From: Mark Brown Date: Mon, 4 May 2020 13:13:25 +0000 (+0100) Subject: arm64: insn: Don't assume unrecognized HINTs are skippable X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=c71052cc9e14db90d9a95fe0991ecc72556f1818;p=linux.git 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 --- diff --git a/arch/arm64/kernel/insn.c b/arch/arm64/kernel/insn.c index 0829bb5b45ecf..15c3f0643e3b2 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; } }