Jeroen Dobbelaere writes:

Because variables are linked to fixed registers, there is a problem in :
     (*__errno_location())=(-_r0);

As __errno_location() uses r0 to return the address of the errno location,
the negated address will be assigned instead of the error code.

Attached patch will resolve this.

libc/sysdeps/linux/arm/syscall.c

@@ -41,7 +41,8 @@ long syscall(long sysnum, long a, long b, long c, long d, long e, long f)
 	      "r"(_r6)
 	    : "memory");
     if(_r0 >=(unsigned long) -4095) {
-	(*__errno_location())=(-_r0);
+	long err = _r0;
+	(*__errno_location())=(-err);
 	_r0=(unsigned long) -1;
     }
     return (long) _r0;