accel/tcg/translator.c

   1 /*
   2  * Generic intermediate code generation.
   3  *
   4  * Copyright (C) 2016-2017 Lluís Vilanova <vilanova@ac.upc.edu>
   5  *
   6  * This work is licensed under the terms of the GNU GPL, version 2 or later.
   7  * See the COPYING file in the top-level directory.
   8  */
   9
  10 #include "qemu/osdep.h"
  11 #include "qemu/error-report.h"
  12 #include "cpu.h"
  13 #include "tcg/tcg.h"
  14 #include "tcg/tcg-op.h"
  15 #include "exec/exec-all.h"
  16 #include "exec/gen-icount.h"
  17 #include "exec/log.h"
  18 #include "exec/translator.h"
  19 #include "exec/plugin-gen.h"
  20 #include "sysemu/replay.h"
  21
  22 /* Pairs with tcg_clear_temp_count.
  23    To be called by #TranslatorOps.{translate_insn,tb_stop} if
  24    (1) the target is sufficiently clean to support reporting,
  25    (2) as and when all temporaries are known to be consumed.
  26    For most targets, (2) is at the end of translate_insn.  */
  27 void translator_loop_temp_check(DisasContextBase *db)
  28 {
  29     if (tcg_check_temp_count()) {
  30         qemu_log("warning: TCG temporary leaks before "
  31                  TARGET_FMT_lx "\n", db->pc_next);
  32     }
  33 }
  34
  35 void translator_loop(const TranslatorOps *ops, DisasContextBase *db,
  36                      CPUState *cpu, TranslationBlock *tb, int max_insns)
  37 {
  38     int bp_insn = 0;
  39     bool plugin_enabled;
  40
  41     /* Initialize DisasContext */
  42     db->tb = tb;
  43     db->pc_first = tb->pc;
  44     db->pc_next = db->pc_first;
  45     db->is_jmp = DISAS_NEXT;
  46     db->num_insns = 0;
  47     db->max_insns = max_insns;
  48     db->singlestep_enabled = cpu->singlestep_enabled;
  49
  50     ops->init_disas_context(db, cpu);
  51     tcg_debug_assert(db->is_jmp == DISAS_NEXT);  /* no early exit */
  52
  53     /* Reset the temp count so that we can identify leaks */
  54     tcg_clear_temp_count();
  55
  56     /* Start translating.  */
  57     gen_tb_start(db->tb);
  58     ops->tb_start(db, cpu);
  59     tcg_debug_assert(db->is_jmp == DISAS_NEXT);  /* no early exit */
  60
  61     plugin_enabled = plugin_gen_tb_start(cpu, tb);
  62
  63     while (true) {
  64         db->num_insns++;
  65         ops->insn_start(db, cpu);
  66         tcg_debug_assert(db->is_jmp == DISAS_NEXT);  /* no early exit */
  67
  68         if (plugin_enabled) {
  69             plugin_gen_insn_start(cpu, db);
  70         }
  71
  72         /* Pass breakpoint hits to target for further processing */
  73         if (!db->singlestep_enabled
  74             && unlikely(!QTAILQ_EMPTY(&cpu->breakpoints))) {
  75             CPUBreakpoint *bp;
  76             QTAILQ_FOREACH(bp, &cpu->breakpoints, entry) {
  77                 if (bp->pc == db->pc_next) {
  78                     if (ops->breakpoint_check(db, cpu, bp)) {
  79                         bp_insn = 1;
  80                         break;
  81                     }
  82                 }
  83             }
  84             /* The breakpoint_check hook may use DISAS_TOO_MANY to indicate
  85                that only one more instruction is to be executed.  Otherwise
  86                it should use DISAS_NORETURN when generating an exception,
  87                but may use a DISAS_TARGET_* value for Something Else.  */
  88             if (db->is_jmp > DISAS_TOO_MANY) {
  89                 break;
  90             }
  91         }
  92
  93         /* Disassemble one instruction.  The translate_insn hook should
  94            update db->pc_next and db->is_jmp to indicate what should be
  95            done next -- either exiting this loop or locate the start of
  96            the next instruction.  */
  97         if (db->num_insns == db->max_insns
  98             && (tb_cflags(db->tb) & CF_LAST_IO)) {
  99             /* Accept I/O on the last instruction.  */
 100             gen_io_start();
 101             ops->translate_insn(db, cpu);
 102         } else {
 103             ops->translate_insn(db, cpu);
 104         }
 105
 106         /* Stop translation if translate_insn so indicated.  */
 107         if (db->is_jmp != DISAS_NEXT) {
 108             break;
 109         }
 110
 111         /*
 112          * We can't instrument after instructions that change control
 113          * flow although this only really affects post-load operations.
 114          */
 115         if (plugin_enabled) {
 116             plugin_gen_insn_end();
 117         }
 118
 119         /* Stop translation if the output buffer is full,
 120            or we have executed all of the allowed instructions.  */
 121         if (tcg_op_buf_full() || db->num_insns >= db->max_insns) {
 122             db->is_jmp = DISAS_TOO_MANY;
 123             break;
 124         }
 125     }
 126
 127     /* Emit code to exit the TB, as indicated by db->is_jmp.  */
 128     ops->tb_stop(db, cpu);
 129     gen_tb_end(db->tb, db->num_insns - bp_insn);
 130
 131     if (plugin_enabled) {
 132         plugin_gen_tb_end(cpu);
 133     }
 134
 135     /* The disas_log hook may use these values rather than recompute.  */
 136     tb->size = db->pc_next - db->pc_first;
 137     tb->icount = db->num_insns;
 138
 139 #ifdef DEBUG_DISAS
 140     if (qemu_loglevel_mask(CPU_LOG_TB_IN_ASM)
 141         && qemu_log_in_addr_range(db->pc_first)) {
 142         FILE *logfile = qemu_log_lock();
 143         qemu_log("----------------\n");
 144         ops->disas_log(db, cpu);
 145         qemu_log("\n");
 146         qemu_log_unlock(logfile);
 147     }
 148 #endif
 149 }