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