diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2025-12-15 17:52:06 +0100 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2026-01-22 11:11:16 +0100 |
| commit | f8380f976804533df4c6c3d3a0b2cd03c2d262bc (patch) | |
| tree | a575c2e92d8ee13ee36669b815113810110285f4 | |
| parent | d7a5da7a0f7fa7ff081140c4f6f971db98882703 (diff) | |
rseq: Provide static branch for time slice extensions
Guard the time slice extension functionality with a static key, which can
be disabled on the kernel command line.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251215155708.733429292@linutronix.de
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 5 | ||||
| -rw-r--r-- | include/linux/rseq_entry.h | 11 | ||||
| -rw-r--r-- | kernel/rseq.c | 17 |
3 files changed, 33 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index a8d0afde7f85..f2348bca36a1 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -6600,6 +6600,11 @@ Kernel parameters rootflags= [KNL] Set root filesystem mount option string + rseq_slice_ext= [KNL] RSEQ based time slice extension + Format: boolean + Control enablement of RSEQ based time slice extension. + Default is 'on'. + initramfs_options= [KNL] Specify mount options for for the initramfs mount. diff --git a/include/linux/rseq_entry.h b/include/linux/rseq_entry.h index a36b472627de..d0ec4714ffd6 100644 --- a/include/linux/rseq_entry.h +++ b/include/linux/rseq_entry.h @@ -75,6 +75,17 @@ DECLARE_STATIC_KEY_MAYBE(CONFIG_RSEQ_DEBUG_DEFAULT_ENABLE, rseq_debug_enabled); #define rseq_inline __always_inline #endif +#ifdef CONFIG_RSEQ_SLICE_EXTENSION +DECLARE_STATIC_KEY_TRUE(rseq_slice_extension_key); + +static __always_inline bool rseq_slice_extension_enabled(void) +{ + return static_branch_likely(&rseq_slice_extension_key); +} +#else /* CONFIG_RSEQ_SLICE_EXTENSION */ +static inline bool rseq_slice_extension_enabled(void) { return false; } +#endif /* !CONFIG_RSEQ_SLICE_EXTENSION */ + bool rseq_debug_update_user_cs(struct task_struct *t, struct pt_regs *regs, unsigned long csaddr); bool rseq_debug_validate_ids(struct task_struct *t); diff --git a/kernel/rseq.c b/kernel/rseq.c index 07c324d5a201..bf75268580ef 100644 --- a/kernel/rseq.c +++ b/kernel/rseq.c @@ -483,3 +483,20 @@ SYSCALL_DEFINE4(rseq, struct rseq __user *, rseq, u32, rseq_len, int, flags, u32 efault: return -EFAULT; } + +#ifdef CONFIG_RSEQ_SLICE_EXTENSION +DEFINE_STATIC_KEY_TRUE(rseq_slice_extension_key); + +static int __init rseq_slice_cmdline(char *str) +{ + bool on; + + if (kstrtobool(str, &on)) + return 0; + + if (!on) + static_branch_disable(&rseq_slice_extension_key); + return 1; +} +__setup("rseq_slice_ext=", rseq_slice_cmdline); +#endif /* CONFIG_RSEQ_SLICE_EXTENSION */ |