sparc: add deprecated context switching functions

Ported over from glibc mostly without changes.
Lightly tested with mongrel2 in qemu-system-sparc.

1 files changed, 92 insertions, 0 deletions

diff --git a/libc/sysdeps/linux/sparc/makecontext.c b/libc/sysdeps/linux/sparc/makecontext.c
new file mode 100644
index 000000000..3a9f70cc5
--- /dev/null
+++ b/libc/sysdeps/linux/sparc/makecontext.c
@@ -0,0 +1,92 @@
+/* Create new context.
+   Copyright (C) 2008-2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by David S. Miller <davem@davemloft.net>, 2008.
+
+   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 <sysdep.h>
+#include <stdarg.h>
+#include <stdint.h>
+#include <ucontext.h>
+
+/* Sets up the outgoing arguments and the program counter for a user
+   context for the requested function call.
+
+   Returning to the correct parent context is pretty simple on
+   Sparc.  We only need to link up the register windows correctly.
+   Since global registers are clobbered by calls, we need not be
+   concerned about those, and thus is all could be worked out without
+   using a trampoline.
+
+   Except that we must deal with the signal mask, thus a trampoline
+   is unavoidable. 32-bit stackframe layout:
+	      +-----------------------------------------+
+	      | 7th and further parameters		|
+	      +-----------------------------------------+
+	      | backup storage for initial 6 parameters |
+	      +-----------------------------------------+
+	      | struct return pointer			|
+	      +-----------------------------------------+
+	      | 8 incoming registers			|
+	      +-----------------------------------------+
+	      | 8 local registers			|
+     %sp -->  +-----------------------------------------+
+
+*/
+
+void
+__makecontext (ucontext_t *ucp, void (*func) (void), int argc, ...)
+{
+  extern void __start_context (void);
+  unsigned long int *sp;
+  va_list ap;
+  int i;
+
+  sp = (unsigned long int *) (ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
+  sp -= 16 + 7 + argc;
+  sp = (unsigned long int *) (((uintptr_t) sp) & ~(8 - 1));
+
+  for (i = 0; i < 8; i++)
+    sp[i + 8] = ucp->uc_mcontext.gregs[REG_O0 + i];
+
+  /* The struct return pointer is essentially unused, so we can
+     place the link there.  */
+  sp[16] = (unsigned long int) ucp->uc_link;
+
+  va_start (ap, argc);
+
+  /* Fill in outgoing arguments, including those which will
+     end up being passed on the stack.  */
+  for (i = 0; i < argc; i++)
+    {
+      unsigned long int arg = va_arg (ap, unsigned long int);
+      if (i < 6)
+	ucp->uc_mcontext.gregs[REG_O0 + i] = arg;
+      else
+	sp[i + 23 - 6] = arg;
+    }
+
+  va_end (ap);
+
+  ucp->uc_mcontext.gregs[REG_O6] = (unsigned long int) sp;
+
+  ucp->uc_mcontext.gregs[REG_O7] = ((unsigned long int) __start_context) - 8;
+
+  ucp->uc_mcontext.gregs[REG_PC] = (unsigned long int) func;
+  ucp->uc_mcontext.gregs[REG_nPC] = ucp->uc_mcontext.gregs[REG_PC] + 4;
+}
+
+weak_alias (__makecontext, makecontext)