mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-05-13 23:29:10 -04:00
24321ac668
Commit0138ba5783("powerpc/64/signal: Balance return predictor stack in signal trampoline") changed __kernel_sigtramp_rt64() VDSO and trampoline code, and introduced a regression in the way glibc's backtrace()[1] detects the signal-handler stack frame. Apart from the practical implications, __kernel_sigtramp_rt64() was a VDSO function with the semantics that it is a function you can call from userspace to end a signal handling. Now this semantics are no longer valid. I believe the aforementioned change affects all releases since 5.9. This patch tries to fix both the semantics and practical aspect of __kernel_sigtramp_rt64() returning it to the previous code, whilst keeping the intended behaviour of0138ba5783by adding a new symbol to serve as the jump target from the kernel to the trampoline. Now the trampoline has two parts, a new entry point and the old return point. [1] https://lists.ozlabs.org/pipermail/linuxppc-dev/2021-January/223194.html Fixes:0138ba5783("powerpc/64/signal: Balance return predictor stack in signal trampoline") Cc: stable@vger.kernel.org # v5.9+ Signed-off-by: Raoni Fassina Firmino <raoni@linux.ibm.com> Acked-by: Nicholas Piggin <npiggin@gmail.com> [mpe: Minor tweaks to change log formatting, add stable tag] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20210201200505.iz46ubcizipnkcxe@work-tp
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.