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debug: add notifier chain debugging, v2

Browse source 
- unbreak ia64 (and powerpc) where function pointers dont
  point at code but at data (reported by Tony Luck)

[ mingo@elte.hu: various cleanups ]

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Arjan van de Ven 2008-08-15 15:29:38 -07:00 committed by Ingo Molnar
parent fb822db465
commit ab7476cf76
4 changed files with 21 additions and 10 deletions
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3
include/linux/kernel.h
View file

@ -187,6 +187,9 @@ extern unsigned long long memparse(char *ptr, char **retptr);
extern int core_kernel_text(unsigned long addr); extern int core_kernel_text(unsigned long addr);
extern int __kernel_text_address(unsigned long addr); extern int __kernel_text_address(unsigned long addr);
extern int kernel_text_address(unsigned long addr); extern int kernel_text_address(unsigned long addr);
extern int func_ptr_is_kernel_text(void *ptr);
extern void *dereference_function_descriptor(void *ptr);
struct pid; struct pid;
extern struct pid *session_of_pgrp(struct pid *pgrp); extern struct pid *session_of_pgrp(struct pid *pgrp);

16
kernel/extable.c
View file

@ -66,3 +66,19 @@ int kernel_text_address(unsigned long addr)
return 1; return 1;
return module_text_address(addr) != NULL; return module_text_address(addr) != NULL;
} }
/*
* On some architectures (PPC64, IA64) function pointers
* are actually only tokens to some data that then holds the
* real function address. As a result, to find if a function
* pointer is part of the kernel text, we need to do some
* special dereferencing first.
*/
int func_ptr_is_kernel_text(void *ptr)
{
unsigned long addr;
addr = (unsigned long) dereference_function_descriptor(ptr);
if (core_kernel_text(addr))
return 1;
return module_text_address(addr) != NULL;
}

10
kernel/notifier.c
View file

@ -21,10 +21,6 @@ BLOCKING_NOTIFIER_HEAD(reboot_notifier_list);
static int notifier_chain_register(struct notifier_block **nl, static int notifier_chain_register(struct notifier_block **nl,
struct notifier_block *n) struct notifier_block *n)
{ {
if (!kernel_text_address((unsigned long)n->notifier_call)) {
WARN(1, "Invalid notifier registered!");
return 0;
}
while ((*nl) != NULL) { while ((*nl) != NULL) {
if (n->priority > (*nl)->priority) if (n->priority > (*nl)->priority)
break; break;
@ -38,10 +34,6 @@ static int notifier_chain_register(struct notifier_block **nl,
static int notifier_chain_cond_register(struct notifier_block **nl, static int notifier_chain_cond_register(struct notifier_block **nl,
struct notifier_block *n) struct notifier_block *n)
{ {
if (!kernel_text_address((unsigned long)n->notifier_call)) {
WARN(1, "Invalid notifier registered!");
return 0;
}
while ((*nl) != NULL) { while ((*nl) != NULL) {
if ((*nl) == n) if ((*nl) == n)
return 0; return 0;
@ -92,7 +84,7 @@ static int __kprobes notifier_call_chain(struct notifier_block **nl,
next_nb = rcu_dereference(nb->next); next_nb = rcu_dereference(nb->next);
#ifdef CONFIG_DEBUG_NOTIFIERS #ifdef CONFIG_DEBUG_NOTIFIERS
if (!kernel_text_address((unsigned long)nb->notifier_call)) { if (unlikely(!func_ptr_is_kernel_text(nb->notifier_call))) {
WARN(1, "Invalid notifier called!"); WARN(1, "Invalid notifier called!");
nb = next_nb; nb = next_nb;
continue; continue;

2
lib/vsprintf.c
View file

@ -513,7 +513,7 @@ static char *string(char *buf, char *end, char *s, int field_width, int precisio
return buf; return buf;
} }
static inline void *dereference_function_descriptor(void *ptr) void *dereference_function_descriptor(void *ptr)
{ {
#if defined(CONFIG_IA64) || defined(CONFIG_PPC64) #if defined(CONFIG_IA64) || defined(CONFIG_PPC64)
void *p; void *p;