Messages in this thread Patch in this message | | | From | "Kirill A. Shutemov" <> | Subject | [PATCHv4 2/4] x86/insn-eval: Introduce insn_get_modrm_reg_ptr() | Date | Tue, 30 Nov 2021 21:49:31 +0300 |
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From: "Kirill A. Shutemov" <kirill@shutemov.name>
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 <kirill.shutemov@linux.intel.com> Reviewed-by: Andi Kleen <ak@linux.intel.com> Reviewed-by: Tony Luck <tony.luck@intel.com> Tested-by: Joerg Roedel <jroedel@suse.de> --- 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 4ec3613551e3..33ae4040c7ee 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 868d80ea85d9..0168378ee2d4 100644 --- a/arch/x86/lib/insn-eval.c +++ b/arch/x86/lib/insn-eval.c @@ -848,6 +848,26 @@ int insn_get_modrm_reg_off(struct insn *insn, struct pt_regs *regs) return get_reg_offset(insn, regs, REG_TYPE_REG); } +/** + * 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. -- 2.32.0
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