[PATCH 2/5] powerpc/kprobes: Roll IS_RFI() macro into IS_RFID()

From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
To: Michael Ellerman <mpe@ellerman.id.au>,
	Christophe Leroy <christophe.leroy@csgroup.eu>,
	Jordan Niethe <jniethe5@gmail.com>
Cc: linuxppc-dev@lists.ozlabs.org
Subject: [PATCH 2/5] powerpc/kprobes: Roll IS_RFI() macro into IS_RFID()
Date: Wed, 19 May 2021 16:17:18 +0530	[thread overview]
Message-ID: <eee32e1b75dae85d471c89b4c0a123ad4b0aabf8.1621416666.git.naveen.n.rao@linux.vnet.ibm.com> (raw)
In-Reply-To: <cover.1621416666.git.naveen.n.rao@linux.vnet.ibm.com>

In kprobes and xmon, we should exclude both 32-bit and 64-bit variants
of mtmsr and rfi instructions from being stepped. Have IS_RFID() also
detect a rfi instruction similar to IS_MTMSRD().

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/sstep.h | 7 +++----
 arch/powerpc/kernel/kprobes.c    | 4 ++--
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/include/asm/sstep.h b/arch/powerpc/include/asm/sstep.h
index 972ed0df154d60..1df867c2e054e5 100644
--- a/arch/powerpc/include/asm/sstep.h
+++ b/arch/powerpc/include/asm/sstep.h
@@ -13,12 +13,11 @@ struct pt_regs;
  * we don't allow putting a breakpoint on an mtmsrd instruction.
  * Similarly we don't allow breakpoints on rfid instructions.
  * These macros tell us if an instruction is a mtmsrd or rfid.
- * Note that IS_MTMSRD returns true for both an mtmsr (32-bit)
- * and an mtmsrd (64-bit).
+ * Note that these return true for both mtmsr/rfi (32-bit)
+ * and mtmsrd/rfid (64-bit).
  */
 #define IS_MTMSRD(instr)	((ppc_inst_val(instr) & 0xfc0007be) == 0x7c000124)
-#define IS_RFID(instr)		((ppc_inst_val(instr) & 0xfc0007fe) == 0x4c000024)
-#define IS_RFI(instr)		((ppc_inst_val(instr) & 0xfc0007fe) == 0x4c000064)
+#define IS_RFID(instr)		((ppc_inst_val(instr) & 0xfc0007be) == 0x4c000024)
 
 enum instruction_type {
 	COMPUTE,		/* arith/logical/CR op, etc. */
diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index f611d9eb3562d7..b7b20875d34d91 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -112,8 +112,8 @@ int arch_prepare_kprobe(struct kprobe *p)
 	if ((unsigned long)p->addr & 0x03) {
 		printk("Attempt to register kprobe at an unaligned address\n");
 		ret = -EINVAL;
-	} else if (IS_MTMSRD(insn) || IS_RFID(insn) || IS_RFI(insn)) {
-		printk("Cannot register a kprobe on rfi/rfid or mtmsr[d]\n");
+	} else if (IS_MTMSRD(insn) || IS_RFID(insn)) {
+		printk("Cannot register a kprobe on mtmsr[d]/rfi[d]\n");
 		ret = -EINVAL;
 	} else if ((unsigned long)p->addr & ~PAGE_MASK &&
 			ppc_inst_prefixed(ppc_inst_read((struct ppc_inst *)(p->addr - 1)))) {
-- 
2.30.2

