This patch adds support for running Genode/Linux on the AARCH64
architecture.
- The kernel-agnostic startup code (crt0) had to be extended to
capture the initial stack pointer, which the Linux kernel uses
to pass the process environment. This is in line with the
existing startup code for x86_32 and x86_64.
- The link order of the host libraries linked to lx_hybrid
programs had to be adjusted such that libgcc appears at last
because the other libraries depend on symbols provided by
libgcc.
- When using AARCH64 Linux as host, one can execute run scripts
via 'make run/<script> KERNEL=linux BOARD=linux' now.
Issue #4136
Until now, Genode's Linux system call bindings were based on original
Unix system calls that were later superseded by more flexibile variants.
E.g., 'openat' is a modern version of 'open'. Even though Linux upholds
the compatiblity with the original versions for existing architectures
like x86, the legacy syscalls are absent for the recently added AARCH64
architecture. A good overview of the system calls accross the prominent
architectures can be found at
https://chromium.googlesource.com/chromiumos/docs/+/master/constants/syscalls.md
This patch updates Genode's syscall bindings to avoid legacy versions,
thereby easing the support for AARCH64. The used "modern" versions
were introduced back in Linux version 2 days. So we are fine to rely
on them.
The patch slightly changes the signature for lx_stat because this system
call is merely used to check for the existance of a file and its size.
The new name 'lx_stat_size' draws a closer connection to its use case.
That said, the stat syscall has not been updated to the modern statx
since statx is still a fairly recent addition.
Issue #4136
base-linux uses seccomp to reduce the available system calls
to the minimum set needed to run base-linux. There are still
some syscalls that allow accessing global state which should
be further reduced.
The combination of seccomp and socket descriptor caps should
provide an intermediate level of security for base-linux
thereby enabling base-linux as a migration path from using
the Linux kernel to the use of microkernel-based Genode.
Fixes#3581
