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x86: explicit call to mmiotrace in do_page_fault()

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The custom page fault handler list is replaced with a single function
pointer. All related functions and variables are renamed for
mmiotrace.

Signed-off-by: Pekka Paalanen <pq@iki.fi>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: pq@iki.fi
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Pekka Paalanen 2008-05-12 21:20:57 +02:00 committed by Thomas Gleixner
parent 63ffa3e456
commit 10c43d2eb5
4 changed files with 52 additions and 54 deletions
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14
arch/x86/Kconfig.debug
View File

@ -168,20 +168,18 @@ config IOMMU_LEAK
Add a simple leak tracer to the IOMMU code. This is useful when you
are debugging a buggy device driver that leaks IOMMU mappings.
config PAGE_FAULT_HANDLERS
bool "Custom page fault handlers"
depends on DEBUG_KERNEL
help
Allow the use of custom page fault handlers. A kernel module may
register a function that is called on every page fault. Custom
handlers are used by some debugging and reverse engineering tools.
config MMIOTRACE_HOOKS
bool
default n
config MMIOTRACE
tristate "Memory mapped IO tracing"
depends on DEBUG_KERNEL && PAGE_FAULT_HANDLERS && RELAY && DEBUG_FS
depends on DEBUG_KERNEL && RELAY && DEBUG_FS
select MMIOTRACE_HOOKS
default n
help
This will build a kernel module called mmiotrace.
Making this a built-in is heavily discouraged.
Mmiotrace traces Memory Mapped I/O access and is meant for debugging
and reverse engineering. The kernel module offers wrapped

14
arch/x86/kernel/mmiotrace/kmmio.c
View File

@ -51,10 +51,6 @@ static LIST_HEAD(kmmio_probes);
static struct kmmio_context kmmio_ctx[NR_CPUS];
static struct pf_handler kmmio_pf_hook = {
.handler = kmmio_page_fault
};
static struct notifier_block nb_die = {
.notifier_call = kmmio_die_notifier
};
@ -77,7 +73,8 @@ void cleanup_kmmio(void)
* kmmio_page_table, kmmio_probes
*/
if (handler_registered) {
unregister_page_fault_handler(&kmmio_pf_hook);
if (mmiotrace_unregister_pf(&kmmio_page_fault))
BUG();
synchronize_rcu();
}
unregister_die_notifier(&nb_die);
@ -343,8 +340,11 @@ int register_kmmio_probe(struct kmmio_probe *p)
}
if (!handler_registered) {
register_page_fault_handler(&kmmio_pf_hook);
handler_registered++;
if (mmiotrace_register_pf(&kmmio_page_fault))
printk(KERN_ERR "mmiotrace: Cannot register page "
"fault handler.\n");
else
handler_registered++;
}
out:

66
arch/x86/mm/fault.c
View File

@ -49,53 +49,55 @@
#define PF_RSVD (1<<3)
#define PF_INSTR (1<<4)
#ifdef CONFIG_PAGE_FAULT_HANDLERS
static HLIST_HEAD(pf_handlers); /* protected by RCU */
static DEFINE_SPINLOCK(pf_handlers_writer);
#ifdef CONFIG_MMIOTRACE_HOOKS
static pf_handler_func mmiotrace_pf_handler; /* protected by RCU */
static DEFINE_SPINLOCK(mmiotrace_handler_lock);
void register_page_fault_handler(struct pf_handler *new_pfh)
int mmiotrace_register_pf(pf_handler_func new_pfh)
{
int ret = 0;
unsigned long flags;
spin_lock_irqsave(&pf_handlers_writer, flags);
hlist_add_head_rcu(&new_pfh->hlist, &pf_handlers);
spin_unlock_irqrestore(&pf_handlers_writer, flags);
spin_lock_irqsave(&mmiotrace_handler_lock, flags);
if (mmiotrace_pf_handler)
ret = -EBUSY;
else
mmiotrace_pf_handler = new_pfh;
spin_unlock_irqrestore(&mmiotrace_handler_lock, flags);
return ret;
}
EXPORT_SYMBOL_GPL(register_page_fault_handler);
EXPORT_SYMBOL_GPL(mmiotrace_register_pf);
/**
* unregister_page_fault_handler:
* mmiotrace_unregister_pf:
* The caller must ensure @old_pfh is not in use anymore before freeing it.
* This function does not guarantee it. The list of handlers is protected by
* RCU, so you can do this by e.g. calling synchronize_rcu().
* This function does not guarantee it. The handler function pointer is
* protected by RCU, so you can do this by e.g. calling synchronize_rcu().
*/
void unregister_page_fault_handler(struct pf_handler *old_pfh)
int mmiotrace_unregister_pf(pf_handler_func old_pfh)
{
int ret = 0;
unsigned long flags;
spin_lock_irqsave(&pf_handlers_writer, flags);
hlist_del_rcu(&old_pfh->hlist);
spin_unlock_irqrestore(&pf_handlers_writer, flags);
spin_lock_irqsave(&mmiotrace_handler_lock, flags);
if (mmiotrace_pf_handler != old_pfh)
ret = -EPERM;
else
mmiotrace_pf_handler = NULL;
spin_unlock_irqrestore(&mmiotrace_handler_lock, flags);
return ret;
}
EXPORT_SYMBOL_GPL(unregister_page_fault_handler);
#endif
EXPORT_SYMBOL_GPL(mmiotrace_unregister_pf);
#endif /* CONFIG_MMIOTRACE_HOOKS */
/* returns non-zero if do_page_fault() should return */
static int handle_custom_pf(struct pt_regs *regs, unsigned long error_code,
unsigned long address)
static inline int call_mmiotrace(struct pt_regs *regs,
unsigned long error_code,
unsigned long address)
{
#ifdef CONFIG_PAGE_FAULT_HANDLERS
#ifdef CONFIG_MMIOTRACE_HOOKS
int ret = 0;
struct pf_handler *cur;
struct hlist_node *ncur;
if (hlist_empty(&pf_handlers))
return 0;
rcu_read_lock();
hlist_for_each_entry_rcu(cur, ncur, &pf_handlers, hlist) {
ret = cur->handler(regs, error_code, address);
if (ret)
break;
}
if (mmiotrace_pf_handler)
ret = mmiotrace_pf_handler(regs, error_code, address);
rcu_read_unlock();
return ret;
#else
@ -655,7 +657,7 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
if (notify_page_fault(regs))
return;
if (handle_custom_pf(regs, error_code, address))
if (call_mmiotrace(regs, error_code, address))
return;
/*

12
include/asm-x86/kdebug.h
View File

@ -35,13 +35,11 @@ extern void show_regs(struct pt_regs *regs);
extern unsigned long oops_begin(void);
extern void oops_end(unsigned long, struct pt_regs *, int signr);
struct pf_handler {
struct hlist_node hlist;
int (*handler)(struct pt_regs *regs, unsigned long error_code,
unsigned long address);
};
typedef int (*pf_handler_func)(struct pt_regs *regs,
unsigned long error_code,
unsigned long address);
extern void register_page_fault_handler(struct pf_handler *new_pfh);
extern void unregister_page_fault_handler(struct pf_handler *old_pfh);
extern int mmiotrace_register_pf(pf_handler_func new_pfh);
extern int mmiotrace_unregister_pf(pf_handler_func old_pfh);
#endif