/*
* PPC64 code to handle Linux booting another kernel.
*
* Copyright (C) 2004-2005, IBM Corp.
*
* Created by: Milton D Miller II
*
* This source code is licensed under the GNU General Public License,
* Version 2. See the file COPYING for more details.
*/
#include <linux/kexec.h>
#include <linux/smp.h>
#include <linux/thread_info.h>
#include <linux/init_task.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/cpu.h>
#include <asm/page.h>
#include <asm/current.h>
#include <asm/machdep.h>
#include <asm/cacheflush.h>
#include <asm/paca.h>
#include <asm/mmu.h>
#include <asm/sections.h> /* _end */
#include <asm/prom.h>
#include <asm/smp.h>
#include <asm/hw_breakpoint.h>
int default_machine_kexec_prepare(struct kimage *image)
{
int i;
unsigned long begin, end; /* limits of segment */
unsigned long low, high; /* limits of blocked memory range */
struct device_node *node;
const unsigned long *basep;
const unsigned int *sizep;
if (!ppc_md.hpte_clear_all)
return -ENOENT;
/*
* Since we use the kernel fault handlers and paging code to
* handle the virtual mode, we must make sure no destination
* overlaps kernel static data or bss.
*/
for (i = 0; i < image->nr_segments; i++)
if (image->segment[i].mem < __pa(_end))
return -ETXTBSY;
/*
* For non-LPAR, we absolutely can not overwrite the mmu hash
* table, since we are still using the bolted entries in it to
* do the copy. Check that here.
*
* It is safe if the end is below the start of the blocked
* region (end <= low), or if the beginning is after the
* end of the blocked region (begin >= high). Use the
* boolean identity !(a || b) === (!a && !b).
*/
if (htab_address) {
low = __pa(htab_address);
high = low + htab_size_bytes;
for (i = 0; i < image->nr_segments; i++) {
begin = image->segment[i].mem;
end = begin + image->segment[i].memsz;
if ((begin < high) && (end > low))
return -ETXTBSY;
}
}
/* We also should not overwrite the tce tables */
for (node = of_find_node_by_type(NULL, "pci"); node != NULL;
node = of_find_node_by_type(node, "pci")) {
basep = of_get_property(node, "linux,tce-base", NULL);
sizep = of_get_property(node, "linux,tce-size", NULL);
if (basep == NULL || sizep == NULL)
continue;
low = *basep;
high = low + (*sizep);
for (i = 0; i < image->nr_segments; i++) {
begin = image->segment[i].mem;
end = begin + image->segment[i].memsz;
if ((begin < high) && (end > low))
return -ETXTBSY;
}
}
return 0;
}
#define IND_FLAGS (IND_DESTINATION | IND_INDIRECTION | IND_DONE | IND_SOURCE)
static void copy_segments(unsigned long ind)
{
unsigned long entry;
unsigned long *ptr;
void *dest;
void *addr;
/*
* We rely on kexec_load to create a lists that properly
* initializes these pointers before they are used.
* We will still crash if the list is wrong, but at least
* the compiler will be quiet.
*/
ptr = NULL;
dest = NULL;
for (entry = ind; !(entry & IND_DONE); entry = *ptr++) {
addr = __va(entry & PAGE_MASK);
switch (entry & IND_FLAGS) {
case IND_DESTINATION:
dest = addr;
break;
case IND_INDIRECTION:
ptr = addr;
break;
case IND_SOURCE:
copy_page(dest, addr);
dest += PAGE_SIZE;
}
}
}
void kexec_copy_flush(struct kimage *image)
{
long i, nr_segments = image->nr_segments;
struct kexec_segment ranges[KEXEC_SEGMENT_MAX];
/* save the ranges on the stack to efficiently flush the icache */
memcpy(ranges, image->segment, sizeof(ranges));
/*
* After this call we may not use anything allocated in dynamic
* memory, including *image.
*
* Only globals and the stack are allowed.
