Re: [PATCH 1/2] objtool/LoongArch: Restrict stack operation instruction

[Tiezhu Yang <yangtiezhu@loongson.cn>]

On 07/30/2024 05:28 PM, Jinyang He wrote:
> On 2024-07-30 14:19, Tiezhu Yang wrote:
>
>> After commit a0f7085f6a63 ("LoongArch: Add RANDOMIZE_KSTACK_OFFSET
>> support"), the code flow of do_syscall() was changed when compiled
>> with GCC due to the secondary stack of add_random_kstack_offset(),
>> something like this:
>>
>>    addi.d          $sp, $sp, -32
>>    st.d            $fp, $sp, 16
>>    st.d            $ra, $sp, 24
>>    addi.d          $fp, $sp, 32
>>    ...
>>    sub.d           $sp, $sp, $t1
> Have you checked the ORC info whether is right or tried backtrace which
> passed do_syscall? The "sub.d $sp, $sp, $t1" has modified the $sp so the
> $sp cannot express CFA here. This patch just clear the warning but ignore
> the validity of ORC info. The wrong ORC info may cause illegally access
> memory when backtrace.

I did testing many times before submitting, the call trace is
expected when testing "echo l > /proc/sysrq-trigger".

Thanks,
Tiezhu