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Pavel Machek reported the following warning on x86-32: WARNING: kernel stack frame pointer at f50cdf98 in swapper/2:0 has bad value (null) The warning is caused by the unwinder not realizing that it reached the end of the stack, due to an unusual prologue which gcc sometimes generates for aligned stacks. The prologue is based on a gcc feature called the Dynamic Realign Argument Pointer (DRAP). It's almost always enabled for aligned stacks when -maccumulate-outgoing-args isn't set. This issue is similar to the one fixed by the following commit:8023e0e2a4("x86/unwind: Adjust last frame check for aligned function stacks") ... but that fix was specific to x86-64. Make the fix more generic to cover x86-32 as well, and also ensure that the return address referred to by the frame pointer is a copy of the original return address. Fixes:acb4608ad1("x86/unwind: Create stack frames for saved syscall registers") Reported-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/50d4924db716c264b14f1633037385ec80bf89d2.1489465609.git.jpoimboe@redhat.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.