1/*
  2 * PPC64 code to handle Linux booting another kernel.
  3 *
  4 * Copyright (C) 2004-2005, IBM Corp.
  5 *
  6 * Created by: Milton D Miller II
  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
 13#include <linux/kexec.h>
 14#include <linux/smp.h>
 15#include <linux/thread_info.h>
 16#include <linux/init_task.h>
 17#include <linux/errno.h>
 18#include <linux/kernel.h>
 19#include <linux/cpu.h>
 20#include <linux/hardirq.h>
 21
 22#include <asm/page.h>
 23#include <asm/current.h>
 24#include <asm/machdep.h>
 25#include <asm/cacheflush.h>
 26#include <asm/firmware.h>
 27#include <asm/paca.h>
 28#include <asm/mmu.h>
 29#include <asm/sections.h>	/* _end */
 30#include <asm/prom.h>
 31#include <asm/smp.h>
 32#include <asm/hw_breakpoint.h>
 33#include <asm/asm-prototypes.h>
 34
 35int default_machine_kexec_prepare(struct kimage *image)
 36{
 37	int i;
 38	unsigned long begin, end;	/* limits of segment */
 39	unsigned long low, high;	/* limits of blocked memory range */
 40	struct device_node *node;
 41	const unsigned long *basep;
 42	const unsigned int *sizep;
 43
 44	/*
 45	 * Since we use the kernel fault handlers and paging code to
 46	 * handle the virtual mode, we must make sure no destination
 47	 * overlaps kernel static data or bss.
 48	 */
 49	for (i = 0; i < image->nr_segments; i++)
 50		if (image->segment[i].mem < __pa(_end))
 51			return -ETXTBSY;
 52
 53	/* We also should not overwrite the tce tables */
 54	for_each_node_by_type(node, "pci") {
 55		basep = of_get_property(node, "linux,tce-base", NULL);
 56		sizep = of_get_property(node, "linux,tce-size", NULL);
 57		if (basep == NULL || sizep == NULL)
 58			continue;
 59
 60		low = *basep;
 61		high = low + (*sizep);
 62
 63		for (i = 0; i < image->nr_segments; i++) {
 64			begin = image->segment[i].mem;
 65			end = begin + image->segment[i].memsz;
 66
 67			if ((begin < high) && (end > low))
 68				return -ETXTBSY;
 69		}
 70	}
 71
 72	return 0;
 73}
 74
 75static void copy_segments(unsigned long ind)
 76{
 77	unsigned long entry;
 78	unsigned long *ptr;
 79	void *dest;
 80	void *addr;
 81
 82	/*
 83	 * We rely on kexec_load to create a lists that properly
 84	 * initializes these pointers before they are used.
 85	 * We will still crash if the list is wrong, but at least
 86	 * the compiler will be quiet.
 87	 */
 88	ptr = NULL;
 89	dest = NULL;
 90
 91	for (entry = ind; !(entry & IND_DONE); entry = *ptr++) {
 92		addr = __va(entry & PAGE_MASK);
 93
 94		switch (entry & IND_FLAGS) {
 95		case IND_DESTINATION:
 96			dest = addr;
 97			break;
 98		case IND_INDIRECTION:
 99			ptr = addr;
100			break;
101		case IND_SOURCE:
102			copy_page(dest, addr);
103			dest += PAGE_SIZE;
104		}
105	}
106}
107
108void kexec_copy_flush(struct kimage *image)
109{
110	long i, nr_segments = image->nr_segments;
111	struct  kexec_segment ranges[KEXEC_SEGMENT_MAX];
112
113	/* save the ranges on the stack to efficiently flush the icache */
114	memcpy(ranges, image->segment, sizeof(ranges));
115
116	/*
117	 * After this call we may not use anything allocated in dynamic
118	 * memory, including *image.
119	 *
120	 * Only globals and the stack are allowed.
121	 */
122	copy_segments(image->head);
123
124	/*
125	 * we need to clear the icache for all dest pages sometime,
126	 * including ones that were in place on the original copy
127	 */
128	for (i = 0; i < nr_segments; i++)
129		flush_icache_range((unsigned long)__va(ranges[i].mem),
130			(unsigned long)__va(ranges[i].mem + ranges[i].memsz));
131}
132
133#ifdef CONFIG_SMP
134
135static int kexec_all_irq_disabled = 0;
136
137static void kexec_smp_down(void *arg)
138{
139	local_irq_disable();
140	hard_irq_disable();
141
142	mb(); /* make sure our irqs are disabled before we say they are */
143	get_paca()->kexec_state = KEXEC_STATE_IRQS_OFF;
144	while(kexec_all_irq_disabled == 0)
145		cpu_relax();
146	mb(); /* make sure all irqs are disabled before this */
147	hw_breakpoint_disable();
148	/*
149	 * Now every CPU has IRQs off, we can clear out any pending
150	 * IPIs and be sure that no more will come in after this.
