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authorPavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>2018-04-09 12:13:20 +0300
committerRichard Henderson <richard.henderson@linaro.org>2018-04-11 09:05:22 +1000
commitafd46fcad2dceffda35c0586f5723c127b6e09d8 (patch)
tree0ffa115279d72c7fd54726561a41cd58f1a1d004 /target/m68k
parent26d6a7c87b05017ffabffb5e16837a0fccf67e90 (diff)
icount: fix cpu_restore_state_from_tb for non-tb-exit cases
In icount mode, instructions that access io memory spaces in the middle of the translation block invoke TB recompilation. After recompilation, such instructions become last in the TB and are allowed to access io memory spaces. When the code includes instruction like i386 'xchg eax, 0xffffd080' which accesses APIC, QEMU goes into an infinite loop of the recompilation. This instruction includes two memory accesses - one read and one write. After the first access, APIC calls cpu_report_tpr_access, which restores the CPU state to get the current eip. But cpu_restore_state_from_tb resets the cpu->can_do_io flag which makes the second memory access invalid. Therefore the second memory access causes a recompilation of the block. Then these operations repeat again and again. This patch moves resetting cpu->can_do_io flag from cpu_restore_state_from_tb to cpu_loop_exit* functions. It also adds a parameter for cpu_restore_state which controls restoring icount. There is no need to restore icount when we only query CPU state without breaking the TB. Restoring it in such cases leads to the incorrect flow of the virtual time. In most cases new parameter is true (icount should be recalculated). But there are two cases in i386 and openrisc when the CPU state is only queried without the need to break the TB. This patch fixes both of these cases. Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru> Message-Id: <20180409091320.12504.35329.stgit@pasha-VirtualBox> [rth: Make can_do_io setting unconditional; move from cpu_exec; make cpu_loop_exit_{noexc,restore} call cpu_loop_exit.] Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Diffstat (limited to 'target/m68k')
-rw-r--r--target/m68k/op_helper.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/target/m68k/op_helper.c b/target/m68k/op_helper.c
index ffea9693fc..3a7f7f2219 100644
--- a/target/m68k/op_helper.c
+++ b/target/m68k/op_helper.c
@@ -1056,7 +1056,7 @@ void HELPER(chk)(CPUM68KState *env, int32_t val, int32_t ub)
CPUState *cs = CPU(m68k_env_get_cpu(env));
/* Recover PC and CC_OP for the beginning of the insn. */
- cpu_restore_state(cs, GETPC());
+ cpu_restore_state(cs, GETPC(), true);
/* flags have been modified by gen_flush_flags() */
env->cc_op = CC_OP_FLAGS;
@@ -1087,7 +1087,7 @@ void HELPER(chk2)(CPUM68KState *env, int32_t val, int32_t lb, int32_t ub)
CPUState *cs = CPU(m68k_env_get_cpu(env));
/* Recover PC and CC_OP for the beginning of the insn. */
- cpu_restore_state(cs, GETPC());
+ cpu_restore_state(cs, GETPC(), true);
/* flags have been modified by gen_flush_flags() */
env->cc_op = CC_OP_FLAGS;