/*
* arch/arm/kernel/kprobes.h
*
- * Contents moved from arch/arm/include/asm/kprobes.h which is
+ * Copyright (C) 2011 Jon Medhurst <tixy@yxit.co.uk>.
+ *
+ * Some contents moved here from arch/arm/include/asm/kprobes.h which is
* Copyright (C) 2006, 2007 Motorola Inc.
*
* This program is free software; you can redistribute it and/or modify
#define _ARM_KERNEL_KPROBES_H
/*
- * This undefined instruction must be unique and
+ * These undefined instructions must be unique and
* reserved solely for kprobes' use.
*/
-#define KPROBE_BREAKPOINT_INSTRUCTION 0xe7f001f8
+#define KPROBE_ARM_BREAKPOINT_INSTRUCTION 0x07f001f8
+#define KPROBE_THUMB16_BREAKPOINT_INSTRUCTION 0xde18
+#define KPROBE_THUMB32_BREAKPOINT_INSTRUCTION 0xf7f0a018
+
enum kprobe_insn {
INSN_REJECTED,
#endif
+/*
+ * Update ITSTATE after normal execution of an IT block instruction.
+ *
+ * The 8 IT state bits are split into two parts in CPSR:
+ * ITSTATE<1:0> are in CPSR<26:25>
+ * ITSTATE<7:2> are in CPSR<15:10>
+ */
+static inline unsigned long it_advance(unsigned long cpsr)
+ {
+ if ((cpsr & 0x06000400) == 0) {
+ /* ITSTATE<2:0> == 0 means end of IT block, so clear IT state */
+ cpsr &= ~PSR_IT_MASK;
+ } else {
+ /* We need to shift left ITSTATE<4:0> */
+ const unsigned long mask = 0x06001c00; /* Mask ITSTATE<4:0> */
+ unsigned long it = cpsr & mask;
+ it <<= 1;
+ it |= it >> (27 - 10); /* Carry ITSTATE<2> to correct place */
+ it &= mask;
+ cpsr &= ~mask;
+ cpsr |= it;
+ }
+ return cpsr;
+}
+
+static inline void __kprobes bx_write_pc(long pcv, struct pt_regs *regs)
+{
+ long cpsr = regs->ARM_cpsr;
+ if (pcv & 0x1) {
+ cpsr |= PSR_T_BIT;
+ pcv &= ~0x1;
+ } else {
+ cpsr &= ~PSR_T_BIT;
+ pcv &= ~0x2; /* Avoid UNPREDICTABLE address allignment */
+ }
+ regs->ARM_cpsr = cpsr;
+ regs->ARM_pc = pcv;
+}
+
+
+#if __LINUX_ARM_ARCH__ >= 6
+
+/* Kernels built for >= ARMv6 should never run on <= ARMv5 hardware, so... */
+#define load_write_pc_interworks true
+#define test_load_write_pc_interworking()
+
+#else /* __LINUX_ARM_ARCH__ < 6 */
+
+/* We need run-time testing to determine if load_write_pc() should interwork. */
+extern bool load_write_pc_interworks;
+void __init test_load_write_pc_interworking(void);
+
+#endif
+
+static inline void __kprobes load_write_pc(long pcv, struct pt_regs *regs)
+{
+ if (load_write_pc_interworks)
+ bx_write_pc(pcv, regs);
+ else
+ regs->ARM_pc = pcv;
+}
+
+
+#if __LINUX_ARM_ARCH__ >= 7
+
+#define alu_write_pc_interworks true
+#define test_alu_write_pc_interworking()
+
+#elif __LINUX_ARM_ARCH__ <= 5
+
+/* Kernels built for <= ARMv5 should never run on >= ARMv6 hardware, so... */
+#define alu_write_pc_interworks false
+#define test_alu_write_pc_interworking()
+
+#else /* __LINUX_ARM_ARCH__ == 6 */
+
+/* We could be an ARMv6 binary on ARMv7 hardware so we need a run-time check. */
+extern bool alu_write_pc_interworks;
+void __init test_alu_write_pc_interworking(void);
+
+#endif /* __LINUX_ARM_ARCH__ == 6 */
+
+static inline void __kprobes alu_write_pc(long pcv, struct pt_regs *regs)
+{
+ if (alu_write_pc_interworks)
+ bx_write_pc(pcv, regs);
+ else
+ regs->ARM_pc = pcv;
+}
+
+
+void __kprobes kprobe_simulate_nop(struct kprobe *p, struct pt_regs *regs);
+void __kprobes kprobe_emulate_none(struct kprobe *p, struct pt_regs *regs);
+
+enum kprobe_insn __kprobes
+kprobe_decode_ldmstm(kprobe_opcode_t insn, struct arch_specific_insn *asi);
+
/*
* Test if load/store instructions writeback the address register.
* if P (bit 24) == 0 or W (bit 21) == 1
*/
#define is_writeback(insn) ((insn ^ 0x01000000) & 0x01200000)
+/*
+ * The following definitions and macros are used to build instruction
+ * decoding tables for use by kprobe_decode_insn.
