linux/kernel/kallsyms.c
Linus Torvalds 4e3c09e954 v6.5-rc1-modules-next
The changes queued up for v6.5-rc1 for modules are pretty tame, mostly
 code removal of moving of code. Only two minor functional changes are
 made, the only one which stands out is Sebastian Andrzej Siewior's
 simplification of module reference counting by removing preempt_disable()
 and that has been tested on linux-next for well over a month without
 no regressions. I'm now, I guess, also a kitchen sink for some kallsyms
 changes.
 -----BEGIN PGP SIGNATURE-----
 
 iQJGBAABCgAwFiEENnNq2KuOejlQLZofziMdCjCSiKcFAmScfl0SHG1jZ3JvZkBr
 ZXJuZWwub3JnAAoJEM4jHQowkoin8oMP/0DQK+r3BZimknzz6rF0EBStNZ/dIK2W
 1Q/r/ER4VKQKYxklc1M74K+7IX8ZDCYxqlaDS9lvAkRDWNC+t69aNZEib2odJleC
 p6WB30P0JIwfZZC0DS/ct3vrWZTyUhw7aOtvABRmjBfiJ3lFlU092Glvk1w1aFbD
 UrNRomPu4CujzfmnGj3VGc+HVSOEK0F1/GLm9ClrsR8SzKEpQmH4ALI/ON69B0ea
 PmL+d1Wyt6WEoH0hlV1TOXNdHUb3ZO1riSSfDYQ7TiG2AM5w1t4n26YRusc16hYU
 6Bx4OGt52ZJYR3btsRQlcylF4R5DUo+boDkM0NqEDU/3ciGMg6DgKdHnYCBN1w+X
 ZO8aXK1MIgF7W6CqSz+8HCsu5CuCos55FgM22dPbpZr3OEFCWemqnV+cYCu1DA+M
 Gbnn883ZLtt+R+qikD3135s+LxYIvxSuQrj+B3ZoQeIKEtAlyxuhrUJbU0tOns0j
 05PrkI8J1FtIysdlNZeIFg752IPtjp/0QNB4R46m40mT16L0TSjEP7c+zcPDryMb
 84SdLqh1gis0QZRkoH6JbMBDeT2dtuxqtQ5dTPka4s1mtg3SvRYr53sCJg+gQ8e2
 CBW6jgrIf3F4RIMMiSfXpSf4yVVxXxJAEFnGLRXhQ2HkUnk3mdGEfsZc7ucrsnlK
 f/KwaEzmLD9c
 =gjKD
 -----END PGP SIGNATURE-----

Merge tag 'v6.5-rc1-modules-next' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux

Pull module updates from Luis Chamberlain:
 "The changes queued up for modules are pretty tame, mostly code removal
  of moving of code.

  Only two minor functional changes are made, the only one which stands
  out is Sebastian Andrzej Siewior's simplification of module reference
  counting by removing preempt_disable() and that has been tested on
  linux-next for well over a month without no regressions.

  I'm now, I guess, also a kitchen sink for some kallsyms changes"

[ There was a mis-communication about the concurrent module load changes
  that I had expected to come through Luis despite me authoring the
  patch. So some of the module updates were left hanging in the email
  ether, and I just committed them separately.

  It's my bad - I should have made it more clear that I expected my
  own patches to come through the module tree too. Now they missed
  linux-next, but hopefully that won't cause any issues    - Linus ]

* tag 'v6.5-rc1-modules-next' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux:
  kallsyms: make kallsyms_show_value() as generic function
  kallsyms: move kallsyms_show_value() out of kallsyms.c
  kallsyms: remove unsed API lookup_symbol_attrs
  kallsyms: remove unused arch_get_kallsym() helper
  module: Remove preempt_disable() from module reference counting.
2023-06-28 15:51:08 -07:00

