linux-kernel - [PATCH v2 3/4] uprobes/powerpc: Introduce routines for save/restore context

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Date:	Mon, 03 Dec 2012 20:39:35 +0530
From:	"Suzuki K. Poulose" <suzuki@...ibm.com>
To:	bigeasy@...utronix.de, oleg@...hat.com, ananth@...ibm.com,
	srikar@...ux.vnet.ibm.com
Cc:	peterz@...radead.org, benh@...nel.crashing.org, mingo@...e.hu,
	anton@...hat.com, linux-kernel@...r.kernel.org
Subject: [PATCH v2 3/4] uprobes/powerpc: Introduce routines for save/restore
 context

From: Suzuki K. Poulose <suzuki@...ibm.com>

Introduce routines for saving and restoring the context
befre/after the single step. No functional changes involved.

These will be extended later to save/restore more info about
the process once we replace the ptrace helpers.

Signed-off-by: Suzuki K. Poulose <suzuki@...ibm.com>
---
 arch/powerpc/kernel/uprobes.c |   16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kernel/uprobes.c b/arch/powerpc/kernel/uprobes.c
index bc77834..1a62353 100644
--- a/arch/powerpc/kernel/uprobes.c
+++ b/arch/powerpc/kernel/uprobes.c
@@ -52,6 +52,16 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe,
 	return 0;
 }
 
+static void uprobe_save_context_sstep(struct arch_uprobe_task *autask)
+{
+	autask->saved_trap_nr = current->thread.trap_nr;
+}
+
+static void uprobe_restore_context_sstep(struct arch_uprobe_task *autask)
+{
+	current->thread.trap_nr = autask->saved_trap_nr;
+}
+
 /*
  * arch_uprobe_pre_xol - prepare to execute out of line.
  * @auprobe: the probepoint information.
@@ -61,7 +71,7 @@ int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
 {
 	struct arch_uprobe_task *autask = &current->utask->autask;
 
-	autask->saved_trap_nr = current->thread.trap_nr;
+	uprobe_save_context_sstep(autask);
 	current->thread.trap_nr = UPROBE_TRAP_NR;
 	regs->nip = current->utask->xol_vaddr;
 
@@ -111,7 +121,7 @@ int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
 
 	WARN_ON_ONCE(current->thread.trap_nr != UPROBE_TRAP_NR);
 
-	current->thread.trap_nr = utask->autask.saved_trap_nr;
+	uprobe_restore_context_sstep(&utask->autask);
 
 	/*
 	 * On powerpc, except for loads and stores, most instructions
@@ -164,7 +174,7 @@ void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
 {
 	struct uprobe_task *utask = current->utask;
 
-	current->thread.trap_nr = utask->autask.saved_trap_nr;
+	uprobe_restore_context_sstep(&utask->autask);
 	instruction_pointer_set(regs, utask->vaddr);
 
 	user_disable_single_step(current);

--
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