diff mbox series

[v2,4/4] arm64: kprobe: disable probe of fault prone ptrauth instruction

Message ID 1586842314-19527-5-git-send-email-amit.kachhap@arm.com (mailing list archive)
State New, archived
Headers show
Series arm64: add Armv8.6 pointer authentication | expand

Commit Message

Amit Daniel Kachhap April 14, 2020, 5:31 a.m. UTC 
This patch disables the probing of authenticate ptrauth instruction
(AUTIASP) which falls under the hint instructions region. This is done
to disallow probe of authenticate instruction in the kernel which may
lead to ptrauth faults with the addition of Armv8.6 enhanced ptrauth
features.

The corresponding append pac ptrauth instruction (PACIASP) is not disabled
and they can still be probed.

Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
---
This patch may need some changes with Mark Brown's work on whitelisting
of hint instructions [1].

[1]: http://lists.infradead.org/pipermail/linux-arm-kernel/2020-March/720280.html

 arch/arm64/include/asm/insn.h          | 13 +++++++------
 arch/arm64/kernel/insn.c               |  1 +
 arch/arm64/kernel/probes/decode-insn.c |  2 +-
 3 files changed, 9 insertions(+), 7 deletions(-)
diff mbox series

Patch

diff --git a/arch/arm64/include/asm/insn.h b/arch/arm64/include/asm/insn.h
index bb313dde58a4..2e01db04c885 100644
--- a/arch/arm64/include/asm/insn.h
+++ b/arch/arm64/include/asm/insn.h
@@ -40,12 +40,13 @@  enum aarch64_insn_encoding_class {
 };
 
 enum aarch64_insn_hint_op {
-	AARCH64_INSN_HINT_NOP	= 0x0 << 5,
-	AARCH64_INSN_HINT_YIELD	= 0x1 << 5,
-	AARCH64_INSN_HINT_WFE	= 0x2 << 5,
-	AARCH64_INSN_HINT_WFI	= 0x3 << 5,
-	AARCH64_INSN_HINT_SEV	= 0x4 << 5,
-	AARCH64_INSN_HINT_SEVL	= 0x5 << 5,
+	AARCH64_INSN_HINT_NOP		= 0x0 << 5,
+	AARCH64_INSN_HINT_YIELD		= 0x1 << 5,
+	AARCH64_INSN_HINT_WFE		= 0x2 << 5,
+	AARCH64_INSN_HINT_WFI		= 0x3 << 5,
+	AARCH64_INSN_HINT_SEV		= 0x4 << 5,
+	AARCH64_INSN_HINT_SEVL		= 0x5 << 5,
+	AARCH64_INSN_HINT_AUTIASP	= (0x3 << 8) | (0x5 << 5),
 };
 
 enum aarch64_insn_imm_type {
diff --git a/arch/arm64/kernel/insn.c b/arch/arm64/kernel/insn.c
index 4a9e773a177f..87f7c8a46b31 100644
--- a/arch/arm64/kernel/insn.c
+++ b/arch/arm64/kernel/insn.c
@@ -63,6 +63,7 @@  bool __kprobes aarch64_insn_is_nop(u32 insn)
 	case AARCH64_INSN_HINT_WFI:
 	case AARCH64_INSN_HINT_SEV:
 	case AARCH64_INSN_HINT_SEVL:
+	case AARCH64_INSN_HINT_AUTIASP:
 		return false;
 	default:
 		return true;
diff --git a/arch/arm64/kernel/probes/decode-insn.c b/arch/arm64/kernel/probes/decode-insn.c
index b78fac9e546c..a7caf84a9baa 100644
--- a/arch/arm64/kernel/probes/decode-insn.c
+++ b/arch/arm64/kernel/probes/decode-insn.c
@@ -42,7 +42,7 @@  static bool __kprobes aarch64_insn_is_steppable(u32 insn)
 			     != AARCH64_INSN_SPCLREG_DAIF;
 
 		/*
-		 * The HINT instruction is is problematic when single-stepping,
+		 * The HINT instruction is problematic when single-stepping,
 		 * except for the NOP case.
 		 */
 		if (aarch64_insn_is_hint(insn))