// SPDX-License-Identifier: GPL-2.0-only/* * kallsyms.c: in-kernel printing of symbolic oopses and stack traces. * * Rewritten and vastly simplified by Rusty Russell for in-kernel * module loader: * Copyright 2002 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation * * ChangeLog: * * (25/Aug/2004) Paulo Marques <pmarques@grupopie.com> * Changed the compression method from stem compression to "table lookup" * compression (see scripts/kallsyms.c for a more complete description) */#include <linux/kallsyms.h>#include <linux/init.h>#include <linux/seq_file.h>#include <linux/fs.h>#include <linux/kdb.h>#include <linux/err.h>#include <linux/proc_fs.h>#include <linux/sched.h> /* for cond_resched */#include <linux/ctype.h>#include <linux/slab.h>#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>#include <linux/bsearch.h>#include <linux/btf_ids.h> #include "kallsyms_internal.h" /* * Expand a compressed symbol data into the resulting uncompressed string, * if uncompressed string is too long (>= maxlen), it will be truncated, * given the offset to where the symbol is in the compressed stream. */static unsigned int kallsyms_expand_symbol(unsigned int off, char *result, size_t maxlen){ int len, skipped_first = 0; const char *tptr; const u8 *data; /* Get the compressed symbol length from the first symbol byte. */ data = &kallsyms_names[off]; len = *data; data++; off++; /* If MSB is 1, it is a "big" symbol, so needs an additional byte. */ if ((len & 0x80) != 0) { len = (len & 0x7F) | (*data << 7); data++; off++; } /* * Update the offset to return the offset for the next symbol on * the compressed stream. */ off += len; /* * For every byte on the compressed symbol data, copy the table * entry for that byte. */ while (len) { tptr = &kallsyms_token_table[kallsyms_token_index[*data]]; data++; len--; while (*tptr) { if (skipped_first) { if (maxlen <= 1) goto tail; *result = *tptr; result++; maxlen--; } else skipped_first = 1; tptr++; } } tail: if (maxlen) *result = '\0'; /* Return to offset to the next symbol. */ return off;} /* * Get symbol type information. This is encoded as a single char at the * beginning of the symbol name. */static char kallsyms_get_symbol_type(unsigned int off){ /* * Get just the first code, look it up in the token table, * and return the first char from this token. If MSB of length * is 1, it is a "big" symbol, so needs an additional byte. */ if (kallsyms_names[off] & 0x80) off++; return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]];} /* * Find the offset on the compressed stream given and index in the * kallsyms array. */static unsigned int get_symbol_offset(unsigned long pos){ const u8 *name; int i, len; /* * Use the closest marker we have. We have markers every 256 positions, * so that should be close enough. */ name = &kallsyms_names[kallsyms_markers[pos >> 8]]; /* * Sequentially scan all the symbols up to the point we're searching * for. Every symbol is stored in a [<len>][<len> bytes of data] format, * so we just need to add the len to the current pointer for every * symbol we wish to skip. */ for (i = 0; i < (pos & 0xFF); i++) { len = *name; /* * If MSB is 1, it is a "big" symbol, so we need to look into * the next byte (and skip it, too). */ if ((len & 0x80) != 0) len = ((len & 0x7F) | (name[1] << 7)) + 1; name = name + len + 1; } return name - kallsyms_names;} unsigned long kallsyms_sym_address(int idx){ /* non-relocatable 32-bit kernels just embed the value directly */ if (!IS_ENABLED(CONFIG_64BIT) && !IS_ENABLED(CONFIG_RELOCATABLE)) return (u32)kallsyms_offsets[idx]; return (unsigned long)offset_to_ptr(kallsyms_offsets + idx);} static unsigned int get_symbol_seq(int index){ unsigned int i, seq = 0; for (i = 0; i < 3; i++) seq = (seq << 8) | kallsyms_seqs_of_names[3 * index + i]; return seq;} static int kallsyms_lookup_names(const