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-rw-r--r--arch/x86/include/asm/insn-eval.h1
-rw-r--r--arch/x86/lib/insn-eval.c17
2 files changed, 18 insertions, 0 deletions
diff --git a/arch/x86/include/asm/insn-eval.h b/arch/x86/include/asm/insn-eval.h
index 5cab1b1da84d..7e8c9633a377 100644
--- a/arch/x86/include/asm/insn-eval.h
+++ b/arch/x86/include/asm/insn-eval.h
@@ -12,5 +12,6 @@
#include <asm/ptrace.h>
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);
#endif /* _ASM_X86_INSN_EVAL_H */
diff --git a/arch/x86/lib/insn-eval.c b/arch/x86/lib/insn-eval.c
index 4931d9252dde..405ffeb1c382 100644
--- a/arch/x86/lib/insn-eval.c
+++ b/arch/x86/lib/insn-eval.c
@@ -100,6 +100,23 @@ static int get_reg_offset(struct insn *insn, struct pt_regs *regs,
return regoff[regno];
}
+/**
+ * insn_get_modrm_rm_off() - Obtain register in r/m part of the ModRM byte
+ * @insn: Instruction containing the ModRM byte
+ * @regs: Register values as seen when entering kernel mode
+ *
+ * Returns:
+ *
+ * The register indicated by the r/m part of the ModRM byte. The
+ * register is obtained as an offset from the base of pt_regs. In specific
+ * cases, the returned value can be -EDOM to indicate that the particular value
+ * of ModRM does not refer to a register and shall be ignored.
+ */
+int insn_get_modrm_rm_off(struct insn *insn, struct pt_regs *regs)
+{
+ return get_reg_offset(insn, regs, REG_TYPE_RM);
+}
+
/*
* return the address being referenced be instruction
* for rm=3 returning the content of the rm reg