linux-dev/tools/include/nolibc, branch linus/master

tools/nolibc/string: Implement `strdup()` and `strndup()`

2022-04-21T00:05:46Z

These functions are currently only available on architectures that have my_syscall6() macro implemented. Since these functions use malloc(), malloc() uses mmap(), mmap() depends on my_syscall6() macro. On architectures that don't support my_syscall6(), these function will always return NULL with errno set to ENOSYS. Acked-by: Willy Tarreau Signed-off-by: Ammar Faizi Signed-off-by: Paul E. McKenney

tools/nolibc/string: Implement `strnlen()`

2022-04-21T00:05:46Z

size_t strnlen(const char *str, size_t maxlen); The strnlen() function returns the number of bytes in the string pointed to by sstr, excluding the terminating null byte ('\0'), but at most maxlen. In doing this, strnlen() looks only at the first maxlen characters in the string pointed to by str and never beyond str[maxlen-1]. The first use case of this function is for determining the memory allocation size in the strndup() function. Link: https://lore.kernel.org/lkml/CAOG64qMpEMh+EkOfjNdAoueC+uQyT2Uv3689_sOr37-JxdJf4g@mail.gmail.com Suggested-by: Alviro Iskandar Setiawan Acked-by: Willy Tarreau Signed-off-by: Ammar Faizi Signed-off-by: Paul E. McKenney

tools/nolibc/stdlib: Implement `malloc()`, `calloc()`, `realloc()` and `free()`

2022-04-21T00:05:46Z

Implement basic dynamic allocator functions. These functions are currently only available on architectures that have nolibc mmap() syscall implemented. These are not a super-fast memory allocator, but at least they can satisfy basic needs for having heap without libc. Cc: David Laight Acked-by: Willy Tarreau Signed-off-by: Ammar Faizi Signed-off-by: Paul E. McKenney

tools/nolibc/types: Implement `offsetof()` and `container_of()` macro

2022-04-21T00:05:46Z

Implement `offsetof()` and `container_of()` macro. The first use case of these macros is for `malloc()`, `realloc()` and `free()`. Acked-by: Willy Tarreau Signed-off-by: Ammar Faizi Signed-off-by: Paul E. McKenney

tools/nolibc/sys: Implement `mmap()` and `munmap()`

2022-04-21T00:05:46Z

Implement mmap() and munmap(). Currently, they are only available for architecures that have my_syscall6 macro. For architectures that don't have, this function will return -1 with errno set to ENOSYS (Function not implemented). This has been tested on x86 and i386. Notes for i386: 1) The common mmap() syscall implementation uses __NR_mmap2 instead of __NR_mmap. 2) The offset must be shifted-right by 12-bit. Acked-by: Willy Tarreau Signed-off-by: Ammar Faizi Signed-off-by: Paul E. McKenney

tools/nolibc: i386: Implement syscall with 6 arguments

2022-04-21T00:05:46Z

On i386, the 6th argument of syscall goes in %ebp. However, both Clang and GCC cannot use %ebp in the clobber list and in the "r" constraint without using -fomit-frame-pointer. To make it always available for any kind of compilation, the below workaround is implemented. 1) Push the 6-th argument. 2) Push %ebp. 3) Load the 6-th argument from 4(%esp) to %ebp. 4) Do the syscall (int $0x80). 5) Pop %ebp (restore the old value of %ebp). 6) Add %esp by 4 (undo the stack pointer). Cc: x86@kernel.org Cc: llvm@lists.linux.dev Link: https://lore.kernel.org/lkml/2e335ac54db44f1d8496583d97f9dab0@AcuMS.aculab.com Suggested-by: David Laight Acked-by: Willy Tarreau Signed-off-by: Ammar Faizi Signed-off-by: Paul E. McKenney

tools/nolibc: Remove .global _start from the entry point code

2022-04-21T00:05:46Z

Building with clang yields the following error: ``` :3:1: error: _start changed binding to STB_GLOBAL .global _start ^ 1 error generated. ``` Make sure only specify one between `.global _start` and `.weak _start`. Remove `.global _start`. Cc: llvm@lists.linux.dev Reviewed-by: Nick Desaulniers Acked-by: Willy Tarreau Signed-off-by: Ammar Faizi Signed-off-by: Paul E. McKenney

tools/nolibc: Replace `asm` with `asm`

2022-04-21T00:05:46Z

Replace `asm` with `__asm__` to support compilation with -std flag. Using `asm` with -std flag makes GCC think `asm()` is a function call instead of an inline assembly. GCC doc says: For the C language, the `asm` keyword is a GNU extension. When writing C code that can be compiled with `-ansi` and the `-std` options that select C dialects without GNU extensions, use `__asm__` instead of `asm`. Link: https://gcc.gnu.org/onlinedocs/gcc/Basic-Asm.html Reported-by: Alviro Iskandar Setiawan Acked-by: Willy Tarreau Signed-off-by: Ammar Faizi Signed-off-by: Paul E. McKenney

tools/nolibc: x86-64: Update System V ABI document link

2022-04-21T00:05:46Z

The old link no longer works, update it. Acked-by: Willy Tarreau Signed-off-by: Ammar Faizi Signed-off-by: Paul E. McKenney

tools/nolibc/stdlib: only reference the external environ when inlined

2022-04-21T00:05:46Z

When building with gcc at -O0 we're seeing link errors due to the "environ" variable being referenced by getenv(). The problem is that at -O0 gcc will not inline getenv() and will not drop the external reference. One solution would be to locally declare the variable as weak, but then it would appear in all programs even those not using it, and would be confusing to users of getenv() who would forget to set environ to envp. An alternate approach used in this patch consists in always inlining the outer part of getenv() that references this extern so that it's always dropped when not used. The biggest part of the function was now moved to a new function called _getenv() that's still not inlined by default. Reported-by: Ammar Faizi Signed-off-by: Willy Tarreau Tested-by: Ammar Faizi Signed-off-by: Paul E. McKenney

linux-dev/tools/include/nolibc, branch linus/master

tools/nolibc/string: Implement `strdup()` and `strndup()`

tools/nolibc/string: Implement `strnlen()`

tools/nolibc/stdlib: Implement `malloc()`, `calloc()`, `realloc()` and `free()`

tools/nolibc/types: Implement `offsetof()` and `container_of()` macro

tools/nolibc/sys: Implement `mmap()` and `munmap()`

tools/nolibc: i386: Implement syscall with 6 arguments

tools/nolibc: Remove .global _start from the entry point code

tools/nolibc: Replace `asm` with `__asm__`

tools/nolibc: x86-64: Update System V ABI document link

tools/nolibc/stdlib: only reference the external environ when inlined

tools/nolibc: Replace `asm` with `asm`