Prasanna S Panchamukhi wrote:
> This patch fixes the broken kprobes fault handling similar
> to i386 architecture.
> 
> Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
> Acked-by: Anil S Keshavamurthy<anil.s.keshavamurthy@intel.com>
> 
> 
>  arch/ia64/kernel/kprobes.c |   55 ++++++++++++++++++++++++++++++++++++++++-----
>  1 files changed, 50 insertions(+), 5 deletions(-)
> 
> diff -puN arch/ia64/kernel/kprobes.c~kprobes-ia64-pagefault-handling arch/ia64/kernel/kprobes.c
> --- linux-2.6.16-rc5-mm2/arch/ia64/kernel/kprobes.c~kprobes-ia64-pagefault-handling	2006-03-07 11:18:46.000000000 +0530
> +++ linux-2.6.16-rc5-mm2-prasanna/arch/ia64/kernel/kprobes.c	2006-03-07 11:21:12.000000000 +0530
> @@ -34,6 +34,7 @@
>  #include <asm/pgtable.h>
>  #include <asm/kdebug.h>
>  #include <asm/sections.h>
> +#include <asm/uaccess.h>
>  
>  extern void jprobe_inst_return(void);
>  
> @@ -722,13 +723,57 @@ static int __kprobes kprobes_fault_handl
>  	struct kprobe *cur = kprobe_running();
>  	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
>  
> -	if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
> -		return 1;
>  
> -	if (kcb->kprobe_status & KPROBE_HIT_SS) {
> -		resume_execution(cur, regs);
> -		reset_current_kprobe();
> +	switch(kcb->kprobe_status) {
> +	case KPROBE_HIT_SS:
> +	case KPROBE_REENTER:
> +		/*
> +		 * We are here because the instruction being single
> +		 * stepped caused a page fault. We reset the current
> +		 * kprobe and the instruction pointer points back to
> +		 * the probe address and allow the page fault handler
> +		 * to continue as a normal page fault.
> +		 */
> +		regs->cr_iip = ((unsigned long)cur->addr) & ~0xFULL;
> +		ia64_psr(regs) = ((unsigned long)cur->addr) & 0xf;
It should be:
		regs->cr_iip = ((unsigned long)cur->addr) & ~0xFULL;
                 ia64_psr(regs)->ri  = ((unsigned long)cur->addr) & 0xf;
And I test this patch in IA64 platform, it passed. But find that 
sometime user space copy is incomplete. If page fault happens in kprobe 
prehandler/posthandler, if will first call fix_exception() and return, 
Normally in page fault process procedure system will load page into 
memory, and the system will call fix_exceptioin if failed to load page 
into memory.

The attachment is my test case in IA64, it is easy to port to other 
platform.

Bibo,mao