char *name, unsigned int *start, unsigned int *end){ int ret; int low, mid, high; unsigned int seq, off; char namebuf[KSYM_NAME_LEN]; low = 0; high = kallsyms_num_syms - 1; while (low <= high) { mid = low + (high - low) / 2; seq = get_symbol_seq(mid); off = get_symbol_offset(seq); kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); ret = strcmp(name, namebuf); if (ret > 0) low = mid + 1; else if (ret < 0) high = mid - 1; else break; } if (low > high) return -ESRCH; low = mid; while (low) { seq = get_symbol_seq(low - 1); off = get_symbol_offset(seq); kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); if (strcmp(name, namebuf)) break; low--; } *start = low; if (end) { high = mid; while (high < kallsyms_num_syms - 1) { seq = get_symbol_seq(high + 1); off = get_symbol_offset(seq); kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); if (strcmp(name, namebuf)) break; high++; } *end = high; } return 0;} /* Lookup the address for this symbol. Returns 0 if not found. */unsigned long kallsyms_lookup_name(const char *name){ int ret; unsigned int i; /* Skip the search for empty string. */ if (!*name) return 0; ret = kallsyms_lookup_names(name, &i, NULL); if (!ret) return kallsyms_sym_address(get_symbol_seq(i)); return module_kallsyms_lookup_name(name);} /* * Iterate over all symbols in vmlinux. For symbols from modules use * module_kallsyms_on_each_symbol instead. */int kallsyms_on_each_symbol(int (*fn)(void *, const char *, unsigned long), void *data){ char namebuf[KSYM_NAME_LEN]; unsigned long i; unsigned int off; int ret; for (i = 0, off = 0; i < kallsyms_num_syms; i++) { off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); ret = fn(data, namebuf, kallsyms_sym_address(i)); if (ret != 0) return ret; cond_resched(); } return 0;} int kallsyms_on_each_match_symbol(int (*fn)(void *, unsigned long), const char *name, void *data){ int ret; unsigned int i, start, end; ret = kallsyms_lookup_names(name, &start, &end); if (ret) return 0; for (i = start; !ret && i <= end; i++) { ret = fn(data, kallsyms_sym_address(get_symbol_seq(i))); cond_resched(); } return ret;} static unsigned long get_symbol_pos(unsigned long addr, unsigned long *symbolsize, unsigned long *offset){ unsigned long symbol_start = 0, symbol_end = 0; unsigned long i, low, high, mid; /* Do a binary search on the sorted kallsyms_offsets array. */ low = 0; high = kallsyms_num_syms; while (high - low > 1) { mid = low + (high - low) / 2; if (kallsyms_sym_address(mid) <= addr) low = mid; else high = mid; } /* * Search for the first aliased symbol. Aliased * symbols are symbols with the same address. */ while (low && kallsyms_sym_address(low-1) == kallsyms_sym_address(low)) --low; symbol_start = kallsyms_sym_address(low); /* Search for next non-aliased symbol. */ for (i = low + 1; i < kallsyms_num_syms; i++) { if (kallsyms_sym_address(i) > symbol_start) { symbol_end = kallsyms_sym_address(i); break; } } /* If we found no next symbol, we use the end of the section. */ if (!symbol_end) { if (is_kernel_inittext(addr)) symbol_end = (unsigned long)_einittext; else if (IS_ENABLED(CONFIG_KALLSYMS_ALL)) symbol_end = (unsigned long)_end; else symbol_end = (unsigned long)_etext; } if (symbolsize) *symbolsize = symbol_end - symbol_start; if (offset) *offset = addr - symbol_start; return low;} /* * Lookup an address but don't bother to find any names. */int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize, unsigned long *offset){ char namebuf[KSYM_NAME_LEN]; if (is_ksym_addr(addr)) { get_symbol_pos(addr, symbolsize, offset); return 1; } return !!module_address_lookup(addr, symbolsize, offset, NULL, NULL, namebuf) || !!bpf_address_lookup(addr, symbolsize, offset, namebuf);} static int kallsyms_lookup_buildid(unsigned long addr, unsigned long *symbolsize, unsigned long *offset, char **modname, const unsigned char **modbuildid, char *namebuf){ int ret; /* * 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; /* * Initialize the module-related return values. They are not set * when the symbol is in vmlinux or it is a bpf address. */ if (modname) *modname = NULL; if (modbuildid) *modbuildid = NULL; if (is_ksym_addr(addr)) { unsigned long pos; pos = get_symbol_pos(addr, symbolsize, offset); /* Grab name */ kallsyms_expand_symbol(get_symbol_offset(pos), namebuf, KSYM_NAME_LEN); return strlen(namebuf); } /* See if it's in a module or a BPF JITed image. */ ret = module_address_lookup(addr, symbolsize, offset, modname, modbuildid, namebuf); if (!ret) ret = bpf_address_lookup(addr, symbolsize, offset, namebuf); if (!ret) ret = ftrace_mod_address_lookup(addr, symbolsize, offset, modname, modbuildid, namebuf); 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){ int ret = kallsyms_lookup_buildid(addr, symbolsize, offset, modname, NULL, namebuf); if (!ret) return NULL; return namebuf;} int lookup_symbol_name(unsigned long addr, char *symname){ symname[0] = '\0'; symname[KSYM_NAME_LEN - 1] = '\0'; if (is_ksym_addr(addr)) { unsigned long pos; pos = get_symbol_pos(addr, NULL, NULL); /* Grab name */ kallsyms_expand_symbol(get_symbol_offset(pos), symname, KSYM_NAME_LEN); return 0; } /* See if it's in a module. */ 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){ char *modname; const unsigned char *buildid; 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); if (!len) return sprintf(buffer, "0x%lx", address - symbol_offset); offset -= symbol_offset; if (add_offset) len += sprintf(buffer + len, "+%#lx/%#lx", offset, size); if (modname) { len += sprintf(buffer + len, " [%s", modname); if (add_buildid) len += append_buildid(buffer + len, modname, buildid); len += sprintf(buffer + len, "]"); } return len;Lines 1–500 of 937. 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// SPDX-License-Identifier: GPL-2.0-only /* * kallsyms.c: in-kernel printing of symbolic oopses and stack traces. * * Rewritten and vastly simplified by Rusty Russell for in-kernel * module loader: * Copyright 2002 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation * * ChangeLog: * * (25/Aug/2004) Paulo Marques <pmarques@grupopie.com> * Changed the compression method from stem compression to "table lookup" * compression (see scripts/kallsyms.c for a more complete description) */ #include <linux/kallsyms.h> #include <linux/init.h> #include <linux/seq_file.h> #include <linux/fs.h> #include <linux/kdb.h> #include <linux/err.h> #include <linux/proc_fs.h> #include <linux/sched.h> /* for cond_resched */ #include <linux/ctype.h> #include <linux/slab.h> #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> #include <linux/bsearch.h> #include <linux/btf_ids.h> #include "kallsyms_internal.h" /* * Expand a compressed symbol data into the resulting uncompressed string, * if uncompressed string is too long (>= maxlen), it will be truncated, * given the offset to where the symbol is in the compressed stream. */ static unsigned int kallsyms_expand_symbol(unsigned int off, char *result, size_t maxlen) { int len, skipped_first = 0; const char *tptr; const u8 *data; /* Get the compressed symbol length from the first symbol byte. */ data = &kallsyms_names[off]; len = *data; data++; off++; /* If MSB is 1, it is a "big" symbol, so needs an additional byte. */ if ((len & 0x80) != 0) { len = (len & 0x7F) | (*data << 7); data++; off++; } /* * Update the offset to return the offset for the next symbol on * the compressed stream. */ off += len; /* * For every byte on the compressed symbol data, copy the table * entry for that byte. */ while (len) { tptr = &kallsyms_token_table[kallsyms_token_index[*data]]; data++; len--; while (*tptr) { if (skipped_first) { if (maxlen <= 1) goto