Provide ksw_stack_init() and ksw_stack_exit() to manage entry and exit probes for the target function from ksw_get_config(). Use atomic PID tracking to ensure singleton watch.
Signed-off-by: Jinchao Wang <[email protected]> --- mm/kstackwatch/kstackwatch.h | 4 ++ mm/kstackwatch/stack.c | 99 ++++++++++++++++++++++++++++++++++++ 2 files changed, 103 insertions(+) diff --git a/mm/kstackwatch/kstackwatch.h b/mm/kstackwatch/kstackwatch.h index 2fa377843f17..79ca40e69268 100644 --- a/mm/kstackwatch/kstackwatch.h +++ b/mm/kstackwatch/kstackwatch.h @@ -38,6 +38,10 @@ struct ksw_config { // singleton, only modified in kernel.c const struct ksw_config *ksw_get_config(void); +/* stack management */ +int ksw_stack_init(void); +void ksw_stack_exit(void); + /* watch management */ int ksw_watch_init(void); void ksw_watch_exit(void); diff --git a/mm/kstackwatch/stack.c b/mm/kstackwatch/stack.c index cec594032515..72409156458f 100644 --- a/mm/kstackwatch/stack.c +++ b/mm/kstackwatch/stack.c @@ -1 +1,100 @@ // SPDX-License-Identifier: GPL-2.0 +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/atomic.h> +#include <linux/fprobe.h> +#include <linux/kprobes.h> +#include <linux/printk.h> +#include <linux/spinlock.h> + +#include "kstackwatch.h" + +static struct kprobe entry_probe; +static struct fprobe exit_probe; +#define INVALID_PID -1 +static atomic_t ksw_stack_pid = ATOMIC_INIT(INVALID_PID); + +static int ksw_stack_prepare_watch(struct pt_regs *regs, + const struct ksw_config *config, + u64 *watch_addr, u64 *watch_len) +{ + /* implement logic will be added in following patches */ + *watch_addr = 0; + *watch_len = 0; + return 0; +} + +static void ksw_stack_entry_handler(struct kprobe *p, struct pt_regs *regs, + unsigned long flags) +{ + u64 watch_addr; + u64 watch_len; + int ret; + + if (atomic_cmpxchg(&ksw_stack_pid, INVALID_PID, current->pid) != + INVALID_PID) + return; + + ret = ksw_stack_prepare_watch(regs, ksw_get_config(), &watch_addr, + &watch_len); + if (ret) { + atomic_set(&ksw_stack_pid, INVALID_PID); + pr_err("failed to prepare watch target: %d\n", ret); + return; + } + + ret = ksw_watch_on(watch_addr, watch_len); + if (ret) { + atomic_set(&ksw_stack_pid, INVALID_PID); + pr_err("failed to watch on addr:0x%llx len:%llu %d\n", + watch_addr, watch_len, ret); + return; + } +} + +static void ksw_stack_exit_handler(struct fprobe *fp, unsigned long ip, + unsigned long ret_ip, + struct ftrace_regs *regs, void *data) +{ + if (atomic_read(&ksw_stack_pid) != current->pid) + return; + + ksw_watch_off(); + + atomic_set(&ksw_stack_pid, INVALID_PID); +} + +int ksw_stack_init(void) +{ + int ret; + char *symbuf = NULL; + + memset(&entry_probe, 0, sizeof(entry_probe)); + entry_probe.symbol_name = ksw_get_config()->function; + entry_probe.offset = ksw_get_config()->ip_offset; + entry_probe.post_handler = ksw_stack_entry_handler; + ret = register_kprobe(&entry_probe); + if (ret) { + pr_err("Failed to register kprobe ret %d\n", ret); + return ret; + } + + memset(&exit_probe, 0, sizeof(exit_probe)); + exit_probe.exit_handler = ksw_stack_exit_handler; + symbuf = (char *)ksw_get_config()->function; + + ret = register_fprobe_syms(&exit_probe, (const char **)&symbuf, 1); + if (ret < 0) { + pr_err("register_fprobe_syms fail %d\n", ret); + unregister_kprobe(&entry_probe); + return ret; + } + + return 0; +} + +void ksw_stack_exit(void) +{ + unregister_fprobe(&exit_probe); + unregister_kprobe(&entry_probe); +} -- 2.43.0
