mirror of https://github.com/proxmox/mirror_qemu
exec.c: Fix breakpoint invalidation race
A bug (1647683) was reported showing a crash when removing
breakpoints. The reproducer was bisected to 3359baad
when tb_flush
was finally made thread safe. While in MTTCG the locking in
breakpoint_invalidate would have prevented any problems, but
currently tb_lock() is a NOP for system emulation.
The race is between a tb_flush from the gdbstub and the
tb_invalidate_phys_addr() in breakpoint_invalidate().
Ideally we'd have actual locking here; for the moment the
simple fix is to do a full tb_flush() for a bp invalidate,
since that is thread-safe even if no lock is taken.
Reported-by: Julian Brown <julian@codesourcery.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1481047629-7763-1-git-send-email-peter.maydell@linaro.org
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
master
parent
d750c3a966
commit
a9353fe897
25
exec.c
25
exec.c
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@ -684,28 +684,15 @@ void cpu_exec_realizefn(CPUState *cpu, Error **errp)
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#endif
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#endif
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}
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}
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#if defined(CONFIG_USER_ONLY)
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static void breakpoint_invalidate(CPUState *cpu, target_ulong pc)
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static void breakpoint_invalidate(CPUState *cpu, target_ulong pc)
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{
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{
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mmap_lock();
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/* Flush the whole TB as this will not have race conditions
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tb_lock();
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* even if we don't have proper locking yet.
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tb_invalidate_phys_page_range(pc, pc + 1, 0);
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* Ideally we would just invalidate the TBs for the
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tb_unlock();
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* specified PC.
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mmap_unlock();
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*/
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tb_flush(cpu);
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}
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}
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#else
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static void breakpoint_invalidate(CPUState *cpu, target_ulong pc)
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{
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MemTxAttrs attrs;
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hwaddr phys = cpu_get_phys_page_attrs_debug(cpu, pc, &attrs);
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int asidx = cpu_asidx_from_attrs(cpu, attrs);
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if (phys != -1) {
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/* Locks grabbed by tb_invalidate_phys_addr */
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tb_invalidate_phys_addr(cpu->cpu_ases[asidx].as,
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phys | (pc & ~TARGET_PAGE_MASK));
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}
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}
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#endif
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#if defined(CONFIG_USER_ONLY)
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#if defined(CONFIG_USER_ONLY)
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void cpu_watchpoint_remove_all(CPUState *cpu, int mask)
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void cpu_watchpoint_remove_all(CPUState *cpu, int mask)
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