xref: /qemu/include/exec/translator.h (revision 306c872103b4d0986c9f671eb7538b0b70bf69b5)

/*
 * Generic intermediate code generation.
 *
 * Copyright (C) 2016-2017 Lluís Vilanova <vilanova@ac.upc.edu>
 *
 * This work is licensed under the terms of the GNU GPL, version 2 or later.
 * See the COPYING file in the top-level directory.
 */

#ifndef EXEC__TRANSLATOR_H
#define EXEC__TRANSLATOR_H

/*
 * Include this header from a target-specific file, and add a
 *
 *     DisasContextBase base;
 *
 * member in your target-specific DisasContext.
 */


#include "qemu/bswap.h"
#include "exec/exec-all.h"
#include "exec/cpu_ldst.h"
#include "exec/plugin-gen.h"
#include "exec/translate-all.h"
#include "tcg/tcg.h"

/**
 * gen_intermediate_code
 * @cpu: cpu context
 * @tb: translation block
 * @max_insns: max number of instructions to translate
 * @pc: guest virtual program counter address
 * @host_pc: host physical program counter address
 *
 * This function must be provided by the target, which should create
 * the target-specific DisasContext, and then invoke translator_loop.
 */
void gen_intermediate_code(CPUState *cpu, TranslationBlock *tb, int max_insns,
                           target_ulong pc, void *host_pc);

/**
 * DisasJumpType:
 * @DISAS_NEXT: Next instruction in program order.
 * @DISAS_TOO_MANY: Too many instructions translated.
 * @DISAS_NORETURN: Following code is dead.
 * @DISAS_TARGET_*: Start of target-specific conditions.
 *
 * What instruction to disassemble next.
 */
typedef enum DisasJumpType {
    DISAS_NEXT,
    DISAS_TOO_MANY,
    DISAS_NORETURN,
    DISAS_TARGET_0,
    DISAS_TARGET_1,
    DISAS_TARGET_2,
    DISAS_TARGET_3,
    DISAS_TARGET_4,
    DISAS_TARGET_5,
    DISAS_TARGET_6,
    DISAS_TARGET_7,
    DISAS_TARGET_8,
    DISAS_TARGET_9,
    DISAS_TARGET_10,
    DISAS_TARGET_11,
} DisasJumpType;

/**
 * DisasContextBase:
 * @tb: Translation block for this disassembly.
 * @pc_first: Address of first guest instruction in this TB.
 * @pc_next: Address of next guest instruction in this TB (current during
 *           disassembly).
 * @is_jmp: What instruction to disassemble next.
 * @num_insns: Number of translated instructions (including current).
 * @max_insns: Maximum number of instructions to be translated in this TB.
 * @singlestep_enabled: "Hardware" single stepping enabled.
 *
 * Architecture-agnostic disassembly context.
 */
typedef struct DisasContextBase {
    const TranslationBlock *tb;
    target_ulong pc_first;
    target_ulong pc_next;
    DisasJumpType is_jmp;
    int num_insns;
    int max_insns;
    bool singlestep_enabled;
#ifdef CONFIG_USER_ONLY
    /*
     * Guest address of the last byte of the last protected page.
     *
     * Pages containing the translated instructions are made non-writable in
     * order to achieve consistency in case another thread is modifying the
     * code while translate_insn() fetches the instruction bytes piecemeal.
     * Such writer threads are blocked on mmap_lock() in page_unprotect().
     */
    target_ulong page_protect_end;
#endif
} DisasContextBase;

