Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
rseq: Provide static branch for runtime debugging
Config based debug is rarely turned on and is not available easily when
things go wrong.
Provide a static branch to allow permanent integration of debug mechanisms
along with the usual toggles in Kconfig, command line and debugfs.
Requested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20251027084307.089270547@linutronix.de
authored by
Thomas Gleixner
and committed by
Ingo Molnar
9c37cb6e
54129104
+90
-4
+4
Documentation/admin-guide/kernel-parameters.txt
+4
Documentation/admin-guide/kernel-parameters.txt
···
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Memory area to be used by remote processor image,
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managed by CMA.
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rseq_debug= [KNL] Enable or disable restartable sequence
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debug mode. Defaults to CONFIG_RSEQ_DEBUG_DEFAULT_ENABLE.
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Format: <bool>
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rt_group_sched= [KNL] Enable or disable SCHED_RR/FIFO group scheduling
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when CONFIG_RT_GROUP_SCHED=y. Defaults to
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!CONFIG_RT_GROUP_SCHED_DEFAULT_DISABLED.
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include/linux/rseq_entry.h
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include/linux/rseq_entry.h
···
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#endif /* !CONFIG_RSEQ_STATS */
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#ifdef CONFIG_RSEQ
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#include <linux/jump_label.h>
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#include <linux/rseq.h>
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#include <linux/tracepoint-defs.h>
···
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static inline void rseq_trace_ip_fixup(unsigned long ip, unsigned long start_ip,
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unsigned long offset, unsigned long abort_ip) { }
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#endif /* !CONFIG_TRACEPOINT */
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DECLARE_STATIC_KEY_MAYBE(CONFIG_RSEQ_DEBUG_DEFAULT_ENABLE, rseq_debug_enabled);
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static __always_inline void rseq_note_user_irq_entry(void)
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{
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init/Kconfig
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init/Kconfig
···
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If unsure, say N.
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config RSEQ_DEBUG_DEFAULT_ENABLE
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default n
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bool "Enable restartable sequences debug mode by default" if EXPERT
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depends on RSEQ
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help
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This enables the static branch for debug mode of restartable
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sequences.
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This also can be controlled on the kernel command line via the
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command line parameter "rseq_debug=0/1" and through debugfs.
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If unsure, say N.
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config DEBUG_RSEQ
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default n
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bool "Enable debugging of rseq() system call" if EXPERT
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depends on RSEQ && DEBUG_KERNEL
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select RSEQ_DEBUG_DEFAULT_ENABLE
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help
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Enable extra debugging checks for the rseq system call.
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-4
kernel/rseq.c
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-4
kernel/rseq.c
···
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RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL | \
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RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE)
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DEFINE_STATIC_KEY_MAYBE(CONFIG_RSEQ_DEBUG_DEFAULT_ENABLE, rseq_debug_enabled);
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static inline void rseq_control_debug(bool on)
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{
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if (on)
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static_branch_enable(&rseq_debug_enabled);
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else
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static_branch_disable(&rseq_debug_enabled);
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}
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static int __init rseq_setup_debug(char *str)
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{
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bool on;
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if (kstrtobool(str, &on))
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return -EINVAL;
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rseq_control_debug(on);
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return 1;
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}
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__setup("rseq_debug=", rseq_setup_debug);
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#ifdef CONFIG_TRACEPOINTS
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/*
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* Out of line, so the actual update functions can be in a header to be
···
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}
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#endif /* CONFIG_TRACEPOINTS */
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#ifdef CONFIG_DEBUG_FS
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#ifdef CONFIG_RSEQ_STATS
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DEFINE_PER_CPU(struct rseq_stats, rseq_stats);
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static int rseq_debug_show(struct seq_file *m, void *p)
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static int rseq_stats_show(struct seq_file *m, void *p)
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{
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struct rseq_stats stats = { };
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unsigned int cpu;
···
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return 0;
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}
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static int rseq_stats_open(struct inode *inode, struct file *file)
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{
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return single_open(file, rseq_stats_show, inode->i_private);
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}
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static const struct file_operations stat_ops = {
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.open = rseq_stats_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = single_release,
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};
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static int __init rseq_stats_init(struct dentry *root_dir)
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{
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debugfs_create_file("stats", 0444, root_dir, NULL, &stat_ops);
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return 0;
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}
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#else
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static inline void rseq_stats_init(struct dentry *root_dir) { }
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#endif /* CONFIG_RSEQ_STATS */
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static int rseq_debug_show(struct seq_file *m, void *p)
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{
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bool on = static_branch_unlikely(&rseq_debug_enabled);
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seq_printf(m, "%d\n", on);
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return 0;
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}
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static ssize_t rseq_debug_write(struct file *file, const char __user *ubuf,
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size_t count, loff_t *ppos)
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{
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bool on;
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if (kstrtobool_from_user(ubuf, count, &on))
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return -EINVAL;
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rseq_control_debug(on);
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return count;
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}
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static int rseq_debug_open(struct inode *inode, struct file *file)
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{
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return single_open(file, rseq_debug_show, inode->i_private);
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}
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static const struct file_operations dfs_ops = {
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static const struct file_operations debug_ops = {
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.open = rseq_debug_open,
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.read = seq_read,
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.write = rseq_debug_write,
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.llseek = seq_lseek,
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.release = single_release,
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};
···
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{
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struct dentry *root_dir = debugfs_create_dir("rseq", NULL);
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debugfs_create_file("stats", 0444, root_dir, NULL, &dfs_ops);
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debugfs_create_file("debug", 0644, root_dir, NULL, &debug_ops);
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rseq_stats_init(root_dir);
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return 0;
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}
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__initcall(rseq_debugfs_init);
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-
#endif /* CONFIG_RSEQ_STATS */
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#endif /* CONFIG_DEBUG_FS */
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#ifdef CONFIG_DEBUG_RSEQ
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static struct rseq *rseq_kernel_fields(struct task_struct *t)