tools/nolibc: add prototypes for non-static functions

With -Wmissing-prototypes the compiler will warn about non-static
functions which don't have a prototype defined.
This warning doesn't make much sense for nolibc itself but for user code
it is still useful.
To pacify the compiler add prototypes next to the function definitions,
similar to how it is handled elsewhere in the kernel.

Acked-by: Willy Tarreau <w@1wt.eu>
Link: https://lore.kernel.org/r/20250123-nolibc-prototype-v1-1-e1afc5c1999a@weissschuh.net
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>

6 files changed, 11 insertions, 0 deletions

diff --git a/tools/include/nolibc/arch-mips.h b/tools/include/nolibc/arch-mips.h
index 1791a8ce58da..753a8ed2cf69 100644
--- a/tools/include/nolibc/arch-mips.h
+++ b/tools/include/nolibc/arch-mips.h
@@ -179,6 +179,7 @@
 })
 
 /* startup code, note that it's called __start on MIPS */
+void __start(void);
 void __attribute__((weak, noreturn)) __nolibc_entrypoint __no_stack_protector __start(void)
 {
 	__asm__ volatile (
diff --git a/tools/include/nolibc/crt.h b/tools/include/nolibc/crt.h
index bbcd5fd09806..c4b10103bbec 100644
--- a/tools/include/nolibc/crt.h
+++ b/tools/include/nolibc/crt.h
@@ -10,6 +10,7 @@
 char **environ __attribute__((weak));
 const unsigned long *_auxv __attribute__((weak));
 
+void _start(void);
 static void __stack_chk_init(void);
 static void exit(int);
 
@@ -22,6 +23,7 @@ extern void (*const __init_array_end[])(int, char **, char**) __attribute__((wea
 extern void (*const __fini_array_start[])(void) __attribute__((weak));
 extern void (*const __fini_array_end[])(void) __attribute__((weak));
 
+void _start_c(long *sp);
 __attribute__((weak,used))
 void _start_c(long *sp)
 {
diff --git a/tools/include/nolibc/signal.h b/tools/include/nolibc/signal.h
index 137552216e46..cdcc5904c51e 100644
--- a/tools/include/nolibc/signal.h
+++ b/tools/include/nolibc/signal.h
@@ -13,6 +13,7 @@
 #include "sys.h"
 
 /* This one is not marked static as it's needed by libgcc for divide by zero */
+int raise(int signal);
 __attribute__((weak,unused,section(".text.nolibc_raise")))
 int raise(int signal)
 {
diff --git a/tools/include/nolibc/stackprotector.h b/tools/include/nolibc/stackprotector.h
index 1d0d5259ec41..c71a2c257177 100644
--- a/tools/include/nolibc/stackprotector.h
+++ b/tools/include/nolibc/stackprotector.h
@@ -18,6 +18,7 @@
  * triggering stack protector errors themselves
  */
 
+void __stack_chk_fail(void);
 __attribute__((weak,used,noreturn,section(".text.nolibc_stack_chk")))
 void __stack_chk_fail(void)
 {
@@ -28,6 +29,7 @@ void __stack_chk_fail(void)
 	for (;;);
 }
 
+void __stack_chk_fail_local(void);
 __attribute__((weak,noreturn,section(".text.nolibc_stack_chk")))
 void __stack_chk_fail_local(void)
 {
diff --git a/tools/include/nolibc/stdlib.h b/tools/include/nolibc/stdlib.h
index 75aa273c23a6..86ad378ab1ea 100644
--- a/tools/include/nolibc/stdlib.h
+++ b/tools/include/nolibc/stdlib.h
@@ -30,6 +30,7 @@ static __attribute__((unused)) char itoa_buffer[21];
  */
 
 /* must be exported, as it's used by libgcc for various divide functions */
+void abort(void);
 __attribute__((weak,unused,noreturn,section(".text.nolibc_abort")))
 void abort(void)
 {
diff --git a/tools/include/nolibc/string.h b/tools/include/nolibc/string.h
index 9ec9c24f38c0..ba84ab700e30 100644
--- a/tools/include/nolibc/string.h
+++ b/tools/include/nolibc/string.h
@@ -32,6 +32,7 @@ int memcmp(const void *s1, const void *s2, size_t n)
 /* might be ignored by the compiler without -ffreestanding, then found as
  * missing.
  */
+void *memmove(void *dst, const void *src, size_t len);
 __attribute__((weak,unused,section(".text.nolibc_memmove")))
 void *memmove(void *dst, const void *src, size_t len)
 {
@@ -56,6 +57,7 @@ void *memmove(void *dst, const void *src, size_t len)
 
 #ifndef NOLIBC_ARCH_HAS_MEMCPY
 /* must be exported, as it's used by libgcc on ARM */
+void *memcpy(void *dst, const void *src, size_t len);
 __attribute__((weak,unused,section(".text.nolibc_memcpy")))
 void *memcpy(void *dst, const void *src, size_t len)
 {
@@ -73,6 +75,7 @@ void *memcpy(void *dst, const void *src, size_t len)
 /* might be ignored by the compiler without -ffreestanding, then found as
  * missing.
  */
+void *memset(void *dst, int b, size_t len);
 __attribute__((weak,unused,section(".text.nolibc_memset")))
 void *memset(void *dst, int b, size_t len)
 {
@@ -124,6 +127,7 @@ char *strcpy(char *dst, const char *src)
  * thus itself, hence the asm() statement below that's meant to disable this
  * confusing practice.
  */
+size_t strlen(const char *str);
 __attribute__((weak,unused,section(".text.nolibc_strlen")))
 size_t strlen(const char *str)
 {