[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [RFC PATCH v4 11/25] cpu-exec: allow temporary disablin
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [RFC PATCH v4 11/25] cpu-exec: allow temporary disabling icount |
Date: |
Fri, 07 Nov 2014 12:22:29 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 |
On 07/11/2014 11:32, Pavel Dovgalyuk wrote:
> This patch is required for deterministic replay to generate an exception
> by trying executing an instruction without changing icount.
> It adds new flag to TB for disabling icount while translating it.
>
> Signed-off-by: Pavel Dovgalyuk <address@hidden>
> ---
> cpu-exec.c | 6 +++---
> include/exec/exec-all.h | 7 ++++---
> translate-all.c | 22 ++++++++++++++++++++--
> 3 files changed, 27 insertions(+), 8 deletions(-)
>
> diff --git a/cpu-exec.c b/cpu-exec.c
> index 011f51f..e7206ac 100644
> --- a/cpu-exec.c
> +++ b/cpu-exec.c
> @@ -198,7 +198,7 @@ static inline tcg_target_ulong cpu_tb_exec(CPUState *cpu,
> uint8_t *tb_ptr)
> /* Execute the code without caching the generated code. An interpreter
> could be used if available. */
> static void cpu_exec_nocache(CPUArchState *env, int max_cycles,
> - TranslationBlock *orig_tb)
> + TranslationBlock *orig_tb, bool ignore_icount)
> {
> CPUState *cpu = ENV_GET_CPU(env);
> TranslationBlock *tb;
> @@ -214,7 +214,7 @@ static void cpu_exec_nocache(CPUArchState *env, int
> max_cycles,
> /* tb_gen_code can flush our orig_tb, invalidate it now */
> tb_phys_invalidate(orig_tb, -1);
> tb = tb_gen_code(cpu, pc, cs_base, flags,
> - max_cycles);
> + max_cycles | (ignore_icount ? CF_IGNORE_ICOUNT : 0));
> cpu->current_tb = tb;
> /* execute the generated code */
> trace_exec_tb_nocache(tb, tb->pc);
> @@ -516,7 +516,7 @@ int cpu_exec(CPUArchState *env)
> } else {
> if (insns_left > 0) {
> /* Execute remaining instructions. */
> - cpu_exec_nocache(env, insns_left, tb);
> + cpu_exec_nocache(env, insns_left, tb, false);
> align_clocks(&sc, cpu);
> }
> cpu->exception_index = EXCP_INTERRUPT;
> diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
> index 1d17f75..052e8ef 100644
> --- a/include/exec/exec-all.h
> +++ b/include/exec/exec-all.h
> @@ -142,9 +142,10 @@ struct TranslationBlock {
> uint64_t flags; /* flags defining in which context the code was
> generated */
> uint16_t size; /* size of target code for this block (1 <=
> size <= TARGET_PAGE_SIZE) */
> - uint16_t cflags; /* compile flags */
> -#define CF_COUNT_MASK 0x7fff
> -#define CF_LAST_IO 0x8000 /* Last insn may be an IO access. */
> + uint32_t cflags; /* compile flags */
> +#define CF_COUNT_MASK 0x7fff
> +#define CF_LAST_IO 0x8000 /* Last insn may be an IO access. */
> +#define CF_IGNORE_ICOUNT 0x10000 /* Do not generate icount code */
>
> void *tc_ptr; /* pointer to the translated code */
> /* next matching tb for physical address. */
> diff --git a/translate-all.c b/translate-all.c
> index 7177b71..182ea7d 100644
> --- a/translate-all.c
> +++ b/translate-all.c
> @@ -207,6 +207,7 @@ static int cpu_restore_state_from_tb(CPUState *cpu,
> TranslationBlock *tb,
> TCGContext *s = &tcg_ctx;
> int j;
> uintptr_t tc_ptr;
> + int old_icount = use_icount;
> #ifdef CONFIG_PROFILER
> int64_t ti;
> #endif
> @@ -218,6 +219,10 @@ static int cpu_restore_state_from_tb(CPUState *cpu,
> TranslationBlock *tb,
>
> gen_intermediate_code_pc(env, tb);
>
> + if (tb->cflags & CF_IGNORE_ICOUNT) {
Would it be possible to instead have a CF_USE_ICOUNT tbflag, and check
it when applicable instead of use_icount? It seems cleaner, because it
would avoid playing with global variables, but perhaps it's hard to do it.
