tools/nolibc: aarch64: shrink _start with _start_c
authorZhangjin Wu <falcon@tinylab.org>
Sat, 15 Jul 2023 18:25:35 +0000 (02:25 +0800)
committerWilly Tarreau <w@1wt.eu>
Wed, 23 Aug 2023 02:40:22 +0000 (04:40 +0200)
move most of the _start operations to _start_c(), include the
stackprotector initialization.

Signed-off-by: Zhangjin Wu <falcon@tinylab.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>
tools/include/nolibc/arch-aarch64.h

index 3c0a5f47b3e8afef7aaf05eb06f7762f19f95eb9..6c33c46848e36ecf9a63b7c4d193987fb9eae6e4 100644 (file)
@@ -8,6 +8,7 @@
 #define _NOLIBC_ARCH_AARCH64_H
 
 #include "compiler.h"
+#include "crt.h"
 
 /* Syscalls for AARCH64 :
  *   - registers are 64-bit
        _arg1;                                                                \
 })
 
-char **environ __attribute__((weak));
-const unsigned long *_auxv __attribute__((weak));
-
 /* startup code */
 void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void)
 {
        __asm__ volatile (
-#ifdef _NOLIBC_STACKPROTECTOR
-               "bl __stack_chk_init\n"   /* initialize stack protector                     */
-#endif
-               "ldr x0, [sp]\n"     /* argc (x0) was in the stack                          */
-               "add x1, sp, 8\n"    /* argv (x1) = sp                                      */
-               "lsl x2, x0, 3\n"    /* envp (x2) = 8*argc ...                              */
-               "add x2, x2, 8\n"    /*           + 8 (skip null)                           */
-               "add x2, x2, x1\n"   /*           + argv                                    */
-               "adrp x3, environ\n"          /* x3 = &environ (high bits)                  */
-               "str x2, [x3, #:lo12:environ]\n" /* store envp into environ                 */
-               "mov x4, x2\n"       /* search for auxv (follows NULL after last env)       */
-               "0:\n"
-               "ldr x5, [x4], 8\n"  /* x5 = *x4; x4 += 8                                   */
-               "cbnz x5, 0b\n"      /* and stop at NULL after last env                     */
-               "adrp x3, _auxv\n"   /* x3 = &_auxv (high bits)                             */
-               "str x4, [x3, #:lo12:_auxv]\n" /* store x4 into _auxv                       */
-               "and sp, x1, -16\n"  /* sp must be 16-byte aligned in the callee            */
-               "bl main\n"          /* main() returns the status code, we'll exit with it. */
-               "mov x8, 93\n"       /* NR_exit == 93                                       */
-               "svc #0\n"
+               "mov x0, sp\n"          /* save stack pointer to x0, as arg1 of _start_c */
+               "and sp, x0, -16\n"     /* sp must be 16-byte aligned in the callee      */
+               "bl  _start_c\n"        /* transfer to c runtime                         */
        );
        __builtin_unreachable();
 }