[PATCH v8 1/3] riscv: Introduce CONFIG_RELOCATABLE
Alexandre Ghiti
alex at ghiti.fr
Mon May 22 03:48:20 PDT 2023
On 19/05/2023 23:55, Palmer Dabbelt wrote:
> On Fri, 19 May 2023 14:48:59 PDT (-0700), schwab at linux-m68k.org wrote:
>> On Mai 19 2023, Alexandre Ghiti wrote:
>>
>>> I have tested the following patch successfully, can you give it a try
>>> while I make sure this is the only place I forgot to add the -fno-pie
>>> flag?
>>>
>>> diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
>>> index fbdccc21418a..153864e4f399 100644
>>> --- a/arch/riscv/kernel/Makefile
>>> +++ b/arch/riscv/kernel/Makefile
>>> @@ -23,6 +23,10 @@ ifdef CONFIG_FTRACE
>>> CFLAGS_REMOVE_alternative.o = $(CC_FLAGS_FTRACE)
>>> CFLAGS_REMOVE_cpufeature.o = $(CC_FLAGS_FTRACE)
>>> endif
>>> +ifdef CONFIG_RELOCATABLE
>>> +CFLAGS_alternative.o += -fno-pie
>>> +CFLAGS_cpufeature.o += -fno-pie
>>> +endif
>>> ifdef CONFIG_KASAN
>>> KASAN_SANITIZE_alternative.o := n
>>> KASAN_SANITIZE_cpufeature.o := n
>>
>> I can confirm that this fixes the crash.
>
> Thanks. Alex: can you send a patch?
I don't think this patch alone will work, all the code in early
alternatives must be compiled with -fno-pie, but I'm a bit scared that's
a "big" constraint. For now, I see 2 solutions:
- Document somewhere the fact that anything called from early
alternatives must be compiled with -fno-pie
- Or relocate once with physical address, call early alternatives, and
then do the final virtual relocation
Both options can be cumbersome in their own way, if anyone has an
opinion, I'd be happy to discuss that :)
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