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From: Amit Daniel Kachhap <amit.kachhap@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: Mark Rutland <mark.rutland@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Mark Brown <broonie@kernel.org>,
	James Morse <james.morse@arm.com>,
	Amit Daniel Kachhap <amit.kachhap@arm.com>,
	Vincenzo Frascino <Vincenzo.Frascino@arm.com>,
	Will Deacon <will@kernel.org>, Dave Martin <Dave.Martin@arm.com>
Subject: [PATCH v6 6/6] arm64: kprobe: clarify the comment of steppable hint instructions
Date: Fri,  4 Sep 2020 16:12:09 +0530	[thread overview]
Message-ID: <20200904104209.32385-7-amit.kachhap@arm.com> (raw)
In-Reply-To: <20200904104209.32385-1-amit.kachhap@arm.com>

The existing comment about steppable hint instruction is not complete
and only describes NOP instructions as steppable. As the function
aarch64_insn_is_steppable_hint allows all white-listed instruction
to be probed so the comment is updated to reflect this.

Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Reviewed-by: Dave Martin <dave.martin@arm.com>
---
Changes since v5: 
* None.

 arch/arm64/kernel/probes/decode-insn.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/probes/decode-insn.c b/arch/arm64/kernel/probes/decode-insn.c
index f9eb8210d6d3..288114d54fb5 100644
--- a/arch/arm64/kernel/probes/decode-insn.c
+++ b/arch/arm64/kernel/probes/decode-insn.c
@@ -44,8 +44,10 @@ static bool __kprobes aarch64_insn_is_steppable(u32 insn)
 			     != AARCH64_INSN_SPCLREG_DAIF;
 
 		/*
-		 * The HINT instruction is is problematic when single-stepping,
-		 * except for the NOP case.
+		 * The HINT instruction is steppable only if it is in whitelist
+		 * and the rest of other such instructions are blocked for
+		 * single stepping as they may cause exception or other
+		 * unintended behaviour.
 		 */
 		if (aarch64_insn_is_hint(insn))
 			return aarch64_insn_is_steppable_hint(insn);
-- 
2.17.1


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      parent reply	other threads:[~2020-09-04 10:44 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-04 10:42 [PATCH v6 0/6] arm64: add Armv8.3 pointer authentication enhancements Amit Daniel Kachhap
2020-09-04 10:42 ` [PATCH v6 1/6] arm64: kprobe: add checks for ARMv8.3-PAuth combined instructions Amit Daniel Kachhap
2020-09-07 21:45   ` Will Deacon
2020-09-08 10:51     ` Dave Martin
2020-09-11 13:55       ` Will Deacon
2020-09-14  8:42         ` Amit Kachhap
2020-09-04 10:42 ` [PATCH v6 2/6] arm64: traps: Allow force_signal_inject to pass esr error code Amit Daniel Kachhap
2020-09-04 10:42 ` [PATCH v6 3/6] arm64: ptrauth: Introduce Armv8.3 pointer authentication enhancements Amit Daniel Kachhap
2020-09-04 10:42 ` [PATCH v6 4/6] arm64: cpufeature: Modify address authentication cpufeature to exact Amit Daniel Kachhap
2020-09-04 10:42 ` [PATCH v6 5/6] arm64: kprobe: disable probe of fault prone ptrauth instruction Amit Daniel Kachhap
2020-09-04 10:42 ` Amit Daniel Kachhap [this message]

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