964 lines
23 KiB
C

// 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.
*/
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)
{
if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
return kallsyms_addresses[idx];
/* values are unsigned offsets if --absolute-percpu is not in effect */
if (!IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU))
return kallsyms_relative_base + (u32)kallsyms_offsets[idx];
/* ...otherwise, positive offsets are absolute values */
if (kallsyms_offsets[idx] >= 0)
return kallsyms_offsets[idx];
/* ...and negative offsets are relative to kallsyms_relative_base - 1 */
return kallsyms_relative_base - 1 - kallsyms_offsets[idx];
}
static bool cleanup_symbol_name(char *s)
{
char *res;
if (!IS_ENABLED(CONFIG_LTO_CLANG))
return false;
/*
* LLVM appends various suffixes for local functions and variables that
* must be promoted to global scope as part of LTO. This can break
* hooking of static functions with kprobes. '.' is not a valid
* character in an identifier in C. Suffixes observed:
* - foo.llvm.[0-9a-f]+
* - foo.[0-9a-f]+
*/
res = strchr(s, '.');
if (res) {
*res = '\0';
return true;
}
return false;
}
static int compare_symbol_name(const char *name, char *namebuf)
{
int ret;
ret = strcmp(name, namebuf);
if (!ret)
return ret;
if (cleanup_symbol_name(namebuf) && !strcmp(name, namebuf))
return 0;
return ret;
}
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 = compare_symbol_name(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 (compare_symbol_name(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 (compare_symbol_name(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;
/* This kernel should never had been booted. */
if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
BUG_ON(!kallsyms_addresses);
else
BUG_ON(!kallsyms_offsets);
/* Do a binary search on the sorted kallsyms_addresses 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 const char *kallsyms_lookup_buildid(unsigned long addr,
unsigned long *symbolsize,
unsigned long *offset, char **modname,
const unsigned char **modbuildid, char *namebuf)
{
const char *ret;
namebuf[KSYM_NAME_LEN - 1] = 0;
namebuf[0] = 0;
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);
if (modname)
*modname = NULL;
if (modbuildid)
*modbuildid = NULL;
ret = namebuf;
goto found;
}
/* 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, modname, namebuf);
if (!ret)
ret = ftrace_mod_address_lookup(addr, symbolsize,
offset, modname, namebuf);
found:
cleanup_symbol_name(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)
{
return kallsyms_lookup_buildid(addr, symbolsize, offset, modname,
NULL, namebuf);
}
int lookup_symbol_name(unsigned long addr, char *symname)
{
int res;
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);
goto found;
}
/* See if it's in a module. */
res = lookup_module_symbol_name(addr, symname);
if (res)
return res;
found:
cleanup_symbol_name(symname);
return 0;
}
/* 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;
const char *name;
unsigned long offset, size;
int len;
address += symbol_offset;
name = kallsyms_lookup_buildid(address, &size, &offset, &modname, &buildid,
buffer);
if (!name)
return sprintf(buffer, "0x%lx", address - symbol_offset);
if (name != buffer)
strcpy(buffer, name);
len = strlen(buffer);
offset -= symbol_offset;
if (add_offset)
len += sprintf(buffer + len, "+%#lx/%#lx", offset, size);
if (modname) {
len += sprintf(buffer + len, " [%s", modname);
#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
if (add_buildid && buildid) {
/* build ID should match length of sprintf */
#if IS_ENABLED(CONFIG_MODULES)
static_assert(sizeof(typeof_member(struct module, build_id)) == 20);
#endif
len += sprintf(buffer + len, " %20phN", buildid);
}
#endif
len += sprintf(buffer + len, "]");
}
return len;
}
/**
* sprint_symbol - Look up a kernel symbol and return it in a text buffer
* @buffer: buffer to be stored
* @address: address to lookup
*
* This function looks up a kernel symbol with @address and stores its name,
* offset, size and module name to @buffer if possible. If no symbol was found,
* just saves its @address as is.
*
* This function returns the number of bytes stored in @buffer.
*/
int sprint_symbol(char *buffer, unsigned long address)
{
return __sprint_symbol(buffer, address, 0, 1, 0);
}
EXPORT_SYMBOL_GPL(sprint_symbol);
/**
* sprint_symbol_build_id - Look up a kernel symbol and return it in a text buffer
* @buffer: buffer to be stored
* @address: address to lookup
*
* This function looks up a kernel symbol with @address and stores its name,
* offset, size, module name and module build ID to @buffer if possible. If no
* symbol was found, just saves its @address as is.
*
* This function returns the number of bytes stored in @buffer.
*/
int sprint_symbol_build_id(char *buffer, unsigned long address)
{
return __sprint_symbol(buffer, address, 0, 1, 1);
}
EXPORT_SYMBOL_GPL(sprint_symbol_build_id);
/**
* sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer
* @buffer: buffer to be stored
* @address: address to lookup
*
* This function looks up a kernel symbol with @address and stores its name
* and module name to @buffer if possible. If no symbol was found, just saves
* its @address as is.
*
* This function returns the number of bytes stored in @buffer.
*/
int sprint_symbol_no_offset(char *buffer, unsigned long address)
{
return __sprint_symbol(buffer, address, 0, 0, 0);
}
EXPORT_SYMBOL_GPL(sprint_symbol_no_offset);
/**
* sprint_backtrace - Look up a backtrace symbol and return it in a text buffer
* @buffer: buffer to be stored
* @address: address to lookup
*
* This function is for stack backtrace and does the same thing as
* sprint_symbol() but with modified/decreased @address. If there is a
* tail-call to the function marked "noreturn", gcc optimized out code after
* the call so that the stack-saved return address could point outside of the
* caller. This function ensures that kallsyms will find the original caller
* by decreasing @address.
*
* This function returns the number of bytes stored in @buffer.
*/
int sprint_backtrace(char *buffer, unsigned long address)
{
return __sprint_symbol(buffer, address, -1, 1, 0);
}
/**
* sprint_backtrace_build_id - Look up a backtrace symbol and return it in a text buffer
* @buffer: buffer to be stored
* @address: address to lookup
*
* This function is for stack backtrace and does the same thing as
* sprint_symbol() but with modified/decreased @address. If there is a
* tail-call to the function marked "noreturn", gcc optimized out code after
* the call so that the stack-saved return address could point outside of the
* caller. This function ensures that kallsyms will find the original caller
* by decreasing @address. This function also appends the module build ID to
* the @buffer if @address is within a kernel module.
*
* This function returns the number of bytes stored in @buffer.
*/
int sprint_backtrace_build_id(char *buffer, unsigned long address)
{
return __sprint_symbol(buffer, address, -1, 1, 1);
}
/* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
struct kallsym_iter {
loff_t pos;
loff_t pos_mod_end;
loff_t pos_ftrace_mod_end;
loff_t pos_bpf_end;
unsigned long value;
unsigned int nameoff; /* If iterating in core kernel symbols. */
char type;
char name[KSYM_NAME_LEN];
char module_name[MODULE_NAME_LEN];
int exported;
int show_value;
};
static int get_ksymbol_mod(struct kallsym_iter *iter)
{
int ret = module_get_kallsym(iter->pos - kallsyms_num_syms,
&iter->value, &iter->type,
iter->name, iter->module_name,
&iter->exported);
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;
strscpy(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)
{
strscpy(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_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_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
};
#ifdef CONFIG_BPF_SYSCALL
struct bpf_iter__ksym {
__bpf_md_ptr(struct bpf_iter_meta *, meta);
__bpf_md_ptr(struct kallsym_iter *, ksym);
};
static int ksym_prog_seq_show(struct seq_file *m, bool in_stop)
{
struct bpf_iter__ksym ctx;
struct bpf_iter_meta meta;
struct bpf_prog *prog;
meta.seq = m;
prog = bpf_iter_get_info(&meta, in_stop);
if (!prog)
return 0;
ctx.meta = &meta;
ctx.ksym = m ? m->private : NULL;
return bpf_iter_run_prog(prog, &ctx);
}
static int bpf_iter_ksym_seq_show(struct seq_file *m, void *p)
{
return ksym_prog_seq_show(m, false);
}
static void bpf_iter_ksym_seq_stop(struct seq_file *m, void *p)
{
if (!p)
(void) ksym_prog_seq_show(m, true);
else
s_stop(m, p);
}
static const struct seq_operations bpf_iter_ksym_ops = {
.start = s_start,
.next = s_next,
.stop = bpf_iter_ksym_seq_stop,
.show = bpf_iter_ksym_seq_show,
};
static int bpf_iter_ksym_init(void *priv_data, struct bpf_iter_aux_info *aux)
{
struct kallsym_iter *iter = priv_data;
reset_iter(iter, 0);
/* cache here as in kallsyms_open() case; use current process
* credentials to tell BPF iterators if values should be shown.
*/
iter->show_value = kallsyms_show_value(current_cred());
return 0;
}
DEFINE_BPF_ITER_FUNC(ksym, struct bpf_iter_meta *meta, struct kallsym_iter *ksym)
static const struct bpf_iter_seq_info ksym_iter_seq_info = {
.seq_ops = &bpf_iter_ksym_ops,
.init_seq_private = bpf_iter_ksym_init,
.fini_seq_private = NULL,
.seq_priv_size = sizeof(struct kallsym_iter),
};
static struct bpf_iter_reg ksym_iter_reg_info = {
.target = "ksym",
.feature = BPF_ITER_RESCHED,
.ctx_arg_info_size = 1,
.ctx_arg_info = {
{ offsetof(struct bpf_iter__ksym, ksym),
PTR_TO_BTF_ID_OR_NULL },
},
.seq_info = &ksym_iter_seq_info,
};
BTF_ID_LIST(btf_ksym_iter_id)
BTF_ID(struct, kallsym_iter)
static int __init bpf_ksym_iter_register(void)
{
ksym_iter_reg_info.ctx_arg_info[0].btf_id = *btf_ksym_iter_id;
return bpf_iter_reg_target(&ksym_iter_reg_info);
}
late_initcall(bpf_ksym_iter_register);
#endif /* CONFIG_BPF_SYSCALL */
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);