*/
copy_segments(image->head);
/*
* we need to clear the icache for all dest pages sometime,
* including ones that were in place on the original copy
*/
for (i = 0; i < nr_segments; i++)
flush_icache_range((unsigned long)__va(ranges[i].mem),
(unsigned long)__va(ranges[i].mem + ranges[i].memsz));
}
#ifdef CONFIG_SMP
static int kexec_all_irq_disabled = 0;
static void kexec_smp_down(void *arg)
{
local_irq_disable();
mb(); /* make sure our irqs are disabled before we say they are */
get_paca()->kexec_state = KEXEC_STATE_IRQS_OFF;
while(kexec_all_irq_disabled == 0)
cpu_relax();
mb(); /* make sure all irqs are disabled before this */
hw_breakpoint_disable();
/*
* Now every CPU has IRQs off, we can clear out any pending
* IPIs and be sure that no more will come in after this.
*/
if (ppc_md.kexec_cpu_down)
ppc_md.kexec_cpu_down(0, 1);
kexec_smp_wait();
/* NOTREACHED */
}
static void kexec_prepare_cpus_wait(int wait_state)
{
int my_cpu, i, notified=-1;
hw_breakpoint_disable();
my_cpu = get_cpu();
/* Make sure each CPU has at least made it to the state we need.
*
* FIXME: There is a (slim) chance of a problem if not all of the CPUs
* are correctly onlined. If somehow we start a CPU on boot with RTAS
* start-cpu, but somehow that CPU doesn't write callin_cpu_map[] in
* time, the boot CPU will timeout. If it does eventually execute
* stuff, the secondary will start up (paca[].cpu_start was written) and
* get into a peculiar state. If the platform supports
* smp_ops->take_timebase(), the secondary CPU will probably be spinning
* in there. If not (i.e. pseries), the secondary will continue on and
* try to online itself/idle/etc. If it survives that, we need to find
* these possible-but-not-online-but-should-be CPUs and chaperone them
* into kexec_smp_wait().
*/
for_each_online_cpu(i) {
if (i == my_cpu)
continue;
while (paca[i].kexec_state < wait_state) {
barrier();
if (i != notified) {
printk(KERN_INFO "kexec: waiting for cpu %d "
"(physical %d) to enter %i state\n",
i, paca[i].hw_cpu_id, wait_state);
notified = i;
}
}
}
mb();
}
/*
* We need to make sure each present CPU is online. The next kernel will scan
* the device tree and assume primary threads are online and query secondary
* threads via RTAS to online them if required. If we don't online primary
* threads, they will be stuck. However, we also online secondary threads as we
* may be using 'cede offline'. In this case RTAS doesn't see the secondary
* threads as offline -- and again, these CPUs will be stuck.
*
* So, we online all CPUs that should be running, including secondary threads.
*/
static void wake_offline_cpus(void)
{
int cpu = 0;
for_each_present_cpu(cpu) {
if (!cpu_online(cpu)) {
printk(KERN_INFO "kexec: Waking offline cpu %d.\n",
cpu);
cpu_up(cpu);
}
}
}
static void kexec_prepare_cpus(void)
{
wake_offline_cpus();
smp_call_function(kexec_smp_down, NULL, /* wait */0);
local_irq_disable();
mb(); /* make sure IRQs are disabled before we say they are */
get_paca()->kexec_state = KEXEC_STATE_IRQS_OFF;
kexec_prepare_cpus_wait(KEXEC_STATE_IRQS_OFF);
/* we are sure every CPU has IRQs off at this point */
kexec_all_irq_disabled = 1;
/* after we tell the others to go down */
if (ppc_md.kexec_cpu_down)
ppc_md.kexec_cpu_down(0, 0);
/*
* Before removing MMU mappings make sure all CPUs have entered real
* mode:
*/
kexec_prepare_cpus_wait(KEXEC_STATE_REAL_MODE);
put_cpu();
}
#else /* ! SMP */
static void kexec_prepare_cpus(void)
{
/*
* move the secondarys to us so that we can copy
* the new kernel 0-0x100 safely
*
* do this if kexec in setup.c ?
