From d5ec1877df6da6a14bbc353aff50689528930dd2 Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Tue, 30 Nov 2021 21:49:31 +0300 Subject: [PATCH] x86/insn-eval: Introduce insn_get_modrm_reg_ptr() The helper returns a pointer to the register indicated by ModRM byte. It's going to replace vc_insn_get_reg() in the SEV MMIO implementation. TDX MMIO implementation will also use it. Signed-off-by: Kirill A. Shutemov Signed-off-by: Dave Hansen Reviewed-by: Andi Kleen Reviewed-by: Tony Luck Tested-by: Joerg Roedel Acked-by: Tom Lendacky Link: https://lkml.kernel.org/r/20211130184933.31005-3-kirill.shutemov@linux.intel.com --- arch/x86/include/asm/insn-eval.h | 1 + arch/x86/lib/insn-eval.c | 20 ++++++++++++++++++++ 2 files changed, 21 insertions(+) diff --git a/arch/x86/include/asm/insn-eval.h b/arch/x86/include/asm/insn-eval.h index 4ec3613..33ae404 100644 --- a/arch/x86/include/asm/insn-eval.h +++ b/arch/x86/include/asm/insn-eval.h @@ -19,6 +19,7 @@ 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); +unsigned long *insn_get_modrm_reg_ptr(struct insn *insn, struct pt_regs *regs); unsigned long insn_get_seg_base(struct pt_regs *regs, int seg_reg_idx); int insn_get_code_seg_params(struct pt_regs *regs); int insn_get_effective_ip(struct pt_regs *regs, unsigned long *ip); diff --git a/arch/x86/lib/insn-eval.c b/arch/x86/lib/insn-eval.c index 1c51e8a..8df6236 100644 --- a/arch/x86/lib/insn-eval.c +++ b/arch/x86/lib/insn-eval.c @@ -849,6 +849,26 @@ int insn_get_modrm_reg_off(struct insn *insn, struct pt_regs *regs) } /** + * insn_get_modrm_reg_ptr() - Obtain register pointer based on ModRM byte + * @insn: Instruction containing the ModRM byte + * @regs: Register values as seen when entering kernel mode + * + * Returns: + * + * The register indicated by the reg part of the ModRM byte. + * The register is obtained as a pointer within pt_regs. + */ +unsigned long *insn_get_modrm_reg_ptr(struct insn *insn, struct pt_regs *regs) +{ + int offset; + + offset = insn_get_modrm_reg_off(insn, regs); + if (offset < 0) + return NULL; + return (void *)regs + offset; +} + +/** * get_seg_base_limit() - obtain base address and limit of a segment * @insn: Instruction. Must be valid. * @regs: Register values as seen when entering kernel mode -- 2.7.4