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
...
> 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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