diff --git a/include/linux/filter.h b/include/linux/filter.h index f5c859b8131a3..b7b95840250a5 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -1362,12 +1362,18 @@ struct bpf_prog *bpf_prog_ksym_find(unsigned long addr); static inline int bpf_address_lookup(unsigned long addr, unsigned long *size, - unsigned long *off, char **modname, char *sym) + unsigned long *off, char **modname, + const unsigned char **modbuildid, char *sym) { int ret = __bpf_address_lookup(addr, size, off, sym); - if (ret && modname) - *modname = NULL; + if (ret) { + if (modname) + *modname = NULL; + if (modbuildid) + *modbuildid = NULL; + } + return ret; } @@ -1433,7 +1439,8 @@ static inline struct bpf_prog *bpf_prog_ksym_find(unsigned long addr) static inline int bpf_address_lookup(unsigned long addr, unsigned long *size, - unsigned long *off, char **modname, char *sym) + unsigned long *off, char **modname, + const unsigned char **modbuildid, char *sym) { return 0; } diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 7ded7df6e9b50..a003cf1b32d07 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -87,11 +87,13 @@ struct ftrace_hash; defined(CONFIG_DYNAMIC_FTRACE) int ftrace_mod_address_lookup(unsigned long addr, unsigned long *size, - unsigned long *off, char **modname, char *sym); + unsigned long *off, char **modname, + const unsigned char **modbuildid, char *sym); #else static inline int ftrace_mod_address_lookup(unsigned long addr, unsigned long *size, - unsigned long *off, char **modname, char *sym) + unsigned long *off, char **modname, + const unsigned char **modbuildid, char *sym) { return 0; } diff --git a/include/linux/module.h b/include/linux/module.h index e135cc79aceea..4decae2b16755 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -747,6 +747,15 @@ static inline void __module_get(struct module *module) __mod ? __mod->name : "kernel"; \ }) +static inline const unsigned char *module_buildid(struct module *mod) +{ +#ifdef CONFIG_STACKTRACE_BUILD_ID + return mod->build_id; +#else + return NULL; +#endif +} + /* Dereference module function descriptor */ void *dereference_module_function_descriptor(struct module *mod, void *ptr); diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c index 1e76358641247..1fda06b6638c4 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -352,7 +352,12 @@ static int kallsyms_lookup_buildid(unsigned long addr, { int ret; - namebuf[KSYM_NAME_LEN - 1] = 0; + /* + * kallsyms_lookus() returns pointer to namebuf on success and + * NULL on error. But some callers ignore the return value. + * Instead they expect @namebuf filled either with valid + * or empty string. + */ namebuf[0] = 0; if (is_ksym_addr(addr)) { @@ -374,12 +379,12 @@ static int kallsyms_lookup_buildid(unsigned long addr, ret = module_address_lookup(addr, symbolsize, offset, modname, modbuildid, namebuf); if (!ret) - ret = bpf_address_lookup(addr, symbolsize, - offset, modname, namebuf); + ret = bpf_address_lookup(addr, symbolsize, offset, + modname, modbuildid, namebuf); if (!ret) - ret = ftrace_mod_address_lookup(addr, symbolsize, - offset, modname, namebuf); + ret = ftrace_mod_address_lookup(addr, symbolsize, offset, + modname, modbuildid, namebuf); return ret; } @@ -423,6 +428,37 @@ int lookup_symbol_name(unsigned long addr, char *symname) return lookup_module_symbol_name(addr, symname); } +#ifdef CONFIG_STACKTRACE_BUILD_ID + +static int append_buildid(char *buffer, const char *modname, + const unsigned char *buildid) +{ + if (!modname) + return 0; + + if (!buildid) { + pr_warn_once("Undefined buildid for the module %s\n", modname); + return 0; + } + + /* build ID should match length of sprintf */ +#ifdef CONFIG_MODULES + static_assert(sizeof(typeof_member(struct module, build_id)) == 20); +#endif + + return sprintf(buffer, " %20phN", buildid); +} + +#else /* CONFIG_STACKTRACE_BUILD_ID */ + +static int append_buildid(char *buffer, const char *modname, + const unsigned char *buildid) +{ + return 0; +} + +#endif /* CONFIG_STACKTRACE_BUILD_ID */ + /* Look up a kernel symbol and return it in a text buffer. */ static int __sprint_symbol(char *buffer, unsigned long address, int symbol_offset, int add_offset, int add_buildid) @@ -432,6 +468,9 @@ static int __sprint_symbol(char *buffer, unsigned long address, unsigned long offset, size; int len; + /* Prevent module removal until modname and modbuildid are printed */ + guard(rcu)(); + address += symbol_offset; len = kallsyms_lookup_buildid(address, &size, &offset, &modname, &buildid, buffer); @@ -445,15 +484,8 @@ static int __sprint_symbol(char *buffer, unsigned long address, if (modname) { len += sprintf(buffer + len, " [%s", modname); -#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID) - if (add_buildid && buildid) { - /* build ID should match length of sprintf */ -#if IS_ENABLED(CONFIG_MODULES) - static_assert(sizeof(typeof_member(struct module, build_id)) == 20); -#endif - len += sprintf(buffer + len, " %20phN", buildid); - } -#endif + if (add_buildid) + len += append_buildid(buffer + len, modname, buildid); len += sprintf(buffer + len, "]"); } diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c index 00a60796327c0..0fc11e45df9b9 100644 --- a/kernel/module/kallsyms.c +++ b/kernel/module/kallsyms.c @@ -334,13 +334,8 @@ int module_address_lookup(unsigned long addr, if (mod) { if (modname) *modname = mod->name; - if (modbuildid) { -#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID) - *modbuildid = mod->build_id; -#else - *modbuildid = NULL; -#endif - } + if (modbuildid) + *modbuildid = module_buildid(mod); sym = find_kallsyms_symbol(mod, addr, size, offset); diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 42bd2ba68a821..11f5096fb60c7 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -7678,7 +7678,8 @@ ftrace_func_address_lookup(struct ftrace_mod_map *mod_map, int ftrace_mod_address_lookup(unsigned long addr, unsigned long *size, - unsigned long *off, char **modname, char *sym) + unsigned long *off, char **modname, + const unsigned char **modbuildid, char *sym) { struct ftrace_mod_map *mod_map; int ret = 0; @@ -7690,6 +7691,8 @@ ftrace_mod_address_lookup(unsigned long addr, unsigned long *size, if (ret) { if (modname) *modname = mod_map->mod->name; + if (modbuildid) + *modbuildid = module_buildid(mod_map->mod); break; } }