Re: [PATCH -fixes] riscv: Fix relocatable kernels with early alternatives using -fno-pie

[Alexandre Ghiti]

On 29/05/2023 21:06, Conor Dooley wrote:
> On Mon, May 29, 2023 at 08:51:57PM +0200, Alexandre Ghiti wrote:
> > On 28/05/2023 15:56, Conor Dooley wrote:
> > > On Sun, May 28, 2023 at 03:42:59PM +0200, Alexandre Ghiti wrote:
> > > > Hmmm, it still works for me with both clang and gcc-9.
> > > gcc-9 is a bit of a relic, do you have more recent compilers lying
> > > around? If not, I can try some older compilers at some point.
> > >
> > > > You don't have to do that now but is there a way I could get your compiled
> > > > image? With the sha1 used to build it? Sorry, I don't see what happens, I
> > > > need to get my hands dirty in some debug!
> > > What do you mean by "sha1"? It falls with v6.4-rc1 which is a stable
> > > hash, if that's what you're looking for.
> > >
> > > Otherwise,
> > > https://github.com/ConchuOD/riscv-env/releases/download/v2022.03/vmlinux.bin
> > > (ignore the release crap haha, too lazy to find a proper hosting
> > > mechanism)
> >
> > Ok, I don't get much info without the symbols, can you also provide the
> > vmlinux please? But at least your image does not boot, not during the early
> > boot though because the mmu is enabled.
> Do you see anything print when you try it? Cos I do not. Iff I have time
> tomorrow, I'll go poking with gdb. I'm sorry I have not really done any
> investigating, I have been really busy this last week or so with
> dt-binding stuff but I should be freer again from tomorrow.
>
> https://github.com/ConchuOD/riscv-env/releases/download/v2022.03/vmlinux


Better, the trap happens in kasan_early_init() when it tries to access a 
global symbol using the GOT but ends up with a NULL pointer, which is 
weird. So to me, this is not related to kasan, it happens that 
kasan_early_init() is the first function called after enabling the mmu, 
I think you may have an issue with the filling of the relocations. Sorry 
to bother you again, but if at some point you can recompile with 
DEBUG_INFO enabled, that would be perfect! And also provide the 
vmlinux.relocs file. Sorry for all that, too bad I can't reproduce it.


> > I tried with gcc-12 and it still works fine on my end, so frustrating!
> Crap! Also, should you not be enjoying a public holiday rather than
> debugging?! Or maybe debugging is enjoyable for you...


Ahah, this is what I enjoy doing when the kids finally sleep :)


Thank you again for your very quick feedback, really appreciated!


> Cheers,
> Conor.