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866 lines
22 KiB
866 lines
22 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* kallsyms.c: in-kernel printing of symbolic oopses and stack traces. |
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* |
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* Rewritten and vastly simplified by Rusty Russell for in-kernel |
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* module loader: |
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* Copyright 2002 Rusty Russell <[email protected]> IBM Corporation |
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* |
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* ChangeLog: |
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* |
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* (25/Aug/2004) Paulo Marques <[email protected]> |
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* Changed the compression method from stem compression to "table lookup" |
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* compression (see scripts/kallsyms.c for a more complete description) |
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*/ |
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#include <linux/kallsyms.h> |
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#include <linux/init.h> |
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#include <linux/seq_file.h> |
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#include <linux/fs.h> |
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#include <linux/kdb.h> |
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#include <linux/err.h> |
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#include <linux/proc_fs.h> |
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#include <linux/sched.h> /* for cond_resched */ |
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#include <linux/ctype.h> |
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#include <linux/slab.h> |
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#include <linux/filter.h> |
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#include <linux/ftrace.h> |
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#include <linux/kprobes.h> |
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#include <linux/build_bug.h> |
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#include <linux/compiler.h> |
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#include <linux/module.h> |
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#include <linux/kernel.h> |
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|
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/* |
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* These will be re-linked against their real values |
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* during the second link stage. |
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*/ |
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extern const unsigned long kallsyms_addresses[] __weak; |
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extern const int kallsyms_offsets[] __weak; |
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extern const u8 kallsyms_names[] __weak; |
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|
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/* |
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* Tell the compiler that the count isn't in the small data section if the arch |
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* has one (eg: FRV). |
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*/ |
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extern const unsigned int kallsyms_num_syms |
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__section(".rodata") __attribute__((weak)); |
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|
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extern const unsigned long kallsyms_relative_base |
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__section(".rodata") __attribute__((weak)); |
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|
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extern const char kallsyms_token_table[] __weak; |
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extern const u16 kallsyms_token_index[] __weak; |
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|
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extern const unsigned int kallsyms_markers[] __weak; |
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|
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/* |
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* Expand a compressed symbol data into the resulting uncompressed string, |
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* if uncompressed string is too long (>= maxlen), it will be truncated, |
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* given the offset to where the symbol is in the compressed stream. |
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*/ |
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static unsigned int kallsyms_expand_symbol(unsigned int off, |
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char *result, size_t maxlen) |
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{ |
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int len, skipped_first = 0; |
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const char *tptr; |
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const u8 *data; |
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|
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/* Get the compressed symbol length from the first symbol byte. */ |
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data = &kallsyms_names[off]; |
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len = *data; |
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data++; |
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|
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/* |
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* Update the offset to return the offset for the next symbol on |
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* the compressed stream. |
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*/ |
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off += len + 1; |
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|
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/* |
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* For every byte on the compressed symbol data, copy the table |
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* entry for that byte. |
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*/ |
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while (len) { |
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tptr = &kallsyms_token_table[kallsyms_token_index[*data]]; |
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data++; |
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len--; |
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|
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while (*tptr) { |
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if (skipped_first) { |
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if (maxlen <= 1) |
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goto tail; |
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*result = *tptr; |
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result++; |
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maxlen--; |
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} else |
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skipped_first = 1; |
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tptr++; |
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} |
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} |
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tail: |
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if (maxlen) |
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*result = '\0'; |
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|
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/* Return to offset to the next symbol. */ |
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return off; |
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} |
