The following commit has been merged into the x86/misc branch of tip:
Commit-ID: d5ec1877df6da6a14bbc353aff50689528930dd2
Gitweb: https://git.kernel.org/tip/d5ec1877df6da6a14bbc353aff50689528930dd2
Author: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
AuthorDate: Tue, 30 Nov 2021 21:49:31 +03:00
Committer: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
CommitterDate: Tue, 30 Nov 2021 14:53:04 -08:00
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@xxxxxxxxxxxxxxx>
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Reviewed-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Reviewed-by: Tony Luck <tony.luck@xxxxxxxxx>
Tested-by: Joerg Roedel <jroedel@xxxxxxx>
Acked-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
Link: https://lkml.kernel.org/r/20211130184933.31005-3-kirill.shutemov@xxxxxxxxxxxxxxx
---
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
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