Re: Boot regression in Linux v6.4-rc3
On Sat, May 27, 2023 at 11:41 AM Frank Scheiner <frank.scheiner@web.de> wrote:
>
> Ok, I put the decoded console messages on [2].
>
> [2]: https://pastebin.com/dLYMijfS
Ugh. Apparently ia64 decoding isn't great. But at least it gives
multiple line numbers:
load_module (kernel/module/main.c:2291 kernel/module/main.c:2412
kernel/module/main.c:2868)
except your kernel obviously has those test-patches, so I still don't
know exactly where they are.
But it looks like it is in move_module(). Strange. I don't know how it
gets to "__copy_user" from there...
[ Looks at the ia64 code ]
Oh.
It turns out that it *says* __copy_user(), but the code is actually
shared with the regular memcpy() function, which does
GLOBAL_ENTRY(memcpy)
and r28=0x7,in0
and r29=0x7,in1
mov f6=f0
mov retval=in0
br.cond.sptk .common_code
;;
where that ".common_code" label is - surprise surprise - the common
copy code, and so when the oops reports that the problem happened in
__copy_user(), it actually is in this case just a normal memcpy.
Ok, so it's probably the
memcpy(dest, (void *)shdr->sh_addr, shdr->sh_size);
in move_module() that takes a fault. And looking at the registers,
the destination is in r17/r18, and your dump has
unable to handle kernel paging request at virtual address 1000000000000000
...
r17 : 0fffffffffffffff r18 : 1000000000000000
so it's almost certainly that 'dest' that is bad.
Which I guess shouldn't surprise anybody.
But that's where my knowledge of ia64 and the new module loader layout ends.
Linus
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