Paolo
> + use_icount = 0;
> + }
> +
> if (use_icount) {
> /* Reset the cycle counter to the start of the block. */
> cpu->icount_decr.u16.low += tb->icount;
> @@ -227,8 +232,10 @@ static int cpu_restore_state_from_tb(CPUState *cpu,
> TranslationBlock *tb,
>
> /* find opc index corresponding to search_pc */
> tc_ptr = (uintptr_t)tb->tc_ptr;
> - if (searched_pc < tc_ptr)
> + if (searched_pc < tc_ptr) {
> + use_icount = old_icount;
> return -1;
> + }
>
> s->tb_next_offset = tb->tb_next_offset;
> #ifdef USE_DIRECT_JUMP
> @@ -240,8 +247,10 @@ static int cpu_restore_state_from_tb(CPUState *cpu,
> TranslationBlock *tb,
> #endif
> j = tcg_gen_code_search_pc(s, (tcg_insn_unit *)tc_ptr,
> searched_pc - tc_ptr);
> - if (j < 0)
> + if (j < 0) {
> + use_icount = old_icount;
> return -1;
> + }
> /* now find start of instruction before */
> while (s->gen_opc_instr_start[j] == 0) {
> j--;
> @@ -254,6 +263,8 @@ static int cpu_restore_state_from_tb(CPUState *cpu,
> TranslationBlock *tb,
> s->restore_time += profile_getclock() - ti;
> s->restore_count++;
> #endif
> + use_icount = old_icount;
> +
> return 0;
> }
>
> @@ -264,6 +275,8 @@ bool cpu_restore_state(CPUState *cpu, uintptr_t retaddr)
> tb = tb_find_pc(retaddr);
> if (tb) {
> cpu_restore_state_from_tb(cpu, tb, retaddr);
> + /* tb could be temporary, generated by exec nocache */
> + tb_phys_invalidate(tb, -1);
> return true;
> }
> return false;
> @@ -1045,6 +1058,7 @@ TranslationBlock *tb_gen_code(CPUState *cpu,
> tb_page_addr_t phys_pc, phys_page2;
> target_ulong virt_page2;
> int code_gen_size;
> + int old_icount = use_icount;
>
> phys_pc = get_page_addr_code(env, pc);
> tb = tb_alloc(pc);
> @@ -1060,9 +1074,13 @@ TranslationBlock *tb_gen_code(CPUState *cpu,
> tb->cs_base = cs_base;
> tb->flags = flags;
> tb->cflags = cflags;
> + if (cflags & CF_IGNORE_ICOUNT) {
> + use_icount = 0;
> + }
> cpu_gen_code(env, tb, &code_gen_size);
> tcg_ctx.code_gen_ptr = (void *)(((uintptr_t)tcg_ctx.code_gen_ptr +
> code_gen_size + CODE_GEN_ALIGN - 1) & ~(CODE_GEN_ALIGN - 1));
> + use_icount = old_icount;
>
> /* check next page if needed */
> virt_page2 = (pc + tb->size - 1) & TARGET_PAGE_MASK;
>
- Re: [Qemu-devel] [RFC PATCH v4 07/25] icount: implement icount requesting, (continued)
[Qemu-devel] [RFC PATCH v4 08/25] icount: improve enable/disable ticks, Pavel Dovgalyuk, 2014/11/07
[Qemu-devel] [RFC PATCH v4 09/25] replay: introduce icount event, Pavel Dovgalyuk, 2014/11/07
[Qemu-devel] [RFC PATCH v4 10/25] i386: do not cross the pages boundaries in replay mode, Pavel Dovgalyuk, 2014/11/07
[Qemu-devel] [RFC PATCH v4 11/25] cpu-exec: allow temporary disabling icount, Pavel Dovgalyuk, 2014/11/07
[Qemu-devel] [RFC PATCH v4 12/25] replay: interrupts and exceptions, Pavel Dovgalyuk, 2014/11/07
[Qemu-devel] [RFC PATCH v4 13/25] replay: asynchronous events infrastructure, Pavel Dovgalyuk, 2014/11/07
[Qemu-devel] [RFC PATCH v4 14/25] cpu: replay instructions sequence, Pavel Dovgalyuk, 2014/11/07
[Qemu-devel] [RFC PATCH v4 15/25] replay: recording and replaying clock ticks, Pavel Dovgalyuk, 2014/11/07
[Qemu-devel] [RFC PATCH v4 17/25] cpus: make icount warp deterministic in replay mode, Pavel Dovgalyuk, 2014/11/07