s390/kernel/machine_kexec.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * Copyright IBM Corp. 2005, 2011
0004  *
0005  * Author(s): Rolf Adelsberger,
0006  *        Michael Holzheu <holzheu@linux.vnet.ibm.com>
0007  */
0008
0009 #include <linux/device.h>
0010 #include <linux/mm.h>
0011 #include <linux/kexec.h>
0012 #include <linux/delay.h>
0013 #include <linux/reboot.h>
0014 #include <linux/ftrace.h>
0015 #include <linux/debug_locks.h>
0016 #include <asm/cio.h>
0017 #include <asm/setup.h>
0018 #include <asm/smp.h>
0019 #include <asm/ipl.h>
0020 #include <asm/diag.h>
0021 #include <asm/elf.h>
0022 #include <asm/asm-offsets.h>
0023 #include <asm/cacheflush.h>
0024 #include <asm/os_info.h>
0025 #include <asm/set_memory.h>
0026 #include <asm/stacktrace.h>
0027 #include <asm/switch_to.h>
0028 #include <asm/nmi.h>
0029 #include <asm/sclp.h>
0030
0031 typedef void (*relocate_kernel_t)(kimage_entry_t *, unsigned long,
0032                   unsigned long);
0033
0034 extern const unsigned char relocate_kernel[];
0035 extern const unsigned long long relocate_kernel_len;
0036
0037 #ifdef CONFIG_CRASH_DUMP
0038
0039 /*
0040  * Reset the system, copy boot CPU registers to absolute zero,
0041  * and jump to the kdump image
0042  */
0043 static void __do_machine_kdump(void *image)
0044 {
0045     int (*start_kdump)(int);
0046     unsigned long prefix;
0047
0048     /* store_status() saved the prefix register to lowcore */
0049     prefix = (unsigned long) S390_lowcore.prefixreg_save_area;
0050
0051     /* Now do the reset  */
0052     s390_reset_system();
0053
0054     /*
0055      * Copy dump CPU store status info to absolute zero.
0056      * This need to be done *after* s390_reset_system set the
0057      * prefix register of this CPU to zero
0058      */
0059     memcpy(absolute_pointer(__LC_FPREGS_SAVE_AREA),
0060            (void *)(prefix + __LC_FPREGS_SAVE_AREA), 512);
0061
0062     __load_psw_mask(PSW_MASK_BASE | PSW_DEFAULT_KEY | PSW_MASK_EA | PSW_MASK_BA);
0063     start_kdump = (void *)((struct kimage *) image)->start;
0064     start_kdump(1);
0065
0066     /* Die if start_kdump returns */
0067     disabled_wait();
0068 }
0069
0070 /*
0071  * Start kdump: create a LGR log entry, store status of all CPUs and
0072  * branch to __do_machine_kdump.
0073  */
0074 static noinline void __machine_kdump(void *image)
0075 {
0076     struct mcesa *mcesa;
0077     union ctlreg2 cr2_old, cr2_new;
0078     int this_cpu, cpu;
0079
0080     lgr_info_log();
0081     /* Get status of the other CPUs */
0082     this_cpu = smp_find_processor_id(stap());
0083     for_each_online_cpu(cpu) {
0084         if (cpu == this_cpu)
0085             continue;
0086         if (smp_store_status(cpu))
0087             continue;
0088     }
0089     /* Store status of the boot CPU */
0090     mcesa = __va(S390_lowcore.mcesad & MCESA_ORIGIN_MASK);
0091     if (MACHINE_HAS_VX)
0092         save_vx_regs((__vector128 *) mcesa->vector_save_area);
0093     if (MACHINE_HAS_GS) {
0094         __ctl_store(cr2_old.val, 2, 2);
0095         cr2_new = cr2_old;
0096         cr2_new.gse = 1;
0097         __ctl_load(cr2_new.val, 2, 2);
0098         save_gs_cb((struct gs_cb *) mcesa->guarded_storage_save_area);
0099         __ctl_load(cr2_old.val, 2, 2);
0100     }
0101     /*
0102      * To create a good backchain for this CPU in the dump store_status
0103      * is passed the address of a function. The address is saved into
0104      * the PSW save area of the boot CPU and the function is invoked as
0105      * a tail call of store_status. The backchain in the dump will look
0106      * like this:
0107      *   restart_int_handler ->  __machine_kexec -> __do_machine_kdump
0108      * The call to store_status() will not return.