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|
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/* |
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* Get symbol type information. This is encoded as a single char at the |
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* beginning of the symbol name. |
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*/ |
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static char kallsyms_get_symbol_type(unsigned int off) |
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{ |
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/* |
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* Get just the first code, look it up in the token table, |
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* and return the first char from this token. |
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*/ |
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return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]]; |
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} |
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|
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/* |
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* Find the offset on the compressed stream given and index in the |
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* kallsyms array. |
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*/ |
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static unsigned int get_symbol_offset(unsigned long pos) |
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{ |
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const u8 *name; |
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int i; |
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|
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/* |
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* Use the closest marker we have. We have markers every 256 positions, |
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* so that should be close enough. |
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*/ |
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name = &kallsyms_names[kallsyms_markers[pos >> 8]]; |
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|
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/* |
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* Sequentially scan all the symbols up to the point we're searching |
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* for. Every symbol is stored in a [<len>][<len> bytes of data] format, |
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* so we just need to add the len to the current pointer for every |
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* symbol we wish to skip. |
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*/ |
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for (i = 0; i < (pos & 0xFF); i++) |
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name = name + (*name) + 1; |
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|
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return name - kallsyms_names; |
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} |
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static unsigned long kallsyms_sym_address(int idx) |
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{ |
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if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE)) |
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return kallsyms_addresses[idx]; |
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|
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/* values are unsigned offsets if --absolute-percpu is not in effect */ |
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if (!IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU)) |
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return kallsyms_relative_base + (u32)kallsyms_offsets[idx]; |
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|
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/* ...otherwise, positive offsets are absolute values */ |
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if (kallsyms_offsets[idx] >= 0) |
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return kallsyms_offsets[idx]; |
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|
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/* ...and negative offsets are relative to kallsyms_relative_base - 1 */ |
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return kallsyms_relative_base - 1 - kallsyms_offsets[idx]; |
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} |
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#if defined(CONFIG_CFI_CLANG) && defined(CONFIG_LTO_CLANG_THIN) |
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/* |
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* LLVM appends a hash to static function names when ThinLTO and CFI are |
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* both enabled, i.e. foo() becomes foo$707af9a22804d33c81801f27dcfe489b. |
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* This causes confusion and potentially breaks user space tools, so we |
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* strip the suffix from expanded symbol names. |
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*/ |
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static inline bool cleanup_symbol_name(char *s) |
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{ |
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char *res; |
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|
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res = strrchr(s, '$'); |
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if (res) |
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*res = '\0'; |
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return res != NULL; |
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} |
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#else |
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static inline bool cleanup_symbol_name(char *s) { return false; } |
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#endif |
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|
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/* Lookup the address for this symbol. Returns 0 if not found. */ |
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unsigned long kallsyms_lookup_name(const char *name) |
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{ |
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char namebuf[KSYM_NAME_LEN]; |
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unsigned long i; |
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unsigned int off; |
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for (i = 0, off = 0; i < kallsyms_num_syms; i++) { |
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off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); |
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if (strcmp(namebuf, name) == 0) |
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return kallsyms_sym_address(i); |
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|
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if (cleanup_symbol_name(namebuf) && strcmp(namebuf, name) == 0) |
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return kallsyms_sym_address(i); |
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} |
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return module_kallsyms_lookup_name(name); |
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} |
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#ifdef CONFIG_LIVEPATCH |
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/* |
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* Iterate over all symbols in vmlinux. For symbols from modules use |
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* module_kallsyms_on_each_symbol instead. |
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*/ |
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int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *, |
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unsigned long), |
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void *data) |
