kernel/linux.git/tools/include/nolibc/sys.h, branch v6.6.134

tools/nolibc: avoid undesired casts in the __sysret() macro

2023-08-23T03:17:07+00:00

Having __sysret() as an inline function has the unfortunate effect of adding casts and large constants comparisons after the syscall returns that significantly inflate some light code that's otherwise syscall- heavy. Even nolibc-test grew by ~1%. Let's switch back to a macro for this, and use it only with signed arguments. Note that it is also possible to design a slightly more complex macro covering unsigned and pointers but we only have 3 such syscalls so it is pointless, and these were just addressed not to use this macro anymore. Now for the argument (the local variable containing the syscall return value), any negative value is an error, that results in -1 being returned and errno to be assigned the opposite value. This may be revisited again in the future if really needed but for now let's get back to something sane. Fixes: 428905da6ec4 ("tools/nolibc: sys.h: add a syscall return helper") Link: https://lore.kernel.org/lkml/20230806095846.GB10627@1wt.eu/ Link: https://lore.kernel.org/lkml/ZNKOJY+g66nkIyvv@1wt.eu/ Cc: Zhangjin Wu Cc: David Laight Cc: Thomas Weißschuh Signed-off-by: Willy Tarreau

tools/nolibc: keep brk(), sbrk(), mmap() away from __sysret()

2023-08-23T03:19:22+00:00

The __sysret() function causes some undesirable casts so we'll revert it. In order to keep it simple it will now only support integer return values like in the past, so we must basically revert the changes that were made to these 3 syscalls which return a pointer so that they simply rely on their own test and the SET_ERRNO() macro. Fixes: 4201cfce15fe ("tools/nolibc: clean up sbrk() routine") Fixes: 924e9539aeaa ("tools/nolibc: clean up mmap() routine") Fixes: d27447bc2e0a ("tools/nolibc: sys.h: apply __sysret() helper") Link: https://lore.kernel.org/lkml/20230806095846.GB10627@1wt.eu/ Link: https://lore.kernel.org/lkml/ZNKOJY+g66nkIyvv@1wt.eu/ Cc: Zhangjin Wu Cc: David Laight Cc: Thomas Weißschuh Signed-off-by: Willy Tarreau

tools/nolibc: sys: avoid implicit sign cast

2023-08-23T03:17:07+00:00

getauxval() returns an unsigned long but the overall type of the ternary operator needs to be signed. Signed-off-by: Thomas Weißschuh Signed-off-by: Willy Tarreau

tools/nolibc: fix return type of getpagesize()

2023-08-23T03:17:07+00:00

It's documented as returning int which is also implemented by glibc and musl, so adopt that return type. Signed-off-by: Thomas Weißschuh Signed-off-by: Willy Tarreau

tools/nolibc: drop unused variables

2023-08-23T03:17:07+00:00

Nobody needs it, get rid of it. Signed-off-by: Thomas Weißschuh Signed-off-by: Willy Tarreau

tools/nolibc: add pipe() and pipe2() support

2023-08-23T03:17:07+00:00

According to manual page [1], posix spec [2] and source code like arch/mips/kernel/syscall.c, for historic reasons, the sys_pipe() syscall on some architectures has an unusual calling convention. It returns results in two registers which means there is no need for it to do verify the validity of a userspace pointer argument. Historically that used to be expensive in Linux. These days the performance advantage is negligible. Nolibc doesn't support the unusual calling convention above, luckily Linux provides a generic sys_pipe2() with an additional flags argument from 2.6.27. If flags is 0, then pipe2() is the same as pipe(). So here we use sys_pipe2() to implement the pipe(). pipe2() is also provided to allow users to use flags argument on demand. [1]: https://man7.org/linux/man-pages/man2/pipe.2.html [2]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/pipe.html Suggested-by: Zhangjin Wu Link: https://lore.kernel.org/all/20230729100401.GA4577@1wt.eu/ Signed-off-by: Yuan Tan Reviewed-by: Thomas Weißschuh Signed-off-by: Willy Tarreau

tools/nolibc: remove the old sys_stat support

2023-08-23T02:40:22+00:00

The statx manpage [1] shows that it has been supported from Linux 4.11 and glibc 2.28, the Linux support can be checked for all of the architectures with this command: $ git grep -r statx v4.11 arch/ include/uapi/asm-generic/unistd.h \ | grep -E "aarch64|arm|mips|s390|x86|:include/uapi" Besides riscv and loongarch, all of the nolibc supported architectures have added sys_statx from Linux v4.11. riscv is mainlined to v4.15, loongarch is mainlined to v5.19, both of them use the generic unistd.h, so, they have added sys_statx from their first mainline versions. The current oldest stable branch is v4.14, only reserving sys_statx still preserves compatibility with all of the supported stable branches, So, let's remove the old arch related and dependent sys_stat support completely. This is friendly to the future new architecture porting. [1]: https://man7.org/linux/man-pages/man2/statx.2.html Signed-off-by: Zhangjin Wu Signed-off-by: Willy Tarreau

tools/nolibc: add rmdir() support

2023-08-23T02:38:02+00:00

a reverse operation of mkdir() is meaningful, add rmdir() here. required by nolibc-test to remove /proc while CONFIG_PROC_FS is not enabled. Reviewed-by: Thomas Weißschuh Signed-off-by: Zhangjin Wu Signed-off-by: Willy Tarreau

tools/nolibc: types.h: add RB_ flags for reboot()

2023-08-23T02:38:02+00:00

Both glibc and musl provide RB_ flags via for reboot(), they don't need to include , let nolibc provide RB_ flags too. Signed-off-by: Zhangjin Wu Signed-off-by: Willy Tarreau

tools/nolibc: clean up sbrk() routine

2023-08-23T02:38:02+00:00

Fix up the error reported by scripts/checkpatch.pl: ERROR: do not use assignment in if condition #95: FILE: tools/include/nolibc/sys.h:95: + if ((ret = sys_brk(0)) && (sys_brk(ret + inc) == ret + inc)) Apply the new generic __sysret() to merge the SET_ERRNO() and return lines. Signed-off-by: Zhangjin Wu Signed-off-by: Willy Tarreau