIG_COMPAT_32BIT_TIME)
 int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
 {
 	return __cvdso_gettimeofday(tv, tz);
@@ -28,6 +29,7 @@ int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
 
 int gettimeofday(struct __kernel_old_timeval *, struct timezone *)
 	__weak __alias(__vdso_gettimeofday);
+#endif
 
 #if defined(CONFIG_SPARC64)
 int __vdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
@@ -40,6 +42,7 @@ int clock_gettime(clockid_t, struct __kernel_timespec *)
 
 #else
 
+#if defined(CONFIG_COMPAT_32BIT_TIME)
 int __vdso_clock_gettime(clockid_t clock, struct old_timespec32 *ts)
 {
 	return __cvdso_clock_gettime32(clock, ts);
@@ -47,6 +50,7 @@ int __vdso_clock_gettime(clockid_t clock, struct old_timespec32 *ts)
 
 int clock_gettime(clockid_t, struct old_timespec32 *)
 	__weak __alias(__vdso_clock_gettime);
+#endif
 
 int __vdso_clock_gettime64(clockid_t clock, struct __kernel_timespec *ts)
 {
diff --git a/arch/sparc/vdso/vdso32/vdso32.lds.S b/arch/sparc/vdso/vdso32/vdso32.lds.S
index a14e4f77e6f2..28052168b875 100644
--- a/arch/sparc/vdso/vdso32/vdso32.lds.S
+++ b/arch/sparc/vdso/vdso32/vdso32.lds.S
@@ -15,12 +15,14 @@
 VERSION {
 	LINUX_2.6 {
 	global:
+#ifdef CONFIG_COMPAT_32BIT_TIME
 		clock_gettime;
 		__vdso_clock_gettime;
-		clock_gettime64;
-		__vdso_clock_gettime64;
 		gettimeofday;
 		__vdso_gettimeofday;
+#endif
+		clock_gettime64;
+		__vdso_clock_gettime64;
 	local: *;
 	};
 }

-- 
2.55.0

Re: [PATCH v2 8/9] sparc: vdso: Respect COMPAT_32BIT_TIME

[Philippe Mathieu-Daudé]

On 30/6/26 09:38, Thomas WeiÃschuh wrote:
> If CONFIG_COMPAT_32BIT_TIME is disabled then the vDSO should not
> provide any 32-bit time related functionality. This is the intended
> effect of the kconfig option and also the fallback system calls would
> also not be implemented.
> 
> Currently the kconfig option does not affect the gettimeofday() syscall,
> so also keep that in the vDSO.
> 
> Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
> ---
>   arch/sparc/vdso/vclock_gettime.c    | 4 ++++
>   arch/sparc/vdso/vdso32/vdso32.lds.S | 6 ++++--
>   2 files changed, 8 insertions(+), 2 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <philmd@oss.qualcomm.com>

[PATCH v2 9/9] vdso/gettimeofday: Verify COMPAT_32BIT_TIME interactions

[Thomas Weißschuh]

If CONFIG_COMPAT_32BIT_TIME is disabled then the vDSO should not
provide any 32-bit time related functionality.

Add some build-time validations to make sure the architecture-specific
glue satisfies this requirement.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
---
 lib/vdso/gettimeofday.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index b8c1fc85eb74..f7a591aba59f 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -25,6 +25,8 @@
  */
 #include <asm/vdso/gettimeofday.h>
 
+#include <linux/build_bug.h>
+
 /* Bring in default accessors */
 #include <vdso/vsyscall.h>
 
@@ -325,6 +327,8 @@ __cvdso_clock_gettime32_data(const struct vdso_time_data *vd, clockid_t clock,
 	struct __kernel_timespec ts;
 	bool ok;
 
+	BUILD_BUG_ON(!IS_ENABLED(CONFIG_COMPAT_32BIT_TIME));
+
 	ok = __cvdso_clock_gettime_common(vd, clock, &ts);
 
 	if (unlikely(!ok))
@@ -354,6 +358,8 @@ __cvdso_gettimeofday_data(const struct vdso_time_data *vd,
 	BUILD_BUG();
 #endif
 
+	BUILD_BUG_ON(sizeof(tv->tv_sec) != 8 && !IS_ENABLED(CONFIG_COMPAT_32BIT_TIME));
+
 	if (likely(tv != NULL)) {
 		struct __kernel_timespec ts;
 
@@ -392,6 +398,8 @@ __cvdso_time_data(const struct vdso_time_data *vd, __kernel_old_time_t *time)
 	BUILD_BUG();
 #endif
 
+	BUILD_BUG_ON(sizeof(*time) != 8 && !IS_ENABLED(CONFIG_COMPAT_32BIT_TIME));
+
 	if (vdso_is_timens_clock(vc)) {
 		vd = vdso_timens_data(vd);
 		vc = vd->clock_data;
@@ -481,6 +489,8 @@ __cvdso_clock_getres_time32_data(const struct vdso_time_data *vd, clockid_t cloc
 	struct __kernel_timespec ts;
 	bool ok;
 
+	BUILD_BUG_ON(!IS_ENABLED(CONFIG_COMPAT_32BIT_TIME));
+
 	ok = __cvdso_clock_getres_common(vd, clock, &ts);
 
 	if (unlikely(!ok))

-- 
2.55.0

Re: [PATCH v2 9/9] vdso/gettimeofday: Verify COMPAT_32BIT_TIME interactions

[Philippe Mathieu-Daudé]

On 30/6/26 09:38, Thomas WeiÃschuh wrote:
> If CONFIG_COMPAT_32BIT_TIME is disabled then the vDSO should not
> provide any 32-bit time related functionality.
> 
> Add some build-time validations to make sure the architecture-specific
> glue satisfies this requirement.
> 
> Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
> ---
>   lib/vdso/gettimeofday.c | 10 ++++++++++
>   1 file changed, 10 insertions(+)

Reviewed-by: Philippe Mathieu-Daudé <philmd@oss.qualcomm.com>

Re: [PATCH v2 0/9] vDSO: Respect COMPAT_32BIT_TIME

[Arnd Bergmann]

On Tue, Jun 30, 2026, at 09:38, Thomas Weißschuh wrote:
> If CONFIG_COMPAT_32BIT_TIME is disabled then the vDSO should not
> provide any 32-bit time related functionality. This is the intended
> effect of the kconfig option and also the fallback system calls would
> also not be implemented.
>
> Currently the kconfig option does not affect the gettimeofday() syscall,
> so also keep that in the vDSO.
>
> I also tried to introduce some helpers to avoid much of the ifdeffery,
> but due to the high variance in the architecture-specific glue code
> these would need to handle they ended up being worse than the current
> proposal.
>
> As a side-effect this will make the self-tests more reliable,
> as there is now always a matching syscall available for each vDSO function.
>
> clock_gettime_time64() was only introduced in v6.19, so libc implementations

   ^ clock_getres_time64()

> Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
> ---

Reviewed-by: Arnd Bergmann <arnd@arndb.de>

once we have consensus on my patch 1/9 comment. Thanks for
continuing this work!

      Arnd