Pre-allocate per-CPU hardware breakpoints at init with a dummy address, which will be retargeted dynamically in kprobe handler. This avoids allocation in atomic contexts.
Signed-off-by: Jinchao Wang <[email protected]> --- mm/kstackwatch/kstackwatch.h | 4 +++ mm/kstackwatch/watch.c | 55 ++++++++++++++++++++++++++++++++++++ 2 files changed, 59 insertions(+) diff --git a/mm/kstackwatch/kstackwatch.h b/mm/kstackwatch/kstackwatch.h index 277b192f80fa..3ea191370970 100644 --- a/mm/kstackwatch/kstackwatch.h +++ b/mm/kstackwatch/kstackwatch.h @@ -38,4 +38,8 @@ struct ksw_config { // singleton, only modified in kernel.c const struct ksw_config *ksw_get_config(void); +/* watch management */ +int ksw_watch_init(void); +void ksw_watch_exit(void); + #endif /* _KSTACKWATCH_H */ diff --git a/mm/kstackwatch/watch.c b/mm/kstackwatch/watch.c index cec594032515..d3399ac840b2 100644 --- a/mm/kstackwatch/watch.c +++ b/mm/kstackwatch/watch.c @@ -1 +1,56 @@ // SPDX-License-Identifier: GPL-2.0 +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/hw_breakpoint.h> +#include <linux/perf_event.h> +#include <linux/printk.h> + +#include "kstackwatch.h" + +static struct perf_event *__percpu *watch_events; + +static unsigned long watch_holder; + +static struct perf_event_attr watch_attr; + +bool panic_on_catch; +module_param(panic_on_catch, bool, 0644); +MODULE_PARM_DESC(panic_on_catch, "panic immediately on corruption catch"); +static void ksw_watch_handler(struct perf_event *bp, + struct perf_sample_data *data, + struct pt_regs *regs) +{ + pr_err("========== KStackWatch: Caught stack corruption =======\n"); + pr_err("config %s\n", ksw_get_config()->config_str); + dump_stack(); + pr_err("=================== KStackWatch End ===================\n"); + + if (panic_on_catch) + panic("Stack corruption detected"); +} + +int ksw_watch_init(void) +{ + int ret; + + hw_breakpoint_init(&watch_attr); + watch_attr.bp_addr = (unsigned long)&watch_holder; + watch_attr.bp_len = sizeof(watch_holder); + watch_attr.bp_type = HW_BREAKPOINT_W; + watch_events = register_wide_hw_breakpoint(&watch_attr, + ksw_watch_handler, + NULL); + if (IS_ERR(watch_events)) { + ret = PTR_ERR(watch_events); + pr_err("failed to register wide hw breakpoint: %d\n", ret); + return ret; + } + + return 0; +} + +void ksw_watch_exit(void) +{ + unregister_wide_hw_breakpoint(watch_events); + watch_events = NULL; +} -- 2.43.0
