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Re: [Qemu-devel] [RFC PATCH v4 11/25] cpu-exec: allow temporary disablin
From: |
Pavel Dovgaluk |
Subject: |
Re: [Qemu-devel] [RFC PATCH v4 11/25] cpu-exec: allow temporary disabling icount |
Date: |
Tue, 11 Nov 2014 12:49:01 +0300 |
> From: Paolo Bonzini [mailto:address@hidden
> 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.
Using context-specific flag is better than using global variable like
use_icount.
But I could not test such changes because they will affect all of the platforms
(and will be also hard to implement for i386).
Pavel Dovgalyuk
- 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