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kernel/kallsyms.c
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/* * 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/module.h> #include <linux/init.h> #include <linux/seq_file.h> #include <linux/fs.h> |
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#include <linux/kdb.h> |
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#include <linux/err.h> #include <linux/proc_fs.h> |
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#include <linux/sched.h> /* for cond_resched */ |
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#include <linux/mm.h> |
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#include <linux/ctype.h> |
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#include <linux/slab.h> |
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#include <asm/sections.h> #ifdef CONFIG_KALLSYMS_ALL #define all_var 1 #else #define all_var 0 #endif |
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/* * These will be re-linked against their real values * during the second link stage. */ |
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extern const unsigned long kallsyms_addresses[] __attribute__((weak)); extern const u8 kallsyms_names[] __attribute__((weak)); |
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/* * Tell the compiler that the count isn't in the small data section if the arch * has one (eg: FRV). |
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*/ extern const unsigned long kallsyms_num_syms |
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__attribute__((weak, section(".rodata"))); |
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extern const u8 kallsyms_token_table[] __attribute__((weak)); extern const u16 kallsyms_token_index[] __attribute__((weak)); |
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extern const unsigned long kallsyms_markers[] __attribute__((weak)); |
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static inline int is_kernel_inittext(unsigned long addr) { if (addr >= (unsigned long)_sinittext && addr <= (unsigned long)_einittext) return 1; return 0; } static inline int is_kernel_text(unsigned long addr) { |
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if ((addr >= (unsigned long)_stext && addr <= (unsigned long)_etext) || arch_is_kernel_text(addr)) |
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return 1; return in_gate_area_no_task(addr); } static inline int is_kernel(unsigned long addr) { if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end) return 1; return in_gate_area_no_task(addr); } |
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static int is_ksym_addr(unsigned long addr) { if (all_var) return is_kernel(addr); |
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return is_kernel_text(addr) || is_kernel_inittext(addr); |
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} |
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/* * Expand a compressed symbol data into the resulting uncompressed string, * given the offset to where the symbol is in the compressed stream. */ |
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static unsigned int kallsyms_expand_symbol(unsigned int off, char *result) { int len, skipped_first = 0; |
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const u8 *tptr, *data; |
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/* Get the compressed symbol length from the first symbol byte. */ |
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data = &kallsyms_names[off]; len = *data; data++; |
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/* * Update the offset to return the offset for the next symbol on * the compressed stream. */ |
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off += len + 1; |
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/* * 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]]; |
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data++; len--; while (*tptr) { |
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if (skipped_first) { |
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*result = *tptr; result++; } else skipped_first = 1; tptr++; } } *result = '\0'; |
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/* Return to offset to the next symbol. */ |
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return off; } |
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/* * Get symbol type information. This is encoded as a single char at the * beginning of the symbol name. */ |
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static char kallsyms_get_symbol_type(unsigned int off) { |
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/* * Get just the first code, look it up in the token table, * and return the first char from this token. */ return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]]; |
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} |
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/* * Find the offset on the compressed stream given and index in the * kallsyms array. */ |
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static unsigned int get_symbol_offset(unsigned long pos) { |
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const u8 *name; |
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int i; |
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/* * 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]]; |
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/* * 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++) |
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name = name + (*name) + 1; return name - kallsyms_names; } /* Lookup the address for this symbol. Returns 0 if not found. */ unsigned long kallsyms_lookup_name(const char *name) { |
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char namebuf[KSYM_NAME_LEN]; |
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unsigned long i; unsigned int off; for (i = 0, off = 0; i < kallsyms_num_syms; i++) { off = kallsyms_expand_symbol(off, namebuf); if (strcmp(namebuf, name) == 0) return kallsyms_addresses[i]; } return module_kallsyms_lookup_name(name); } |
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EXPORT_SYMBOL_GPL(kallsyms_lookup_name); |
