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[].cpu_start was written) and
172	 * get into a peculiar state.  If the platform supports
173	 * smp_ops->take_timebase(), the secondary CPU will probably be spinning
174	 * in there.  If not (i.e. pseries), the secondary will continue on and
175	 * try to online itself/idle/etc. If it survives that, we need to find
176	 * these possible-but-not-online-but-should-be CPUs and chaperone them
177	 * into kexec_smp_wait().
178	 */
179	for_each_online_cpu(i) {
180		if (i == my_cpu)
181			continue;
182
183		while (paca[i].kexec_state < wait_state) {
184			barrier();
185			if (i != notified) {
186				printk(KERN_INFO "kexec: waiting for cpu %d "
187				       "(physical %d) to enter %i state\n",
188				       i, paca[i].hw_cpu_id, wait_state);
189				notified = i;
190			}
191		}
192	}
193	mb();
194}
195
196/*
197 * We need to make sure each present CPU is online.  The next kernel will scan
198 * the device tree and assume primary threads are online and query secondary
199 * threads via RTAS to online them if required.  If we don't online primary
200 * threads, they will be stuck.  However, we also online secondary threads as we
201 * may be using 'cede offline'.  In this case RTAS doesn't see the secondary
202 * threads as offline -- and again, these CPUs will be stuck.
203 *
204 * So, we online all CPUs that should be running, including secondary threads.
205 */
206static void wake_offline_cpus(void)
207{
208	int cpu = 0;
209
210	for_each_present_cpu(cpu) {
211		if (!cpu_online(cpu)) {
212			printk(KERN_INFO "kexec: Waking offline cpu %d.\n",
213			       cpu);
214			WARN_ON(cpu_up(cpu));
215		}
216	}
217}
218
219static void kexec_prepare_cpus(void)
220{
221	wake_offline_cpus();
222	smp_call_function(kexec_smp_down, NULL, /* wait */0);
223	local_irq_disable();
224	hard_irq_disable();
225
226	mb(); /* make sure IRQs are disabled before we say they are */
227	get_paca()->kexec_state = KEXEC_STATE_IRQS_OFF;
228
229	kexec_prepare_cpus_wait(KEXEC_STATE_IRQS_OFF);
230	/* we are sure every CPU has IRQs off at this point */
231	kexec_all_irq_disabled = 1;
232
233	/* after we tell the others to go down */
234	if (ppc_md.kexec_cpu_down)
235		ppc_md.kexec_cpu_down(0, 0);
236
237	/*
238	 * Before removing MMU mappings make sure all CPUs have entered real
239	 * mode:
240	 */
241	kexec_prepare_cpus_wait(KEXEC_STATE_REAL_MODE);
242
243	put_cpu();
244}
245
246#else /* ! SMP */
247
248static void kexec_prepare_cpus(void)
249{
250	/*
251	 * move the secondarys to us so that we can copy
252	 * the new kernel 0-0x100 safely
253	 *
254	 * do this if kexec in setup.c ?
255	 *
256	 * We need to release the cpus if we are ever going from an
257	 * UP to an SMP kernel.
258	 */
259	smp_release_cpus();
260	if (ppc_md.kexec_cpu_down)
261		ppc_md.kexec_cpu_down(0, 0);
262	local_irq_disable();
263	hard_irq_disable();
264}
265
266#endif /* SMP */
267
268/*
269 * kexec thread structure and stack.
270 *
271 * We need to make sure that this is 16384-byte aligned due to the
272 * way process stacks are handled.  It also must be statically allocated
273 * or allocated as part of the kimage, because everything else may be
274 * overwritten when we copy the kexec image.  We piggyback on the
275 * "init_task" linker section here to statically allocate a stack.
276 *
277 * We could use a smaller stack if we don't care about anything using
278 * current, but that audit has not been performed.
279 */
280static union thread_union kexec_stack __init_task_data =
281	{ };
282
283/*
284 * For similar reasons to the stack above, the kexecing CPU needs to be on a
285 * static PACA; we switch to kexec_paca.
286 */
287struct paca_struct kexec_paca;
288
289/* Our assembly helper, in misc_64.S */
290extern void kexec_sequence(void *newstack, unsigned long start,
291			   void *image, void *control,
292			   void (*clear_all)(void),
293			   bool copy_with_mmu_off) __noreturn;
294
295/* too late to fail here */
296void default_machine_kexec(struct kimage *image)
297{
298	bool copy_with_mmu_off;
299
300	/* prepare control code if any */
301
302	/*
303        * If the kexec boot is the normal one, need to shutdown other cpus
304        * into our wait loop and quiesce interrupts.
