linux-toradex.git/tools/include/nolibc, branch v6.12-rc4

tools/nolibc: x86_64: use local label in memcpy/memmove

2024-08-16T15:23:13+00:00

Compiling arch-x86_64.h with clang and binutils LD yields
duplicate label errors:

.../gcc-13.2.0-nolibc/x86_64-linux/bin/x86_64-linux-ld: error: LLVM gold plugin: :44:1: symbol '.Lbackward_copy' is already defined
.Lbackward_copy:leaq -1(%rdi, %rcx, 1), %rdi

Instead of a local symbol use a local label which can be defined
multiple times and therefore avoids the error.

Reviewed-by: Ammar Faizi 
Acked-by: Willy Tarreau 
Link: https://lore.kernel.org/r/20240812-nolibc-lto-v2-3-736af7bbefa8@weissschuh.net
Signed-off-by: Thomas Weißschuh

tools/nolibc: stackprotector: mark implicitly used symbols as used

2024-08-16T15:23:13+00:00

During LTO the references from the compiler-generated prologue and
epilogues to the stack protector symbols are not visible and the symbols
are removed.
This will then lead to errors during linking.
As those symbols are already #ifdeffed-out if unused mark them as "used"
to prevent their removal.

Acked-by: Willy Tarreau 
Link: https://lore.kernel.org/r/20240812-nolibc-lto-v2-2-736af7bbefa8@weissschuh.net
Signed-off-by: Thomas Weißschuh

tools/nolibc: crt: mark _start_c() as used

2024-08-16T15:23:13+00:00

During LTO the reference from the asm startup code to the _start_c()
function is not visible and _start_c() is removed.
This will then lead to errors during linking.
As _start_c() is indeed always used, mark it as such.

Acked-by: Willy Tarreau 
Link: https://lore.kernel.org/r/20240812-nolibc-lto-v2-1-736af7bbefa8@weissschuh.net
Signed-off-by: Thomas Weißschuh

tools/nolibc: compiler: use attribute((naked)) if available

2024-08-12T20:22:03+00:00

The current entrypoint attributes optimize("Os", "omit-frame-pointer")
are intended to avoid all compiler generated code, like function
porologue and epilogue.
This is the exact usecase implemented by the attribute "naked".

Unfortunately this is not implemented by GCC for all targets,
so only use it where available.
This also provides compatibility with clang, which recognizes the
"naked" attribute but not the previously used attribute "optimized".

Acked-by: Willy Tarreau 
Link: https://lore.kernel.org/r/20240807-nolibc-llvm-v2-6-c20f2f5fc7c2@weissschuh.net
Signed-off-by: Thomas Weißschuh

tools/nolibc: move entrypoint specifics to compiler.h

2024-08-12T20:21:00+00:00

The specific attributes for the _start entrypoint are duplicated for
each architecture.
Deduplicate it into a dedicated #define into compiler.h.

For clang compatibility, the epilogue will also need to be adapted, so
move that one, too.

Acked-by: Willy Tarreau 
Link: https://lore.kernel.org/r/20240807-nolibc-llvm-v2-5-c20f2f5fc7c2@weissschuh.net
Signed-off-by: Thomas Weißschuh

tools/nolibc: compiler: introduce __nolibc_has_attribute()

2024-08-10T15:08:19+00:00

Recent compilers support __has_attribute() to check if a certain
compiler attribute is supported.
Unfortunately we have to first check if __has_attribute is supported in
the first place and then if a specific attribute is present.
These two checks can't be folded into a single condition as that would
lead to errors.

Nesting the two conditions like below works, but becomes ugly as soon
as #else blocks are used as those need to be duplicated for both levels
of #if.

    #if defined __has_attribute
    #  if __has_attribute (nonnull)
    #    define ATTR_NONNULL __attribute__ ((nonnull))
    #  endif
    #endif

Introduce a new helper which makes the usage of __has_attribute() nicer
and migrate the current user to it.

Acked-by: Willy Tarreau 
Link: https://lore.kernel.org/r/20240807-nolibc-llvm-v2-4-c20f2f5fc7c2@weissschuh.net
Signed-off-by: Thomas Weißschuh

tools/nolibc: powerpc: limit stack-protector workaround to GCC

2024-08-10T15:08:15+00:00

As mentioned in the comment, the workaround for
__attribute__((no_stack_protector)) is only necessary on GCC.
Avoid applying the workaround on clang, as clang does not recognize
__attribute__((__optimize__)) and would fail.

Acked-by: Willy Tarreau 
Link: https://lore.kernel.org/r/20240807-nolibc-llvm-v2-3-c20f2f5fc7c2@weissschuh.net
Signed-off-by: Thomas Weißschuh

tools/nolibc: mips: load current function to $t9

2024-08-10T15:08:10+00:00

The MIPS calling convention requires the address of the current function
to be available in $t9.
This was not done so far.

For GCC this seems to have worked, but when compiled with clang the
executable segfault instantly.
Properly load the address of _start_c() into $t9 before calling it.

Acked-by: Willy Tarreau 
Link: https://lore.kernel.org/r/20240807-nolibc-llvm-v2-2-c20f2f5fc7c2@weissschuh.net
Signed-off-by: Thomas Weißschuh

tools/nolibc: arm: use clang-compatible asm syntax

2024-08-10T15:08:04+00:00

The clang assembler rejects the current syntax.
Switch to a syntax accepted by both GCC and clang.

Acked-by: Willy Tarreau 
Link: https://lore.kernel.org/r/20240807-nolibc-llvm-v2-1-c20f2f5fc7c2@weissschuh.net
Signed-off-by: Thomas Weißschuh

tools/nolibc: pass argc, argv and envp to constructors

2024-08-09T05:40:18+00:00

Since 2005 glibc has passed argc, argv, and envp to all constructors.
As it is cheap and easy to do so, mirror that behaviour in nolibc.
This makes it easier to migrate applications to nolibc.

Link: https://lore.kernel.org/r/20240728-nolibc-constructor-args-v1-1-36d0bf5cd4c0@weissschuh.net
Signed-off-by: Thomas Weißschuh