From c71052cc9e14db90d9a95fe0991ecc72556f1818 Mon Sep 17 00:00:00 2001 From: Mark Brown Date: Mon, 4 May 2020 14:13:25 +0100 Subject: [PATCH] arm64: insn: Don't assume unrecognized HINTs are skippable Currently the kernel assumes that any HINT which it does not explicitly recognise is skippable. This is not robust as new instructions may be added which need special handling, and in any case software should only be using explicit NOP instructions for deliberate NOPs. This has the effect of rendering PAC and BTI instructions unprobeable which means that probes can't be inserted on the first instruction of functions built with those features. Signed-off-by: Mark Brown Acked-by: Catalin Marinas Acked-by: Mark Rutland Link: https://lore.kernel.org/r/20200504131326.18290-4-broonie@kernel.org Signed-off-by: Will Deacon --- arch/arm64/kernel/insn.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/arch/arm64/kernel/insn.c b/arch/arm64/kernel/insn.c index 0829bb5b45ec..15c3f0643e3b 100644 --- a/arch/arm64/kernel/insn.c +++ b/arch/arm64/kernel/insn.c @@ -57,14 +57,10 @@ bool __kprobes aarch64_insn_is_steppable_hint(u32 insn) return false; switch (insn & 0xFE0) { - case AARCH64_INSN_HINT_YIELD: - case AARCH64_INSN_HINT_WFE: - case AARCH64_INSN_HINT_WFI: - case AARCH64_INSN_HINT_SEV: - case AARCH64_INSN_HINT_SEVL: - return false; - default: + case AARCH64_INSN_HINT_NOP: return true; + default: + return false; } }