> On Dec 15, 2021, at 1:17 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>
> On Tue, Dec 14, 2021 at 10:01:00PM -0800, Song Liu wrote:
>> This will be used by BPF jit compiler to dump JITed binary to a RWX huge
>
> OK, I read the actually allocator you use and the relevant code for this
> patch and the above is a typo, you meant: RX. Those pages are most
> definitely not writable.
Yeah, it was a typo. I meant to say ROX.
Thanks,
Song
>
>
>> +void *text_poke_jit(void *addr, const void *opcode, size_t len)
>> +{
>> + unsigned long start = (unsigned long)addr;
>> + size_t patched = 0;
>> +
>> + if (WARN_ON_ONCE(core_kernel_text(start)))
>> + return NULL;
>> +
>> + while (patched < len) {
>> + unsigned long ptr = start + patched;
>> + size_t s;
>> +
>> + s = min_t(size_t, PAGE_SIZE * 2 - offset_in_page(ptr), len - patched);
>
> Cute, should work.
>
>> +
>> + __text_poke((void *)ptr, opcode + patched, s);
>> + patched += s;
>> + }
>> + return addr;
>> +}
