patch_instruction() can fail in some scenarios. Add appropriate error
checking so that such failures are caught and logged, and suitable error
code is returned.

Fixes: d07df82c43be8 ("powerpc/kprobes: Move kprobes over to patch_instruction()")
Fixes: f3eca95638931 ("powerpc/kprobes/optprobes: Use patch_instruction()")
Signed-off-by: Naveen N. Rao <redacted>
---
  arch/powerpc/kernel/kprobes.c   | 10 +++-
  arch/powerpc/kernel/optprobes.c | 99 ++++++++++++++++++++++++++-------
  2 files changed, 87 insertions(+), 22 deletions(-)

diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index 81efb605113e..4a297ae2bd87 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c

@@ -138,13 +138,19 @@ NOKPROBE_SYMBOL(arch_prepare_kprobe);
  
  void arch_arm_kprobe(struct kprobe *p)
  {
-	patch_instruction(p->addr, BREAKPOINT_INSTRUCTION);
+	int rc = patch_instruction(p->addr, BREAKPOINT_INSTRUCTION);
+
+	if (rc)
+		WARN("Failed to patch trap at 0x%pK: %d\n", (void *)p->addr, rc);
  }
  NOKPROBE_SYMBOL(arch_arm_kprobe);
  
  void arch_disarm_kprobe(struct kprobe *p)
  {
-	patch_instruction(p->addr, p->opcode);
+	int rc = patch_instruction(p->addr, p->opcode);
+
+	if (rc)
+		WARN("Failed to remove trap at 0x%pK: %d\n", (void *)p->addr, rc);
  }
  NOKPROBE_SYMBOL(arch_disarm_kprobe);
  

diff --git a/arch/powerpc/kernel/optprobes.c b/arch/powerpc/kernel/optprobes.c
index 024f7aad1952..046485bb0a52 100644
--- a/arch/powerpc/kernel/optprobes.c
+++ b/arch/powerpc/kernel/optprobes.c

@@ -139,52 +139,67 @@ void arch_remove_optimized_kprobe(struct optimized_kprobe *op)
  	}
  }
  
+#define PATCH_INSN(addr, instr)						     \
+do {									     \
+	int rc = patch_instruction((unsigned int *)(addr), instr);	     \
+	if (rc) {							     \
+		pr_err("%s:%d Error patching instruction at 0x%pK (%pS): %d\n", \
+				__func__, __LINE__,			     \
+				(void *)(addr), (void *)(addr), rc);	     \
+		return rc;						     \
+	}								     \
+} while (0)
+