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https://github.com/yuzu-emu/unicorn.git
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b4bf3c776b
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. Backports commit afd46fcad2dceffda35c0586f5723c127b6e09d8 from qemu
53 lines
1.4 KiB
C
53 lines
1.4 KiB
C
/*
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* emulator main execution loop
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*
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* Copyright (c) 2003-2005 Fabrice Bellard
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*/
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#include "qemu/osdep.h"
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#include "cpu.h"
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#include "sysemu/cpus.h"
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#include "exec/exec-all.h"
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#include "exec/memory-internal.h"
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/* exit the current TB, but without causing any exception to be raised */
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void cpu_loop_exit_noexc(CPUState *cpu)
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{
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cpu->exception_index = -1;
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cpu_loop_exit(cpu);
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}
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void cpu_loop_exit(CPUState *cpu)
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{
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/* Undo the setting in cpu_tb_exec. */
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cpu->can_do_io = 1;
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siglongjmp(cpu->jmp_env, 1);
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}
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void cpu_loop_exit_restore(CPUState *cpu, uintptr_t pc)
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{
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if (pc) {
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cpu_restore_state(cpu, pc, true);
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}
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cpu_loop_exit(cpu);
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}
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void cpu_loop_exit_atomic(CPUState *cpu, uintptr_t pc)
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{
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cpu->exception_index = EXCP_ATOMIC;
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cpu_loop_exit_restore(cpu, pc);
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}
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