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int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *, 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); ret = fn(data, namebuf, NULL, kallsyms_addresses[i]); if (ret != 0) return ret; } return module_kallsyms_on_each_symbol(fn, data); } EXPORT_SYMBOL_GPL(kallsyms_on_each_symbol); |
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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; |
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/* This kernel should never had been booted. */ BUG_ON(!kallsyms_addresses); |
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/* Do a binary search on the sorted kallsyms_addresses array. */ |
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low = 0; high = kallsyms_num_syms; while (high - low > 1) { |
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mid = low + (high - low) / 2; |
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if (kallsyms_addresses[mid] <= addr) low = mid; else high = mid; } /* |
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* Search for the first aliased symbol. Aliased * symbols are symbols with the same address. |
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*/ while (low && kallsyms_addresses[low-1] == kallsyms_addresses[low]) --low; symbol_start = kallsyms_addresses[low]; |
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/* Search for next non-aliased symbol. */ |
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for (i = low + 1; i < kallsyms_num_syms; i++) { if (kallsyms_addresses[i] > symbol_start) { symbol_end = kallsyms_addresses[i]; break; } } |
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/* If we found no next symbol, we use the end of the section. */ |
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if (!symbol_end) { if (is_kernel_inittext(addr)) symbol_end = (unsigned long)_einittext; else if (all_var) symbol_end = (unsigned long)_end; else symbol_end = (unsigned long)_etext; } |
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if (symbolsize) *symbolsize = symbol_end - symbol_start; if (offset) *offset = addr - symbol_start; |
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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) { |
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char namebuf[KSYM_NAME_LEN]; |
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if (is_ksym_addr(addr)) return !!get_symbol_pos(addr, symbolsize, offset); |
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return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf); |
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} |
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/* * Lookup an address |
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* - 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. |
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*/ const char *kallsyms_lookup(unsigned long addr, unsigned long *symbolsize, unsigned long *offset, char **modname, char *namebuf) { |
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namebuf[KSYM_NAME_LEN - 1] = 0; |
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namebuf[0] = 0; |
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if (is_ksym_addr(addr)) { unsigned long pos; |
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pos = get_symbol_pos(addr, symbolsize, offset); |
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/* Grab name */ |
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kallsyms_expand_symbol(get_symbol_offset(pos), namebuf); |
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if (modname) *modname = NULL; |
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return namebuf; } |
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/* See if it's in a module. */ |
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return module_address_lookup(addr, symbolsize, offset, modname, namebuf); |
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} |
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int lookup_symbol_name(unsigned long addr, char *symname) { symname[0] = '\0'; |
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symname[KSYM_NAME_LEN - 1] = '\0'; |
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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); return 0; } |
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/* See if it's in a module. */ |
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return lookup_module_symbol_name(addr, symname); } |
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int lookup_symbol_attrs(unsigned long addr, unsigned long *size, unsigned long *offset, char *modname, char *name) { name[0] = '\0'; |
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name[KSYM_NAME_LEN - 1] = '\0'; |
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if (is_ksym_addr(addr)) { unsigned long pos; pos = get_symbol_pos(addr, size, offset); /* Grab name */ kallsyms_expand_symbol(get_symbol_offset(pos), name); modname[0] = '\0'; return 0; } |
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/* See if it's in a module. */ |
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return lookup_module_symbol_attrs(addr, size, offset, modname, name); } |
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/* Look up a kernel symbol and return it in a text buffer. */ int sprint_symbol(char *buffer, unsigned long address) |
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{ char *modname; const char *name; unsigned long offset, size; |
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int len; |
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name = kallsyms_lookup(address, &size, &offset, &modname, buffer); |
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if (!name) |
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return sprintf(buffer, "0x%lx", address); |
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if (name != buffer) strcpy(buffer, name); len = strlen(buffer); buffer += len; |
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if (modname) |
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len += sprintf(buffer, "+%#lx/%#lx [%s]", offset, size, modname); |
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else |
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len += sprintf(buffer, "+%#lx/%#lx", offset, size); return len; |
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} |