151	 */
152	if (ppc_md.kexec_cpu_down)
153		ppc_md.kexec_cpu_down(0, 1);
154
155	kexec_smp_wait();
156	/* NOTREACHED */
157}
158
159static void kexec_prepare_cpus_wait(int wait_state)
160{
161	int my_cpu, i, notified=-1;
162
163	hw_breakpoint_disable();
164	my_cpu = get_cpu();
165	/* Make sure each CPU has at least made it to the state we need.
166	 *
167	 * FIXME: There is a (slim) chance of a problem if not all of the CPUs
168	 * are correctly onlined.  If somehow we start a CPU on boot with RTAS
169	 * start-cpu, but somehow that CPU doesn't write callin_cpu_map[] in
170	 * time, the boot CPU will timeout.  If it does eventually execute
171	 * stuff, the secondary will start up (paca_ptrs[]->cpu_start was
172	 * written) and get into a peculiar state.
173	 * If the platform supports smp_ops->take_timebase(), the secondary CPU
174	 * will probably be spinning in there.  If not (i.e. pseries), the
175	 * secondary will continue on and try to online itself/idle/etc. If it
176	 * survives that, we need to find these
177	 * possible-but-not-online-but-should-be CPUs and chaperone them into
178	 * kexec_smp_wait().
179	 */
180	for_each_online_cpu(i) {
181		if (i == my_cpu)
182			continue;
183
184		while (paca_ptrs[i]->kexec_state < wait_state) {
185			barrier();
186			if (i != notified) {
187				printk(KERN_INFO "kexec: waiting for cpu %d "
188				       "(physical %d) to enter %i state\n",
189				       i, paca_ptrs[i]->hw_cpu_id, wait_state);
190				notified = i;
191			}
192		}
193	}
194	mb();
195}
196
197/*
198 * We need to make sure each present CPU is online.  The next kernel will scan
199 * the device tree and assume primary threads are online and query secondary
200 * threads via RTAS to online them if required.  If we don't online primary
201 * threads, they will be stuck.  However, we also online secondary threads as we
202 * may be using 'cede offline'.  In this case RTAS doesn't see the secondary
203 * threads as offline -- and again, these CPUs will be stuck.
204 *
205 * So, we online all CPUs that should be running, including secondary threads.
206 */
207static void wake_offline_cpus(void)
208{
209	int cpu = 0;
210
211	for_each_present_cpu(cpu) {
212		if (!cpu_online(cpu)) {
213			printk(KERN_INFO "kexec: Waking offline cpu %d.\n",
214			       cpu);
215			WARN_ON(cpu_up(cpu));
216		}
217	}
218}
219
220static void kexec_prepare_cpus(void)
221{
222	wake_offline_cpus();
223	smp_call_function(kexec_smp_down, NULL, /* wait */0);
224	local_irq_disable();
225	hard_irq_disable();
226
227	mb(); /* make sure IRQs are disabled before we say they are */
228	get_paca()->kexec_state = KEXEC_STATE_IRQS_OFF;
229
230	kexec_prepare_cpus_wait(KEXEC_STATE_IRQS_OFF);
231	/* we are sure every CPU has IRQs off at this point */
232	kexec_all_irq_disabled = 1;
233
234	/* after we tell the others to go down */
235	if (ppc_md.kexec_cpu_down)
236		ppc_md.kexec_cpu_down(0, 0);
237
238	/*
239	 * Before removing MMU mappings make sure all CPUs have entered real
240	 * mode:
241	 */
242	kexec_prepare_cpus_wait(KEXEC_STATE_REAL_MODE);
243
244	put_cpu();
245}
246
247#else /* ! SMP */
248
249static void kexec_prepare_cpus(void)
250{
251	/*
252	 * move the secondarys to us so that we can copy
253	 * the new kernel 0-0x100 safely
254	 *
255	 * do this if kexec in setup.c ?
256	 *
257	 * We need to release the cpus if we are ever going from an
258	 * UP to an SMP kernel.
259	 */
260	smp_release_cpus();
261	if (ppc_md.kexec_cpu_down)
262		ppc_md.kexec_cpu_down(0, 0);
263	local_irq_disable();
264	hard_irq_disable();
265}
266
267#endif /* SMP */
268
269/*
270 * kexec thread structure and stack.
271 *
272 * We need to make sure that this is 16384-byte aligned due to the
273 * way process stacks are handled.  It also must be statically allocated
274 * or allocated as part of the kimage, because everything else may be
275 * overwritten when we copy the kexec image.  We piggyback on the
276 * "init_task" linker section here to statically allocate a stack.
277 *
278 * We could use a smaller stack if we don't care about anything using
279 * current, but that audit has not been performed.
280 */
281static union thread_union kexec_stack __init_task_data =
282	{ };
283
284/*
285 * For similar reasons to the stack above, the kexecing CPU needs to be on a
286 * static PACA; we switch to kexec_paca.
