linux-kernel - [PATCH 2/3] uprobes/powerpc: teach uprobes to ignore gdb breakpoints

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Date:	Fri, 22 Mar 2013 17:15:43 +0530
From:	Ananth N Mavinakayanahalli <ananth@...ibm.com>
To:	lkml <linux-kernel@...r.kernel.org>
Cc:	oleg@...hat.com, Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	benh@...nel.crashing.org, ppcdev <linuxppc-dev@...ts.ozlabs.org>
Subject: [PATCH 2/3] uprobes/powerpc: teach uprobes to ignore gdb
	breakpoints

From: Ananth N Mavinakayanahalli <ananth@...ibm.com>

Powerpc has many trap variants that could be used by entities like gdb.
Currently, running gdb on a program being traced by uprobes causes an
endless loop since uprobes doesn't understand that the trap was inserted
by some other entity and a SIGTRAP needs to be delivered.

Teach uprobes to ignore breakpoints that do not belong to it.

Signed-off-by: Ananth N Mavinakayanahalli <ananth@...ibm.com>
---
 arch/powerpc/kernel/uprobes.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

Index: linux-3.9-rc3/arch/powerpc/kernel/uprobes.c
===================================================================
--- linux-3.9-rc3.orig/arch/powerpc/kernel/uprobes.c
+++ linux-3.9-rc3/arch/powerpc/kernel/uprobes.c
@@ -31,6 +31,16 @@
 #define UPROBE_TRAP_NR	UINT_MAX
 
 /**
+ * is_trap_insn - check if the instruction is a trap variant
+ * @insn: instruction to be checked.
+ * Returns true if @insn is a trap variant.
+ */
+bool is_trap_insn(uprobe_opcode_t *insn)
+{
+	return (is_trap(*insn));
+}
+
+/**
  * arch_uprobe_analyze_insn
  * @mm: the probed address space.
  * @arch_uprobe: the probepoint information.

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