diff options
Diffstat (limited to 'sysdeps/mach/hurd/i386/makecontext-helper.c')
-rw-r--r-- | sysdeps/mach/hurd/i386/makecontext-helper.c | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/sysdeps/mach/hurd/i386/makecontext-helper.c b/sysdeps/mach/hurd/i386/makecontext-helper.c new file mode 100644 index 0000000000..c6fb90ca5a --- /dev/null +++ b/sysdeps/mach/hurd/i386/makecontext-helper.c @@ -0,0 +1,71 @@ +/* Helper for makecontext: handle threadvars. + Copyright (C) 2013-2015 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 + <http://www.gnu.org/licenses/>. */ + +#include <hurd/threadvar.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <ucontext.h> + +#if 0 + +void +__makecontext_helper (ucontext_t *ucp) +{ + if (__hurd_threadvar_stack_mask == 0) + { + /* We are not using threads, so per init-first.c:init, the threadvars + live in a malloced space, addressed relative to the base of the + virtual address space. Just keep using that one. */ + } + else + { + /* The following is only prepared to work with libpthread, which only + keeps the threadvars at the bottom of the stack -- contrary to + libthreads, which also puts additional data there. */ + + void *s = ucp->uc_stack.ss_sp; + size_t s_size = ucp->uc_stack.ss_size; + + /* Is the new stack suitable? Check that that the last threadvar + occupies the last storage unit within the bounds of the new stack. + Alignment according to (sp & __hurd_threadvar_stack_mask) == sp is not + actually a requirement (though, in practice it often will be). */ + if (__hurd_threadvar_location_from_sp (_HURD_THREADVAR_MAX, s) + != s + s_size) + { + /* Instead of having makecontext return an error, we bail out the + hard way, as we can't expect its caller to be able to properly + react to this situation. */ + fprintf (stderr, + "*** makecontext: a stack at %p with size %#x is not " + "usable with threadvars\n", + s, s_size); + abort (); + } + + /* Copy the threadvars to the new stack. */ + void *t_old = __hurd_threadvar_location (0); + void *t_new = __hurd_threadvar_location_from_sp (0, s); + size_t t_size = __hurd_threadvar_max * sizeof (unsigned long int); + memcpy (t_new, t_old, t_size); + /* Account for the space taken by the threadvars. */ + ucp->uc_stack.ss_size -= t_size; + } +} +#endif |