Expose targeted sampling through the KCSAN debugfs file. Accept address and kallsyms targets, including module:symbol names, and allow sampling to be disabled with target=off.
Use KSYM_SYMBOL_LEN for the input buffer so documented module symbols fit, and return -E2BIG for oversized writes. Signed-off-by: Hui Su <[email protected]> --- kernel/kcsan/debugfs.c | 28 +++++++++++++++++++++++++++- 1 file changed, 27 insertions(+), 1 deletion(-) diff --git a/kernel/kcsan/debugfs.c b/kernel/kcsan/debugfs.c index 2af39ba5b70b..47becde9f1ae 100644 --- a/kernel/kcsan/debugfs.c +++ b/kernel/kcsan/debugfs.c @@ -191,6 +191,7 @@ static ssize_t insert_report_filterlist(const char *func) static int show_info(struct seq_file *file, void *v) { int i; + unsigned long target; unsigned long flags; /* show stats */ @@ -199,6 +200,12 @@ static int show_info(struct seq_file *file, void *v) seq_printf(file, "%s: %ld\n", counter_names[i], atomic_long_read(&kcsan_counters[i])); } + target = kcsan_target_get(); + if (target) + seq_printf(file, "\ntarget: %pK (%pS)\n", (void *)target, + (void *)target); + else + seq_puts(file, "\ntarget: none\n"); /* show filter functions, and filter type */ raw_spin_lock_irqsave(&report_filterlist_lock, flags); @@ -220,10 +227,13 @@ static int debugfs_open(struct inode *inode, struct file *file) static ssize_t debugfs_write(struct file *file, const char __user *buf, size_t count, loff_t *off) { - char kbuf[KSYM_NAME_LEN]; + char kbuf[KSYM_SYMBOL_LEN + sizeof("target=")]; char *arg; const size_t read_len = min(count, sizeof(kbuf) - 1); + if (count > sizeof(kbuf) - 1) + return -E2BIG; + if (copy_from_user(kbuf, buf, read_len)) return -EFAULT; kbuf[read_len] = '\0'; @@ -239,6 +249,22 @@ debugfs_write(struct file *file, const char __user *buf, size_t count, loff_t *o if (kstrtoul(&arg[strlen("microbench=")], 0, &iters)) return -EINVAL; microbenchmark(iters); + } else if (str_has_prefix(arg, "target=")) { + char *target = &arg[strlen("target=")]; + unsigned long addr; + + if (!strcmp(target, "off")) { + kcsan_target_set(0); + } else if (!kstrtoul(target, 0, &addr)) { + if (!addr) + return -EINVAL; + kcsan_target_set(addr); + } else { + addr = kallsyms_lookup_name(target); + if (!addr) + return -ENOENT; + kcsan_target_set(addr); + } } else if (!strcmp(arg, "whitelist")) { set_report_filterlist_whitelist(true); } else if (!strcmp(arg, "blacklist")) { -- 2.55.0
