mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2025-12-22 12:17:45 +01:00
1d17e808cf
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
137 lines
3.1 KiB
C
137 lines
3.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
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#ifndef _LINUX_RSEQ_H
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#define _LINUX_RSEQ_H
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#ifdef CONFIG_RSEQ
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#include <linux/preempt.h>
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#include <linux/sched.h>
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#ifdef CONFIG_MEMBARRIER
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# define RSEQ_EVENT_GUARD irq
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#else
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# define RSEQ_EVENT_GUARD preempt
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#endif
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/*
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* Map the event mask on the user-space ABI enum rseq_cs_flags
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* for direct mask checks.
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*/
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enum rseq_event_mask_bits {
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RSEQ_EVENT_PREEMPT_BIT = RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT,
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RSEQ_EVENT_SIGNAL_BIT = RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT,
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RSEQ_EVENT_MIGRATE_BIT = RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT,
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};
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enum rseq_event_mask {
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RSEQ_EVENT_PREEMPT = (1U << RSEQ_EVENT_PREEMPT_BIT),
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RSEQ_EVENT_SIGNAL = (1U << RSEQ_EVENT_SIGNAL_BIT),
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RSEQ_EVENT_MIGRATE = (1U << RSEQ_EVENT_MIGRATE_BIT),
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};
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static inline void rseq_set_notify_resume(struct task_struct *t)
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{
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if (t->rseq)
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set_tsk_thread_flag(t, TIF_NOTIFY_RESUME);
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}
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void __rseq_handle_notify_resume(struct ksignal *sig, struct pt_regs *regs);
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static inline void rseq_handle_notify_resume(struct ksignal *ksig,
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struct pt_regs *regs)
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{
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if (current->rseq)
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__rseq_handle_notify_resume(ksig, regs);
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}
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static inline void rseq_signal_deliver(struct ksignal *ksig,
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struct pt_regs *regs)
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{
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scoped_guard(RSEQ_EVENT_GUARD)
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__set_bit(RSEQ_EVENT_SIGNAL_BIT, ¤t->rseq_event_mask);
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rseq_handle_notify_resume(ksig, regs);
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}
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/* rseq_preempt() requires preemption to be disabled. */
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static inline void rseq_preempt(struct task_struct *t)
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{
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__set_bit(RSEQ_EVENT_PREEMPT_BIT, &t->rseq_event_mask);
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rseq_set_notify_resume(t);
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}
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/* rseq_migrate() requires preemption to be disabled. */
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static inline void rseq_migrate(struct task_struct *t)
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{
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__set_bit(RSEQ_EVENT_MIGRATE_BIT, &t->rseq_event_mask);
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rseq_set_notify_resume(t);
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}
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/*
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* If parent process has a registered restartable sequences area, the
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* child inherits. Unregister rseq for a clone with CLONE_VM set.
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*/
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static inline void rseq_fork(struct task_struct *t, u64 clone_flags)
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{
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if (clone_flags & CLONE_VM) {
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t->rseq = NULL;
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t->rseq_len = 0;
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t->rseq_sig = 0;
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t->rseq_event_mask = 0;
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} else {
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t->rseq = current->rseq;
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t->rseq_len = current->rseq_len;
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t->rseq_sig = current->rseq_sig;
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t->rseq_event_mask = current->rseq_event_mask;
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}
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}
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static inline void rseq_execve(struct task_struct *t)
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{
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t->rseq = NULL;
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t->rseq_len = 0;
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t->rseq_sig = 0;
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t->rseq_event_mask = 0;
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}
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#else
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static inline void rseq_set_notify_resume(struct task_struct *t)
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{
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}
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static inline void rseq_handle_notify_resume(struct ksignal *ksig,
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struct pt_regs *regs)
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{
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}
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static inline void rseq_signal_deliver(struct ksignal *ksig,
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struct pt_regs *regs)
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{
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}
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static inline void rseq_preempt(struct task_struct *t)
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{
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}
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static inline void rseq_migrate(struct task_struct *t)
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{
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}
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static inline void rseq_fork(struct task_struct *t, u64 clone_flags)
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{
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}
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static inline void rseq_execve(struct task_struct *t)
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{
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}
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#endif
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#ifdef CONFIG_DEBUG_RSEQ
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void rseq_syscall(struct pt_regs *regs);
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#else
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static inline void rseq_syscall(struct pt_regs *regs)
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{
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}
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#endif
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#endif /* _LINUX_RSEQ_H */
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