The standard syscall() function or macro uses the libc return value
convention. Errors returned from the kernel as negative values are
stored in errno and -1 is returned. Users who want to avoid using
errno don't have a way to call raw syscalls and check the returned
error.
Add a new macro _syscall() which works like the standard syscall()
but passes through the return value from the kernel unchanged.
The naming scheme and return values match the named _sys_foo()
system call wrappers already part of nolibc.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Acked-by: Willy Tarreau <w@1wt.eu>
Link: https://patch.msgid.link/20260405-nolibc-syscall-v1-3-e5b12bc63211@weissschuh.net
__sysret() transforms the return value from the kernel into the libc
return value convention. There is no reason for it to be called in the
middle of the internals of the syscall() implementation macros.
Move the call up, directly into syscall(), to make the code simpler.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Acked-by: Willy Tarreau <w@1wt.eu>
Link: https://patch.msgid.link/20260405-nolibc-syscall-v1-2-e5b12bc63211@weissschuh.net
Functions make it easier to keep the input and output types straight and
avoid duplicate evaluations of their arguments.
Also these functions will become a bit more complex to handle full
64-bit 'dev_t' which is easier to read in a function.
Still stay compatible with code which expects these to be macros.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Acked-by: Willy Tarreau <w@1wt.eu>
Link: https://patch.msgid.link/20260404-nolibc-makedev-v2-3-456a429bf60c@weissschuh.net
The sys_foo() naming scheme used by the syscall wrappers may collide
with application symbols. Especially as 'sys_' is an obvious naming
scheme an application may choose for its own custom systemcall wrappers.
Avoid these conflicts by using an leading underscore which moves the
names into the implementation's namespace. This naming scheme was chosen
over a '__nolibc_' prefix, as these functions are not an implementation
detail but a documented interface meant to be used by applications.
While this may break some existing users, adapting them should be
straightforward. Given that nolibc is most-likely vendored, no
unexpected breakage should happen. No in-tree users are affected.
These conflicts happen when compiling some of the kernel selftests
with nolibc.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Acked-by: Willy Tarreau <w@1wt.eu>
Link: https://patch.msgid.link/20260319-nolibc-namespacing-v1-1-33c22eaddb5e@weissschuh.net
The naming convention of the my_syscallX() macros is a bit unfortunate.
They may conflict with application code and the name is very generic.
Switch to __nolibc_syscallX(). The leading underscores place the symbols
in the implementation-defined namespace, avoiding conflicting names.
It is also clearer that these are non-standard extensions from nolibc.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Acked-by: Willy Tarreau <w@1wt.eu>
Link: https://patch.msgid.link/20260223-nolibc-namespacing-v1-1-52574ffebb2c@weissschuh.net
timeval::tv_usec is going to be 64-bit wide even on 32-bit
architectures. As not all architectures support 64-bit multiplications
instructions, calls to libgcc (__multi3()) may be emitted by the
compiler which are not provided by nolibc.
As tv_usec and tv_nsec are guaranteed to always fit into an uint32_t,
perform a 32-bit multiplication instead.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Acked-by: Willy Tarreau <w@1wt.eu>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20251220-nolibc-uapi-types-v3-7-c662992f75d7@weissschuh.net
timespec::tv_nsec is going to be 64-bit wide even on 32-bit
architectures. As not all architectures support 64-bit division
instructions, calls to libgcc (__divdi3()) may be emitted by the
compiler which are not provided by nolibc.
As tv_nsec is guaranteed to always fit into an uint32_t, perform a
32-bit division instead.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Willy Tarreau <w@1wt.eu>
Link: https://patch.msgid.link/20251220-nolibc-uapi-types-v3-6-c662992f75d7@weissschuh.net
These implementations use the libc 'struct timeval' with system calls
which can lead to type mismatches. Currently this is fine, but will
break with upcoming changes to 'struct timeval'.
If the structure needs to be converted anyways, the implementations
based on pselect can be used for all architectures. This simplifies the
logic.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Acked-by: Willy Tarreau <w@1wt.eu>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20251220-nolibc-uapi-types-v3-3-c662992f75d7@weissschuh.net
Add ptrace support, as it will be useful in UML.
Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
[Thomas: drop va_args usage and linux/uio.h inclusion]
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Modern programs tend to include sys/select.h to get FD_SET() and
FD_CLR() definitions as well as struct fd_set, but in our case it
didn't exist.
The definitions were moved from types.h to sys/select.h, which is
now included from nolibc.h, and the sys_select() definition moved
there as well from sys.h.
Signed-off-by: Willy Tarreau <w@1wt.eu>
[Thomas: adapt to current -next branch]
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
This is generally useful and struct iovec is also needed for other
purposes such as ptrace.
Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
In principle, it is possible to use nolibc for only some object files in
a program. In that case, the startup code in _start and _start_c is not
going to be used. Add the NOLIBC_NO_RUNTIME compile time option to
disable it entirely and also remove anything that depends on it.
Doing this avoids warnings from modpost for UML as the _start_c code
references the main function from the .init.text section while it is not
inside .init itself.
Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Since commit fb01ff635e ("tools/nolibc: keep brk(), sbrk(), mmap()
away from __sysret()") the implementation of mmap() does not use the
__sysret() macro anymore.
Remove the outdated comment.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
wstatus is allowed to be NULL. Avoid a segmentation fault in this case.
Fixes: 0c89abf5ab ("tools/nolibc: implement waitpid() in terms of waitid()")
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Acked-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
The compiler does not know that waitid() will only ever return 0 or -1.
If waitid() would return a positive value than waitpid() would return that
same value and *status would not be initialized.
However users calling waitpid() know that the only possible return values
of it are 0 or -1. They therefore might check for errors with
'ret == -1' or 'ret < 0' and use *status otherwise. The compiler will then
warn about the usage of a potentially uninitialized variable.
Example:
$ cat test.c
#include <stdio.h>
#include <unistd.h>
int main(void)
{
int ret, status;
ret = waitpid(0, &status, 0);
if (ret == -1)
return 0;
printf("status %x\n", status);
return 0;
}
$ gcc --version
gcc (GCC) 15.1.1 20250425
$ gcc -Wall -Os -Werror -nostdlib -nostdinc -static -Iusr/include -Itools/include/nolibc/ -o /dev/null test.c
test.c: In function ‘main’:
test.c:12:9: error: ‘status’ may be used uninitialized [-Werror=maybe-uninitialized]
12 | printf("status %x\n", status);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
test.c:6:18: note: ‘status’ was declared here
6 | int ret, status;
| ^~~~~~
cc1: all warnings being treated as errors
Avoid the warning by normalizing waitid() errors to '-1' in waitpid().
Fixes: 0c89abf5ab ("tools/nolibc: implement waitpid() in terms of waitid()")
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Acked-by: Willy Tarreau <w@1wt.eu>
Link: https://lore.kernel.org/r/20250707-nolibc-waitpid-uninitialized-v1-1-dcd4e70bcd8f@linutronix.de
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Inclusion of any nolibc header file should also bring all other headers.
On the other hand it should also be possible to include any nolibc header
files
in any order.
Currently this is implemented by including the catch-all nolibc.h after the
headers own definitions.
This is problematic if one nolibc header depends on another one.
The first header has to include the other one before defining any symbols.
That in turn will include the rest of nolibc while the current header has
not defined anything yet. If any other part of nolibc depends on
definitions from the current header, errors are encountered.
This is already the case today. Effectively nolibc can only be included in
the order of nolibc.h.
Restructure the way "nolibc.h" is included.
Move it to the beginning of the header files and before the include guards.
Now any header will behave exactly like "nolibc.h" while the include
guards prevent any duplicate definitions.
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Acked-by: Willy Tarreau <w@1wt.eu>
Link: https://lore.kernel.org/r/20250424-nolibc-header-check-v1-2-011576b6ed6f@linutronix.de
The old wait4() syscall used by waitpid() before is not available everywhere.
Switch to the waitid() syscall which is the new replacement.
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Acked-by: Willy Tarreau <w@1wt.eu>
