linux-kernel - [PATCH 2/2] uprobes/powerpc: Make use of generic routines to enable single step

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Date:	Mon, 26 Nov 2012 16:36:56 +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 2/2] uprobes/powerpc: Make use of generic routines to enable
 single step

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

Replace the ptrace helpers with the powerpc generic routines to
enable/disable single step. We save/restore the MSR (and DCBR for BookE)
across for the operation.


Signed-off-by: Suzuki K. Poulose <suzuki@...ibm.com>
---
 arch/powerpc/include/asm/uprobes.h |    4 ++++
 arch/powerpc/kernel/uprobes.c      |   11 +++++++++--
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/uprobes.h b/arch/powerpc/include/asm/uprobes.h
index b532060..884be93 100644
--- a/arch/powerpc/include/asm/uprobes.h
+++ b/arch/powerpc/include/asm/uprobes.h
@@ -43,6 +43,10 @@ struct arch_uprobe {
 
 struct arch_uprobe_task {
 	unsigned long	saved_trap_nr;
+	unsigned long	saved_msr;
+#ifdef CONFIG_PPC_ADV_DEBUG_REGS
+	unsigned long	saved_dbcr;
+#endif
 };
 
 extern int  arch_uprobe_analyze_insn(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long addr);
diff --git a/arch/powerpc/kernel/uprobes.c b/arch/powerpc/kernel/uprobes.c
index bc77834..c407c07 100644
--- a/arch/powerpc/kernel/uprobes.c
+++ b/arch/powerpc/kernel/uprobes.c
@@ -62,10 +62,14 @@ 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;
+	autask->saved_msr = regs->msr;
+#ifdef CONFIG_PPC_ADV_DEBUG_REGS
+	autask->saved_dbcr = mfspr(SPRN_DBCR0);
+#endif
 	current->thread.trap_nr = UPROBE_TRAP_NR;
 	regs->nip = current->utask->xol_vaddr;
 
-	user_enable_single_step(current);
+	enable_single_step(regs);
 	return 0;
 }
 
@@ -121,8 +125,11 @@ int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
 	 * to be executed.
 	 */
 	regs->nip = utask->vaddr + MAX_UINSN_BYTES;
+	regs->msr = utask->autask.saved_msr;
+#ifdef CONFIG_PPC_ADV_DEBUG_REGS
+	mtspr(SPRN_DBCR0, utask->autask.saved_dbcr);
+#endif
 
-	user_disable_single_step(current);
 	return 0;
 }
 

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