Re: X stopped working with 5.14 on iBook
On 10/22/21 11:35 AM, Stan Johnson wrote:
> ...
>
> $ git reset --hard
> HEAD is now at 62fb9874f5da Linux 5.13
> $ git bisect start v5.13
> Updating files: 100% (12992/12992), done.
> Previous HEAD position was 62fb9874f5da Linux 5.13
> HEAD is now at 9f4ad9e425a1 Linux 5.12
> $ git bisect bad v5.13
> $ git bisect good v5.12
> Bisecting: 8739 revisions left to test after this (roughly 13 steps)
>> 85f3f17b5db2dd9f8a094a0ddc665555135afd22] Merge branch 'md-fixes' of
> https://git.kernel.org/pub/scm/linux/kernel/git/song/md into block-5.13
>
> After the bisect, git reports this:
>
> ----------
>
> d3ccc9781560af051554017c702631560bdc0811 is the first bad commit
> commit d3ccc9781560af051554017c702631560bdc0811
> Author: Christopher M. Riedl <cmr@codefail.de>
> Date: Fri Feb 26 19:12:59 2021 -0600
>
> powerpc/signal: Use __get_user() to copy sigset_t
>
> Usually sigset_t is exactly 8B which is a "trivial" size and does not
> warrant using __copy_from_user(). Use __get_user() directly in
> anticipation of future work to remove the trivial size optimizations
> from __copy_from_user().
>
> The ppc32 implementation of get_sigset_t() previously called
> copy_from_user() which, unlike __copy_from_user(), calls access_ok().
> Replacing this w/ __get_user() (no access_ok()) is fine here since
both
> callsites in signal_32.c are preceded by an earlier access_ok().
>
> Signed-off-by: Christopher M. Riedl <cmr@codefail.de>
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
> Link:
https://lore.kernel.org/r/20210227011259.11992-11-cmr@codefail.de
>
> arch/powerpc/kernel/signal.h | 7 +++++++
> arch/powerpc/kernel/signal_32.c | 2 +-
> arch/powerpc/kernel/signal_64.c | 4 ++--
> 3 files changed, 10 insertions(+), 3 deletions(-)
>
Update:
Kernel developers have found the bug in the "bad commit" that was
identified above. Details can be found in the
linuxppc-dev@lists.ozlabs.org mailing list.
Since I'm not a kernel developer, I have no idea when the bug correction
will be implemented, but it will probably happen by the time 5.16 is
released. In the meantime, a workaround is to set "CONFIG_USER_NS=n" in
the kernel .config file if X is not working on your G4 system.
-Stan
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