From 0cc4746cadda16826a1b3214c042a2f75445b71c Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Sun, 4 Dec 2005 18:39:37 +1100 Subject: [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 Signed-off-by: Paul Mackerras --- arch/powerpc/kernel/crash_dump.c | 53 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) create mode 100644 arch/powerpc/kernel/crash_dump.c (limited to 'arch/powerpc/kernel/crash_dump.c') diff --git a/arch/powerpc/kernel/crash_dump.c b/arch/powerpc/kernel/crash_dump.c new file mode 100644 index 000000000000..63919bcfc9fe --- /dev/null +++ b/arch/powerpc/kernel/crash_dump.c @@ -0,0 +1,53 @@ +/* + * 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 +#include +#include + +#ifdef DEBUG +#include +#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"); +} -- cgit v1.2.3