Adjust for new NaCl startup ABI

sysdeps/nacl/start.c

+/* This is the universal C startup code (crt1.o) for NaCl applications.
+   The initial stack and register state is arranged by the NaCl trusted
+   runtime as for a normal C function call of one argument.  */
+
+#include <stdint.h>
+
+int main (int argc, char **argv, char **envp);
+
+int __libc_csu_init (int argc, char **argv, char **envp);
+void __libc_csu_fini (void);
+
+void __libc_start_main (int (*main) (int argc, char **argv, char **envp),
+                        int argc, char **argv,
+                        int (*init) (int argc, char **argv, char **envp),
+                        void (*fini) (void),
+                        void (*rtld_fini) (void),
+                        void *stack_end);
+
+/* This is the true entry point for untrusted code.
+   It's called with the normal C ABI, taking one argument.
+   This is a pointer to stack space containing these words:
+   [0]             cleanup function pointer (always NULL in actual startup)
+   [1]             envc, count of envp[] pointers
+   [2]             argc, count of argv[] pointers
+   [3]             argv[0..argc] pointers, argv[argc] being NULL
+   [3+argc]        envp[0..envc] pointers, envp[envc] being NULL
+   [3+argc+envc]   auxv[] pairs
+*/
+void
+_start (uint32_t *info)
+{
+  void (*rtld_fini) (void) = (void (*) (void)) info[0];
+  int argc = info[2];
+  char **argv = (void *) &info[3];
+
+  /* The generic code actually assumes that envp follows argv
+     and that auxv follows envp.  */
+
+  __libc_start_main (&main, argc, argv,
+                     &__libc_csu_init, &__libc_csu_fini, rtld_fini,
+                     __builtin_frame_address (0));
+
+  /* That should not return.  Make sure we crash if it did.  */
+  while (1) *(volatile int *) 0;
+}