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[PATCH] Create kallsyms_lookup_size_offset()

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Some uses of kallsyms_lookup() do not need to find out the name of a symbol
and its module's name it belongs.  This is specially true in arch specific
code, which needs to unwind the stack to show the back trace during oops
(mips is an example).  In this specific case, we just need to retreive the
function's size and the offset of the active intruction inside it.

Adds a new entry "kallsyms_lookup_size_offset()" This new entry does
exactly the same as kallsyms_lookup() but does not require any buffers to
store any names.

It returns 0 if it fails otherwise 1.

Signed-off-by: Franck Bui-Huu <vagabon.xyz@gmail.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Franck Bui-Huu 2006-10-03 01:13:48 -07:00 committed by Linus Torvalds
parent 339b0c0813
commit ffc5089196
3 changed files with 93 additions and 44 deletions
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11
include/linux/kallsyms.h
View file

@ -12,6 +12,10 @@
/* Lookup the address for a symbol. Returns 0 if not found. */
unsigned long kallsyms_lookup_name(const char *name);
extern int kallsyms_lookup_size_offset(unsigned long addr,
unsigned long *symbolsize,
unsigned long *offset);
/* Lookup an address. modname is set to NULL if it's in the kernel. */
const char *kallsyms_lookup(unsigned long addr,
unsigned long *symbolsize,
@ -28,6 +32,13 @@ static inline unsigned long kallsyms_lookup_name(const char *name)
return 0;
}
static inline int kallsyms_lookup_size_offset(unsigned long addr,
unsigned long *symbolsize,
unsigned long *offset)
{
return 0;
}
static inline const char *kallsyms_lookup(unsigned long addr,
unsigned long *symbolsize,
unsigned long *offset,

123
kernel/kallsyms.c
View file

@ -69,6 +69,15 @@ static inline int is_kernel(unsigned long addr)
return in_gate_area_no_task(addr);
}
static int is_ksym_addr(unsigned long addr)
{
if (all_var)
return is_kernel(addr);
return is_kernel_text(addr) || is_kernel_inittext(addr) ||
is_kernel_extratext(addr);
}
/* expand a compressed symbol data into the resulting uncompressed string,
given the offset to where the symbol is in the compressed stream */
static unsigned int kallsyms_expand_symbol(unsigned int off, char *result)
@ -155,6 +164,73 @@ unsigned long kallsyms_lookup_name(const char *name)
return module_kallsyms_lookup_name(name);
}
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. */
BUG_ON(!kallsyms_addresses);
/* do a binary search on the sorted kallsyms_addresses array */
low = 0;
high = kallsyms_num_syms;
while (high - low > 1) {
mid = (low + high) / 2;
if (kallsyms_addresses[mid] <= addr)
low = mid;
else
high = mid;
}
/*
* search for the first aliased symbol. Aliased
* symbols are symbols with the same address
*/
while (low && kallsyms_addresses[low-1] == kallsyms_addresses[low])
--low;
symbol_start = kallsyms_addresses[low];
/* Search for next non-aliased symbol */
for (i = low + 1; i < kallsyms_num_syms; i++) {
if (kallsyms_addresses[i] > symbol_start) {
symbol_end = kallsyms_addresses[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 (all_var)
symbol_end = (unsigned long)_end;
else
symbol_end = (unsigned long)_etext;
}
*symbolsize = symbol_end - symbol_start;
*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)
{
if (is_ksym_addr(addr))
return !!get_symbol_pos(addr, symbolsize, offset);
return !!module_address_lookup(addr, symbolsize, offset, NULL);
}
/*
* Lookup an address
* - modname is set to NULL if it's in the kernel
@ -167,57 +243,18 @@ const char *kallsyms_lookup(unsigned long addr,
unsigned long *offset,
char **modname, char *namebuf)
{
unsigned long i, low, high, mid;
const char *msym;
/* This kernel should never had been booted. */
BUG_ON(!kallsyms_addresses);
namebuf[KSYM_NAME_LEN] = 0;
namebuf[0] = 0;
if ((all_var && is_kernel(addr)) ||
(!all_var && (is_kernel_text(addr) || is_kernel_inittext(addr) ||
is_kernel_extratext(addr)))) {
unsigned long symbol_end = 0;
/* do a binary search on the sorted kallsyms_addresses array */
low = 0;
high = kallsyms_num_syms;
while (high-low > 1) {
mid = (low + high) / 2;
if (kallsyms_addresses[mid] <= addr) low = mid;
else high = mid;
}
/* search for the first aliased symbol. Aliased symbols are
symbols with the same address */
while (low && kallsyms_addresses[low - 1] == kallsyms_addresses[low])
--low;
if (is_ksym_addr(addr)) {
unsigned long pos;
pos = get_symbol_pos(addr, symbolsize, offset);
/* Grab name */
kallsyms_expand_symbol(get_symbol_offset(low), namebuf);
/* Search for next non-aliased symbol */
for (i = low + 1; i < kallsyms_num_syms; i++) {
if (kallsyms_addresses[i] > kallsyms_addresses[low]) {
symbol_end = kallsyms_addresses[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
symbol_end = all_var ? (unsigned long)_end : (unsigned long)_etext;
}
*symbolsize = symbol_end - kallsyms_addresses[low];
kallsyms_expand_symbol(get_symbol_offset(pos), namebuf);
*modname = NULL;
*offset = addr - kallsyms_addresses[low];
return namebuf;
}

3
kernel/module.c
View file

@ -2040,7 +2040,8 @@ const char *module_address_lookup(unsigned long addr,
list_for_each_entry(mod, &modules, list) {
if (within(addr, mod->module_init, mod->init_size)
|| within(addr, mod->module_core, mod->core_size)) {
*modname = mod->name;
if (modname)
*modname = mod->name;
return get_ksymbol(mod, addr, size, offset);
}
}