From 03c9c8fad6cb5e8fdfb40287fa1cdf8ee2db0b67 Mon Sep 17 00:00:00 2001 From: Amit Daniel Kachhap Date: Mon, 14 Sep 2020 14:06:56 +0530 Subject: [PATCH] arm64: kprobe: clarify the comment of steppable hint instructions 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 Reviewed-by: Dave Martin Link: https://lore.kernel.org/r/20200914083656.21428-7-amit.kachhap@arm.com Signed-off-by: Will Deacon --- 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 c541fb48886e..104101f633b1 100644 --- a/arch/arm64/kernel/probes/decode-insn.c +++ b/arch/arm64/kernel/probes/decode-insn.c @@ -43,8 +43,10 @@ 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);