287 */
288struct paca_struct kexec_paca;
289
290/* Our assembly helper, in misc_64.S */
291extern void kexec_sequence(void *newstack, unsigned long start,
292			   void *image, void *control,
293			   void (*clear_all)(void),
294			   bool copy_with_mmu_off) __noreturn;
295
296/* too late to fail here */
297void default_machine_kexec(struct kimage *image)
298{
299	bool copy_with_mmu_off;
300
301	/* prepare control code if any */
302
303	/*
304        * If the kexec boot is the normal one, need to shutdown other cpus
305        * into our wait loop and quiesce interrupts.
306        * Otherwise, in the case of crashed mode (crashing_cpu >= 0),
307        * stopping other CPUs and collecting their pt_regs is done before
308        * using debugger IPI.
309        */
310
311	if (!kdump_in_progress())
312		kexec_prepare_cpus();
313
314	printk("kexec: Starting switchover sequence.\n");
315
316	/* switch to a staticly allocated stack.  Based on irq stack code.
317	 * We setup preempt_count to avoid using VMX in memcpy.
318	 * XXX: the task struct will likely be invalid once we do the copy!
319	 */
320	kexec_stack.thread_info.task = current_thread_info()->task;
321	kexec_stack.thread_info.flags = 0;
322	kexec_stack.thread_info.preempt_count = HARDIRQ_OFFSET;
323	kexec_stack.thread_info.cpu = current_thread_info()->cpu;
324
325	/* We need a static PACA, too; copy this CPU's PACA over and switch to
326	 * it. Also poison per_cpu_offset and NULL lppaca to catch anyone using
327	 * non-static data.
328	 */
329	memcpy(&kexec_paca, get_paca(), sizeof(struct paca_struct));
330	kexec_paca.data_offset = 0xedeaddeadeeeeeeeUL;
331#ifdef CONFIG_PPC_PSERIES
332	kexec_paca.lppaca_ptr = NULL;
333#endif
334	paca_ptrs[kexec_paca.paca_index] = &kexec_paca;
335
336	setup_paca(&kexec_paca);
337
338	/*
339	 * The lppaca should be unregistered at this point so the HV won't
340	 * touch it. In the case of a crash, none of the lppacas are
341	 * unregistered so there is not much we can do about it here.
342	 */
343
344	/*
345	 * On Book3S, the copy must happen with the MMU off if we are either
346	 * using Radix page tables or we are not in an LPAR since we can
347	 * overwrite the page tables while copying.
348	 *
349	 * In an LPAR, we keep the MMU on otherwise we can't access beyond
350	 * the RMA. On BookE there is no real MMU off mode, so we have to
351	 * keep it enabled as well (but then we have bolted TLB entries).
352	 */
353#ifdef CONFIG_PPC_BOOK3E
354	copy_with_mmu_off = false;
355#else
356	copy_with_mmu_off = radix_enabled() ||
357		!(firmware_has_feature(FW_FEATURE_LPAR) ||
358		  firmware_has_feature(FW_FEATURE_PS3_LV1));
359#endif
360
361	/* Some things are best done in assembly.  Finding globals with
362	 * a toc is easier in C, so pass in what we can.
363	 */
364	kexec_sequence(&kexec_stack, image->start, image,
365		       page_address(image->control_code_page),
366		       mmu_cleanup_all, copy_with_mmu_off);
367	/* NOTREACHED */
368}
369
370#ifdef CONFIG_PPC_BOOK3S_64
371/* Values we need to export to the second kernel via the device tree. */
372static unsigned long htab_base;
373static unsigned long htab_size;
374
375static struct property htab_base_prop = {
376	.name = "linux,htab-base",
377	.length = sizeof(unsigned long),
378	.value = &htab_base,
379};
380
381static struct property htab_size_prop = {
382	.name = "linux,htab-size",
383	.length = sizeof(unsigned long),
384	.value = &htab_size,
385};
386
387static int __init export_htab_values(void)
388{
389	struct device_node *node;
390
391	/* On machines with no htab htab_address is NULL */
392	if (!htab_address)
393		return -ENODEV;
394
395	node = of_find_node_by_path("/chosen");
396	if (!node)
397		return -ENODEV;
398
399	/* remove any stale propertys so ours can be found */
400	of_remove_property(node, of_find_property(node, htab_base_prop.name, NULL));
401	of_remove_property(node, of_find_property(node, htab_size_prop.name, NULL));
402
403	htab_base = cpu_to_be64(__pa(htab_address));
404	of_add_property(node, &htab_base_prop);
405	htab_size = cpu_to_be64(htab_size_bytes);
406	of_add_property(node, &htab_size_prop);
407
408	of_node_put(node);
409	return 0;
410}
411late_initcall(export_htab_values);
412#endif /* CONFIG_PPC_BOOK3S_64 */