Re: [Qemu-devel] [PATCH 3/5] exec: fix code tlb entry misused as iotlb in get_page_addr_code()

[Max Filippov]

>> >>> get_page_addr_code() reads a code tlb entry, but interprets it as an
>> >>> iotlb entry.  This works by accident since the low bits of a RAM code
>> >>> tlb entry are clear, and match a RAM iotlb entry.  This accident is
>> >>> about to unhappen, so fix the code to use an iotlb entry (using the
>> >>> code entry with TLB_MMIO may fail if the page is a watchpoint).
>> >>>
>> >>> Signed-off-by: Avi Kivity<address@hidden>
>> >>> ---
>> >>>   exec.c |    2 +-
>> >>>   1 files changed, 1 insertions(+), 1 deletions(-)
>> >>>
>> >>> diff --git a/exec.c b/exec.c
>> >>> index a35eb4f..f26d1b0 100644
>> >>> --- a/exec.c
>> >>> +++ b/exec.c
>> >>> @@ -4685,7 +4685,7 @@ tb_page_addr_t get_page_addr_code(CPUState
>> >>> *env1, target_ulong addr)
>> >>>                    (addr&  TARGET_PAGE_MASK))) {
>> >>>           ldub_code(addr);
>> >>>       }
>> >>> -    pd = env1->tlb_table[mmu_idx][page_index].addr_code&
>> >>> ~TARGET_PAGE_MASK;
>> >>> +    pd = env1->iotlb[mmu_idx][page_index]&  ~TARGET_PAGE_MASK;
>> >>>       if (pd != io_mem_ram.ram_addr&&  pd != io_mem_rom.ram_addr
>> >>>           &&  !io_mem_region[pd]->rom_device) {
>> >>>   #if defined(TARGET_ALPHA) || defined(TARGET_MIPS) ||
>> >>> defined(TARGET_SPARC)
>> >>
>> >> With this patch xtensa debug option unit test causes qemu abort with
>> >> the message
>> >>
>> >>  qemu: fatal: Trying to execute code outside RAM or ROM at 0xd000088c
>> >>
>> >> This happens immediately after a watchpoint setup for a data
>> >> breakpoint at the same memory page where the currently
>> >> executed code is located. Any idea on how to fix it?
>> >
>> > Can you provide details on how to reproduce this?
>>
>> It may be reproduced by running test_break.tst unit test:
>>
>> qemu-system-xtensa -M sim -cpu dc232b -nographic -semihosting  -kernel
>> ./test_break.tst
>>
>> Compiled test binary is here:
>> http://jcmvbkbc.spb.ru/~dumb/ws/osll/qemu-xtensa/20120318/test_break.tst
>>
>
> Thanks.  Please try out the attached patch.

Thanks, with this patch it works.

-- Max