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{ |
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char namebuf[KSYM_NAME_LEN]; |
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unsigned long i; |
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unsigned int off; |
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int ret; |
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for (i = 0, off = 0; i < kallsyms_num_syms; i++) { |
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off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); |
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ret = fn(data, namebuf, NULL, kallsyms_sym_address(i)); |
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if (ret != 0) |
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return ret; |
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} |
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return 0; |
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} |
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#endif /* CONFIG_LIVEPATCH */ |
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static unsigned long get_symbol_pos(unsigned long addr, |
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unsigned long *symbolsize, |
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unsigned long *offset) |
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{ |
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unsigned long symbol_start = 0, symbol_end = 0; |
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unsigned long i, low, high, mid; |
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|
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/* This kernel should never had been booted. */ |
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if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE)) |
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BUG_ON(!kallsyms_addresses); |
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else |
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BUG_ON(!kallsyms_offsets); |
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|
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/* Do a binary search on the sorted kallsyms_addresses array. */ |
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low = 0; |
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high = kallsyms_num_syms; |
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while (high - low > 1) { |
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mid = low + (high - low) / 2; |
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if (kallsyms_sym_address(mid) <= addr) |
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low = mid; |
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else |
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high = mid; |
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} |
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/* |
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* Search for the first aliased symbol. Aliased |
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* symbols are symbols with the same address. |
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*/ |
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while (low && kallsyms_sym_address(low-1) == kallsyms_sym_address(low)) |
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--low; |
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symbol_start = kallsyms_sym_address(low); |
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|
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/* Search for next non-aliased symbol. */ |
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for (i = low + 1; i < kallsyms_num_syms; i++) { |
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if (kallsyms_sym_address(i) > symbol_start) { |
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symbol_end = kallsyms_sym_address(i); |
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break; |
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} |
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} |
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|
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/* If we found no next symbol, we use the end of the section. */ |
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if (!symbol_end) { |
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if (is_kernel_inittext(addr)) |
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symbol_end = (unsigned long)_einittext; |
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else if (IS_ENABLED(CONFIG_KALLSYMS_ALL)) |
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symbol_end = (unsigned long)_end; |
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else |
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symbol_end = (unsigned long)_etext; |
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} |
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if (symbolsize) |
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*symbolsize = symbol_end - symbol_start; |
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if (offset) |
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*offset = addr - symbol_start; |
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return low; |
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} |
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/* |
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* Lookup an address but don't bother to find any names. |
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*/ |
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int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize, |
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unsigned long *offset) |
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{ |
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char namebuf[KSYM_NAME_LEN]; |
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if (is_ksym_addr(addr)) { |
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get_symbol_pos(addr, symbolsize, offset); |
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return 1; |
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} |
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return !!module_address_lookup(addr, symbolsize, offset, NULL, NULL, namebuf) || |
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!!__bpf_address_lookup(addr, symbolsize, offset, namebuf); |
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} |
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static const char *kallsyms_lookup_buildid(unsigned long addr, |
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unsigned long *symbolsize, |
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unsigned long *offset, char **modname, |
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const unsigned char **modbuildid, char *namebuf) |
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{ |
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const char *ret; |
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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)) { |
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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), |
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namebuf, KSYM_NAME_LEN); |
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if (modname) |
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*modname = NULL; |
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if (modbuildid) |
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*modbuildid = NULL; |
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ret = namebuf; |
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goto found; |
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} |
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/* See if it's in a module or a BPF JITed image. */ |
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ret = module_address_lookup(addr, symbolsize, offset, |
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modname, modbuildid, namebuf); |
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if (!ret) |
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ret = bpf_address_lookup(addr, symbolsize, |