305        * Otherwise, in the case of crashed mode (crashing_cpu >= 0),
306        * stopping other CPUs and collecting their pt_regs is done before
307        * using debugger IPI.
308        */
309
310	if (!kdump_in_progress())
311		kexec_prepare_cpus();
312
313	printk("kexec: Starting switchover sequence.\n");
314
315	/* switch to a staticly allocated stack.  Based on irq stack code.
316	 * We setup preempt_count to avoid using VMX in memcpy.
317	 * XXX: the task struct will likely be invalid once we do the copy!
318	 */
319	kexec_stack.thread_info.task = current_thread_info()->task;
320	kexec_stack.thread_info.flags = 0;
321	kexec_stack.thread_info.preempt_count = HARDIRQ_OFFSET;
322	kexec_stack.thread_info.cpu = current_thread_info()->cpu;
323
324	/* We need a static PACA, too; copy this CPU's PACA over and switch to
325	 * it.  Also poison per_cpu_offset to catch anyone using non-static
326	 * data.
327	 */
328	memcpy(&kexec_paca, get_paca(), sizeof(struct paca_struct));
329	kexec_paca.data_offset = 0xedeaddeadeeeeeeeUL;
330	paca = (struct paca_struct *)RELOC_HIDE(&kexec_paca, 0) -
331		kexec_paca.paca_index;
332	setup_paca(&kexec_paca);
333
334	/* XXX: If anyone does 'dynamic lppacas' this will also need to be
335	 * switched to a static version!
336	 */
337	/*
338	 * On Book3S, the copy must happen with the MMU off if we are either
339	 * using Radix page tables or we are not in an LPAR since we can
340	 * overwrite the page tables while copying.
341	 *
342	 * In an LPAR, we keep the MMU on otherwise we can't access beyond
343	 * the RMA. On BookE there is no real MMU off mode, so we have to
344	 * keep it enabled as well (but then we have bolted TLB entries).
345	 */
346#ifdef CONFIG_PPC_BOOK3E
347	copy_with_mmu_off = false;
348#else
349	copy_with_mmu_off = radix_enabled() ||
350		!(firmware_has_feature(FW_FEATURE_LPAR) ||
351		  firmware_has_feature(FW_FEATURE_PS3_LV1));
352#endif
353
354	/* Some things are best done in assembly.  Finding globals with
355	 * a toc is easier in C, so pass in what we can.
356	 */
357	kexec_sequence(&kexec_stack, image->start, image,
358		       page_address(image->control_code_page),
359		       mmu_cleanup_all, copy_with_mmu_off);
360	/* NOTREACHED */
361}
362
363#ifdef CONFIG_PPC_STD_MMU_64
364/* Values we need to export to the second kernel via the device tree. */
365static unsigned long htab_base;
366static unsigned long htab_size;
367
368static struct property htab_base_prop = {
369	.name = "linux,htab-base",
370	.length = sizeof(unsigned long),
371	.value = &htab_base,
372};
373
374static struct property htab_size_prop = {
375	.name = "linux,htab-size",
376	.length = sizeof(unsigned long),
377	.value = &htab_size,
378};
379
380static int __init export_htab_values(void)
381{
382	struct device_node *node;
383
384	/* On machines with no htab htab_address is NULL */
385	if (!htab_address)
386		return -ENODEV;
387
388	node = of_find_node_by_path("/chosen");
389	if (!node)
390		return -ENODEV;
391
392	/* remove any stale propertys so ours can be found */
393	of_remove_property(node, of_find_property(node, htab_base_prop.name, NULL));
394	of_remove_property(node, of_find_property(node, htab_size_prop.name, NULL));
395
396	htab_base = cpu_to_be64(__pa(htab_address));
397	of_add_property(node, &htab_base_prop);
398	htab_size = cpu_to_be64(htab_size_bytes);
399	of_add_property(node, &htab_size_prop);
400
401	of_node_put(node);
402	return 0;
403}
404late_initcall(export_htab_values);
405#endif /* CONFIG_PPC_STD_MMU_64 */