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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 <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@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>
Acked-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lkml.kernel.org/r/20211130184933.31005-3-kirill.shutemov@linux.intel.com
This commit is contained in:
Kirill A. Shutemov 2021-11-30 21:49:31 +03:00 committed by Dave Hansen
parent 23ef731e43
commit d5ec1877df
2 changed files with 21 additions and 0 deletions
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1
arch/x86/include/asm/insn-eval.h
View File

@ -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);

20
arch/x86/lib/insn-eval.c
View File

@ -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.