Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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
authored by
Thomas Gleixner
and committed by
Peter Zijlstra
f8380f97
d7a5da7a
+33
+5
Documentation/admin-guide/kernel-parameters.txt
+5
Documentation/admin-guide/kernel-parameters.txt
···
6600
6600
6601
6601
rootflags= [KNL] Set root filesystem mount option string
6602
6602
6603
+
rseq_slice_ext= [KNL] RSEQ based time slice extension
6604
+
Format: boolean
6605
+
Control enablement of RSEQ based time slice extension.
6606
+
Default is 'on'.
6607
+
6603
6608
initramfs_options= [KNL]
6604
6609
Specify mount options for for the initramfs mount.
6605
6610
+11
include/linux/rseq_entry.h
+11
include/linux/rseq_entry.h
···
75
75
#define rseq_inline __always_inline
76
76
#endif
77
77
78
+
#ifdef CONFIG_RSEQ_SLICE_EXTENSION
79
+
DECLARE_STATIC_KEY_TRUE(rseq_slice_extension_key);
80
+
81
+
static __always_inline bool rseq_slice_extension_enabled(void)
82
+
{
83
+
return static_branch_likely(&rseq_slice_extension_key);
84
+
}
85
+
#else /* CONFIG_RSEQ_SLICE_EXTENSION */
86
+
static inline bool rseq_slice_extension_enabled(void) { return false; }
87
+
#endif /* !CONFIG_RSEQ_SLICE_EXTENSION */
88
+
78
89
bool rseq_debug_update_user_cs(struct task_struct *t, struct pt_regs *regs, unsigned long csaddr);
79
90
bool rseq_debug_validate_ids(struct task_struct *t);
80
91
+17
kernel/rseq.c
+17
kernel/rseq.c
···
483
483
efault:
484
484
return -EFAULT;
485
485
}
486
+
487
+
#ifdef CONFIG_RSEQ_SLICE_EXTENSION
488
+
DEFINE_STATIC_KEY_TRUE(rseq_slice_extension_key);
489
+
490
+
static int __init rseq_slice_cmdline(char *str)
491
+
{
492
+
bool on;
493
+
494
+
if (kstrtobool(str, &on))
495
+
return 0;
496
+
497
+
if (!on)
498
+
static_branch_disable(&rseq_slice_extension_key);
499
+
return 1;
500
+
}
501
+
__setup("rseq_slice_ext=", rseq_slice_cmdline);
502
+
#endif /* CONFIG_RSEQ_SLICE_EXTENSION */