tail; *result = *tptr; result++; maxlen--; } else skipped_first = 1; tptr++; } } tail: if (maxlen) *result = '\0'; /* Return to offset to the next symbol. */ return off; } /* * Get symbol type information. This is encoded as a single char at the * beginning of the symbol name. */ static char kallsyms_get_symbol_type(unsigned int off) { /* * Get just the first code, look it up in the token table, * and return the first char from this token. If MSB of length * is 1, it is a "big" symbol, so needs an additional byte. */ if (kallsyms_names[off] & 0x80) off++; return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]]; } /* * Find the offset on the compressed stream given and index in the * kallsyms array. */ static unsigned int get_symbol_offset(unsigned long pos) { const u8 *name; int i, len; /* * Use the closest marker we have. We have markers every 256 positions, * so that should be close enough. */ name = &kallsyms_names[kallsyms_markers[pos >> 8]]; /* * Sequentially scan all the symbols up to the point we're searching * for. Every symbol is stored in a [<len>][<len> bytes of data] format, * so we just need to add the len to the current pointer for every * symbol we wish to skip. */ for (i = 0; i < (pos & 0xFF); i++) { len = *name; /* * If MSB is 1, it is a "big" symbol, so we need to look into * the next byte (and skip it, too). */ if ((len & 0x80) != 0) len = ((len & 0x7F) | (name[1] << 7)) + 1; name = name + len + 1; } return name - kallsyms_names; } unsigned long kallsyms_sym_address(int idx) { /* non-relocatable 32-bit kernels just embed the value directly */ if (!IS_ENABLED(CONFIG_64BIT) && !IS_ENABLED(CONFIG_RELOCATABLE)) return (u32)kallsyms_offsets[idx]; return (unsigned long)offset_to_ptr(kallsyms_offsets + idx); } static unsigned int get_symbol_seq(int index) { unsigned int i, seq = 0; for (i = 0; i < 3; i++) seq = (seq << 8) | kallsyms_seqs_of_names[3 * index + i]; return seq; } static int kallsyms_lookup_names(const char *name, unsigned int *start, unsigned int *end) { int ret; int low, mid, high; unsigned int seq, off; char namebuf[KSYM_NAME_LEN]; low = 0; high = kallsyms_num_syms - 1; while (low <= high) { mid = low + (high - low) / 2; seq = get_symbol_seq(mid); off = get_symbol_offset(seq); kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); ret = strcmp(name, namebuf); if (ret > 0) low = mid + 1; else if (ret < 0) high = mid - 1; else break; } if (low > high) return -ESRCH; low = mid; while (low) { seq = get_symbol_seq(low - 1); off = get_symbol_offset(seq); kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); if (strcmp(name, namebuf)) break; low--; } *start = low; if (end) { high = mid; while (high < kallsyms_num_syms - 1) { seq = get_symbol_seq(high + 1); off = get_symbol_offset(seq); kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); if (strcmp(name, namebuf)) break; high++; } *end = high; } return 0; } /* Lookup the address for this symbol. Returns 0 if not found. */ unsigned long kallsyms_lookup_name(const char *name) { int ret; unsigned int i; /* Skip the search for empty string. */ if (!*name) return 0; ret = kallsyms_lookup_names(name, &i, NULL); if (!ret) return kallsyms_sym_address(get_symbol_seq(i)); return module_kallsyms_lookup_name(name); } /* * Iterate over all symbols in vmlinux. For symbols from modules use * module_kallsyms_on_each_symbol instead. */ int kallsyms_on_each_symbol(int (*fn)(void *, const char *, unsigned long), void *data) { char namebuf[KSYM_NAME_LEN]; unsigned long i; unsigned int off; int ret; for (i = 0, off = 0; i < kallsyms_num_syms; i++) { off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); ret = fn(data, namebuf, kallsyms_sym_address(i)); if (ret != 0) return ret; cond_resched(); } return 0; } int kallsyms_on_each_match_symbol(int (*fn)(void *, unsigned long), const char *name, void *data) { int ret; unsigned int i, start, end; ret = kallsyms_lookup_names(name, &start, &end); if (ret) return 0; for (i = start; !ret && i <= end; i++) { ret = fn(data, kallsyms_sym_address(get_symbol_seq(i))); cond_resched(); } return ret; } static unsigned long get_symbol_pos(unsigned long addr, unsigned long *symbolsize, unsigned long *offset) { unsigned long symbol_start = 0, symbol_end = 0; unsigned long i, low, high, mid; /* Do a binary search on the sorted kallsyms_offsets array. */ low = 0; high = kallsyms_num_syms; while (high - low > 1) { mid = low + (high - low) / 2; if (kallsyms_sym_address(mid) <= addr) low = mid; else high = mid; } /* * Search for the first aliased symbol. Aliased * symbols are symbols with the same address. */ while (low && kallsyms_sym_address(low-1) == kallsyms_sym_address(low)) --low; symbol_start = kallsyms_sym_address(low); /* Search for next non-aliased symbol. */ for (i = low + 1; i < kallsyms_num_syms; i++) { if (kallsyms_sym_address(i) > symbol_start) { symbol_end = kallsyms_sym_address(i); break; } } /* If we found no next symbol, we use the end of the section. */ if (!symbol_end) { if (is_kernel_inittext(addr)) symbol_end = (unsigned long)_einittext; else if (IS_ENABLED(CONFIG_KALLSYMS_ALL)) symbol_end = (unsigned long)_end; else symbol_end = (unsigned long)_etext; } if (symbolsize) *symbolsize = symbol_end - symbol_start; if (offset) *offset = addr - symbol_start; return low; } /* * Lookup an address but don't bother to find any names. */ int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize, unsigned long *offset) { char namebuf[KSYM_NAME_LEN]; if (is_ksym_addr(addr)) { get_symbol_pos(addr, symbolsize, offset); return 1; } return !!module_address_lookup(addr, symbolsize, offset, NULL, NULL, namebuf) || !!bpf_address_lookup(addr, symbolsize, offset, namebuf); } static int kallsyms_lookup_buildid(unsigned long addr, unsigned long *symbolsize, unsigned long *offset, char **modname, const unsigned char **modbuildid, char *namebuf) { int ret; /* * 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; /* * Initialize the module-related return values. They are not set * when the symbol is in vmlinux or it is a bpf address. */ if (modname) *modname = NULL; if (modbuildid) *modbuildid = NULL; if (is_ksym_addr(addr)) { unsigned long pos; pos = get_symbol_pos(addr, symbolsize, offset); /* Grab name */ kallsyms_expand_symbol(get_symbol_offset(pos), namebuf, KSYM_NAME_LEN); return strlen(namebuf); } /* See if it's in a module or a BPF JITed image. */ ret = module_address_lookup(addr, symbolsize, offset, modname, modbuildid, namebuf); if (!ret) ret = bpf_address_lookup(addr, symbolsize, offset, namebuf); if (!ret) ret = ftrace_mod_address_lookup(addr, symbolsize, offset, modname, modbuildid, namebuf); 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) { int ret = kallsyms_lookup_buildid(addr, symbolsize, offset, modname, NULL, namebuf); if (!ret) return NULL; return namebuf; } int lookup_symbol_name(unsigned long addr, char *symname) { symname[0] = '\0'; symname[KSYM_NAME_LEN - 1] = '\0'; if (is_ksym_addr(addr)) { unsigned long pos; pos = get_symbol_pos(addr, NULL, NULL); /* Grab name */ kallsyms_expand_symbol(get_symbol_offset(pos), symname, KSYM_NAME_LEN); return 0; } /* See if it's in a module. */ 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) { char *modname; const unsigned char *buildid; 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); if (!len) return sprintf(buffer, "0x%lx", address - symbol_offset); offset -= symbol_offset; if (add_offset) len += sprintf(buffer + len, "+%#lx/%#lx", offset, size); if (modname) { len += sprintf(buffer + len, " [%s", modname); if (add_buildid) len += append_buildid(buffer + len, modname, buildid); len += sprintf(buffer + len, "]"); } return len;