Commit d9f5f32a authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Ingo Molnar

kprobes/x86: Do not jump-optimize kprobes on irq entry code

Since the kernel segment registers are not prepared at the
entry of irq-entry code, if a kprobe on such code is
jump-optimized, accessing per-CPU variables may cause a
kernel panic.

However, if the kprobe is not optimized, it triggers an int3
exception and sets segment registers correctly.

With this patch we check the probe-address and if it is in the
irq-entry code, it prohibits optimizing such kprobes.

This means we can continue probing such interrupt handlers by kprobes
but it is not optimized anymore.
Reported-by: default avatarFrancis Deslauriers <francis.deslauriers@efficios.com>
Tested-by: default avatarFrancis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David S . Miller <davem@davemloft.net>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: linux-arch@vger.kernel.org
Cc: linux-cris-kernel@axis.com
Cc: mathieu.desnoyers@efficios.com
Link: http://lkml.kernel.org/r/150172795654.27216.9824039077047777477.stgit@devboxSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 229a7186
......@@ -39,6 +39,7 @@
#include <asm/insn.h>
#include <asm/debugreg.h>
#include <asm/set_memory.h>
#include <asm/sections.h>
#include "common.h"
......@@ -251,10 +252,12 @@ static int can_optimize(unsigned long paddr)
/*
* Do not optimize in the entry code due to the unstable
* stack handling.
* stack handling and registers setup.
*/
if ((paddr >= (unsigned long)__entry_text_start) &&
(paddr < (unsigned long)__entry_text_end))
if (((paddr >= (unsigned long)__entry_text_start) &&
(paddr < (unsigned long)__entry_text_end)) ||
((paddr >= (unsigned long)__irqentry_text_start) &&
(paddr < (unsigned long)__irqentry_text_end)))
return 0;
/* Check there is enough space for a relative jump. */
......
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