diff options
| -rw-r--r-- | Documentation/core-api/printk-formats.rst | 11 | ||||
| -rw-r--r-- | include/linux/kallsyms.h | 21 | ||||
| -rw-r--r-- | include/linux/module.h | 9 | ||||
| -rw-r--r-- | kernel/kallsyms.c | 104 | ||||
| -rw-r--r-- | kernel/module.c | 42 | ||||
| -rw-r--r-- | lib/vsprintf.c | 8 |
6 files changed, 166 insertions, 29 deletions
diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst index 4346ae17a72c..d941717a191b 100644 --- a/Documentation/core-api/printk-formats.rst +++ b/Documentation/core-api/printk-formats.rst @@ -125,6 +125,17 @@ used when printing stack backtraces. The specifier takes into consideration the effect of compiler optimisations which may occur when tail-calls are used and marked with the noreturn GCC attribute. +If the pointer is within a module, the module name and optionally build ID is +printed after the symbol name with an extra ``b`` appended to the end of the +specifier. + +:: + %pS versatile_init+0x0/0x110 [module_name] + %pSb versatile_init+0x0/0x110 [module_name ed5019fdf5e53be37cb1ba7899292d7e143b259e] + %pSRb versatile_init+0x9/0x110 [module_name ed5019fdf5e53be37cb1ba7899292d7e143b259e] + (with __builtin_extract_return_addr() translation) + %pBb prev_fn_of_versatile_init+0x88/0x88 [module_name ed5019fdf5e53be37cb1ba7899292d7e143b259e] + Probed Pointers from BPF / tracing ---------------------------------- diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h index 465060acc981..a1d6fc82d7f0 100644 --- a/include/linux/kallsyms.h +++ b/include/linux/kallsyms.h @@ -7,6 +7,7 @@ #define _LINUX_KALLSYMS_H #include <linux/errno.h> +#include <linux/buildid.h> #include <linux/kernel.h> #include <linux/stddef.h> #include <linux/mm.h> @@ -15,8 +16,10 @@ #include <asm/sections.h> #define KSYM_NAME_LEN 128 -#define KSYM_SYMBOL_LEN (sizeof("%s+%#lx/%#lx [%s]") + (KSYM_NAME_LEN - 1) + \ - 2*(BITS_PER_LONG*3/10) + (MODULE_NAME_LEN - 1) + 1) +#define KSYM_SYMBOL_LEN (sizeof("%s+%#lx/%#lx [%s %s]") + \ + (KSYM_NAME_LEN - 1) + \ + 2*(BITS_PER_LONG*3/10) + (MODULE_NAME_LEN - 1) + \ + (BUILD_ID_SIZE_MAX * 2) + 1) struct cred; struct module; @@ -91,8 +94,10 @@ const char *kallsyms_lookup(unsigned long addr, /* Look up a kernel symbol and return it in a text buffer. */ extern int sprint_symbol(char *buffer, unsigned long address); +extern int sprint_symbol_build_id(char *buffer, unsigned long address); extern int sprint_symbol_no_offset(char *buffer, unsigned long address); extern int sprint_backtrace(char *buffer, unsigned long address); +extern int sprint_backtrace_build_id(char *buffer, unsigned long address); int lookup_symbol_name(unsigned long addr, char *symname); int lookup_symbol_attrs(unsigned long addr, unsigned long *size, unsigned long *offset, char *modname, char *name); @@ -128,6 +133,12 @@ static inline int sprint_symbol(char *buffer, unsigned long addr) return 0; } +static inline int sprint_symbol_build_id(char *buffer, unsigned long address) +{ + *buffer = '\0'; + return 0; +} + static inline int sprint_symbol_no_offset(char *buffer, unsigned long addr) { *buffer = '\0'; @@ -140,6 +151,12 @@ static inline int sprint_backtrace(char *buffer, unsigned long addr) return 0; } +static inline int sprint_backtrace_build_id(char *buffer, unsigned long addr) +{ + *buffer = '\0'; + return 0; +} + static inline int lookup_symbol_name(unsigned long addr, char *symname) { return -ERANGE; diff --git a/include/linux/module.h b/include/linux/module.h index 8100bb477d86..8a298d820dbc 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -11,6 +11,7 @@ #include <linux/list.h> #include <linux/stat.h> +#include <linux/buildid.h> #include <linux/compiler.h> #include <linux/cache.h> #include <linux/kmod.h> @@ -369,6 +370,11 @@ struct module { /* Unique handle for this module */ char name[MODULE_NAME_LEN]; +#ifdef CONFIG_STACKTRACE_BUILD_ID + /* Module build ID */ + unsigned char build_id[BUILD_ID_SIZE_MAX]; +#endif + /* Sysfs stuff. */ struct module_kobject mkobj; struct module_attribute *modinfo_attrs; @@ -636,7 +642,7 @@ void *dereference_module_function_descriptor(struct module *mod, void *ptr); const char *module_address_lookup(unsigned long addr, unsigned long *symbolsize, unsigned long *offset, - char **modname, + char **modname, const unsigned char **modbuildid, char *namebuf); int lookup_module_symbol_name(unsigned long addr, char *symname); int lookup_module_symbol_attrs(unsigned long addr, unsigned long *size, unsigned long *offset, char *modname, char *name); @@ -740,6 +746,7 @@ static inline const char *module_address_lookup(unsigned long addr, unsigned long *symbolsize, unsigned long *offset, char **modname, + const unsigned char **modbuildid, char *namebuf) { return NULL; diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c index c851ca0ed357..0ba87982d017 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -25,7 +25,10 @@ #include <linux/filter.h> #include <linux/ftrace.h> #include <linux/kprobes.h> +#include <linux/build_bug.h> #include <linux/compiler.h> +#include <linux/module.h> +#include <linux/kernel.h> /* * These will be re-linked against their real values @@ -297,21 +300,14 @@ int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize, get_symbol_pos(addr, symbolsize, offset); return 1; } - return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf) || + return !!module_address_lookup(addr, symbolsize, offset, NULL, NULL, namebuf) || !!__bpf_address_lookup(addr, symbolsize, offset, namebuf); } -/* - * Lookup an address - * - modname is set to NULL if it's in the kernel. - * - We guarantee that the returned name is valid until we reschedule even if. - * It resides in a module. - * - We also guarantee that modname will be valid until rescheduled. - */ -const char *kallsyms_lookup(unsigned long addr, - unsigned long *symbolsize, - unsigned long *offset, - char **modname, char *namebuf) +static const char *kallsyms_lookup_buildid(unsigned long addr, + unsigned long *symbolsize, + unsigned long *offset, char **modname, + const unsigned char **modbuildid, char *namebuf) { const char *ret; @@ -327,6 +323,8 @@ const char *kallsyms_lookup(unsigned long addr, namebuf, KSYM_NAME_LEN); if (modname) *modname = NULL; + if (modbuildid) + *modbuildid = NULL; ret = namebuf; goto found; @@ -334,7 +332,7 @@ const char *kallsyms_lookup(unsigned long addr, /* See if it's in a module or a BPF JITed image. */ ret = module_address_lookup(addr, symbolsize, offset, - modname, namebuf); + modname, modbuildid, namebuf); if (!ret) ret = bpf_address_lookup(addr, symbolsize, offset, modname, namebuf); @@ -348,6 +346,22 @@ found: return ret; } +/* + * Lookup an address + * - modname is set to NULL if it's in the kernel. + * - We guarantee that the returned name is valid until we reschedule even if. + * It resides in a module. + * - We also guarantee that modname will be valid until rescheduled. + */ +const char *kallsyms_lookup(unsigned long addr, + unsigned long *symbolsize, + unsigned long *offset, + char **modname, char *namebuf) +{ + return kallsyms_lookup_buildid(addr, symbolsize, offset, modname, + NULL, namebuf); +} + int