Adds support for all relocation type produced by GCC
on AARCH64 platform using partial linking (-r flag) or
shared link (-fpic and -shared flag).
Signed-off-by: Adam Wojasinski <awojasinski@baylibre.com>
This patch sets the default value for LLEXT_STORAGE_WRITABLE to 'y' on
the Xtensa architecture. This is necessary because it does not currently
support the read-only mode for the LLEXT storage.
Make sure the default reflects this instead of asking the user to
manually set it.
Signed-off-by: Luca Burelli <l.burelli@arduino.cc>
This commit introduces support for an alternate linking method in the
LLEXT subsystem, called "SLID" (short for Symbol Link Identifier),
enabled by the CONFIG_LLEXT_EXPORT_BUILTINS_BY_SLID Kconfig option.
SLID-based linking uses a unique identifier (integer) to identify
exported symbols, instead of using the symbol name as done currently.
This approach provides several benefits:
* linking is faster because the comparison operation to determine
whether we found the correct symbol in the export table is now an
integer compare, instead of a string compare
* binary size is reduced as symbol names can be dropped from the binary
* confidentiality is improved as a side-effect, as symbol names are no
longer present in the binary
Signed-off-by: Mathieu Choplain <mathieu.choplain@st.com>
Use an existing variable instead of re-calculating and fix swapped
space and a paranthesis.
Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
A new Kconfig option which generates syscall stubs assuming that
extensions will always run on userspace, thus simplifying linking
them, as there's no need for z_impl_ stubs (used for direct syscalls),
CONFIG_LLEXT_EDK_USERSPACE_ONLY.
While defining __ZEPHYR_USER__ could have the same effect for optmised
builds, people building extensions on debug environments - thus
non-optimised - would suffer, as they'd need to somehow make the stubs
available (by either exporting the symbol or implementing dummy stubs).
Signed-off-by: Ederson de Souza <ederson.desouza@intel.com>
Loadable extensions need access to Zephyr (and Zephyr application)
includes and some CFLAGS to be properly built. This patch adds a new
target, `llext-edk`, which generates a tar file with those includes and
flags that can be loaded from cmake and make files.
A Zephyr application willing to expose some API to extensions it loads
only need to add the include directories describing such APIs to the
Zephyr ones via zephyr_include_directories() CMake call.
A new Kconfig option, CONFIG_LLEXT_EDK_NAME allows one to control some
aspects of the generated file, which enables some customization - think
of an application called ACME, willing to have a ACME_EXTENSION_KIT or
something.
All EDK Kconfig options are behind CONFIG_LLEXT_EDK, which doesn't
depend on LLEXT directly - so that EDK features can be leveraged by
downstream variations of loadable extensions.
Also, each arch may need different compiler flags for extensions: those
are handled by the `LLEXT_CFLAGS` cmake flag. An example is set for GCC
ARM.
Finally, EDK throughout this patch means Extension Development Kit,
which is a bad name, but at least doesn't conflict with SDK.
Signed-off-by: Ederson de Souza <ederson.desouza@intel.com>
Dynamic code execution applications not using LLEXT for "extension"
loading are subject to the same linker optimization symbol resolution
issue described in commit 321e395 (in summary, libkernel.a syscalls
not used directly by the application result in weak symbol resolution
of their z_mrsh_ wrapper).
To support usecases where an application is using alternative methods
to load and execute code calling syscalls (likely from userspace) or
is using a mechanism where the linker may not be aware, the configuration
option has been decoupled from CONFIG_LLEXT (who is now a selector) to
KERNEL_WHOLE_ARCHIVE.
Signed-off-by: Daniel Apperloo <daniel.apperloo@intel.com>
This commit adds support for building relocatable (partially linked)
ELF files as the binary object type for the llext subsystem.
Signed-off-by: Luca Burelli <l.burelli@arduino.cc>
Add a new Kconfig option to select the binary object type for the llext
subsystem. This will allow to fully decouple the architecture type from
the kind of binary object that is expected by the loader.
The defaults have been chosen to match the current behavior of the ARM
and Xtensa architectures, but developers can now more easily experiment
with other object types.
Signed-off-by: Luca Burelli <l.burelli@arduino.cc>
Targets that have a data cache must enable CACHE_MANAGEMENT to allow the
llext API to flush it when loading an extension. This patch forces the
flag to be enabled when the target has a data cache.
Signed-off-by: Luca Burelli <l.burelli@arduino.cc>
When using the LLEXT buffer loader we now avoid copying extensions
from storage to allocated memory by pointing directly into the stored
image. We then also perform linking and relocation in that memory,
which modifies its contents. However, this is impossible if that
storage is read-only. Add a Kconfig flag to distinguish between
writable and read-only storage types. Also use that flag to decide,
whether the extension image in test_llext_simple.c should be defined
as const or not.
Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
The maximum size of an extension accept by the shell
was previously a define and is now made configurable through Kconfig.
Signed-off-by: Kai Meinhard <meinhard@gessler.de>
Adds the linkable loadable extensions (llext) subsystem which provides
functionality for reading, parsing, and linking ELF encoded executable
code into a managed extension to the running elf base image.
A loader interface, and default buffer loader implementation,
make available to the llext subsystem the elf data. A simple management
API provide the ability to load and unload extensions as needed. A shell
interface for extension loading and unloading makes it easy to try.
Adds initial support for armv7 thumb built elfs with very specific
compiler flags.
Signed-off-by: Tom Burdick <thomas.burdick@intel.com>
Co-authored-by: Chen Peng1 <peng1.chen@intel.com>
Co-authored-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