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offset, modname, namebuf); |
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if (!ret) |
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ret = ftrace_mod_address_lookup(addr, symbolsize, |
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offset, modname, namebuf); |
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found: |
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cleanup_symbol_name(namebuf); |
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return ret; |
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} |
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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. |
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* - We guarantee that the returned name is valid until we reschedule even if. |
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* It resides in a module. |
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* - We also guarantee that modname will be valid until rescheduled. |
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*/ |
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const char *kallsyms_lookup(unsigned long addr, |
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unsigned long *symbolsize, |
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unsigned long *offset, |
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char **modname, char *namebuf) |
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{ |
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return kallsyms_lookup_buildid(addr, symbolsize, offset, modname, |
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NULL, namebuf); |
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} |
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int lookup_symbol_name(unsigned long addr, char *symname) |
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{ |
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int res; |
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symname[0] = '\0'; |
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symname[KSYM_NAME_LEN - 1] = '\0'; |
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if (is_ksym_addr(addr)) { |
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unsigned long pos; |
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pos = get_symbol_pos(addr, NULL, NULL); |
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/* Grab name */ |
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kallsyms_expand_symbol(get_symbol_offset(pos), |
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symname, KSYM_NAME_LEN); |
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goto found; |
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} |
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/* See if it's in a module. */ |
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res = lookup_module_symbol_name(addr, symname); |
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if (res) |
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return res; |
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found: |
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cleanup_symbol_name(symname); |
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return 0; |
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} |
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int lookup_symbol_attrs(unsigned long addr, unsigned long *size, |
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unsigned long *offset, char *modname, char *name) |
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{ |
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int res; |
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name[0] = '\0'; |
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name[KSYM_NAME_LEN - 1] = '\0'; |
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if (is_ksym_addr(addr)) { |
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unsigned long pos; |
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pos = get_symbol_pos(addr, size, offset); |
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/* Grab name */ |
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kallsyms_expand_symbol(get_symbol_offset(pos), |
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name, KSYM_NAME_LEN); |
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modname[0] = '\0'; |
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goto found; |
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} |
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/* See if it's in a module. */ |
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res = lookup_module_symbol_attrs(addr, size, offset, modname, name); |
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if (res) |
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return res; |
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found: |
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cleanup_symbol_name(name); |
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return 0; |
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} |
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|
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/* Look up a kernel symbol and return it in a text buffer. */ |
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static int __sprint_symbol(char *buffer, unsigned long address, |
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int symbol_offset, int add_offset, int add_buildid) |
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{ |
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char *modname; |
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const unsigned char *buildid; |
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const char *name; |
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unsigned long offset, size; |
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int len; |
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address += symbol_offset; |
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name = kallsyms_lookup_buildid(address, &size, &offset, &modname, &buildid, |
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buffer); |
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if (!name) |
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return sprintf(buffer, "0x%lx", address - symbol_offset); |
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|
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if (name != buffer) |
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strcpy(buffer, name); |
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len = strlen(buffer); |
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offset -= symbol_offset; |
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if (add_offset) |
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len += sprintf(buffer + len, "+%#lx/%#lx", offset, size); |
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if (modname) { |
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len += sprintf(buffer + len, " [%s", modname); |
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#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID) |
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if (add_buildid && buildid) { |
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/* build ID should match length of sprintf */ |
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#if IS_ENABLED(CONFIG_MODULES) |
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static_assert(sizeof(typeof_member(struct module, build_id)) == 20); |
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#endif |
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len += sprintf(buffer + len, " %20phN", buildid); |
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} |
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#endif |
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len += sprintf(buffer + len, "]"); |
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} |
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return len; |
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} |
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|
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/** |
