Let's move most of the _start operations to _start_c().
Signed-off-by: Zhangjin Wu <falcon@xxxxxxxxxxx>
---
tools/include/nolibc/arch-arm.h | 42 ++++-----------------------------
1 file changed, 5 insertions(+), 37 deletions(-)
diff --git a/tools/include/nolibc/arch-arm.h b/tools/include/nolibc/arch-arm.h
index a2ea5756cef2..573f8fe31cee 100644
--- a/tools/include/nolibc/arch-arm.h
+++ b/tools/include/nolibc/arch-arm.h
@@ -183,49 +183,17 @@
_arg1; \
})
-
-char **environ __attribute__((weak));
-const unsigned long *_auxv __attribute__((weak));
-
/* startup code */
void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) __no_stack_protector _start(void)
{
__asm__ volatile (
#ifdef _NOLIBC_STACKPROTECTOR
- "bl __stack_chk_init\n" /* initialize stack protector */
+ "bl __stack_chk_init\n" /* initialize stack protector */
#endif
- "pop {%r0}\n" /* argc was in the stack */
- "mov %r1, %sp\n" /* argv = sp */
-
- "add %r2, %r0, $1\n" /* envp = (argc + 1) ... */
- "lsl %r2, %r2, $2\n" /* * 4 ... */
- "add %r2, %r2, %r1\n" /* + argv */
- "ldr %r3, 1f\n" /* r3 = &environ (see below) */
- "str %r2, [r3]\n" /* store envp into environ */
-
- "mov r4, r2\n" /* search for auxv (follows NULL after last env) */
- "0:\n"
- "mov r5, r4\n" /* r5 = r4 */
- "add r4, r4, #4\n" /* r4 += 4 */
- "ldr r5,[r5]\n" /* r5 = *r5 = *(r4-4) */
- "cmp r5, #0\n" /* and stop at NULL after last env */
- "bne 0b\n"
- "ldr %r3, 2f\n" /* r3 = &_auxv (low bits) */
- "str r4, [r3]\n" /* store r4 into _auxv */
-
- "mov %r3, $8\n" /* AAPCS : sp must be 8-byte aligned in the */
- "neg %r3, %r3\n" /* callee, and bl doesn't push (lr=pc) */
- "and %r3, %r3, %r1\n" /* so we do sp = r1(=sp) & r3(=-8); */
- "mov %sp, %r3\n"
-
- "bl main\n" /* main() returns the status code, we'll exit with it. */
- "movs r7, $1\n" /* NR_exit == 1 */
- "svc $0x00\n"
- ".align 2\n" /* below are the pointers to a few variables */
- "1:\n"
- ".word environ\n"
- "2:\n"
- ".word _auxv\n"
+ "mov %r0, sp\n" /* save stack pointer to r0, as arg1 of _start_c*/
+ "and ip, %r0, #-8\n" /* sp must be 8-byte aligned in the callee */
+ "mov sp, ip\n"
+ "bl _start_c\n" /* transfer to c runtime */
);
__builtin_unreachable();
}
--
2.25.1
