From 9cc63f8bcd560c760d0b12e15bba8f81c86237cf Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 14 Aug 2026 15:43:51 -0700 Subject: Merge branches 'expcb.2026.07.24a', 'misc.2026.07.30a', 'rcu-tasks.2026.07.30a', 'srcu.2026.08.11a' and 'torture.2026.08.14a' into HEAD Changes: Make expedited grace periods expedite normal RCU callbacks Miscellaneous fixes: * Improve diagnostic output with character task states. * Mark accesses to inform KCSAN of concurrency design. * Move from kmalloc() to kmalloc_obj(). * Documentation updates. * Improve handling of RCU deferred quiescent states. * Clean up unused function arguments and structure fields. * Reduce show_rcu_gp_kthreads() stack space. Tasks RCU updates: * Clean up after SRCU re-implementation of Tasks Trace RCU. * Mark accesses to inform KCSAN of concurrency design. * Add ->lazy_timer status to diagnostic output. * Remove an unnecessary memory barrier. * Fix a data race, courtesy of KCSAN. * Documentation updates. * Convert cond_resched_tasks_rcu_qs() from macro to static inline function. SRCU updates: * Add Rust helpers for SRCU. * Avoid losing queued work at cleanup_srcu_struct() time. Torture-test updates: * Preparation work for immediate RCU priority deboosting. * Test RCU readers from real interrupt handlers (as opposed to softirq). * Simplify code through use of cpumask_next_wrap(). * Improve diagnostic output with character task states. * Add rcutorture.nwriters parameter to allow lightweight stall testing, and rcutorture.stall_only to make doing so easier. * Test an RCU Tasks Trace grace period implying an RCU grace period. * Make RCU Tasks Trace torturing track reader batches. * Fix a data race, courtesy of KCSAN. * Plug a shuffle_tmp_mask memory leak on kthread spawn failure. --- samples/hw_breakpoint/Makefile | 2 + samples/hw_breakpoint/data_breakpoint.c | 84 +++++++++++++++++++++++++++++++++ 2 files changed, 86 insertions(+) create mode 100644 samples/hw_breakpoint/Makefile create mode 100644 samples/hw_breakpoint/data_breakpoint.c (limited to 'samples/hw_breakpoint') diff --git a/samples/hw_breakpoint/Makefile b/samples/hw_breakpoint/Makefile new file mode 100644 index 000000000..ef4b6fdd7 --- /dev/null +++ b/samples/hw_breakpoint/Makefile @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0-only +obj-$(CONFIG_SAMPLE_HW_BREAKPOINT) += data_breakpoint.o diff --git a/samples/hw_breakpoint/data_breakpoint.c b/samples/hw_breakpoint/data_breakpoint.c new file mode 100644 index 000000000..fbb03b66d --- /dev/null +++ b/samples/hw_breakpoint/data_breakpoint.c @@ -0,0 +1,84 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * data_breakpoint.c - Sample HW Breakpoint file to watch kernel data address + * + * usage: insmod data_breakpoint.ko ksym= + * + * This file is a kernel module that places a breakpoint over ksym_name kernel + * variable using Hardware Breakpoint register. The corresponding handler which + * prints a backtrace is invoked every time a write operation is performed on + * that variable. + * + * Copyright (C) IBM Corporation, 2009 + * + * Author: K.Prasad + */ +#include /* Needed by all modules */ +#include /* Needed for KERN_INFO */ +#include /* Needed for the macros */ +#include + +#include +#include + +static struct perf_event * __percpu *sample_hbp; + +static char ksym_name[KSYM_NAME_LEN] = "jiffies"; +module_param_string(ksym, ksym_name, KSYM_NAME_LEN, S_IRUGO); +MODULE_PARM_DESC(ksym, "Kernel symbol to monitor; this module will report any" + " write operations on the kernel symbol"); + +static void sample_hbp_handler(struct perf_event *bp, + struct perf_sample_data *data, + struct pt_regs *regs) +{ + printk(KERN_INFO "%s value is changed\n", ksym_name); + dump_stack(); + printk(KERN_INFO "Dump stack from sample_hbp_handler\n"); +} + +static int __init hw_break_module_init(void) +{ + int ret; + struct perf_event_attr attr; + void *addr = __symbol_get(ksym_name); + + if (!addr) + return -ENXIO; + + hw_breakpoint_init(&attr); + attr.bp_addr = (unsigned long)addr; + attr.bp_len = HW_BREAKPOINT_LEN_4; + attr.bp_type = HW_BREAKPOINT_W; + + sample_hbp = register_wide_hw_breakpoint(&attr, sample_hbp_handler, NULL); + if (IS_ERR_PCPU(sample_hbp)) { + ret = PTR_ERR_PCPU(sample_hbp); + goto fail; + } + + printk(KERN_INFO "HW Breakpoint for %s write installed\n", ksym_name); + + return 0; + +fail: + printk(KERN_INFO "Breakpoint registration failed\n"); + + return ret; +} + +static void __exit hw_break_module_exit(void) +{ + unregister_wide_hw_breakpoint(sample_hbp); +#ifdef CONFIG_MODULE_UNLOAD + __symbol_put(ksym_name); +#endif + printk(KERN_INFO "HW Breakpoint for %s write uninstalled\n", ksym_name); +} + +module_init(hw_break_module_init); +module_exit(hw_break_module_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("K.Prasad"); +MODULE_DESCRIPTION("ksym breakpoint"); -- cgit v1.3.1