Re: [Qemu-devel] int128_get64: Assertion `!a.hi' failed

[Max Filippov]

On Fri, Sep 27, 2013 at 11:36 PM, Paolo Bonzini <address@hidden> wrote:
> Il 27/09/2013 20:29, Max Filippov ha scritto:
>> Hi,
>>
>> I'm getting said assertion failure debugging linux userspace
>> application through the qemu gdbstub. The backtrace looks like this:
>>
>> qemu-system-xtensa: include/qemu/int128.h:22: int128_get64: Assertion 
>> `!a.hi' failed.
>>
>> Program received signal SIGABRT, Aborted.
>> [Switching to Thread 0x7ffff7fe8880 (LWP 15378)]
>> 0x00007ffff639e285 in raise () from /lib64/libc.so.6
>> (gdb) bt
>> #0  0x00007ffff639e285 in raise () from /lib64/libc.so.6
>> #1  0x00007ffff639fb9b in abort () from /lib64/libc.so.6
>> #2  0x00007ffff6396e9e in __assert_fail_base () from /lib64/libc.so.6
>> #3  0x00007ffff6396f42 in __assert_fail () from /lib64/libc.so.6
>> #4  0x00005555556eea6a in int128_get64 (a=...) at include/qemu/int128.h:22
>> #5  0x00005555556efb81 in address_space_translate_internal 
>> (d=0x7fffdc01c920, addr=18446744069448138751, xlat=0x7fffffffa4b0, 
>> plen=0x7fffffffa540,
>> resolve_subpage=true) at exec.c:264
>> #6  0x00005555556efc03 in address_space_translate (as=0x555555e8d100, 
>> addr=18446744069448138751, xlat=0x7fffffffa538, plen=0x7fffffffa540,
>> is_write=false) at exec.c:278
>> #7  0x0000555555757dd3 in tb_invalidate_phys_addr 
>> (addr=18446744073709551615) at translate-all.c:1373
>> #8  0x00005555556f00f2 in breakpoint_invalidate (cpu=0x555555f1df80, 
>> pc=537189728) at exec.c:413
>> #9  0x00005555556f0725 in cpu_breakpoint_remove_by_ref (env=0x555555f1e0b8, 
>> breakpoint=0x555555f4bc20) at exec.c:557
>> #10 0x00005555556f0649 in cpu_breakpoint_remove (env=0x555555f1e0b8, 
>> pc=537189728, flags=16) at exec.c:541
>> #11 0x000055555570c13b in gdb_breakpoint_remove (addr=537189728, len=2, 
>> type=0) at gdbstub.c:691
>> #12 0x000055555570d031 in gdb_handle_packet (s=0x555555f38100, 
>> line_buf=0x555555f3811c "z0,2004dd60,2") at gdbstub.c:991
>> #13 0x000055555570e45c in gdb_read_byte (s=0x555555f38100, ch=56) at 
>> gdbstub.c:1405
>> #14 0x000055555570e5b0 in gdb_chr_receive (opaque=0x0, buf=0x7fffffffc810 
>> "$z0,2004dd60,2#289process+;qRelocInsn+#2a+=\366\377\177", size=17) at
>> gdbstub.c:1623
>> #15 0x000055555567d463 in qemu_chr_be_write (s=0x555555f0c640, 
>> buf=0x7fffffffc810 
>> "$z0,2004dd60,2#289process+;qRelocInsn+#2a+=\366\377\177", len=17)
>> at qemu-char.c:165
>> #16 0x000055555568185b in tcp_chr_read (chan=0x555555f0c050, cond=G_IO_IN, 
>> opaque=0x555555f0c640) at qemu-char.c:2505
>> #17 0x00007ffff76f1f3d in g_main_context_dispatch () from 
>> /lib64/libglib-2.0.so.0
>> #18 0x000055555564a301 in glib_pollfds_poll () at main-loop.c:189
>> #19 0x000055555564a3f5 in os_host_main_loop_wait (timeout=-1) at 
>> main-loop.c:234
>> #20 0x000055555564a4c8 in main_loop_wait (nonblocking=0) at main-loop.c:483
