linux-kernel - [PATCH 12/X] uprobes: x86: introduce abort

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Message-ID: <20111019215326.GF16395@redhat.com>
Date:	Wed, 19 Oct 2011 23:53:26 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc:	Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...e.hu>,
	Steven Rostedt <rostedt@...dmis.org>,
	Linux-mm <linux-mm@...ck.org>,
	Arnaldo Carvalho de Melo <acme@...radead.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Jonathan Corbet <corbet@....net>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Hugh Dickins <hughd@...gle.com>,
	Christoph Hellwig <hch@...radead.org>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andi Kleen <andi@...stfloor.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jim Keniston <jkenisto@...ux.vnet.ibm.com>,
	Roland McGrath <roland@...k.frob.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 12/X] uprobes: x86: introduce abort_xol()

A separate "patch", just to emphasize that I do not know what
actually abort_xol() should do! I do not understand this asm
magic.

This patch simply changes regs->ip back to the probed insn,
obviously this is not enough to handle UPROBES_FIX_*. Please
take care.

If it is not clear, abort_xol() is needed when we should
re-execute the original insn (replaced with int3), see the
next patch.
---
 arch/x86/include/asm/uprobes.h |    1 +
 arch/x86/kernel/uprobes.c      |    9 +++++++++
 2 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h
index f0fbdab..6209da1 100644
--- a/arch/x86/include/asm/uprobes.h
+++ b/arch/x86/include/asm/uprobes.h
@@ -51,6 +51,7 @@ extern void set_instruction_pointer(struct pt_regs *regs, unsigned long vaddr);
 extern int pre_xol(struct uprobe *uprobe, struct pt_regs *regs);
 extern int post_xol(struct uprobe *uprobe, struct pt_regs *regs);
 extern bool xol_was_trapped(struct task_struct *tsk);
+extern void abort_xol(struct pt_regs *regs);
 extern int uprobe_exception_notify(struct notifier_block *self,
 				       unsigned long val, void *data);
 #endif	/* _ASM_UPROBES_H */
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index c861c27..bc11a89 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -511,6 +511,15 @@ bool xol_was_trapped(struct task_struct *tsk)
 	return false;
 }
 
+void abort_xol(struct pt_regs *regs)
+{
+	// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+	// !!! Dear Srikar and Ananth, please implement me !!!
+	// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+	struct uprobe_task *utask = current->utask;
+	regs->ip = utask->vaddr;
+}
+
 /*
  * Called after single-stepping. To avoid the SMP problems that can
  * occur when we temporarily put back the original opcode to
-- 
1.5.5.1


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