+ *
+ * These tables are a concatenation of entries each of which consist of one of
+ * the decode_* structs. All of the fields in every type of decode structure
+ * are of the union type decode_item, therefore the entire decode table can be
+ * viewed as an array of these and declared like:
+ *
+ * static const union decode_item table_name[] = {};
+ *
+ * In order to construct each entry in the table, macros are used to
+ * initialise a number of sequential decode_item values in a layout which
+ * matches the relevant struct. E.g. DECODE_SIMULATE initialise a struct
+ * decode_simulate by initialising four decode_item objects like this...
+ *
+ * {.bits = _type},
+ * {.bits = _mask},
+ * {.bits = _value},
+ * {.handler = _handler},
+ *
+ * Initialising a specified member of the union means that the compiler
+ * will produce a warning if the argument is of an incorrect type.
+ *
+ * Below is a list of each of the macros used to initialise entries and a
+ * description of the action performed when that entry is matched to an
+ * instruction. A match is found when (instruction & mask) == value.
+ *
+ * DECODE_TABLE(mask, value, table)
+ * Instruction decoding jumps to parsing the new sub-table 'table'.
+ *
+ * DECODE_CUSTOM(mask, value, decoder)
+ * The custom function 'decoder' is called to the complete decoding
+ * of an instruction.
+ *
+ * DECODE_SIMULATE(mask, value, handler)
+ * Set the probes instruction handler to 'handler', this will be used
+ * to simulate the instruction when the probe is hit. Decoding returns
+ * with INSN_GOOD_NO_SLOT.
+ *
+ * DECODE_EMULATE(mask, value, handler)
+ * Set the probes instruction handler to 'handler', this will be used
+ * to emulate the instruction when the probe is hit. The modified
+ * instruction (see below) is placed in the probes instruction slot so it
+ * may be called by the emulation code. Decoding returns with INSN_GOOD.
+ *
+ * DECODE_REJECT(mask, value)
+ * Instruction decoding fails with INSN_REJECTED
+ *
+ * DECODE_OR(mask, value)
+ * This allows the mask/value test of multiple table entries to be
+ * logically ORed. Once an 'or' entry is matched the decoding action to
+ * be performed is that of the next entry which isn't an 'or'. E.g.
+ *
+ * DECODE_OR (mask1, value1)
+ * DECODE_OR (mask2, value2)
+ * DECODE_SIMULATE (mask3, value3, simulation_handler)
+ *
+ * This means that if any of the three mask/value pairs match the
+ * instruction being decoded, then 'simulation_handler' will be used
+ * for it.
+ *
+ * Both the SIMULATE and EMULATE macros have a second form which take an
+ * additional 'regs' argument.
+ *
+ * DECODE_SIMULATEX(mask, value, handler, regs)
+ * DECODE_EMULATEX (mask, value, handler, regs)
+ *
+ * These are used to specify what kind of CPU register is encoded in each of the
+ * least significant 5 nibbles of the instruction being decoded. The regs value
+ * is specified using the REGS macro, this takes any of the REG_TYPE_* values
+ * from enum decode_reg_type as arguments; only the '*' part of the name is
+ * given. E.g.
+ *
+ * REGS(0, ANY, NOPC, 0, ANY)
+ *
+ * This indicates an instruction is encoded like:
+ *
+ * bits 19..16 ignore
+ * bits 15..12 any register allowed here
+ * bits 11.. 8 any register except PC allowed here
+ * bits 7.. 4 ignore
+ * bits 3.. 0 any register allowed here
+ *
+ * This register specification is checked after a decode table entry is found to
+ * match an instruction (through the mask/value test). Any invalid register then
+ * found in the instruction will cause decoding to fail with INSN_REJECTED. In
+ * the above example this would happen if bits 11..8 of the instruction were
+ * 1111, indicating R15 or PC.
+ *
+ * As well as checking for legal combinations of registers, this data is also
+ * used to modify the registers encoded in the instructions so that an
+ * emulation routines can use it. (See decode_regs() and INSN_NEW_BITS.)
+ *
+ * Here is a real example which matches ARM instructions of the form
+ * "AND <Rd>,<Rn>,<Rm>,<shift> <Rs>"
+ *
+ * DECODE_EMULATEX (0x0e000090, 0x00000010, emulate_rd12rn16rm0rs8_rwflags,
+ * REGS(ANY, ANY, NOPC, 0, ANY)),
+ * ^ ^ ^ ^
+ * Rn Rd Rs Rm
+ *
+ * Decoding the instruction "AND R4, R5, R6, ASL R15" will be rejected because
+ * Rs == R15
+ *
+ * Decoding the instruction "AND R4, R5, R6, ASL R7" will be accepted and the
+ * instruction will be modified to "AND R0, R2, R3, ASL R1" and then placed into
+ * the kprobes instruction slot. This can then be called later by the handler
+ * function emulate_rd12rn16rm0rs8_rwflags in order to simulate the instruction.
