machine_kexec.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright IBM Corp. 2005, 2011
  4 *
  5 * Author(s): Rolf Adelsberger,
  6 *	      Michael Holzheu <holzheu@linux.vnet.ibm.com>
  7 */
  8
  9#include <linux/device.h>
 10#include <linux/mm.h>
 11#include <linux/kexec.h>
 12#include <linux/delay.h>
 13#include <linux/reboot.h>
 14#include <linux/ftrace.h>
 15#include <linux/debug_locks.h>
 16#include <linux/cpufeature.h>
 17#include <asm/guarded_storage.h>
 18#include <asm/machine.h>
 19#include <asm/pfault.h>
 20#include <asm/cio.h>
 21#include <asm/fpu.h>
 22#include <asm/setup.h>
 23#include <asm/smp.h>
 24#include <asm/ipl.h>
 25#include <asm/diag.h>
 26#include <asm/elf.h>
 27#include <asm/asm-offsets.h>
 28#include <asm/cacheflush.h>
 29#include <asm/abs_lowcore.h>
 30#include <asm/os_info.h>
 31#include <asm/set_memory.h>
 32#include <asm/stacktrace.h>
 33#include <asm/nmi.h>
 34#include <asm/sclp.h>
 35
 36typedef void (*relocate_kernel_t)(unsigned long, unsigned long, unsigned long);
 37typedef int (*purgatory_t)(int);
 38
 39extern const unsigned char relocate_kernel[];
 40extern const unsigned long long relocate_kernel_len;
 41
 42#ifdef CONFIG_CRASH_DUMP
 43
 44/*
 45 * Reset the system, copy boot CPU registers to absolute zero,
 46 * and jump to the kdump image
 47 */
 48static void __do_machine_kdump(void *data)
 49{
 50	struct kimage *image = data;
 51	purgatory_t purgatory;
 52	unsigned long prefix;
 53
 54	purgatory = (purgatory_t)image->start;
 55
 56	/* store_status() saved the prefix register to lowcore */
 57	prefix = (unsigned long)get_lowcore()->prefixreg_save_area;
 58
 59	/* Now do the reset  */
 60	s390_reset_system();
 61
 62	/*
 63	 * Copy dump CPU store status info to absolute zero.
 64	 * This need to be done *after* s390_reset_system set the
 65	 * prefix register of this CPU to zero
 66	 */
 67	memcpy(absolute_pointer(get_lowcore()->floating_pt_save_area),
 68	       phys_to_virt(prefix + __LC_FPREGS_SAVE_AREA), 512);
 69
 70	call_nodat(1, int, purgatory, int, 1);
 71
 72	/* Die if kdump returns */
 73	disabled_wait();
 74}
 75
 76/*
 77 * Start kdump: create a LGR log entry, store status of all CPUs and
 78 * branch to __do_machine_kdump.
 79 */
 80static noinline void __machine_kdump(void *image)
 81{
 82	struct mcesa *mcesa;
 83	union ctlreg2 cr2_old, cr2_new;
 84	int this_cpu, cpu;
 85
 86	lgr_info_log();
 87	/* Get status of the other CPUs */
 88	this_cpu = smp_find_processor_id(stap());
 89	for_each_online_cpu(cpu) {
 90		if (cpu == this_cpu)
 91			continue;
 92		if (smp_store_status(cpu))
 93			continue;
 94	}
 95	/* Store status of the boot CPU */
 96	mcesa = __va(get_lowcore()->mcesad & MCESA_ORIGIN_MASK);
 97	if (cpu_has_vx())
 98		save_vx_regs((__vector128 *) mcesa->vector_save_area);
 99	if (cpu_has_gs()) {
100		local_ctl_store(2, &cr2_old.reg);
101		cr2_new = cr2_old;
102		cr2_new.gse = 1;
103		local_ctl_load(2, &cr2_new.reg);
104		save_gs_cb((struct gs_cb *) mcesa->guarded_storage_save_area);
105		local_ctl_load(2, &cr2_old.reg);
106	}
107	/*
108	 * To create a good backchain for this CPU in the dump store_status
109	 * is passed the address of a function. The address is saved into
110	 * the PSW save area of the boot CPU and the function is invoked as
111	 * a tail call of store_status. The backchain in the dump will look
112	 * like this:
113	 *   restart_int_handler ->  __machine_kexec -> __do_machine_kdump
114	 * The call to store_status() will not return.
