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