linux-stable.git/tools/include/nolibc, branch v6.0

tools/nolibc: add a help target to list supported targets

2022-06-20T16:43:19+00:00

The "help" target simply presents the list of supported targets
and the current set of variables being used to build the sysroot.

Since the help in tools/ suggests to use "install", which is
supported by most tools while such a target is not really relevant
here, an "install" target was also added, redirecting to "help".

Signed-off-by: Willy Tarreau 
Signed-off-by: Paul E. McKenney

tools/nolibc: make the default target build the headers

2022-06-20T16:43:19+00:00

The help in "make -C tools" enumerates nolibc as a valid target so we
must at least make it do something. Let's make it do the equivalent
of "make headers" in that it will prepare a sysroot with the arch's
headers, but will not install the kernel's headers. This is the
minimum some tools will need when built with a full-blown toolchain
anyway.

Signed-off-by: Willy Tarreau 
Signed-off-by: Paul E. McKenney

tools/nolibc: fix the makefile to also work as "make -C tools ..."

2022-06-20T16:43:19+00:00

As reported by Linus, the nolibc's makefile is currently broken when
invoked as per the documented method (make -C tools nolibc_),
because it now relies on the ARCH and OUTPUT variables that are not
set in this case.

This patch addresses this by sourcing subarch.include, and by
presetting OUTPUT to the current directory if not set. This is
sufficient to make the commands work both as a standalone target
and as a tools/ sub-target.

Signed-off-by: Willy Tarreau 
Signed-off-by: Paul E. McKenney

tools/nolibc/stdio: Add format attribute to enable printf warnings

2022-06-20T16:43:19+00:00

When we use printf and fprintf functions from the nolibc, we don't
get any warning from the compiler if we have the wrong arguments.
For example, the following calls will compile silently:
```
  printf("%s %s\n", "aaa");
  fprintf(stdout, "%s %s\n", "xxx", 1);
```
(Note the wrong arguments).

Those calls are undefined behavior. The compiler can help us warn
about the above mistakes by adding a `printf` format attribute to
those functions declaration. This patch adds it, and now it yields
these warnings for those mistakes:
```
  warning: format `%s` expects a matching `char *` argument [-Wformat=]
  warning: format `%s` expects argument of type `char *`, but argument 4 has type `int` [-Wformat=]
```

  [ ammarfaizi2: Simplify the attribute placement. ]

Signed-off-by: Alviro Iskandar Setiawan 
Signed-off-by: Ammar Faizi 
Acked-by: Willy Tarreau 
Signed-off-by: Paul E. McKenney

tools/nolibc/stdlib: Support overflow checking for older compiler versions

2022-06-20T16:43:19+00:00

Previously, we used __builtin_mul_overflow() to check for overflow in
the multiplication operation in the calloc() function. However, older
compiler versions don't support this built-in. This patch changes the
overflow checking mechanism to make it work on any compiler version
by using a division method to check for overflow. No functional change
intended. While in there, remove the unused variable `void *orig`.

Link: https://lore.kernel.org/lkml/20220330024114.GA18892@1wt.eu
Suggested-by: Willy Tarreau 
Cc: Alviro Iskandar Setiawan 
Signed-off-by: Ammar Faizi 
Acked-by: Willy Tarreau 
Reviewed-by: Alviro Iskandar Setiawan 
Signed-off-by: Paul E. McKenney

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

2022-04-21T00:05:46+00:00

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()`

2022-04-21T00:05:46+00:00

  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()`

2022-04-21T00:05:46+00:00

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

2022-04-21T00:05:46+00:00

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()`

2022-04-21T00:05:46+00:00

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