+ */
+
+enum decode_type {
+ DECODE_TYPE_END,
+ DECODE_TYPE_TABLE,
+ DECODE_TYPE_CUSTOM,
+ DECODE_TYPE_SIMULATE,
+ DECODE_TYPE_EMULATE,
+ DECODE_TYPE_OR,
+ DECODE_TYPE_REJECT,
+ NUM_DECODE_TYPES /* Must be last enum */
+};
+
+#define DECODE_TYPE_BITS 4
+#define DECODE_TYPE_MASK ((1 << DECODE_TYPE_BITS) - 1)
+
+enum decode_reg_type {
+ REG_TYPE_NONE = 0, /* Not a register, ignore */
+ REG_TYPE_ANY, /* Any register allowed */
+ REG_TYPE_SAMEAS16, /* Register should be same as that at bits 19..16 */
+ REG_TYPE_SP, /* Register must be SP */
+ REG_TYPE_PC, /* Register must be PC */
+ REG_TYPE_NOSP, /* Register must not be SP */
+ REG_TYPE_NOSPPC, /* Register must not be SP or PC */
+ REG_TYPE_NOPC, /* Register must not be PC */
+ REG_TYPE_NOPCWB, /* No PC if load/store write-back flag also set */
+
+ /* The following types are used when the encoding for PC indicates
+ * another instruction form. This distiction only matters for test
+ * case coverage checks.
+ */
+ REG_TYPE_NOPCX, /* Register must not be PC */
+ REG_TYPE_NOSPPCX, /* Register must not be SP or PC */
+
+ /* Alias to allow '0' arg to be used in REGS macro. */
+ REG_TYPE_0 = REG_TYPE_NONE
+};
+
+#define REGS(r16, r12, r8, r4, r0) \
+ ((REG_TYPE_##r16) << 16) + \
+ ((REG_TYPE_##r12) << 12) + \
+ ((REG_TYPE_##r8) << 8) + \
+ ((REG_TYPE_##r4) << 4) + \
+ (REG_TYPE_##r0)
+
+union decode_item {
+ u32 bits;
+ const union decode_item *table;
+ kprobe_insn_handler_t *handler;
+ kprobe_decode_insn_t *decoder;
+};
+
+
+#define DECODE_END \
+ {.bits = DECODE_TYPE_END}
+
+
+struct decode_header {
+ union decode_item type_regs;
+ union decode_item mask;
+ union decode_item value;
+};
+
+#define DECODE_HEADER(_type, _mask, _value, _regs) \
+ {.bits = (_type) | ((_regs) << DECODE_TYPE_BITS)}, \
+ {.bits = (_mask)}, \
+ {.bits = (_value)}
+
+
+struct decode_table {
+ struct decode_header header;
+ union decode_item table;
+};
+
+#define DECODE_TABLE(_mask, _value, _table) \
+ DECODE_HEADER(DECODE_TYPE_TABLE, _mask, _value, 0), \
+ {.table = (_table)}
+
+
+struct decode_custom {
+ struct decode_header header;
+ union decode_item decoder;
+};
+
+#define DECODE_CUSTOM(_mask, _value, _decoder) \
+ DECODE_HEADER(DECODE_TYPE_CUSTOM, _mask, _value, 0), \
+ {.decoder = (_decoder)}
+
+
+struct decode_simulate {
+ struct decode_header header;
+ union decode_item handler;
+};
+
+#define DECODE_SIMULATEX(_mask, _value, _handler, _regs) \
+ DECODE_HEADER(DECODE_TYPE_SIMULATE, _mask, _value, _regs), \
+ {.handler = (_handler)}
+
+#define DECODE_SIMULATE(_mask, _value, _handler) \
+ DECODE_SIMULATEX(_mask, _value, _handler, 0)
+
+
+struct decode_emulate {
+ struct decode_header header;
+ union decode_item handler;
+};
+
+#define DECODE_EMULATEX(_mask, _value, _handler, _regs) \
+ DECODE_HEADER(DECODE_TYPE_EMULATE, _mask, _value, _regs), \
+ {.handler = (_handler)}
+
+#define DECODE_EMULATE(_mask, _value, _handler) \
+ DECODE_EMULATEX(_mask, _value, _handler, 0)
+
+
+struct decode_or {
+ struct decode_header header;
+};
+
+#define DECODE_OR(_mask, _value) \
+ DECODE_HEADER(DECODE_TYPE_OR, _mask, _value, 0)
+
+
+struct decode_reject {
+ struct decode_header header;
+};
+
+#define DECODE_REJECT(_mask, _value) \
+ DECODE_HEADER(DECODE_TYPE_REJECT, _mask, _value, 0)
+
+
+#ifdef CONFIG_THUMB2_KERNEL
+extern const union decode_item kprobe_decode_thumb16_table[];
+extern const union decode_item kprobe_decode_thumb32_table[];
+#else
+extern const union decode_item kprobe_decode_arm_table[];
+#endif
+
+
+int kprobe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi,
+ const union decode_item *table, bool thumb16);
+
+
#endif /* _ARM_KERNEL_KPROBES_H */
Code Review / linux-3.10.git / blobdiff