103a4908ad
On 64-bit, the startup_64_setup_env() function added in
866b556efa12 ("x86/head/64: Install startup GDT")
has stack protection enabled because of set_bringup_idt_handler().
This happens when CONFIG_STACKPROTECTOR_STRONG is enabled. It
also currently needs CONFIG_AMD_MEM_ENCRYPT enabled because then
set_bringup_idt_handler() is not an empty stub but that might change in
the future, when the other vendor adds their similar technology.
At this point, %gs is not yet initialized, and this doesn't cause a
crash only because the #PF handler from the decompressor stub is still
installed and handles the page fault.
Disable stack protection for the whole file, and do it on 32-bit as
well to avoid surprises.
[ bp: Extend commit message with the exact explanation how it happens. ]
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Joerg Roedel <jroedel@suse.de>
Link: https://lkml.kernel.org/r/20201008191623.2881677-6-nivedita@alum.mit.edu
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.