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Miller" , Mathieu Desnoyers , linux-trace-kernel@vger.kernel.org Cc: Jinchao Wang Subject: [PATCH v4 05/21] mm/ksw: add ksw_config struct and parser Date: Fri, 12 Sep 2025 18:11:15 +0800 Message-ID: <20250912101145.465708-6-wangjinchao600@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250912101145.465708-1-wangjinchao600@gmail.com> References: <20250912101145.465708-1-wangjinchao600@gmail.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add struct ksw_config and ksw_parse_config() to parse user string. Signed-off-by: Jinchao Wang --- mm/kstackwatch/kernel.c | 91 ++++++++++++++++++++++++++++++++++++ mm/kstackwatch/kstackwatch.h | 33 +++++++++++++ 2 files changed, 124 insertions(+) diff --git a/mm/kstackwatch/kernel.c b/mm/kstackwatch/kernel.c index 40aa7e9ff513..1502795e02af 100644 --- a/mm/kstackwatch/kernel.c +++ b/mm/kstackwatch/kernel.c @@ -1,20 +1,111 @@ // SPDX-License-Identifier: GPL-2.0 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt +#include #include +#include + +#include "kstackwatch.h" MODULE_AUTHOR("Jinchao Wang"); MODULE_DESCRIPTION("Kernel Stack Watch"); MODULE_LICENSE("GPL"); +static struct ksw_config *ksw_config; + +/* + * Format of the configuration string: + * function+ip_offset[+depth] [local_var_offset:local_var_len] + * + * - function : name of the target function + * - ip_offset : instruction pointer offset within the function + * - depth : recursion depth to watch + * - local_var_offset : offset from the stack pointer at function+ip_offset + * - local_var_len : length of the local variable(1,2,4,8) + */ +static int __maybe_unused ksw_parse_config(char *buf, struct ksw_config *config) +{ + char *func_part, *local_var_part = NULL; + char *token; + u16 local_var_len; + + memset(ksw_config, 0, sizeof(*ksw_config)); + + /* set the watch type to the default canary-based watching */ + config->type = WATCH_CANARY; + + func_part = strim(buf); + strscpy(config->config_str, func_part, MAX_CONFIG_STR_LEN); + + local_var_part = strchr(func_part, ' '); + if (local_var_part) { + *local_var_part = '\0'; // terminate the function part + local_var_part = strim(local_var_part + 1); + } + + /* parse the function part: function+ip_offset[+depth] */ + token = strsep(&func_part, "+"); + if (!token) + goto fail; + + strscpy(config->function, token, MAX_FUNC_NAME_LEN - 1); + + token = strsep(&func_part, "+"); + if (!token || kstrtou16(token, 0, &config->ip_offset)) { + pr_err("failed to parse instruction offset\n"); + goto fail; + } + + token = strsep(&func_part, "+"); + if (token && kstrtou16(token, 0, &config->depth)) { + pr_err("failed to parse depth\n"); + goto fail; + } + if (!local_var_part || !(*local_var_part)) + return 0; + + /* parse the optional local var offset:len */ + config->type = WATCH_LOCAL_VAR; + token = strsep(&local_var_part, ":"); + if (!token || kstrtou16(token, 0, &config->local_var_offset)) { + pr_err("failed to parse local var offset\n"); + goto fail; + } + + if (!local_var_part || kstrtou16(local_var_part, 0, &local_var_len)) { + pr_err("failed to parse local var len\n"); + goto fail; + } + + if (local_var_len != 1 && local_var_len != 2 && + local_var_len != 4 && local_var_len != 8) { + pr_err("invalid local var len %u (must be 1,2,4,8)\n", + local_var_len); + goto fail; + } + config->local_var_len = local_var_len; + + return 0; +fail: + pr_err("invalid input: %s\n", config->config_str); + config->config_str[0] = '\0'; + return -EINVAL; +} + static int __init kstackwatch_init(void) { + ksw_config = kzalloc(sizeof(*ksw_config), GFP_KERNEL); + if (!ksw_config) + return -ENOMEM; + pr_info("module loaded\n"); return 0; } static void __exit kstackwatch_exit(void) { + kfree(ksw_config); + pr_info("module unloaded\n"); } diff --git a/mm/kstackwatch/kstackwatch.h b/mm/kstackwatch/kstackwatch.h index 0273ef478a26..7c595c5c24d1 100644 --- a/mm/kstackwatch/kstackwatch.h +++ b/mm/kstackwatch/kstackwatch.h @@ -2,4 +2,37 @@ #ifndef _KSTACKWATCH_H #define _KSTACKWATCH_H +#include + +#define MAX_FUNC_NAME_LEN 64 +#define MAX_CONFIG_STR_LEN 128 + +enum watch_type { + WATCH_CANARY = 0, + WATCH_LOCAL_VAR, +}; + +struct ksw_config { + /* function part */ + char function[MAX_FUNC_NAME_LEN]; + u16 ip_offset; + u16 depth; + + /* local var, useless for canary watch */ + /* offset from rsp at function+ip_offset */ + u16 local_var_offset; + + /* + * local var size (1,2,4,8 bytes) + * it will be the watching len + */ + u16 local_var_len; + + /* easy for understand*/ + enum watch_type type; + + /* save to show */ + char config_str[MAX_CONFIG_STR_LEN]; +}; + #endif /* _KSTACKWATCH_H */ -- 2.43.0