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EXPORT_SYMBOL_GPL(sprint_symbol); |
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/* Look up a kernel symbol and print it to the kernel messages. */ void __print_symbol(const char *fmt, unsigned long address) { char buffer[KSYM_SYMBOL_LEN]; sprint_symbol(buffer, address); |
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printk(fmt, buffer); } |
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EXPORT_SYMBOL(__print_symbol); |
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/* To avoid using get_symbol_offset for every symbol, we carry prefix along. */ |
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struct kallsym_iter { |
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loff_t pos; |
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unsigned long value; |
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unsigned int nameoff; /* If iterating in core kernel symbols. */ |
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char type; |
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char name[KSYM_NAME_LEN]; char module_name[MODULE_NAME_LEN]; |
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int exported; |
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}; |
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static int get_ksymbol_mod(struct kallsym_iter *iter) { |
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if (module_get_kallsym(iter->pos - kallsyms_num_syms, &iter->value, &iter->type, iter->name, iter->module_name, &iter->exported) < 0) |
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return 0; |
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return 1; } /* Returns space to next name. */ static unsigned long get_ksymbol_core(struct kallsym_iter *iter) { unsigned off = iter->nameoff; |
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iter->module_name[0] = '\0'; |
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iter->value = kallsyms_addresses[iter->pos]; iter->type = kallsyms_get_symbol_type(off); off = kallsyms_expand_symbol(off, iter->name); return off - iter->nameoff; } static void reset_iter(struct kallsym_iter *iter, loff_t new_pos) { iter->name[0] = '\0'; iter->nameoff = get_symbol_offset(new_pos); iter->pos = new_pos; } /* Returns false if pos at or past end of file. */ static int update_iter(struct kallsym_iter *iter, loff_t pos) { /* Module symbols can be accessed randomly. */ if (pos >= kallsyms_num_syms) { iter->pos = pos; return get_ksymbol_mod(iter); } |
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/* If we're not on the desired position, reset to new position. */ if (pos != iter->pos) reset_iter(iter, pos); iter->nameoff += get_ksymbol_core(iter); iter->pos++; return 1; } static void *s_next(struct seq_file *m, void *p, loff_t *pos) { (*pos)++; if (!update_iter(m->private, *pos)) return NULL; return p; } static void *s_start(struct seq_file *m, loff_t *pos) { if (!update_iter(m->private, *pos)) return NULL; return m->private; } static void s_stop(struct seq_file *m, void *p) { } static int s_show(struct seq_file *m, void *p) { struct kallsym_iter *iter = m->private; |
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/* Some debugging symbols have no name. Ignore them. */ |
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if (!iter->name[0]) return 0; |
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if (iter->module_name[0]) { char type; |
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/* * Label it "global" if it is exported, * "local" if not exported. */ |
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type = iter->exported ? toupper(iter->type) : tolower(iter->type); |
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seq_printf(m, "%0*lx %c %s\t[%s] ", |
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(int)(2 * sizeof(void *)), |
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iter->value, type, iter->name, iter->module_name); } else |
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seq_printf(m, "%0*lx %c %s ", |
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(int)(2 * sizeof(void *)), |
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iter->value, iter->type, iter->name); return 0; } |
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static const struct seq_operations kallsyms_op = { |
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.start = s_start, .next = s_next, .stop = s_stop, .show = s_show }; static int kallsyms_open(struct inode *inode, struct file *file) { |
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/* * We keep iterator in m->private, since normal case is to |
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* s_start from where we left off, so we avoid doing |
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* using get_symbol_offset for every symbol. */ |
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struct kallsym_iter *iter; int ret; iter = kmalloc(sizeof(*iter), GFP_KERNEL); if (!iter) return -ENOMEM; reset_iter(iter, 0); ret = seq_open(file, &kallsyms_op); if (ret == 0) ((struct seq_file *)file->private_data)->private = iter; else kfree(iter); return ret; } |
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#ifdef CONFIG_KGDB_KDB const char *kdb_walk_kallsyms(loff_t *pos) { static struct kallsym_iter kdb_walk_kallsyms_iter; if (*pos == 0) { memset(&kdb_walk_kallsyms_iter, 0, sizeof(kdb_walk_kallsyms_iter)); reset_iter(&kdb_walk_kallsyms_iter, 0); } while (1) { if (!update_iter(&kdb_walk_kallsyms_iter, *pos)) return NULL; ++*pos; /* Some debugging symbols have no name. Ignore them. */ if (kdb_walk_kallsyms_iter.name[0]) return kdb_walk_kallsyms_iter.name; } } #endif /* CONFIG_KGDB_KDB */ |
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static const struct file_operations kallsyms_operations = { |
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.open = kallsyms_open, .read = seq_read, .llseek = seq_lseek, |
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.release = seq_release_private, |
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}; static int __init kallsyms_init(void) { |
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proc_create("kallsyms", 0444, NULL, &kallsyms_operations); |
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return 0; } |
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device_initcall(kallsyms_init); |