lookup_symbol_name(unsigned long addr, char *symname) { int res; @@ -404,15 +418,17 @@ found: /* 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 symbol_offset, int add_offset, int add_buildid) { char *modname; + const unsigned char *buildid; const char *name; unsigned long offset, size; int len; address += symbol_offset; - name = kallsyms_lookup(address, &size, &offset, &modname, buffer); + name = kallsyms_lookup_buildid(address, &size, &offset, &modname, &buildid, + buffer); if (!name) return sprintf(buffer, "0x%lx", address - symbol_offset); @@ -424,8 +440,19 @@ static int __sprint_symbol(char *buffer, unsigned long address, if (add_offset) len += sprintf(buffer + len, "+%#lx/%#lx", offset, size); - if (modname) - len += sprintf(buffer + len, " [%s]", modname); + 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 + len += sprintf(buffer + len, "]"); + } return len; } @@ -443,11 +470,28 @@ static int __sprint_symbol(char *buffer, unsigned long address, */ int sprint_symbol(char *buffer, unsigned long address) { - return __sprint_symbol(buffer, address, 0, 1); + return __sprint_symbol(buffer, address, 0, 1, 0); } EXPORT_SYMBOL_GPL(sprint_symbol); /** + * sprint_symbol_build_id - Look up a kernel symbol and return it in a text buffer + * @buffer: buffer to be stored + * @address: address to lookup + * + * This function looks up a kernel symbol with @address and stores its name, + * offset, size, module name and module build ID to @buffer if possible. If no + * symbol was found, just saves its @address as is. + * + * This function returns the number of bytes stored in @buffer. + */ +int sprint_symbol_build_id(char *buffer, unsigned long address) +{ + return __sprint_symbol(buffer, address, 0, 1, 1); +} +EXPORT_SYMBOL_GPL(sprint_symbol_build_id); + +/** * sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer * @buffer: buffer to be stored * @address: address to lookup @@ -460,7 +504,7 @@ EXPORT_SYMBOL_GPL(sprint_symbol); */ int sprint_symbol_no_offset(char *buffer, unsigned long address) { - return __sprint_symbol(buffer, address, 0, 0); + return __sprint_symbol(buffer, address, 0, 0, 0); } EXPORT_SYMBOL_GPL(sprint_symbol_no_offset); @@ -480,7 +524,27 @@ EXPORT_SYMBOL_GPL(sprint_symbol_no_offset); */ int sprint_backtrace(char *buffer, unsigned long address) { - return __sprint_symbol(buffer, address, -1, 1); + return __sprint_symbol(buffer, address, -1, 1, 0); +} + +/** + * sprint_backtrace_build_id - Look up a backtrace symbol and return it in a text buffer + * @buffer: buffer to be stored + * @address: address to lookup + * + * This function is for stack backtrace and does the same thing as + * sprint_symbol() but with modified/decreased @address. If there is a + * tail-call to the function marked "noreturn", gcc optimized out code after + * the call so that the stack-saved return address could point outside of the + * caller. This function ensures that kallsyms will find the original caller + * by decreasing @address. This function also appends the module build ID to + * the @buffer if @address is within a kernel module. + * + * This function returns the number of bytes stored in @buffer. + */ +int sprint_backtrace_build_id(char *buffer, unsigned long address) +{ + return __sprint_symbol(buffer, address, -1, 1, 1); } /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */ diff --git a/kernel/module.c b/kernel/module.c index 64bd61b2d3ad..ed13917ea5f3 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -13,6 +13,7 @@ #include <linux/trace_events.h> #include <linux/init.h> #include <linux/kallsyms.h> +#include <linux/buildid.h> #include <linux/file.h> #include <linux/fs.h> #include <linux/sysfs.h> @@ -1465,6 +1466,13 @@ resolve_symbol_wait(struct module *mod, return ksym; } +#ifdef CONFIG_KALLSYMS +static inline bool sect_empty(const Elf_Shdr *sect) +{ + return !