qemu/include/exec/translation-block.h

/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
 * Definition of TranslationBlock.
 *  Copyright (c) 2003 Fabrice Bellard
 */

#ifndef EXEC_TRANSLATION_BLOCK_H
#define EXEC_TRANSLATION_BLOCK_H

#include "qemu/thread.h"
#include "exec/cpu-common.h"
#ifdef CONFIG_USER_ONLY
#include "qemu/interval-tree.h"
#endif

/*
 * Page tracking code uses ram addresses in system mode, and virtual
 * addresses in userspace mode.  Define tb_page_addr_t to be an
 * appropriate type.
 */
#if defined(CONFIG_USER_ONLY)
typedef vaddr tb_page_addr_t;
#define TB_PAGE_ADDR_FMT "%" VADDR_PRIx
#else
typedef ram_addr_t tb_page_addr_t;
#define TB_PAGE_ADDR_FMT RAM_ADDR_FMT
#endif

/*
 * Translation Cache-related fields of a TB.
 * This struct exists just for convenience; we keep track of TB's in a binary
 * search tree, and the only fields needed to compare TB's in the tree are
 * @ptr and @size.
 * Note: the address of search data can be obtained by adding @size to @ptr.
 */
struct tb_tc {
    const void *ptr;    /* pointer to the translated code */
    size_t size;
};

struct TranslationBlock {
    /*
     * Guest PC corresponding to this block.  This must be the true
     * virtual address.  Therefore e.g. x86 stores EIP + CS_BASE, and
     * targets like Arm, MIPS, HP-PA, which reuse low bits for ISA or
     * privilege, must store those bits elsewhere.
     *
     * If CF_PCREL, the opcodes for the TranslationBlock are written
     * such that the TB is associated only with the physical page and
     * may be run in any virtual address context.  In this case, PC
     * must always be taken from ENV in a target-specific manner.
     * Unwind information is taken as offsets from the page, to be
     * deposited into the "current" PC.
     */
    vaddr pc;

    /*
     * Target-specific data associated with the TranslationBlock, e.g.:
     * x86: the original user, the Code Segment virtual base,
     * arm: an extension of tb->flags,
     * s390x: instruction data for EXECUTE,
     * sparc: the next pc of the instruction queue (for delay slots).
     */
    uint64_t cs_base;

    uint32_t flags; /* flags defining in which context the code was generated */
    uint32_t cflags;    /* compile flags */

/* Note that TCG_MAX_INSNS is 512; we validate this match elsewhere. */
#define CF_COUNT_MASK    0x000001ff
#define CF_NO_GOTO_TB    0x00000200 /* Do not chain with goto_tb */
#define CF_NO_GOTO_PTR   0x00000400 /* Do not chain with goto_ptr */
#define CF_SINGLE_STEP   0x00000800 /* gdbstub single-step in effect */
#define CF_MEMI_ONLY     0x00001000 /* Only instrument memory ops */
#define CF_USE_ICOUNT    0x00002000
#define CF_INVALID       0x00004000 /* TB is stale. Set with @jmp_lock held */
#define CF_PARALLEL      0x00008000 /* Generate code for a parallel context */
#define CF_NOIRQ         0x00010000 /* Generate an uninterruptible TB */
#define CF_PCREL         0x00020000 /* Opcodes in TB are PC-relative */
#define CF_BP_PAGE       0x00040000 /* Breakpoint present in code page */
#define CF_CLUSTER_MASK  0xff000000 /* Top 8 bits are cluster ID */
#define CF_CLUSTER_SHIFT 24

    /*
     * Above fields used for comparing
     */

    /* size of target code for this block (1 <= size <= TARGET_PAGE_SIZE) */
    uint16_t size;
    uint16_t icount;

    struct tb_tc tc;

    /*
     * Track tb_page_addr_t intervals that intersect this TB.
     * For user-only, the virtual addresses are always contiguous,
     * and we use a unified interval tree.  For system, we use a
     * linked list headed in each PageDesc.  Within the list, the lsb
     * of the previous pointer tells the index of page_next[], and the
     * list is protected by the PageDesc lock(s).
     */
#ifdef CONFIG_USER_ONLY
    IntervalTreeNode itree;
#else
    uintptr_t page_next[2];
    tb_page_addr_t page_addr[2];
#endif

    /* jmp_lock placed here to fill a 4-byte hole. Its documentation is below */
    QemuSpin jmp_lock;

    /* The following data are used to directly call another TB from
     * the code of this one. This can be done either by emitting direct or
     * indirect native jump instructions. These jumps are reset so that the TB
     * just continues its execution. The TB can be linked to another one by
     * setting one of the jump targets (or patching the jump instruction). Only
     * two of such jumps are supported.
     */
#define TB_JMP_OFFSET_INVALID 0xffff /* indicates no jump generated */
    uint16_t jmp_reset_offset[2]; /* offset of original jump target */
    uint16_t jmp_insn_offset[2];  /* offset of direct jump insn */
    uintptr_t jmp_target_addr[2]; /* target address */

    /*
     * Each TB has a NULL-terminated list (jmp_list_head) of incoming jumps.
     * Each TB can have two outgoing jumps, and therefore can participate
     * in two lists. The list entries are kept in jmp_list_next[2]. The least
     * significant bit (LSB) of the pointers in these lists is used to encode
     * which of the two list entries is to be used in the pointed TB.
     *
     * List traversals are protected by jmp_lock. The destination TB of each
     * outgoing jump is kept in jmp_dest[] so that the appropriate jmp_lock
     * can be acquired from any origin TB.
     *
     * jmp_dest[] are tagged pointers as well. The LSB is set when the TB is
     * being invalidated, so that no further outgoing jumps from it can be set.
     *
     * jmp_lock also protects the CF_INVALID cflag; a jump must not be chained
     * to a destination TB that has CF_INVALID set.
     */
    uintptr_t jmp_list_head;
    uintptr_t jmp_list_next[2];
    uintptr_t jmp_dest[2];
};

/* The alignment given to TranslationBlock during allocation. */
#define CODE_GEN_ALIGN  16

/* Hide the qatomic_read to make code a little easier on the eyes */
static inline uint32_t tb_cflags(const TranslationBlock *tb)
{
    return qatomic_read(&tb->cflags);
}

#endif /* EXEC_TRANSLATION_BLOCK_H */