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Commit 0cc4746c authored by Michael Ellerman's avatar Michael Ellerman Committed by Paul Mackerras
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[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: default avatarMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent 8c4f1f29

arch/powerpc/kernel/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -34,6 +34,7 @@ obj-$(CONFIG_IBMVIO) += vio.o 
obj-$(CONFIG_IBMEBUS)           += ibmebus.o

obj-$(CONFIG_GENERIC_TBSYNC)	+= smp-tbsync.o

obj64-$(CONFIG_PPC_MULTIPLATFORM) += nvram_64.o

obj-$(CONFIG_CRASH_DUMP)	+= crash_dump.o



ifeq ($(CONFIG_PPC_MERGE),y)

arch/powerpc/kernel/crash_dump.c

0 → 100644
+53 −0
Original line number Diff line number Diff line 
/*

 * 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");

}

arch/powerpc/kernel/prom.c

+5 −1
Original line number Diff line number Diff line
@@ -37,6 +37,7 @@ 
#include <asm/processor.h>

#include <asm/irq.h>

#include <asm/io.h>

#include <asm/kdump.h>

#include <asm/smp.h>

#include <asm/system.h>

#include <asm/mmu.h>
@@ -1335,11 +1336,14 @@ void __init early_init_devtree(void *params) 
	of_scan_flat_dt(early_init_dt_scan_memory, NULL);

	lmb_enforce_memory_limit(memory_limit);

	lmb_analyze();

	lmb_reserve(0, __pa(klimit));



	DBG("Phys. mem: %lx\n", lmb_phys_mem_size());



	/* Reserve LMB regions used by kernel, initrd, dt, etc... */

	lmb_reserve(PHYSICAL_START, __pa(klimit) - PHYSICAL_START);

#ifdef CONFIG_CRASH_DUMP

	lmb_reserve(0, KDUMP_RESERVE_LIMIT);

#endif

	early_reserve_mem();



	DBG("Scanning CPUs ...\n");

arch/powerpc/kernel/setup_64.c

+5 −0
Original line number Diff line number Diff line
@@ -34,6 +34,7 @@ 
#include <linux/serial.h>

#include <linux/serial_8250.h>

#include <asm/io.h>

#include <asm/kdump.h>

#include <asm/prom.h>

#include <asm/processor.h>

#include <asm/pgtable.h>
@@ -268,6 +269,10 @@ void __init early_setup(unsigned long dt_ptr) 
	}

	ppc_md = **mach;



#ifdef CONFIG_CRASH_DUMP

	kdump_setup();

#endif



	DBG("Found, Initializing memory management...\n");



	/*

include/asm-powerpc/kdump.h

0 → 100644
+13 −0
Original line number Diff line number Diff line 
#ifndef _PPC64_KDUMP_H

#define _PPC64_KDUMP_H



/* How many bytes to reserve at zero for kdump. The reserve limit should

 * be greater or equal to the trampoline's end address. */

#define KDUMP_RESERVE_LIMIT	0x8000



#define KDUMP_TRAMPOLINE_START	0x0100

#define KDUMP_TRAMPOLINE_END	0x3000



extern void kdump_setup(void);



#endif /* __PPC64_KDUMP_H */