(sect->sh_flags & SHF_ALLOC) || sect->sh_size == 0; +} +#endif + /* * /sys/module/foo/sections stuff * J. Corbet <corbet@lwn.net> @@ -1472,11 +1480,6 @@ resolve_symbol_wait(struct module *mod, #ifdef CONFIG_SYSFS #ifdef CONFIG_KALLSYMS -static inline bool sect_empty(const Elf_Shdr *sect) -{ - return !(sect->sh_flags & SHF_ALLOC) || sect->sh_size == 0; -} - struct module_sect_attr { struct bin_attribute battr; unsigned long address; @@ -2797,6 +2800,26 @@ static void add_kallsyms(struct module *mod, const struct load_info *info) } #endif /* CONFIG_KALLSYMS */ +#if IS_ENABLED(CONFIG_KALLSYMS) && IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID) +static void init_build_id(struct module *mod, const struct load_info *info) +{ + const Elf_Shdr *sechdr; + unsigned int i; + + for (i = 0; i < info->hdr->e_shnum; i++) { + sechdr = &info->sechdrs[i]; + if (!sect_empty(sechdr) && sechdr->sh_type == SHT_NOTE && + !build_id_parse_buf((void *)sechdr->sh_addr, mod->build_id, + sechdr->sh_size)) + break; + } +} +#else +static void init_build_id(struct module *mod, const struct load_info *info) +{ +} +#endif + static void dynamic_debug_setup(struct module *mod, struct _ddebug *debug, unsigned int num) { if (!debug) @@ -4021,6 +4044,7 @@ static int load_module(struct load_info *info, const char __user *uargs, goto free_arch_cleanup; } + init_build_id(mod, info); dynamic_debug_setup(mod, info->debug, info->num_debug); /* Ftrace init must be called in the MODULE_STATE_UNFORMED state */ @@ -4254,6 +4278,7 @@ const char *module_address_lookup(unsigned long addr, unsigned long *size, unsigned long *offset, char **modname, + const unsigned char **modbuildid, char *namebuf) { const char *ret = NULL; @@ -4264,6 +4289,13 @@ const char *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 + } ret = find_kallsyms_symbol(mod, addr, size, offset); } diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 77ba1c40a99d..26c83943748a 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -993,8 +993,12 @@ char *symbol_string(char *buf, char *end, void *ptr, value = (unsigned long)ptr; #ifdef CONFIG_KALLSYMS - if (*fmt == 'B') + if (*fmt == 'B' && fmt[1] == 'b') + sprint_backtrace_build_id(sym, value); + else if (*fmt == 'B') sprint_backtrace(sym, value); + else if (*fmt == 'S' && (fmt[1] == 'b' || (fmt[1] == 'R' && fmt[2] == 'b'))) + sprint_symbol_build_id(sym, value); else if (*fmt != 's') sprint_symbol(sym, value); else @@ -2263,9 +2267,11 @@ early_param("no_hash_pointers", no_hash_pointers_enable); * - 'S' For symbolic direct pointers (or function descriptors) with offset * - 's' For symbolic direct pointers (or function descriptors) without offset * - '[Ss]R' as above with __builtin_extract_return_addr() translation + * - 'S[R]b' as above with module build ID (for use in backtraces) * - '[Ff]' %pf and %pF were obsoleted and later removed in favor of * %ps and %pS. Be careful when re-using these specifiers. * - 'B' For backtraced symbolic direct pointers with offset + * - 'Bb' as above with module build ID (for use in backtraces) * - 'R' For decoded struct resource, e.g., [mem 0x0-0x1f 64bit pref] * - 'r' For raw struct resource, e.g., [mem 0x0-0x1f flags 0x201] * - 'b[l]' For a bitmap, the number of bits is determined by the field |