*
* We need to release the cpus if we are ever going from an
* UP to an SMP kernel.
*/
smp_release_cpus();
if (ppc_md.kexec_cpu_down)
ppc_md.kexec_cpu_down(0, 0);
local_irq_disable();
}
#endif /* SMP */
/*
* kexec thread structure and stack.
*
* We need to make sure that this is 16384-byte aligned due to the
* way process stacks are handled. It also must be statically allocated
* or allocated as part of the kimage, because everything else may be
* overwritten when we copy the kexec image. We piggyback on the
* "init_task" linker section here to statically allocate a stack.
*
* We could use a smaller stack if we don't care about anything using
* current, but that audit has not been performed.
*/
static union thread_union kexec_stack __init_task_data =
{ };
/*
* For similar reasons to the stack above, the kexecing CPU needs to be on a
* static PACA; we switch to kexec_paca.
*/
struct paca_struct kexec_paca;
/* Our assembly helper, in kexec_stub.S */
extern NORET_TYPE void kexec_sequence(void *newstack, unsigned long start,
void *image, void *control,
void (*clear_all)(void)) ATTRIB_NORET;
/* too late to fail here */
void default_machine_kexec(struct kimage *image)
{
/* prepare control code if any */
/*
* If the kexec boot is the normal one, need to shutdown other cpus
* into our wait loop and quiesce interrupts.
* Otherwise, in the case of crashed mode (crashing_cpu >= 0),
* stopping other CPUs and collecting their pt_regs is done before
* using debugger IPI.
*/
if (crashing_cpu == -1)
kexec_prepare_cpus();
pr_debug("kexec: Starting switchover sequence.\n");
/* switch to a staticly allocated stack. Based on irq stack code.
* XXX: the task struct will likely be invalid once we do the copy!
*/
kexec_stack.thread_info.task = current_thread_info()->task;
kexec_stack.thread_info.flags = 0;
/* We need a static PACA, too; copy this CPU's PACA over and switch to
* it. Also poison per_cpu_offset to catch anyone using non-static
* data.
*/
memcpy(&kexec_paca, get_paca(), sizeof(struct paca_struct));
kexec_paca.data_offset = 0xedeaddeadeeeeeeeUL;
paca = (struct paca_struct *)RELOC_HIDE(&kexec_paca, 0) -
kexec_paca.paca_index;
setup_paca(&kexec_paca);
/* XXX: If anyone does 'dynamic lppacas' this will also need to be
* switched to a static version!
*/
/* Some things are best done in assembly. Finding globals with
* a toc is easier in C, so pass in what we can.
*/
kexec_sequence(&kexec_stack, image->start, image,
page_address(image->control_code_page),
ppc_md.hpte_clear_all);
/* NOTREACHED */
}
/* Values we need to export to the second kernel via the device tree. */
static unsigned long htab_base;
static struct property htab_base_prop = {
.name = "linux,htab-base",
.length = sizeof(unsigned long),
.value = &htab_base,
};
static struct property htab_size_prop = {
.name = "linux,htab-size",
.length = sizeof(unsigned long),
.value = &htab_size_bytes,
};
static int __init export_htab_values(void)
{
struct device_node *node;
struct property *prop;
/* On machines with no htab htab_address is NULL */
if (!htab_address)
return -ENODEV;
node = of_find_node_by_path("/chosen");
if (!node)
return -ENODEV;
/* remove any stale propertys so ours can be found */
prop = of_find_property(node, htab_base_prop.name, NULL);
if (prop)
prom_remove_property(node, prop);
prop = of_find_property(node, htab_size_prop.name, NULL);
if (prop)
prom_remove_property(node, prop);
htab_base = __pa(htab_address);
prom_add_property(node, &htab_base_prop);
prom_add_property(node, &htab_size_prop);
of_node_put(node);
return 0;
}
late_initcall(export_htab_values);