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* sprint_symbol - Look up a kernel symbol and return it in a text buffer |
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* @buffer: buffer to be stored |
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* @address: address to lookup |
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* |
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* This function looks up a kernel symbol with @address and stores its name, |
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* offset, size and module name to @buffer if possible. If no symbol was found, |
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* just saves its @address as is. |
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* |
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* This function returns the number of bytes stored in @buffer. |
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*/ |
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int sprint_symbol(char *buffer, unsigned long address) |
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{ |
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return __sprint_symbol(buffer, address, 0, 1, 0); |
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} |
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EXPORT_SYMBOL_GPL(sprint_symbol); |
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|
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/** |
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* sprint_symbol_build_id - Look up a kernel symbol and return it in a text buffer |
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* @buffer: buffer to be stored |
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* @address: address to lookup |
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* |
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* This function looks up a kernel symbol with @address and stores its name, |
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* offset, size, module name and module build ID to @buffer if possible. If no |
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* symbol was found, just saves its @address as is. |
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* |
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* This function returns the number of bytes stored in @buffer. |
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*/ |
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int sprint_symbol_build_id(char *buffer, unsigned long address) |
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{ |
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return __sprint_symbol(buffer, address, 0, 1, 1); |
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} |
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EXPORT_SYMBOL_GPL(sprint_symbol_build_id); |
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|
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/** |
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* sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer |
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* @buffer: buffer to be stored |
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* @address: address to lookup |
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* |
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* This function looks up a kernel symbol with @address and stores its name |
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* and module name to @buffer if possible. If no symbol was found, just saves |
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* its @address as is. |
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* |
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* This function returns the number of bytes stored in @buffer. |
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*/ |
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int sprint_symbol_no_offset(char *buffer, unsigned long address) |
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{ |
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return __sprint_symbol(buffer, address, 0, 0, 0); |
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} |
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EXPORT_SYMBOL_GPL(sprint_symbol_no_offset); |
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|
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/** |
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* sprint_backtrace - Look up a backtrace symbol and return it in a text buffer |
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* @buffer: buffer to be stored |
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* @address: address to lookup |
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* |
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* This function is for stack backtrace and does the same thing as |
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* sprint_symbol() but with modified/decreased @address. If there is a |
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* tail-call to the function marked "noreturn", gcc optimized out code after |
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* the call so that the stack-saved return address could point outside of the |
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* caller. This function ensures that kallsyms will find the original caller |
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* by decreasing @address. |
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* |
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* This function returns the number of bytes stored in @buffer. |
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*/ |
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int sprint_backtrace(char *buffer, unsigned long address) |
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{ |
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return __sprint_symbol(buffer, address, -1, 1, 0); |
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} |
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|
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/** |
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* sprint_backtrace_build_id - Look up a backtrace symbol and return it in a text buffer |
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* @buffer: buffer to be stored |
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* @address: address to lookup |
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* |
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* This function is for stack backtrace and does the same thing as |
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* sprint_symbol() but with modified/decreased @address. If there is a |
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* tail-call to the function marked "noreturn", gcc optimized out code after |
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* the call so that the stack-saved return address could point outside of the |
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* caller. This function ensures that kallsyms will find the original caller |
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* by decreasing @address. This function also appends the module build ID to |
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* the @buffer if @address is within a kernel module. |
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* |
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* This function returns the number of bytes stored in @buffer. |
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*/ |
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int sprint_backtrace_build_id(char *buffer, unsigned long address) |
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{ |
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return __sprint_symbol(buffer, address, -1, 1, 1); |
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} |
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|
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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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loff_t pos_arch_end; |
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loff_t pos_mod_end; |
