Commit ded8af47 authored by Zhangjin Wu's avatar Zhangjin Wu Committed by Willy Tarreau
Browse files

tools/nolibc: aarch64: shrink _start with _start_c 



move most of the _start operations to _start_c(), include the
stackprotector initialization.

Signed-off-by: default avatarZhangjin Wu <falcon@tinylab.org>
Signed-off-by: default avatarWilly Tarreau <w@1wt.eu>
parent 61f98807

tools/include/nolibc/arch-aarch64.h

+4 −23
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 
#define _NOLIBC_ARCH_AARCH64_H



#include "compiler.h"

#include "crt.h"



/* Syscalls for AARCH64 :

 *   - registers are 64-bit
@@ -143,33 +144,13 @@ 
	_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();

}