99280413a5
The EFI runtime wrappers are a sandbox for calling into EFI runtime
services, which are invoked using indirect calls. When running with kCFI
enabled, the compiler will require the target of any indirect call to be
type annotated.
Given that the EFI runtime services prototypes and calling convention
are governed by the EFI spec, not the Linux kernel, adding such type
annotations for firmware routines is infeasible, and so the compiler
must be informed that prototype validation should be omitted.
Add the __nocfi annotation at the appropriate places in the EFI runtime
wrapper code to achieve this.
Note that this currently only affects 32-bit ARM, given that other
architectures that support both kCFI and EFI use an asm wrapper to call
EFI runtime services, and this hides the indirect call from the
compiler.
Fixes: 1a4fec49efe5 ("ARM: 9392/2: Support CLANG CFI")
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
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 reStructuredText 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.