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loff_t pos_ftrace_mod_end; |
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loff_t pos_bpf_end; |
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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]; |
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char module_name[MODULE_NAME_LEN]; |
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int exported; |
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int show_value; |
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}; |
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|
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int __weak arch_get_kallsym(unsigned int symnum, unsigned long *value, |
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char *type, char *name) |
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{ |
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return -EINVAL; |
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} |
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|
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static int get_ksymbol_arch(struct kallsym_iter *iter) |
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{ |
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int ret = arch_get_kallsym(iter->pos - kallsyms_num_syms, |
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&iter->value, &iter->type, |
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iter->name); |
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|
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if (ret < 0) { |
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iter->pos_arch_end = iter->pos; |
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return 0; |
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} |
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|
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return 1; |
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} |
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|
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static int get_ksymbol_mod(struct kallsym_iter *iter) |
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{ |
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int ret = module_get_kallsym(iter->pos - iter->pos_arch_end, |
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&iter->value, &iter->type, |
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iter->name, iter->module_name, |
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&iter->exported); |
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if (ret < 0) { |
|
iter->pos_mod_end = iter->pos; |
|
return 0; |
|
} |
|
|
|
return 1; |
|
} |
|
|
|
/* |
|
* ftrace_mod_get_kallsym() may also get symbols for pages allocated for ftrace |
|
* purposes. In that case "__builtin__ftrace" is used as a module name, even |
|
* though "__builtin__ftrace" is not a module. |
|
*/ |
|
static int get_ksymbol_ftrace_mod(struct kallsym_iter *iter) |
|
{ |
|
int ret = ftrace_mod_get_kallsym(iter->pos - iter->pos_mod_end, |
|
&iter->value, &iter->type, |
|
iter->name, iter->module_name, |
|
&iter->exported); |
|
if (ret < 0) { |
|
iter->pos_ftrace_mod_end = iter->pos; |
|
return 0; |
|
} |
|
|
|
return 1; |
|
} |
|
|
|
static int get_ksymbol_bpf(struct kallsym_iter *iter) |
|
{ |
|
int ret; |
|
|
|
strlcpy(iter->module_name, "bpf", MODULE_NAME_LEN); |
|
iter->exported = 0; |
|
ret = bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end, |
|
&iter->value, &iter->type, |
|
iter->name); |
|
if (ret < 0) { |
|
iter->pos_bpf_end = iter->pos; |
|
return 0; |
|
} |
|
|
|
return 1; |
|
} |
|
|
|
/* |
|
* This uses "__builtin__kprobes" as a module name for symbols for pages |
|
* allocated for kprobes' purposes, even though "__builtin__kprobes" is not a |
|
* module. |
|
*/ |
|
static int get_ksymbol_kprobe(struct kallsym_iter *iter) |
|
{ |
|
strlcpy(iter->module_name, "__builtin__kprobes", MODULE_NAME_LEN); |
|
iter->exported = 0; |
|
return kprobe_get_kallsym(iter->pos - iter->pos_bpf_end, |
|
&iter->value, &iter->type, |
|
iter->name) < 0 ? 0 : 1; |
|
} |
|
|
|
/* Returns space to next name. */ |
|
static unsigned long get_ksymbol_core(struct kallsym_iter *iter) |
|
{ |
|
unsigned off = iter->nameoff; |
|
|
|
iter->module_name[0] = '\0'; |
|
iter->value = kallsyms_sym_address(iter->pos); |
|
|
|
iter->type = kallsyms_get_symbol_type(off); |
|
|
|
off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(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; |
|
if (new_pos == 0) { |
|
iter->pos_arch_end = 0; |
|
iter->pos_mod_end = 0; |
|
iter->pos_ftrace_mod_end = 0; |
|
iter->pos_bpf_end = 0; |
|
} |
|
} |
|
|
|
/* |
|
* The end position (last + 1) of each additional kallsyms section is recorded |
|
* in iter->pos_..._end as each section is added, and so can be used to |
|
* determine which get_ksymbol_...() function to call next. |
|
*/ |
|
static int update_iter_mod(struct kallsym_iter *iter, loff_t pos) |
|
{ |
|
iter->pos = pos; |
|
|
|
if ((!iter->pos_arch_end || iter->pos_arch_end > pos) && |
|
get_ksymbol_arch(iter)) |
|
return 1; |
|
|
|
if ((!iter->pos_mod_end || iter->pos_mod_end > pos) && |
|
get_ksymbol_mod(iter)) |
|
return 1; |
|
|
|
if ((!iter->pos_ftrace_mod_end || iter->pos_ftrace_mod_end > pos) && |
|
get_ksymbol_ftrace_mod(iter)) |
|
return 1; |
|
|
|
if ((!iter->pos_bpf_end || iter->pos_bpf_end > pos) && |
|
get_ksymbol_bpf(iter)) |
|
return 1; |
|
|
|
return get_ksymbol_kprobe(iter); |
|
} |
|
|
|
/* 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) |
|
return update_iter_mod(iter, pos); |
|
|
|
/* 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) |
|
{ |
|
void *value; |
|
struct kallsym_iter *iter = m->private; |
|
|
|
/* Some debugging symbols have no name. Ignore them. */ |
|
if (!iter->name[0]) |
|
return 0; |
|
|
|
value = iter->show_value ? (void *)iter->value : NULL; |
|
|
|
if (iter->module_name[0]) { |
|
char type; |
|
|
|
/* |
|
* Label it "global" if it is exported, |
|
* "local" if not exported. |
|
*/ |
|
type = iter->exported ? toupper(iter->type) : |
|
tolower(iter->type); |
|
seq_printf(m, "%px %c %s\t[%s]\n", value, |
|
type, iter->name, iter->module_name); |
|
} else |
|
seq_printf(m, "%px %c %s\n", value, |
|
iter->type, iter->name); |
|
return 0; |
|
} |
|
|
|
static const struct seq_operations kallsyms_op = { |
|
.start = s_start, |
|
.next = s_next, |
|
.stop = s_stop, |
|
.show = s_show |
|
}; |
|
|
|
static inline int kallsyms_for_perf(void) |
|
{ |
|
#ifdef CONFIG_PERF_EVENTS |
|
extern int sysctl_perf_event_paranoid; |
|
if (sysctl_perf_event_paranoid <= 1) |
|
return 1; |
|
#endif |
|
return 0; |
|
} |
|
|
|
/* |
|
* We show kallsyms information even to normal users if we've enabled |
|
* kernel profiling and are explicitly not paranoid (so kptr_restrict |
|
* is clear, and sysctl_perf_event_paranoid isn't set). |
|
* |
|
* Otherwise, require CAP_SYSLOG (assuming kptr_restrict isn't set to |
|
* block even that). |
|
*/ |
|
bool kallsyms_show_value(const struct cred *cred) |
|
{ |
|
switch (kptr_restrict) { |
|
case 0: |
|
if (kallsyms_for_perf()) |
|
return true; |
|
fallthrough; |
|
case 1: |
|
if (security_capable(cred, &init_user_ns, CAP_SYSLOG, |
|
CAP_OPT_NOAUDIT) == 0) |
|
return true; |
|
fallthrough; |
|
default: |
|
return false; |
|
} |
|
} |
|
|
|
static int kallsyms_open(struct inode *inode, struct file *file) |
|
{ |
|
/* |
|
* We keep iterator in m->private, since normal case is to |
|
* s_start from where we left off, so we avoid doing |
|
* using get_symbol_offset for every symbol. |
|
*/ |
|
struct kallsym_iter *iter; |
|
iter = __seq_open_private(file, &kallsyms_op, sizeof(*iter)); |
|
if (!iter) |
|
return -ENOMEM; |
|
reset_iter(iter, 0); |
|
|
|
/* |
|
* Instead of checking this on every s_show() call, cache |
|
* the result here at open time. |
|
*/ |
|
iter->show_value = kallsyms_show_value(file->f_cred); |
|
return 0; |
|
} |
|
|
|
#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 */ |
|
|
|
static const struct proc_ops kallsyms_proc_ops = { |
|
.proc_open = kallsyms_open, |
|
.proc_read = seq_read, |
|
.proc_lseek = seq_lseek, |
|
.proc_release = seq_release_private, |
|
}; |
|
|
|
static int __init kallsyms_init(void) |
|
{ |
|
proc_create("kallsyms", 0444, NULL, &kallsyms_proc_ops); |
|
return 0; |
|
} |
|
device_initcall(kallsyms_init);
|
|
|