From 35742523e3daa0e59de0c1c3fdd8e5ff52891967 Mon Sep 17 00:00:00 2001

From: Petr Machata <pmachata@redhat.com>

Date: Thu, 9 Jan 2014 23:41:50 +0100

Subject: [PATCH] Fix a problem in tracing across fork on PPC64

In order to avoid single-stepping through large portions of the

dynamic linker, ltrace remembers at which address the instruction that

resolved a PLT slot is.  It then puts a breakpoint to this address so

that it can fast-forward to that address next time it needs to catch a

PLT slot being resolved.

When a process is cloned, the pointer to this breakpoint is simply

copied over to the new process, instead of being looked up in the new

process structures.  This patches fixes this.

---

 sysdeps/linux-gnu/ppc/plt.c |   14 +++++++++++++-

 1 files changed, 13 insertions(+), 1 deletions(-)

diff --git a/sysdeps/linux-gnu/ppc/plt.c b/sysdeps/linux-gnu/ppc/plt.c

index 3ec1397..8715da6 100644

--- a/sysdeps/linux-gnu/ppc/plt.c

+++ b/sysdeps/linux-gnu/ppc/plt.c

@@ -1,6 +1,6 @@

 /*

  * This file is part of ltrace.

- * Copyright (C) 2012,2013 Petr Machata, Red Hat Inc.

+ * Copyright (C) 2012,2013,2014 Petr Machata, Red Hat Inc.

  * Copyright (C) 2004,2008,2009 Juan Cespedes

  * Copyright (C) 2006 Paul Gilliam

  *

@@ -1157,6 +1157,18 @@ int

 arch_process_clone(struct process *retp, struct process *proc)

 {

 	retp->arch = proc->arch;

+

+	if (retp->arch.dl_plt_update_bp != NULL) {

+		/* Point it to the corresponding breakpoint in RETP.

+		 * It must be there, this part of PROC has already

+		 * been cloned to RETP.  */

+		retp->arch.dl_plt_update_bp

+			= address2bpstruct(retp,

+					   retp->arch.dl_plt_update_bp->addr);

+

+		assert(retp->arch.dl_plt_update_bp != NULL);

+	}

+

 	return 0;

 }

-- 

1.7.6.5