From 5901781a11175a5e5ee91746ec8627f18d47eebd Mon Sep 17 00:00:00 2001 From: Joerg Roedel Date: Mon, 7 Sep 2020 15:15:12 +0200 Subject: [PATCH] x86/insn: Add insn_has_rep_prefix() helper Add a function to check whether an instruction has a REP prefix. Signed-off-by: Joerg Roedel Signed-off-by: Borislav Petkov Reviewed-by: Masami Hiramatsu Link: https://lkml.kernel.org/r/20200907131613.12703-12-joro@8bytes.org --- arch/x86/include/asm/insn-eval.h | 1 + arch/x86/lib/insn-eval.c | 24 ++++++++++++++++++++++++ 2 files changed, 25 insertions(+) diff --git a/arch/x86/include/asm/insn-eval.h b/arch/x86/include/asm/insn-eval.h index f748f57..a0f839a 100644 --- a/arch/x86/include/asm/insn-eval.h +++ b/arch/x86/include/asm/insn-eval.h @@ -15,6 +15,7 @@ #define INSN_CODE_SEG_OPND_SZ(params) (params & 0xf) #define INSN_CODE_SEG_PARAMS(oper_sz, addr_sz) (oper_sz | (addr_sz << 4)) +bool insn_has_rep_prefix(struct insn *insn); void __user *insn_get_addr_ref(struct insn *insn, struct pt_regs *regs); int insn_get_modrm_rm_off(struct insn *insn, struct pt_regs *regs); int insn_get_modrm_reg_off(struct insn *insn, struct pt_regs *regs); diff --git a/arch/x86/lib/insn-eval.c b/arch/x86/lib/insn-eval.c index f20942c..58f7fb9 100644 --- a/arch/x86/lib/insn-eval.c +++ b/arch/x86/lib/insn-eval.c @@ -54,6 +54,30 @@ static bool is_string_insn(struct insn *insn) } /** + * insn_has_rep_prefix() - Determine if instruction has a REP prefix + * @insn: Instruction containing the prefix to inspect + * + * Returns: + * + * true if the instruction has a REP prefix, false if not. + */ +bool insn_has_rep_prefix(struct insn *insn) +{ + int i; + + insn_get_prefixes(insn); + + for (i = 0; i < insn->prefixes.nbytes; i++) { + insn_byte_t p = insn->prefixes.bytes[i]; + + if (p == 0xf2 || p == 0xf3) + return true; + } + + return false; +} + +/** * get_seg_reg_override_idx() - obtain segment register override index * @insn: Valid instruction with segment override prefixes * -- 2.7.4