powerpc: Move the single step enable code to a generic path

This patch moves the single step enable code used by kprobe to a generic
routine header so that, it can be re-used by other code, in this case,
uprobes. No functional changes.

Signed-off-by: Suzuki K. Poulose <suzuki@in.ibm.com>
Cc:	Ananth N Mavinakaynahalli <ananth@in.ibm.com>
Cc:	Kumar Gala <galak@kernel.crashing.org>
Cc:	linuxppc-dev@ozlabs.org
Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 25 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/probes.h b/arch/powerpc/include/asm/probes.h
index 5f1e15b68704..3421637cfd7b 100644
--- a/arch/powerpc/include/asm/probes.h
+++ b/arch/powerpc/include/asm/probes.h
@@ -38,5 +38,30 @@ typedef u32 ppc_opcode_t;
 #define is_trap(instr)          (IS_TW(instr) || IS_TWI(instr))
 #endif /* CONFIG_PPC64 */
 
+#ifdef CONFIG_PPC_ADV_DEBUG_REGS
+#define MSR_SINGLESTEP  (MSR_DE)
+#else
+#define MSR_SINGLESTEP  (MSR_SE)
+#endif
+
+/* Enable single stepping for the current task */
+static inline void enable_single_step(struct pt_regs *regs)
+{
+        regs->msr |= MSR_SINGLESTEP;
+#ifdef CONFIG_PPC_ADV_DEBUG_REGS
+        /*
+         * We turn off Critical Input Exception(CE) to ensure that the single
+         * step will be for the instruction we have the probe on; if we don't,
+         * it is possible we'd get the single step reported for CE.
+         */
+        regs->msr &= ~MSR_CE;
+        mtspr(SPRN_DBCR0, mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM);
+#ifdef CONFIG_PPC_47x
+        isync();
+#endif
+#endif
+}
+
+
 #endif /* __KERNEL__ */
 #endif  /* _ASM_POWERPC_PROBES_H */