1) Protect the event mask modification against the membarrier() IPI as
otherwise the RmW operation is unprotected and events might be lost.
2) Fix the weak symbol reference in rseq selftests
The current weak RSEQ symbols definitions which were added to allow
static linkage are not working correctly as the effectively re-define
the glibc symbols leading to multiple versions of the symbols when
compiled with -fno-common. Mark them as 'extern' to convert them from
weak symbol definitions to weak symbol references. That works with
static and dynamic linkage independent of -fcommon and -fno-common.
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Merge tag 'core-rseq-2025-09-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull rseq updates from Thomas Gleixner:
"Two fixes for RSEQ:
- Protect the event mask modification against the membarrier() IPI as
otherwise the RmW operation is unprotected and events might be lost
- Fix the weak symbol reference in rseq selftests
The current weak RSEQ symbols definitions which were added to allow
static linkage are not working correctly as they effectively
re-define the glibc symbols leading to multiple versions of the
symbols when compiled with -fno-common.
Mark them as 'extern' to convert them from weak symbol definitions
to weak symbol references. That works with static and dynamic
linkage independent of -fcommon and -fno-common"
* tag 'core-rseq-2025-09-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
rseq/selftests: Use weak symbol reference, not definition, to link with glibc
rseq: Protect event mask against membarrier IPI
rseq_need_restart() reads and clears task::rseq_event_mask with preemption
disabled to guard against the scheduler.
But membarrier() uses an IPI and sets the PREEMPT bit in the event mask
from the IPI, which leaves that RMW operation unprotected.
Use guard(irq) if CONFIG_MEMBARRIER is enabled to fix that.
Fixes: 2a36ab717e ("rseq/membarrier: Add MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: stable@vger.kernel.org
With the introduction of clone3 in commit 7f192e3cd3 ("fork: add
clone3") the effective bit width of clone_flags on all architectures was
increased from 32-bit to 64-bit, with a new type of u64 for the flags.
However, for most consumers of clone_flags the interface was not
changed from the previous type of unsigned long.
While this works fine as long as none of the new 64-bit flag bits
(CLONE_CLEAR_SIGHAND and CLONE_INTO_CGROUP) are evaluated, this is still
undesirable in terms of the principle of least surprise.
Thus, this commit fixes all relevant interfaces of callees to
sys_clone3/copy_process (excluding the architecture-specific
copy_thread) to consistently pass clone_flags as u64, so that
no truncation to 32-bit integers occurs on 32-bit architectures.
Signed-off-by: Simon Schuster <schuster.simon@siemens-energy.com>
Link: https://lore.kernel.org/20250901-nios2-implement-clone3-v2-2-53fcf5577d57@siemens-energy.com
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
We're trying to get sched.h down to more or less just types only, not
code - rseq can live in its own header.
This helps us kill the dependency on preempt.h in sched.h.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Linus Torvalds