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Commit 0b9e2cac authored May 05, 2005 by Prasanna S Panchamukhi Committed by Linus Torvalds May 05, 2005

[PATCH] Kprobes: Incorrect handling of probes on ret/lret instruction



Kprobes could not handle the insertion of a probe on the ret/lret
instruction and used to oops after single stepping since kprobes was
modifying eip/rip incorrectly.  Adjustment of eip/rip is not required after
single stepping in case of ret/lret instruction, because eip/rip points to
the correct location after execution of the ret/lret instruction.  This
patch fixes the above problem.

Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

parent 3a0a64e6

arch/i386/kernel/kprobes.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -217,6 +217,13 @@ static void resume_execution(struct kprobe p, struct pt_regs regs)
		*tos &= ~(TF_MASK \| IF_MASK);
		*tos \|= kprobe_old_eflags;
		break;
		case 0xc3: /* ret/lret */
		case 0xcb:
		case 0xc2:
		case 0xca:
		regs->eflags &= ~TF_MASK;
		/* eip is already adjusted, no more changes required*/
		return;
		case 0xe8: /* call relative - Fix return addr */
		tos = orig_eip + (tos - copy_eip);
		break;

arch/x86_64/kernel/kprobes.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -355,6 +355,13 @@ static void resume_execution(struct kprobe p, struct pt_regs regs)
		*tos &= ~(TF_MASK \| IF_MASK);
		*tos \|= kprobe_old_rflags;
		break;
		case 0xc3: /* ret/lret */
		case 0xcb:
		case 0xc2:
		case 0xca:
		regs->eflags &= ~TF_MASK;
		/* rip is already adjusted, no more changes required*/
		return;
		case 0xe8: /* call relative - Fix return addr */
		tos = orig_rip + (tos - copy_rip);
		break;