2 * Routines for doing kexec-based kdump.
4 * Copyright (C) 2005, IBM Corp.
6 * Created by: Michael Ellerman
8 * This source code is licensed under the GNU General Public License,
9 * Version 2. See the file COPYING for more details.
14 #include <asm/kdump.h>
16 #include <asm/firmware.h>
20 #define DBG(fmt...) udbg_printf(fmt)
25 static void __init create_trampoline(unsigned long addr)
27 /* The maximum range of a single instruction branch, is the current
28 * instruction's address + (32 MB - 4) bytes. For the trampoline we
29 * need to branch to current address + 32 MB. So we insert a nop at
30 * the trampoline address, then the next instruction (+ 4 bytes)
31 * does a branch to (32 MB - 4). The net effect is that when we
32 * branch to "addr" we jump to ("addr" + 32 MB). Although it requires
33 * two instructions it doesn't require any registers.
35 create_instruction(addr, 0x60000000); /* nop */
36 create_branch(addr + 4, addr + PHYSICAL_START, 0);
39 void __init kdump_setup(void)
43 DBG(" -> kdump_setup()\n");
45 for (i = KDUMP_TRAMPOLINE_START; i < KDUMP_TRAMPOLINE_END; i += 8) {
49 create_trampoline(__pa(system_reset_fwnmi) - PHYSICAL_START);
50 create_trampoline(__pa(machine_check_fwnmi) - PHYSICAL_START);
52 DBG(" <- kdump_setup()\n");