>> #21 0x00005555556d9c04 in main_loop () at vl.c:2016
>> #22 0x00005555556e0e6b in main (argc=20, argv=0x7fffffffdd88, 
>> envp=0x7fffffffde30) at vl.c:4361
>>
>>
>> breakpoint_invalidate couldn't map breakpoint's virtual address,
>> and get_phys_page_debug returned -1:
>>
>> (gdb) f 7
>> #7  0x0000555555757dd3 in tb_invalidate_phys_addr 
>> (addr=18446744073709551615) at translate-all.c:1373
>> 1373        mr = address_space_translate(&address_space_memory, addr, &addr, 
>> &l, false);
>> (gdb) p/x addr
>> $2 = 0xffffffffffffffff
>>
>>
>> Later address_space_translate_internal found a section that didn't actually
>> contain the addr and made a diff with non-zero .hi:
>>
>> (gdb) f 5
>> #5  0x00005555556efb81 in address_space_translate_internal 
>> (d=0x7fffdc01c920, addr=18446744069448138751, xlat=0x7fffffffa4b0, 
>> plen=0x7fffffffa540,
>> resolve_subpage=true) at exec.c:264
>> 264         *plen = int128_get64(int128_min(diff, int128_make64(*plen)));
>> (gdb) p/x diff
>> $4 = {
>>   lo = 0x100000001,
>>   hi = 0xffffffffffffffff
>> }
>> (gdb) p/x *section
>> $6 = {
>>   mr = 0x555555f04b00,
>>   address_space = 0x555555e8d100,
>>   offset_within_region = 0x0,
>>   size = {
>>     lo = 0x2000000,
>>     hi = 0x0
>>   },
>>   offset_within_address_space = 0xfe000000,
>>   readonly = 0x0
>> }
>>
>>
>> I'm not sure what's the proper fix, returning -1 for the failed 
>> get_phys_page_debug
>> is common for 32-bit targets. The easiest seems to be checking the result of
>> cpu_get_phys_page debug in the breakpoint_invalidate:
>>
>> --- >8 ---
>> commit cb3f9f90688be062b8a1f12b116f3d48c7ded232
>> Author: Max Filippov <address@hidden>
>> Date:   Fri Sep 27 22:19:16 2013 +0400
>>
>>     exec: fix breakpoint_invalidate when pc may not be translated
>>
>>     This fixes qemu abort with the following message:
>>
>>         include/qemu/int128.h:22: int128_get64: Assertion `!a.hi' failed.
>>
>>     which happens due to attempt to invalidate breakpoint by virtual address
>>     for which get_phys_page_debug couldn't find mapping.
>>
>>     Signed-off-by: Max Filippov <address@hidden>
>>
>> diff --git a/exec.c b/exec.c
>> index 26681ce..a7e284a 100644
>> --- a/exec.c
>> +++ b/exec.c
>> @@ -410,8 +410,10 @@ static void breakpoint_invalidate(CPUState *cpu, 
>> target_ulong pc)
>>  #else
>>  static void breakpoint_invalidate(CPUState *cpu, target_ulong pc)
>>  {
>> -    tb_invalidate_phys_addr(cpu_get_phys_page_debug(cpu, pc) |
>> -            (pc & ~TARGET_PAGE_MASK));
>> +    hwaddr phys = cpu_get_phys_page_debug(cpu, pc);
>> +    if (phys != -1) {
>> +        tb_invalidate_phys_addr(phys | (pc & ~TARGET_PAGE_MASK));
>> +    }
>>  }
>>  #endif
>>  #endif /* TARGET_HAS_ICE */
>>
>>
>
> Yes, this makes sense.  I'll queue it for 1.6.2 and 1.7.

Ping? Paolo, do you need this patch resent without scissors?

-- 
Thanks.
-- Max