diff options
Diffstat (limited to 'tcg/tcg.h')
| -rw-r--r-- | tcg/tcg.h | 19 |
1 files changed, 10 insertions, 9 deletions
@@ -925,7 +925,7 @@ static inline unsigned get_mmuidx(TCGMemOpIdx oi) /** * tcg_qemu_tb_exec: - * @env: CPUArchState * for the CPU + * @env: pointer to CPUArchState for the CPU * @tb_ptr: address of generated code for the TB to execute * * Start executing code from a given translation block. @@ -936,30 +936,31 @@ static inline unsigned get_mmuidx(TCGMemOpIdx oi) * which has not yet been directly linked, or an asynchronous * event such as an interrupt needs handling. * - * The return value is a pointer to the next TB to execute - * (if known; otherwise zero). This pointer is assumed to be - * 4-aligned, and the bottom two bits are used to return further - * information: + * Return: The return value is the value passed to the corresponding + * tcg_gen_exit_tb() at translation time of the last TB attempted to execute. + * The value is either zero or a 4-byte aligned pointer to that TB combined + * with additional information in its two least significant bits. The + * additional information is encoded as follows: * 0, 1: the link between this TB and the next is via the specified * TB index (0 or 1). That is, we left the TB via (the equivalent * of) "goto_tb <index>". The main loop uses this to determine * how to link the TB just executed to the next. * 2: we are using instruction counting code generation, and we * did not start executing this TB because the instruction counter - * would hit zero midway through it. In this case the next-TB pointer + * would hit zero midway through it. In this case the pointer * returned is the TB we were about to execute, and the caller must * arrange to execute the remaining count of instructions. * 3: we stopped because the CPU's exit_request flag was set * (usually meaning that there is an interrupt that needs to be - * handled). The next-TB pointer returned is the TB we were - * about to execute when we noticed the pending exit request. + * handled). The pointer returned is the TB we were about to execute + * when we noticed the pending exit request. * * If the bottom two bits indicate an exit-via-index then the CPU * state is correctly synchronised and ready for execution of the next * TB (and in particular the guest PC is the address to execute next). * Otherwise, we gave up on execution of this TB before it started, and * the caller must fix up the CPU state by calling the CPU's - * synchronize_from_tb() method with the next-TB pointer we return (falling + * synchronize_from_tb() method with the TB pointer we return (falling * back to calling the CPU's set_pc method with tb->pb if no * synchronize_from_tb() method exists). * |