115	 */
116	store_status(__do_machine_kdump, image);
117}
118
119#endif /* CONFIG_CRASH_DUMP */
120
121/*
122 * Check if kdump checksums are valid: We call purgatory with parameter "0"
123 */
124static bool kdump_csum_valid(struct kimage *image)
125{
126#ifdef CONFIG_CRASH_DUMP
127	purgatory_t purgatory = (purgatory_t)image->start;
128	int rc;
129
130	rc = call_nodat(1, int, purgatory, int, 0);
131	return rc == 0;
132#else
133	return false;
134#endif
135}
136
137#ifdef CONFIG_CRASH_DUMP
138
139void crash_free_reserved_phys_range(unsigned long begin, unsigned long end)
140{
141	unsigned long addr, size;
142
143	for (addr = begin; addr < end; addr += PAGE_SIZE)
144		free_reserved_page(pfn_to_page(addr >> PAGE_SHIFT));
145	size = begin - crashk_res.start;
146	if (size)
147		os_info_crashkernel_add(crashk_res.start, size);
148	else
149		os_info_crashkernel_add(0, 0);
150}
151
152static void crash_protect_pages(int protect)
153{
154	unsigned long size;
155
156	if (!crashk_res.end)
157		return;
158	size = resource_size(&crashk_res);
159	if (protect)
160		set_memory_ro(crashk_res.start, size >> PAGE_SHIFT);
161	else
162		set_memory_rw(crashk_res.start, size >> PAGE_SHIFT);
163}
164
165void arch_kexec_protect_crashkres(void)
166{
167	crash_protect_pages(1);
168}
169
170void arch_kexec_unprotect_crashkres(void)
171{
172	crash_protect_pages(0);
173}
174
175#endif
176
177/*
178 * Give back memory to hypervisor before new kdump is loaded
179 */
180static int machine_kexec_prepare_kdump(void)
181{
182#ifdef CONFIG_CRASH_DUMP
183	if (machine_is_vm())
184		diag10_range(PFN_DOWN(crashk_res.start),
185			     PFN_DOWN(crashk_res.end - crashk_res.start + 1));
186	return 0;
187#else
188	return -EINVAL;
189#endif
190}
191
192int machine_kexec_prepare(struct kimage *image)
193{
194	void *reboot_code_buffer;
195
196	if (image->type == KEXEC_TYPE_CRASH)
197		return machine_kexec_prepare_kdump();
198
199	/* We don't support anything but the default image type for now. */
200	if (image->type != KEXEC_TYPE_DEFAULT)
201		return -EINVAL;
202
203	/* Get the destination where the assembler code should be copied to.*/
204	reboot_code_buffer = page_to_virt(image->control_code_page);
205
206	/* Then copy it */
207	memcpy(reboot_code_buffer, relocate_kernel, relocate_kernel_len);
208	return 0;
209}
210
211void machine_kexec_cleanup(struct kimage *image)
212{
213}
214
215void machine_shutdown(void)
216{
217}
218
219void machine_crash_shutdown(struct pt_regs *regs)
220{
221	set_os_info_reipl_block();
222}
223
224/*
225 * Do normal kexec
226 */
227static void __do_machine_kexec(void *data)
228{
229	unsigned long data_mover, entry, diag308_subcode;
230	struct kimage *image = data;
231
232	data_mover = page_to_phys(image->control_code_page);
233	entry = virt_to_phys(&image->head);
234	diag308_subcode = DIAG308_CLEAR_RESET;
235	if (sclp.has_iplcc)
236		diag308_subcode |= DIAG308_FLAG_EI;
237	s390_reset_system();
238
239	call_nodat(3, void, (relocate_kernel_t)data_mover,
240		   unsigned long, entry,
241		   unsigned long, image->start,
242		   unsigned long, diag308_subcode);
243
244	/* Die if kexec returns */
245	disabled_wait();
246}
247
248/*
249 * Reset system and call either kdump or normal kexec
250 */
251static void __machine_kexec(void *data)
252{
253	pfault_fini();
254	tracing_off();
255	debug_locks_off();
256#ifdef CONFIG_CRASH_DUMP
257	if (((struct kimage *) data)->type == KEXEC_TYPE_CRASH)
258		__machine_kdump(data);
259#endif
260	__do_machine_kexec(data);
261}
262
263/*
264 * Do either kdump or normal kexec. In case of kdump we first ask
265 * purgatory, if kdump checksums are valid.
266 */
267void machine_kexec(struct kimage *image)
268{
269	if (image->type == KEXEC_TYPE_CRASH && !kdump_csum_valid(image))
270		return;
271	tracer_disable();
272	smp_send_stop();
273	smp_call_ipl_cpu(__machine_kexec, image);
274}