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From 35742523e3daa0e59de0c1c3fdd8e5ff52891967 Mon Sep 17 00:00:00 2001
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From: Petr Machata <pmachata@redhat.com>
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Date: Thu, 9 Jan 2014 23:41:50 +0100
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Subject: [PATCH] Fix a problem in tracing across fork on PPC64
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In order to avoid single-stepping through large portions of the
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dynamic linker, ltrace remembers at which address the instruction that
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resolved a PLT slot is. It then puts a breakpoint to this address so
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that it can fast-forward to that address next time it needs to catch a
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PLT slot being resolved.
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When a process is cloned, the pointer to this breakpoint is simply
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copied over to the new process, instead of being looked up in the new
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process structures. This patches fixes this.
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---
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sysdeps/linux-gnu/ppc/plt.c | 14 +++++++++++++-
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1 files changed, 13 insertions(+), 1 deletions(-)
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diff --git a/sysdeps/linux-gnu/ppc/plt.c b/sysdeps/linux-gnu/ppc/plt.c
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index 3ec1397..8715da6 100644
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--- a/sysdeps/linux-gnu/ppc/plt.c
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+++ b/sysdeps/linux-gnu/ppc/plt.c
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@@ -1,6 +1,6 @@
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/*
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* This file is part of ltrace.
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- * Copyright (C) 2012,2013 Petr Machata, Red Hat Inc.
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+ * Copyright (C) 2012,2013,2014 Petr Machata, Red Hat Inc.
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* Copyright (C) 2004,2008,2009 Juan Cespedes
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* Copyright (C) 2006 Paul Gilliam
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*
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@@ -1157,6 +1157,18 @@ int
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arch_process_clone(struct process *retp, struct process *proc)
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{
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retp->arch = proc->arch;
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+
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+ if (retp->arch.dl_plt_update_bp != NULL) {
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+ /* Point it to the corresponding breakpoint in RETP.
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+ * It must be there, this part of PROC has already
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+ * been cloned to RETP. */
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+ retp->arch.dl_plt_update_bp
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+ = address2bpstruct(retp,
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+ retp->arch.dl_plt_update_bp->addr);
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+
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+ assert(retp->arch.dl_plt_update_bp != NULL);
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+ }
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+
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return 0;
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}
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--
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1.7.6.5
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