kprobes/x86: Clear TF bit in fault on single-stepping

[pandora-kernel.git] / arch / x86 / kernel / kprobes.c

diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
index 7da647d..29aed8d 100644 (file)
--- a/arch/x86/kernel/kprobes.c
+++ b/arch/x86/kernel/kprobes.c
@@ -949,7 +949,19 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
                 * normal page fault.
                 */
                regs->ip = (unsigned long)cur->addr;
+               /*
+                * Trap flag (TF) has been set here because this fault
+                * happened where the single stepping will be done.
+                * So clear it by resetting the current kprobe:
+                */
+               regs->flags &= ~X86_EFLAGS_TF;
+
+               /*
+                * If the TF flag was set before the kprobe hit,
+                * don't touch it:
+                */
                regs->flags |= kcb->kprobe_old_flags;
+
                if (kcb->kprobe_status == KPROBE_REENTER)
                        restore_previous_kprobe(kcb);
                else
@@ -1058,6 +1070,15 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
        regs->flags &= ~X86_EFLAGS_IF;
        trace_hardirqs_off();
        regs->ip = (unsigned long)(jp->entry);
+
+       /*
+        * jprobes use jprobe_return() which skips the normal return
+        * path of the function, and this messes up the accounting of the
+        * function graph tracer to get messed up.
+        *
+        * Pause function graph tracing while performing the jprobe function.
+        */
+       pause_graph_tracing();
        return 1;
 }
 
@@ -1083,24 +1104,25 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
        u8 *addr = (u8 *) (regs->ip - 1);
        struct jprobe *jp = container_of(p, struct jprobe, kp);
+       void *saved_sp = kcb->jprobe_saved_sp;
 
        if ((addr > (u8 *) jprobe_return) &&
            (addr < (u8 *) jprobe_return_end)) {
-               if (stack_addr(regs) != kcb->jprobe_saved_sp) {
+               if (stack_addr(regs) != saved_sp) {
                        struct pt_regs *saved_regs = &kcb->jprobe_saved_regs;
                        printk(KERN_ERR
                               "current sp %p does not match saved sp %p\n",
-                              stack_addr(regs), kcb->jprobe_saved_sp);
+                              stack_addr(regs), saved_sp);
                        printk(KERN_ERR "Saved registers for jprobe %p\n", jp);
                        show_registers(saved_regs);
                        printk(KERN_ERR "Current registers\n");
                        show_registers(regs);
                        BUG();
                }
+               /* It's OK to start function graph tracing again */
+               unpause_graph_tracing();
                *regs = kcb->jprobe_saved_regs;
-               memcpy((kprobe_opcode_t *)(kcb->jprobe_saved_sp),
-                      kcb->jprobes_stack,
-                      MIN_STACK_SIZE(kcb->jprobe_saved_sp));
+               memcpy(saved_sp, kcb->jprobes_stack, MIN_STACK_SIZE(saved_sp));
                preempt_enable_no_resched();
                return 1;
        }