libgcc/config/nios2/tramp.c

   1 /* Copyright (C) 2013-2015 Free Software Foundation, Inc.
   2    Contributed by Altera and Mentor Graphics, Inc.
   3
   4 This file is free software; you can redistribute it and/or modify it
   5 under the terms of the GNU General Public License as published by the
   6 Free Software Foundation; either version 3, or (at your option) any
   7 later version.
   8
   9 This file is distributed in the hope that it will be useful, but
  10 WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12 General Public License for more details.
  13
  14 Under Section 7 of GPL version 3, you are granted additional
  15 permissions described in the GCC Runtime Library Exception, version
  16 3.1, as published by the Free Software Foundation.
  17
  18 You should have received a copy of the GNU General Public License and
  19 a copy of the GCC Runtime Library Exception along with this program;
  20 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  21 <http://www.gnu.org/licenses/>.  */
  22
  23 /* Set up trampolines.
  24    R12 is the static chain register.
  25    R2 is AT, the assembler temporary.
  26    The trampoline code looks like:
  27         movhi   r12,%hi(chain)
  28         ori     r12,%lo(chain)
  29         movhi   r2,%hi(fn)
  30         ori     r2,%lo(fn)
  31         jmp     r2
  32 */
  33
  34 #define SC_REGNO 12
  35
  36 #define MOVHI(reg,imm16) \
  37   (((reg) << 22) | ((imm16) << 6) | 0x34)
  38 #define ORI(reg,imm16) \
  39   (((reg) << 27) | ((reg) << 22) | ((imm16) << 6) | 0x14)
  40 #define JMP(reg) \
  41   (((reg) << 27) | (0x0d << 11) | 0x3a)
  42
  43 void
  44 __trampoline_setup (unsigned int *addr, void *fnptr, void *chainptr)
  45 {
  46   unsigned int fn = (unsigned int) fnptr;
  47   unsigned int chain = (unsigned int) chainptr;
  48   int i;
  49
  50   addr[0] = MOVHI (SC_REGNO, ((chain >> 16) & 0xffff));
  51   addr[1] = ORI (SC_REGNO, (chain & 0xffff));
  52   addr[2] = MOVHI (2, ((fn >> 16) & 0xffff));
  53   addr[3] = ORI (2, (fn & 0xffff));
  54   addr[4] = JMP (2);
  55
  56   /* Flush the caches.
  57      See Example 9-4 in the Nios II Software Developer's Handbook.  */
  58   for (i = 0; i < 5; i++)
  59     asm volatile ("flushd 0(%0); flushi %0" :: "r"(addr + i) : "memory");
  60   asm volatile ("flushp" ::: "memory");
  61 }