0109      */
0110     store_status(__do_machine_kdump, image);
0111 }
0112
0113 static unsigned long do_start_kdump(unsigned long addr)
0114 {
0115     struct kimage *image = (struct kimage *) addr;
0116     int (*start_kdump)(int) = (void *)image->start;
0117     int rc;
0118
0119     __arch_local_irq_stnsm(0xfb); /* disable DAT */
0120     rc = start_kdump(0);
0121     __arch_local_irq_stosm(0x04); /* enable DAT */
0122     return rc;
0123 }
0124
0125 #endif /* CONFIG_CRASH_DUMP */
0126
0127 /*
0128  * Check if kdump checksums are valid: We call purgatory with parameter "0"
0129  */
0130 static bool kdump_csum_valid(struct kimage *image)
0131 {
0132 #ifdef CONFIG_CRASH_DUMP
0133     int rc;
0134
0135     preempt_disable();
0136     rc = call_on_stack(1, S390_lowcore.nodat_stack, unsigned long, do_start_kdump,
0137                unsigned long, (unsigned long)image);
0138     preempt_enable();
0139     return rc == 0;
0140 #else
0141     return false;
0142 #endif
0143 }
0144
0145 #ifdef CONFIG_CRASH_DUMP
0146
0147 void crash_free_reserved_phys_range(unsigned long begin, unsigned long end)
0148 {
0149     unsigned long addr, size;
0150
0151     for (addr = begin; addr < end; addr += PAGE_SIZE)
0152         free_reserved_page(pfn_to_page(addr >> PAGE_SHIFT));
0153     size = begin - crashk_res.start;
0154     if (size)
0155         os_info_crashkernel_add(crashk_res.start, size);
0156     else
0157         os_info_crashkernel_add(0, 0);
0158 }
0159
0160 static void crash_protect_pages(int protect)
0161 {
0162     unsigned long size;
0163
0164     if (!crashk_res.end)
0165         return;
0166     size = resource_size(&crashk_res);
0167     if (protect)
0168         set_memory_ro(crashk_res.start, size >> PAGE_SHIFT);
0169     else
0170         set_memory_rw(crashk_res.start, size >> PAGE_SHIFT);
0171 }
0172
0173 void arch_kexec_protect_crashkres(void)
0174 {
0175     crash_protect_pages(1);
0176 }
0177
0178 void arch_kexec_unprotect_crashkres(void)
0179 {
0180     crash_protect_pages(0);
0181 }
0182
0183 #endif
0184
0185 /*
0186  * Give back memory to hypervisor before new kdump is loaded
0187  */
0188 static int machine_kexec_prepare_kdump(void)
0189 {
0190 #ifdef CONFIG_CRASH_DUMP
0191     if (MACHINE_IS_VM)
0192         diag10_range(PFN_DOWN(crashk_res.start),
0193                  PFN_DOWN(crashk_res.end - crashk_res.start + 1));
0194     return 0;
0195 #else
0196     return -EINVAL;
0197 #endif
0198 }
0199
0200 int machine_kexec_prepare(struct kimage *image)
0201 {
0202     void *reboot_code_buffer;
0203
0204     if (image->type == KEXEC_TYPE_CRASH)
0205         return machine_kexec_prepare_kdump();
0206
0207     /* We don't support anything but the default image type for now. */
0208     if (image->type != KEXEC_TYPE_DEFAULT)
0209         return -EINVAL;
0210
0211     /* Get the destination where the assembler code should be copied to.*/
0212     reboot_code_buffer = (void *) page_to_phys(image->control_code_page);
0213
0214     /* Then copy it */
0215     memcpy(reboot_code_buffer, relocate_kernel, relocate_kernel_len);
0216     return 0;
0217 }
0218
0219 void machine_kexec_cleanup(struct kimage *image)
0220 {
0221 }
0222
0223 void arch_crash_save_vmcoreinfo(void)
0224 {
0225     VMCOREINFO_SYMBOL(lowcore_ptr);
0226     VMCOREINFO_SYMBOL(high_memory);
0227     VMCOREINFO_LENGTH(lowcore_ptr, NR_CPUS);
0228     vmcoreinfo_append_str("SAMODE31=%lx\n", __samode31);
0229     vmcoreinfo_append_str("EAMODE31=%lx\n", __eamode31);
0230     vmcoreinfo_append_str("KERNELOFFSET=%lx\n", kaslr_offset());
0231     put_abs_lowcore(vmcore_info, paddr_vmcoreinfo_note());
0232 }
0233
0234 void machine_shutdown(void)
0235 {
0236 }
0237
0238 void machine_crash_shutdown(struct pt_regs *regs)
0239 {
0240     set_os_info_reipl_block();
0241 }
0242
0243 /*
0244  * Do normal kexec
0245  */
0246 static void __do_machine_kexec(void *data)
0247 {
0248     unsigned long diag308_subcode;
0249     relocate_kernel_t data_mover;
0250     struct kimage *image = data;
0251
0252     s390_reset_system();
0253     data_mover = (relocate_kernel_t) page_to_phys(image->control_code_page);
0254
0255     __arch_local_irq_stnsm(0xfb); /* disable DAT - avoid no-execute */
0256     /* Call the moving routine */
0257     diag308_subcode = DIAG308_CLEAR_RESET;
0258     if (sclp.has_iplcc)
0259         diag308_subcode |= DIAG308_FLAG_EI;
0260     (*data_mover)(&image->head, image->start, diag308_subcode);
0261
0262     /* Die if kexec returns */
0263     disabled_wait();
0264 }
0265
0266 /*
0267  * Reset system and call either kdump or normal kexec
0268  */
0269 static void __machine_kexec(void *data)
0270 {
0271     pfault_fini();
0272     tracing_off();
0273     debug_locks_off();
0274 #ifdef CONFIG_CRASH_DUMP
0275     if (((struct kimage *) data)->type == KEXEC_TYPE_CRASH)
0276         __machine_kdump(data);
0277 #endif
0278     __do_machine_kexec(data);
0279 }
0280
0281 /*
0282  * Do either kdump or normal kexec. In case of kdump we first ask
0283  * purgatory, if kdump checksums are valid.
0284  */
0285 void machine_kexec(struct kimage *image)
0286 {
0287     if (image->type == KEXEC_TYPE_CRASH && !kdump_csum_valid(image))
0288         return;
0289     tracer_disable();
0290     smp_send_stop();
0291     smp_call_ipl_cpu(__machine_kexec, image);
0292 }