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Re: [4/5 PATCH] Kprobes fix for broken fault handling for ia64
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;
+ if (kcb->kprobe_status == KPROBE_REENTER)
+ restore_previous_kprobe(kcb);
+ else
+ reset_current_kprobe();
preempt_enable_no_resched();
+ break;
+ case KPROBE_HIT_ACTIVE:
+ case KPROBE_HIT_SSDONE:
+ /*
+ * We increment the nmissed count for accounting,
+ * we can also use npre/npostfault count for accouting
+ * these specific fault cases.
+ */
+ kprobes_inc_nmissed_count(cur);
+
+ /*
+ * We come here because instructions in the pre/post
+ * handler caused the page_fault, this could happen
+ * if handler tries to access user space by
+ * copy_from_user(), get_user() etc. Let the
+ * user-specified handler try to fix it first.
+ */
+ if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
+ return 1;
+
+ /*
+ * In case the user-specified fault handler returned
+ * zero, try to fix up.
+ */
+ if (ia64_done_with_exception(regs))
+ return 1;
+ /*
+ * ia64_done_with_exception() could not handle it,
+ * Let ia64_do_page_fault() fix it.
+ */
+ break;
+ default:
+ break;
}
return 0;
_
--
Prasanna S Panchamukhi
Linux Technology Center
India Software Labs, IBM Bangalore
Email: prasanna@in.ibm.com
Ph: 91-80-51776329