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cpu-exec: Do not invalidate original TB in cpu_exec_nocache()

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Instead of invalidating an original TB in cpu_exec_nocache()
prematurely, just save a link to it in the temporary generated TB. If
cpu_io_recompile() is raised subsequently from the temporary TB,
invalidate the original one as well. That allows reusing the original TB
each time cpu_exec_nocache() is called to handle expired instruction
counter in icount mode.

Signed-off-by: Sergey Fedorov <serge.fdrv@gmail.com>
Message-Id: <1435656909-29116-1-git-send-email-serge.fdrv@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sergey Fedorov 2015-06-30 12:35:09 +03:00 committed by Paolo Bonzini
parent af103c9310
commit 02d57ea115
3 changed files with 12 additions and 6 deletions
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8
cpu-exec.c
View File

@ -231,19 +231,15 @@ static void cpu_exec_nocache(CPUState *cpu, int max_cycles,
TranslationBlock *orig_tb)
{
TranslationBlock *tb;
target_ulong pc = orig_tb->pc;
target_ulong cs_base = orig_tb->cs_base;
uint64_t flags = orig_tb->flags;
/* Should never happen.
We only end up here when an existing TB is too long. */
if (max_cycles > CF_COUNT_MASK)
max_cycles = CF_COUNT_MASK;
/* 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,
tb = tb_gen_code(cpu, orig_tb->pc, orig_tb->cs_base, orig_tb->flags,
max_cycles | CF_NOCACHE);
tb->orig_tb = tcg_ctx.tb_ctx.tb_invalidated_flag ? NULL : orig_tb;
cpu->current_tb = tb;
/* execute the generated code */
trace_exec_tb_nocache(tb, tb->pc);

2
include/exec/exec-all.h
View File

@ -155,6 +155,8 @@ struct TranslationBlock {
void *tc_ptr; /* pointer to the translated code */
/* next matching tb for physical address. */
struct TranslationBlock *phys_hash_next;
/* original tb when cflags has CF_NOCACHE */
struct TranslationBlock *orig_tb;
/* first and second physical page containing code. The lower bit
of the pointer tells the index in page_next[] */
struct TranslationBlock *page_next[2];

8
translate-all.c
View File

@ -1533,6 +1533,14 @@ void cpu_io_recompile(CPUState *cpu, uintptr_t retaddr)
cs_base = tb->cs_base;
flags = tb->flags;
tb_phys_invalidate(tb, -1);
if (tb->cflags & CF_NOCACHE) {
if (tb->orig_tb) {
/* Invalidate original TB if this TB was generated in
* cpu_exec_nocache() */
tb_phys_invalidate(tb->orig_tb, -1);
}
tb_free(tb);
}
/* FIXME: In theory this could raise an exception. In practice
we have already translated the block once so it's probably ok. */
tb_gen_code(cpu, pc, cs_base, flags, cflags);