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authorMichael Ellerman <michael@ellerman.id.au>2005-12-04 02:39:37 -0500
committerPaul Mackerras <paulus@samba.org>2006-01-08 22:52:21 -0500
commit0cc4746cadda16826a1b3214c042a2f75445b71c (patch)
treeec8decc81a3f9fd09454ff208fd3b82cf5bdb730 /arch/powerpc/kernel/crash_dump.c
parent8c4f1f2958ff9d4a6760f3bdd0cfb7d2b9e12093 (diff)
[PATCH] powerpc: Reroute interrupts from 0 + offset to PHYSICAL_START + offset
Regardless of where the kernel's linked we always get interrupts at low addresses. This patch creates a trampoline in the first 3 pages of memory, where interrupts land, and patches those addresses to jump into the real kernel code at PHYSICAL_START. We also need to reserve the trampoline code and a bit more in prom.c Signed-off-by: Michael Ellerman <michael@ellerman.id.au> Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'arch/powerpc/kernel/crash_dump.c')
-rw-r--r--arch/powerpc/kernel/crash_dump.c53
1 files changed, 53 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/crash_dump.c b/arch/powerpc/kernel/crash_dump.c
new file mode 100644
index 00000000000..63919bcfc9f
--- /dev/null
+++ b/arch/powerpc/kernel/crash_dump.c
@@ -0,0 +1,53 @@
1/*
2 * Routines for doing kexec-based kdump.
3 *
4 * Copyright (C) 2005, IBM Corp.
5 *
6 * Created by: Michael Ellerman
7 *
8 * This source code is licensed under the GNU General Public License,
9 * Version 2. See the file COPYING for more details.
10 */
11
12#undef DEBUG
13
14#include <asm/kdump.h>
15#include <asm/lmb.h>
16#include <asm/firmware.h>
17
18#ifdef DEBUG
19#include <asm/udbg.h>
20#define DBG(fmt...) udbg_printf(fmt)
21#else
22#define DBG(fmt...)
23#endif
24
25static void __init create_trampoline(unsigned long addr)
26{
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.
34 */
35 create_instruction(addr, 0x60000000); /* nop */
36 create_branch(addr + 4, addr + PHYSICAL_START, 0);
37}
38
39void __init kdump_setup(void)
40{
41 unsigned long i;
42
43 DBG(" -> kdump_setup()\n");
44
45 for (i = KDUMP_TRAMPOLINE_START; i < KDUMP_TRAMPOLINE_END; i += 8) {
46 create_trampoline(i);
47 }
48
49 create_trampoline(__pa(system_reset_fwnmi) - PHYSICAL_START);
50 create_trampoline(__pa(machine_check_fwnmi) - PHYSICAL_START);
51
52 DBG(" <- kdump_setup()\n");
53}