diff options
| -rw-r--r-- | arch/x86/Kconfig.debug | 14 | ||||
| -rw-r--r-- | arch/x86/kernel/mmiotrace/kmmio.c | 14 | ||||
| -rw-r--r-- | arch/x86/mm/fault.c | 66 | ||||
| -rw-r--r-- | include/asm-x86/kdebug.h | 12 |
4 files changed, 52 insertions, 54 deletions
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug index 7c6496e2225..9491c0ae03a 100644 --- a/arch/x86/Kconfig.debug +++ b/arch/x86/Kconfig.debug @@ -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 diff --git a/arch/x86/kernel/mmiotrace/kmmio.c b/arch/x86/kernel/mmiotrace/kmmio.c index 28411dadb8b..e759f7c3878 100644 --- a/arch/x86/kernel/mmiotrace/kmmio.c +++ b/arch/x86/kernel/mmiotrace/kmmio.c @@ -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: diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 343f5c1aacc..e9a086a1a9f 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -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; /* diff --git a/include/asm-x86/kdebug.h b/include/asm-x86/kdebug.h index a80f2d6cc73..7063281040d 100644 --- a/include/asm-x86/kdebug.h +++ b/include/asm-x86/kdebug.h @@ -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 |