Other kernel submodules can benefit from using the utility functions
defined in mpx.c to obtain the addresses and values of operands contained
in the general purpose registers. An instance of this is the emulation code
used for instructions protected by the Intel User-Mode Instruction
Prevention feature.
Thus, these functions are relocated to a new insn-eval.c file. The reason
to not relocate these utilities into insn.c is that the latter solely
analyses instructions given by a struct insn without any knowledge of the
meaning of the values of instruction operands. This new utility insn-
eval.c aims to be used to resolve effective and userspace linear addresses
based on the contents of the instruction operands as well as the contents
of pt_regs structure.
These utilities come with a separate header. This is to avoid taking insn.c
out of sync from the instructions decoders under tools/obj and tools/perf.
This also avoids adding cumbersome #ifdef's for the #include'd files
required to decode instructions in a kernel context.
Functions are simply relocated. There are not functional or indentation
changes.
Cc: Dave Hansen
Cc: Adam Buchbinder
Cc: Colin Ian King
Cc: Lorenzo Stoakes
Cc: Qiaowei Ren
Cc: Arnaldo Carvalho de Melo
Cc: Masami Hiramatsu
Cc: Adrian Hunter
Cc: Kees Cook
Cc: Thomas Garnier
Cc: Peter Zijlstra
Cc: Borislav Petkov
Cc: Dmitry Vyukov
Cc: Ravi V. Shankar
Cc: x...@kernel.org
Signed-off-by: Ricardo Neri
---
arch/x86/include/asm/insn-eval.h | 16
arch/x86/lib/Makefile| 2 +-
arch/x86/lib/insn-eval.c | 160 +++
arch/x86/mm/mpx.c| 153 +
4 files changed, 179 insertions(+), 152 deletions(-)
create mode 100644 arch/x86/include/asm/insn-eval.h
create mode 100644 arch/x86/lib/insn-eval.c
diff --git a/arch/x86/include/asm/insn-eval.h b/arch/x86/include/asm/insn-eval.h
new file mode 100644
index 000..5cab1b1
--- /dev/null
+++ b/arch/x86/include/asm/insn-eval.h
@@ -0,0 +1,16 @@
+#ifndef _ASM_X86_INSN_EVAL_H
+#define _ASM_X86_INSN_EVAL_H
+/*
+ * A collection of utility functions for x86 instruction analysis to be
+ * used in a kernel context. Useful when, for instance, making sense
+ * of the registers indicated by operands.
+ */
+
+#include
+#include
+#include
+#include
+
+void __user *insn_get_addr_ref(struct insn *insn, struct pt_regs *regs);
+
+#endif /* _ASM_X86_INSN_EVAL_H */
diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index 34a7413..675d7b0 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -23,7 +23,7 @@ lib-y := delay.o misc.o cmdline.o cpu.o
lib-y += usercopy_$(BITS).o usercopy.o getuser.o putuser.o
lib-y += memcpy_$(BITS).o
lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o
-lib-$(CONFIG_INSTRUCTION_DECODER) += insn.o inat.o
+lib-$(CONFIG_INSTRUCTION_DECODER) += insn.o inat.o insn-eval.o
lib-$(CONFIG_RANDOMIZE_BASE) += kaslr.o
obj-y += msr.o msr-reg.o msr-reg-export.o hweight.o
diff --git a/arch/x86/lib/insn-eval.c b/arch/x86/lib/insn-eval.c
new file mode 100644
index 000..23cf010
--- /dev/null
+++ b/arch/x86/lib/insn-eval.c
@@ -0,0 +1,160 @@
+/*
+ * Utility functions for x86 operand and address decoding
+ *
+ * Copyright (C) Intel Corporation 2017
+ */
+#include
+#include
+#include
+#include
+#include
+
+enum reg_type {
+ REG_TYPE_RM = 0,
+ REG_TYPE_INDEX,
+ REG_TYPE_BASE,
+};
+
+static int get_reg_offset(struct insn *insn, struct pt_regs *regs,
+ enum reg_type type)
+{
+ int regno = 0;
+
+ static const int regoff[] = {
+ offsetof(struct pt_regs, ax),
+ offsetof(struct pt_regs, cx),
+ offsetof(struct pt_regs, dx),
+ offsetof(struct pt_regs, bx),
+ offsetof(struct pt_regs, sp),
+ offsetof(struct pt_regs, bp),
+ offsetof(struct pt_regs, si),
+ offsetof(struct pt_regs, di),
+#ifdef CONFIG_X86_64
+ offsetof(struct pt_regs, r8),
+ offsetof(struct pt_regs, r9),
+ offsetof(struct pt_regs, r10),
+ offsetof(struct pt_regs, r11),
+ offsetof(struct pt_regs, r12),
+ offsetof(struct pt_regs, r13),
+ offsetof(struct pt_regs, r14),
+ offsetof(struct pt_regs, r15),
+#endif
+ };
+ int nr_registers = ARRAY_SIZE(regoff);
+ /*
+* Don't possibly decode a 32-bit instructions as
+* reading a 64-bit-only register.
+*/
+ if (IS_ENABLED(CONFIG_X86_64) && !insn->x86_64)
+ nr_registers -= 8;
+
+ switch (type) {
+ case REG_TYPE_RM:
+ regno = X86_MODRM_RM(insn->modrm.value);
+ if (X86_REX_B(insn->rex_prefix.value))
+ regno += 8;
+ break;
+
+ case REG_TYPE_INDEX:
+ regno = X86_SIB_INDEX(insn->sib.value);
+
