On 2023-07-13 14:12:27+0800, Zhangjin Wu wrote:
On 2023-07-12 17:17:39+0800, Zhangjin Wu wrote:
[..]
diff --git a/tools/include/nolibc/crt.h b/tools/include/nolibc/crt.h new file mode 100644 index 000000000000..f9db2389acd2 --- /dev/null +++ b/tools/include/nolibc/crt.h @@ -0,0 +1,59 @@ +/* SPDX-License-Identifier: LGPL-2.1 OR MIT */ +/*
- C Run Time support for NOLIBC
- Copyright (C) 2023 Zhangjin Wu falcon@tinylab.org
- */
+#ifndef _NOLIBC_CRT_H +#define _NOLIBC_CRT_H
+char **environ __attribute__((weak)); +const unsigned long *_auxv __attribute__((weak));
+typedef int (_nolibc_main_fn)(int, char **, char **);
What's the advantage of the typedef over using the pointer type inline?
With the extra comment added, this is not required anymore, will remove this typedef.
+static void exit(int);
+void _start_c(long *sp) +{
- int argc, i;
- char **argv;
- char **envp;
- /* silence potential warning: conflicting types for 'main' */
- _nolibc_main_fn _nolibc_main __asm__ ("main");
What about the stackprotector initialization? It would really fit great into this series.
Ok, which gcc version supports stackprotector? seems the test even skip on gcc 10, I will find one to verify the code change.
For crosscompilation I use the crosstools from kernel.org at https://mirrors.edge.kernel.org/pub/tools/crosstool/
It seems to be at least in their gcc 9.5.0. And also in their 11.2 which I use mostly at the moment.
- /*
* sp : argc <-- argument count, required by main()* argv: argv[0] <-- argument vector, required by main()* argv[1]* ...* argv[argc-1]* null* envp: envp[0] <-- environment variables, required by main() and getenv()* envp[1]* ...* null* _auxv: auxv[0] <-- auxiliary vector, required by getauxval()* auxv[1]* ...* null*/- /* assign argc and argv */
- argc = sp[0];
- argv = (void *)(sp + 1);
Bit of a weird mismatch between array syntax and pointer arithmetic.
This 'argc = *sp;' may be better ;-)
- /* find envp */
- envp = argv + argc + 1;
- environ = envp;
Is envp really needed? Could just be assigned directly to environ.
Ok, let's save one variable, envp is used to be consistent with the frequenty declaration of main().
- /* find auxv */
- i = 0;
- while (envp[i])
i++;- _auxv = (void *)(envp + i + 1);
Could be simplified a bit:
_auxv = (void *) envp; while (_auxv) _auxv++;
Yeah, it is better, but needs a little change.
_auxv = (void *) envp; while (*_auxv)_auxv++; _auxv++;
Good catch, thanks.
[..]
Thomas