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authorKirill A. Shutemov <kirill@shutemov.name>2021-11-30 21:49:31 +0300
committerDave Hansen <dave.hansen@linux.intel.com>2021-11-30 14:53:04 -0800
commitd5ec1877df6da6a14bbc353aff50689528930dd2 (patch)
treea5e6b273c022191205ade9be185fa33e83b97b3d
parent23ef731e4365196bfc186358eb4f6265d60ab352 (diff)
downloadlinux-d5ec1877df6da6a14bbc353aff50689528930dd2.tar.bz2
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
-rw-r--r--arch/x86/include/asm/insn-eval.h1
-rw-r--r--arch/x86/lib/insn-eval.c20
2 files changed, 21 insertions, 0 deletions
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 1c51e8a415e2..8df6236e441c 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