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authorRichard Henderson <richard.henderson@linaro.org>2018-03-19 11:15:45 +0800
committerPaolo Bonzini <pbonzini@redhat.com>2018-03-26 14:37:14 +0200
commit87f963be66a32453e001d1052b000f1653605caa (patch)
treefbf9e91be60a6e3c53f99f20509dab2906eacd5e /accel/tcg/translate-all.c
parent8e029fd64ea09cea4cd5cfd7c4c04714571cbae6 (diff)
tcg: Really fix cpu_io_recompile
We have confused the number of instructions that have been executed in the TB with the number of instructions needed to repeat the I/O instruction. We have used cpu_restore_state_from_tb, which means that the guest pc is pointing to the I/O instruction. The only time the answer to the later question is not 1 is when MIPS or SH4 need to re-execute the branch for the delay slot as well. We must rely on cpu->cflags_next_tb to generate the next TB, as otherwise we have a race condition with other guest cpus within the TB cache. Fixes: 0790f86861079b1932679d0f011e431aaf4ee9e2 Signed-off-by: Richard Henderson <richard.henderson@linaro.org> Message-Id: <20180319031545.29359-1-richard.henderson@linaro.org> Tested-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'accel/tcg/translate-all.c')
-rw-r--r--accel/tcg/translate-all.c37
1 files changed, 10 insertions, 27 deletions
diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
index 5ad1b919bc..d4190602d1 100644
--- a/accel/tcg/translate-all.c
+++ b/accel/tcg/translate-all.c
@@ -1728,8 +1728,7 @@ void cpu_io_recompile(CPUState *cpu, uintptr_t retaddr)
CPUArchState *env = cpu->env_ptr;
#endif
TranslationBlock *tb;
- uint32_t n, flags;
- target_ulong pc, cs_base;
+ uint32_t n;
tb_lock();
tb = tb_find_pc(retaddr);
@@ -1737,44 +1736,33 @@ void cpu_io_recompile(CPUState *cpu, uintptr_t retaddr)
cpu_abort(cpu, "cpu_io_recompile: could not find TB for pc=%p",
(void *)retaddr);
}
- n = cpu->icount_decr.u16.low + tb->icount;
cpu_restore_state_from_tb(cpu, tb, retaddr);
- /* Calculate how many instructions had been executed before the fault
- occurred. */
- n = n - cpu->icount_decr.u16.low;
- /* Generate a new TB ending on the I/O insn. */
- n++;
+
/* On MIPS and SH, delay slot instructions can only be restarted if
they were already the first instruction in the TB. If this is not
the first instruction in a TB then re-execute the preceding
branch. */
+ n = 1;
#if defined(TARGET_MIPS)
- if ((env->hflags & MIPS_HFLAG_BMASK) != 0 && n > 1) {
+ if ((env->hflags & MIPS_HFLAG_BMASK) != 0
+ && env->active_tc.PC != tb->pc) {
env->active_tc.PC -= (env->hflags & MIPS_HFLAG_B16 ? 2 : 4);
cpu->icount_decr.u16.low++;
env->hflags &= ~MIPS_HFLAG_BMASK;
+ n = 2;
}
#elif defined(TARGET_SH4)
if ((env->flags & ((DELAY_SLOT | DELAY_SLOT_CONDITIONAL))) != 0
- && n > 1) {
+ && env->pc != tb->pc) {
env->pc -= 2;
cpu->icount_decr.u16.low++;
env->flags &= ~(DELAY_SLOT | DELAY_SLOT_CONDITIONAL);
+ n = 2;
}
#endif
- /* This should never happen. */
- if (n > CF_COUNT_MASK) {
- cpu_abort(cpu, "TB too big during recompile");
- }
- pc = tb->pc;
- cs_base = tb->cs_base;
- flags = tb->flags;
- tb_phys_invalidate(tb, -1);
-
- /* Execute one IO instruction without caching
- instead of creating large TB. */
- cpu->cflags_next_tb = curr_cflags() | CF_LAST_IO | CF_NOCACHE | 1;
+ /* Generate a new TB executing the I/O insn. */
+ cpu->cflags_next_tb = curr_cflags() | CF_LAST_IO | n;
if (tb->cflags & CF_NOCACHE) {
if (tb->orig_tb) {
@@ -1785,11 +1773,6 @@ void cpu_io_recompile(CPUState *cpu, uintptr_t retaddr)
tb_remove(tb);
}
- /* Generate new TB instead of the current one. */
- /* 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, curr_cflags() | CF_LAST_IO | n);
-
/* TODO: If env->pc != tb->pc (i.e. the faulting instruction was not
* the first in the TB) then we end up generating a whole new TB and
* repeating the fault, which is horribly inefficient.