Alex Bennée <alex.ben...@linaro.org> writes:
> Laurent Vivier <laur...@vivier.eu> writes:
>
>> On 15/05/2020 16:43, Alex Bennée wrote:
>>> From: Richard Henderson <richard.hender...@linaro.org>
>>>
>>> We cannot at present limit a 64-bit guest to a virtual address
>>> space smaller than the host. It will mostly work to ignore this
>>> limitation, except if the guest uses high bits of the address
>>> space for tags. But it will certainly work better, as presently
>>> we can wind up failing to allocate the guest stack.
>>>
>>> Widen our user-only page tree to the host or abi pointer width.
>>> Remove the workaround for this problem from target/alpha.
>>> Always validate guest addresses vs reserved_va, as there we
>>> control allocation ourselves.
>>>
>>> Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
>>> Signed-off-by: Alex Bennée <alex.ben...@linaro.org>
>>>
>>> Message-Id: <20200513175134.19619-7-alex.ben...@linaro.org>
>>>
>>
>> This patch breaks a test case in LTP with 64bit targets on x86_64 host:
>>
>> sudo linux-user/mips64el-linux-user/qemu-mips64el \
>> -L chroot/mips64el/stretch/ \
>> chroot/mips64el/stretch/opt/ltp/testcases/bin/mmap15
>>
>> qemu-mips64el: accel/tcg/translate-all.c:2533: page_set_flags: Assertion
>> `start < end' failed.
>> qemu:handle_cpu_signal received signal outside vCPU context @
>> pc=0x7f0015f6e7cb
>>
>> Could you have a look?
>
> Can confirm I've replicated:
>
> 18:30:20 [alex.bennee@hackbox2:~/l/q/b/user.static] next/various-fixes|✔ 32
> +
> sudo ./mips64el-linux-user/qemu-mips64el -L
> ~/lsrc/buildroot.git/builds/mips64el/target/
> ~/lsrc/buildroot.git/builds/mips64el/target/usr/lib/ltp-testsuite/testcases/bin/mmap
> 15
> [sudo] password for alex.bennee:
> qemu-mips64el:
> /home/alex.bennee/lsrc/qemu.git/accel/tcg/translate-all.c:2533:
> page_set_flags: Assertion `start < end' failed.
> qemu:handle_cpu_signal received signal outside vCPU context @ pc=0x6c28c2
>
> Also TIL you can use buildroot to build ltp ;-)
I'm not sure how the change has tripped this failure but it seems to be
a simple overflow. The following fixes it but I'm curious about the
formulation of guest_addr_valid and why it's written that way:
modified linux-user/mmap.c
@@ -467,7 +467,7 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int
prot,
* It can fail only on 64-bit host with 32-bit target.
* On any other target/host host mmap() handles this error correctly.
*/
- if (!guest_range_valid(start, len)) {
+ if (end < start || !guest_range_valid(start, len)) {
errno = ENOMEM;
goto fail;
}
>
>>
>> Thanks,
>> Laurent
--
Alex Bennée