/**
 * TranslatorOps:
 * @init_disas_context:
 *      Initialize the target-specific portions of DisasContext struct.
 *      The generic DisasContextBase has already been initialized.
 *
 * @tb_start:
 *      Emit any code required before the start of the main loop,
 *      after the generic gen_tb_start().
 *
 * @insn_start:
 *      Emit the tcg_gen_insn_start opcode.
 *
 * @translate_insn:
 *      Disassemble one instruction and set db->pc_next for the start
 *      of the following instruction.  Set db->is_jmp as necessary to
 *      terminate the main loop.
 *
 * @tb_stop:
 *      Emit any opcodes required to exit the TB, based on db->is_jmp.
 *
 * @disas_log:
 *      Print instruction disassembly to log.
 */
typedef struct TranslatorOps {
    void (*init_disas_context)(DisasContextBase *db, CPUState *cpu);
    void (*tb_start)(DisasContextBase *db, CPUState *cpu);
    void (*insn_start)(DisasContextBase *db, CPUState *cpu);
    void (*translate_insn)(DisasContextBase *db, CPUState *cpu);
    void (*tb_stop)(DisasContextBase *db, CPUState *cpu);
    void (*disas_log)(const DisasContextBase *db, CPUState *cpu, FILE *f);
} TranslatorOps;

/**
 * translator_loop:
 * @cpu: Target vCPU.
 * @tb: Translation block.
 * @max_insns: Maximum number of insns to translate.
 * @pc: guest virtual program counter address
 * @host_pc: host physical program counter address
 * @ops: Target-specific operations.
 * @db: Disassembly context.
 *
 * Generic translator loop.
 *
 * Translation will stop in the following cases (in order):
 * - When is_jmp set by #TranslatorOps::breakpoint_check.
 *   - set to DISAS_TOO_MANY exits after translating one more insn
 *   - set to any other value than DISAS_NEXT exits immediately.
 * - When is_jmp set by #TranslatorOps::translate_insn.
 *   - set to any value other than DISAS_NEXT exits immediately.
 * - When the TCG operation buffer is full.
 * - When single-stepping is enabled (system-wide or on the current vCPU).
 * - When too many instructions have been translated.
 */
void translator_loop(CPUState *cpu, TranslationBlock *tb, int max_insns,
                     target_ulong pc, void *host_pc,
                     const TranslatorOps *ops, DisasContextBase *db);

void translator_loop_temp_check(DisasContextBase *db);

/**
 * translator_use_goto_tb
 * @db: Disassembly context
 * @dest: target pc of the goto
 *
 * Return true if goto_tb is allowed between the current TB
 * and the destination PC.
 */
bool translator_use_goto_tb(DisasContextBase *db, target_ulong dest);

/*
 * Translator Load Functions
 *
 * These are intended to replace the direct usage of the cpu_ld*_code
 * functions and are mandatory for front-ends that have been migrated
 * to the common translator_loop. These functions are only intended
 * to be called from the translation stage and should not be called
 * from helper functions. Those functions should be converted to encode
 * the relevant information at translation time.
 */

#define GEN_TRANSLATOR_LD(fullname, type, load_fn, swap_fn)             \
    type fullname ## _swap(CPUArchState *env, DisasContextBase *dcbase, \
                           abi_ptr pc, bool do_swap);                   \
    static inline type fullname(CPUArchState *env,                      \
                                DisasContextBase *dcbase, abi_ptr pc)   \
    {                                                                   \
        return fullname ## _swap(env, dcbase, pc, false);               \
    }

#define FOR_EACH_TRANSLATOR_LD(F)                                       \
    F(translator_ldub, uint8_t, cpu_ldub_code, /* no swap */)           \
    F(translator_lduw, uint16_t, cpu_lduw_code, bswap16)                \
    F(translator_ldl, uint32_t, cpu_ldl_code, bswap32)                  \
    F(translator_ldq, uint64_t, cpu_ldq_code, bswap64)

FOR_EACH_TRANSLATOR_LD(GEN_TRANSLATOR_LD)

#undef GEN_TRANSLATOR_LD

/*
 * Return whether addr is on the same page as where disassembly started.
 * Translators can use this to enforce the rule that only single-insn
 * translation blocks are allowed to cross page boundaries.
 */
static inline bool is_same_page(const DisasContextBase *db, target_ulong addr)
{
    return ((addr ^ db->pc_first) & TARGET_PAGE_MASK) == 0;
}

#endif /* EXEC__TRANSLATOR_H */