Messages in this thread Patch in this message | | | Date | Thu, 3 Jan 2008 12:35:26 +0530 | From | Ananth N Mavinakayanahalli <> | Subject | Re: [PATCH] kprobes: Introduce is_kprobe_fault() |
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On Wed, Jan 02, 2008 at 08:05:14PM -0800, Harvey Harrison wrote:
Thanks for the cleanup...
...
> diff --git a/arch/x86/mm/fault_32.c b/arch/x86/mm/fault_32.c > index a2273d4..f2e909b 100644 > --- a/arch/x86/mm/fault_32.c > +++ b/arch/x86/mm/fault_32.c > @@ -33,28 +33,6 @@ > > extern void die(const char *,struct pt_regs *,long); > > -#ifdef CONFIG_KPROBES > -static inline int notify_page_fault(struct pt_regs *regs) > -{ > - int ret = 0; > - > - /* kprobe_running() needs smp_processor_id() */ > - if (!user_mode_vm(regs)) { ^^^^^^^^^^^ For x86_32, this check is important. See commit 6444541671bd821b950dbaafee70d65188198aa6 (Never allow int3 traps from V8086 mode to enter the kprobes handler) for precise reason why its user_mode_vm() and not user_mode() for x86_32.
You'll need to make room for this check in the generic macro below...
> - preempt_disable(); > - if (kprobe_running() && kprobe_fault_handler(regs, 14)) > - ret = 1; > - preempt_enable(); > - } > - > - return ret; > -} > -#else > -static inline int notify_page_fault(struct pt_regs *regs) > -{ > - return 0; > -} > -#endif > - > /* > * Return EIP plus the CS segment base. The segment limit is also > * adjusted, clamped to the kernel/user address space (whichever is > @@ -331,7 +309,7 @@ fastcall void __kprobes do_page_fault(struct pt_regs *regs, > if (unlikely(address >= TASK_SIZE)) { > if (!(error_code & 0x0000000d) && vmalloc_fault(address) >= 0) > return; > - if (notify_page_fault(regs)) > + if (is_kprobe_fault(regs, 14)) > return; > /* > * Don't take the mm semaphore here. If we fixup a prefetch > @@ -340,7 +318,7 @@ fastcall void __kprobes do_page_fault(struct pt_regs *regs, > goto bad_area_nosemaphore; > } > > - if (notify_page_fault(regs)) > + if (is_kprobe_fault(regs, 14)) > return; > > /* It's safe to allow irq's after cr2 has been saved and the vmalloc
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> diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h > index 8189158..65c1ffb 100644 > --- a/include/linux/kprobes.h > +++ b/include/linux/kprobes.h > @@ -36,6 +36,7 @@ > #include <linux/spinlock.h> > #include <linux/rcupdate.h> > #include <linux/mutex.h> > +#include <linux/hardirq.h> > > #ifdef CONFIG_KPROBES > #include <asm/kprobes.h> > @@ -203,6 +204,20 @@ static inline struct kprobe *kprobe_running(void) > return (__get_cpu_var(current_kprobe)); > } > > +/* > + * If it is a kprobe pagefault we can not be premptible so return before > + * calling kprobe_running() as it will assert on smp_processor_id if > + * preemption is enabled. > + */ > +static inline int is_kprobe_fault(struct pt_regs *regs, int trapnr) > +{ > + if (!user_mode(regs) && !preemptible() && kprobe_running() && > + kprobe_fault_handler(regs, trapnr)) > + return 1; > + else > + return 0; > +} > + > static inline void reset_current_kprobe(void) > { > __get_cpu_var(current_kprobe) = NULL; > @@ -237,6 +252,10 @@ static inline struct kprobe *kprobe_running(void) > { > return NULL; > } > +static inline int is_kprobe_fault(struct pt_regs *regs, int trapnr) > +{ > + return 0; > +} > static inline int register_kprobe(struct kprobe *p) > { > return -ENOSYS;
Ananth
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