zephyr/subsys/llext/llext_export.c

20 lines
372 B
C
Raw Normal View History

/*
* Copyright (c) 2023 Intel Corporation
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <string.h>
#include <zephyr/llext/symbol.h>
EXPORT_SYMBOL(strcpy);
EXPORT_SYMBOL(strncpy);
EXPORT_SYMBOL(strlen);
EXPORT_SYMBOL(strcmp);
EXPORT_SYMBOL(strncmp);
EXPORT_SYMBOL(memcmp);
EXPORT_SYMBOL(memcpy);
EXPORT_SYMBOL(memset);
syscalls: llext: Export z_impl symbols so they are available to kernel commit 67bb6db3f8e5 ("syscall: Export all emitted syscalls, enabling them for extensions") exports all emitted syscalls, however, it does that only for the `z_mrsh` symbols, effectively only available for userspace. If an extension running at kernel level tries to use a syscall, it will fail to load. This patch fixes that by exposing the `z_impl` symbols instead. However, this is not as straightforward as the `z_mrsh` ones. As, in their signatures, they can basically contain any type, it's not just a matter of emitting `EXPORT_SYMBOL(z_impl_<syscall>)`, as the compiler will complain about the undefined types. Here, there are a few approaches. One of them is to have the `EXPORT_SYMBOL` being generated on the same files where the syscall is implemented - injecting it there would allow it to access all known symbols. But changing a lot of files is undesirable, and it was one of the nice points of first patch. Another one would be to reconstruct - or simply use the absolute path - for the includes where the syscalls are defined. Reconstruct the paths seems fragile and I'm not sure using absolute paths is portable. Finally, the approach used in this patch is to declare, on a different generated file, all `z_impl_` symbols as `void *` - after all, only the address (and the name) to the function is relevant to EXPORT_SYMBOL. By living in an compilation unit that doesn't include any header which would expose any of the syscalls, there shouldn't be any conflicts. And to account for the possibility that a syscall is not compiled - due being configured out via Kconfig - all those symbols are also weak aliases to a pointer to NULL. This file is then included in `llext_export.c` (which should naturally not include any conflicting header). Signed-off-by: Ederson de Souza <ederson.desouza@intel.com>
2024-03-22 06:51:15 +08:00
#include <zephyr/syscall_export_llext.c>