Commit d5ec1877 authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Dave Hansen
Browse files

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: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: default avatarAndi Kleen <ak@linux.intel.com>
Reviewed-by: default avatarTony Luck <tony.luck@intel.com>
Tested-by: default avatarJoerg Roedel <jroedel@suse.de>
Acked-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
Link: https://lkml.kernel.org/r/20211130184933.31005-3-kirill.shutemov@linux.intel.com
parent 23ef731e

arch/x86/include/asm/insn-eval.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

arch/x86/lib/insn-eval.c

+20 −0
Original line number Diff line number Diff line
@@ -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.