csu: Move calling main out of __libc_start_main_impl

This code depends on whether glibc has unwinding support for
a particular port.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

2 files changed, 112 insertions, 0 deletions

diff --git a/sysdeps/generic/libc_start_call_main.h b/sysdeps/generic/libc_start_call_main.h
new file mode 100644
index 0000000000..8a06eec4a3
--- /dev/null
+++ b/sysdeps/generic/libc_start_call_main.h
@@ -0,0 +1,24 @@
+/* Invoking main from __libc_start.  Generic version without unwinding.
+   Copyright (C) 1998-2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+_Noreturn static __always_inline void
+__libc_start_call_main (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL),
+                        int argc, char **argv MAIN_AUXVEC_DECL)
+{
+  exit (main (argc, argv, __environ MAIN_AUXVEC_PARAM));
+}
diff --git a/sysdeps/nptl/libc_start_call_main.h b/sysdeps/nptl/libc_start_call_main.h
new file mode 100644
index 0000000000..5218e7ab1e
--- /dev/null
+++ b/sysdeps/nptl/libc_start_call_main.h
@@ -0,0 +1,88 @@
+/* Invoking main from __libc_start_main.  nptl version.
+   Copyright (C) 1998-2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <atomic.h>
+
+_Noreturn static void
+__libc_start_call_main (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL),
+                        int argc, char **argv
+#ifdef LIBC_START_MAIN_AUXVEC_ARG
+                            , ElfW(auxv_t) *auxvec
+#endif
+                        )
+{
+  int result;
+
+  /* Memory for the cancellation buffer.  */
+  struct pthread_unwind_buf unwind_buf;
+
+  int not_first_call;
+  DIAG_PUSH_NEEDS_COMMENT;
+#if __GNUC_PREREQ (7, 0)
+  /* This call results in a -Wstringop-overflow warning because struct
+     pthread_unwind_buf is smaller than jmp_buf.  setjmp and longjmp
+     do not use anything beyond the common prefix (they never access
+     the saved signal mask), so that is a false positive.  */
+  DIAG_IGNORE_NEEDS_COMMENT (11, "-Wstringop-overflow=");
+#endif
+  not_first_call = setjmp ((struct __jmp_buf_tag *) unwind_buf.cancel_jmp_buf);
+  DIAG_POP_NEEDS_COMMENT;
+  if (__glibc_likely (! not_first_call))
+    {
+      struct pthread *self = THREAD_SELF;
+
+      /* Store old info.  */
+      unwind_buf.priv.data.prev = THREAD_GETMEM (self, cleanup_jmp_buf);
+      unwind_buf.priv.data.cleanup = THREAD_GETMEM (self, cleanup);
+
+      /* Store the new cleanup handler info.  */
+      THREAD_SETMEM (self, cleanup_jmp_buf, &unwind_buf);
+
+      /* Run the program.  */
+      result = main (argc, argv, __environ MAIN_AUXVEC_PARAM);
+    }
+  else
+    {
+      /* Remove the thread-local data.  */
+# ifdef SHARED
+      PTHFCT_CALL (ptr__nptl_deallocate_tsd, ());
+# else
+      extern void __nptl_deallocate_tsd (void) __attribute ((weak));
+      __nptl_deallocate_tsd ();
+# endif
+
+      /* One less thread.  Decrement the counter.  If it is zero we
+         terminate the entire process.  */
+      result = 0;
+# ifdef SHARED
+      unsigned int *ptr = __libc_pthread_functions.ptr_nthreads;
+#  ifdef PTR_DEMANGLE
+      PTR_DEMANGLE (ptr);
+#  endif
+# else
+      extern unsigned int __nptl_nthreads __attribute ((weak));
+      unsigned int *const ptr = &__nptl_nthreads;
+# endif
+
+      if (! atomic_decrement_and_test (ptr))
+        /* Not much left to do but to exit the thread, not the process.  */
+        __exit_thread ();
+    }
+
+  exit (result);
+}