arch/tile/kernel/machine_kexec.c

   1 /*
   2  * Copyright 2010 Tilera Corporation. All Rights Reserved.
   3  *
   4  *   This program is free software; you can redistribute it and/or
   5  *   modify it under the terms of the GNU General Public License
   6  *   as published by the Free Software Foundation, version 2.
   7  *
   8  *   This program is distributed in the hope that it will be useful, but
   9  *   WITHOUT ANY WARRANTY; without even the implied warranty of
  10  *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  11  *   NON INFRINGEMENT.  See the GNU General Public License for
  12  *   more details.
  13  *
  14  * based on machine_kexec.c from other architectures in linux-2.6.18
  15  */
  16
  17 #include <linux/mm.h>
  18 #include <linux/kexec.h>
  19 #include <linux/delay.h>
  20 #include <linux/reboot.h>
  21 #include <linux/errno.h>
  22 #include <linux/vmalloc.h>
  23 #include <linux/cpumask.h>
  24 #include <linux/kernel.h>
  25 #include <linux/elf.h>
  26 #include <linux/highmem.h>
  27 #include <linux/mmu_context.h>
  28 #include <linux/io.h>
  29 #include <linux/timex.h>
  30 #include <asm/pgtable.h>
  31 #include <asm/pgalloc.h>
  32 #include <asm/cacheflush.h>
  33 #include <asm/checksum.h>
  34 #include <asm/tlbflush.h>
  35 #include <asm/homecache.h>
  36 #include <hv/hypervisor.h>
  37
  38
  39 /*
  40  * This stuff is not in elf.h and is not in any other kernel include.
  41  * This stuff is needed below in the little boot notes parser to
  42  * extract the command line so we can pass it to the hypervisor.
  43  */
  44 struct Elf32_Bhdr {
  45         Elf32_Word b_signature;
  46         Elf32_Word b_size;
  47         Elf32_Half b_checksum;
  48         Elf32_Half b_records;
  49 };
  50 #define ELF_BOOT_MAGIC          0x0E1FB007
  51 #define EBN_COMMAND_LINE        0x00000004
  52 #define roundupsz(X) (((X) + 3) & ~3)
  53
  54 /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
  55
  56
  57 void machine_shutdown(void)
  58 {
  59         /*
  60          * Normally we would stop all the other processors here, but
  61          * the check in machine_kexec_prepare below ensures we'll only
  62          * get this far if we've been booted with "nosmp" on the
  63          * command line or without CONFIG_SMP so there's nothing to do
  64          * here (for now).
  65          */
  66 }
  67
  68 void machine_crash_shutdown(struct pt_regs *regs)
  69 {
  70         /*
  71          * Cannot happen.  This type of kexec is disabled on this
  72          * architecture (and enforced in machine_kexec_prepare below).
  73          */
  74 }
  75
  76
  77 int machine_kexec_prepare(struct kimage *image)
  78 {
  79         if (num_online_cpus() > 1) {
  80                 pr_warning("%s: detected attempt to kexec "
  81                        "with num_online_cpus() > 1\n",
  82                        __func__);
  83                 return -ENOSYS;
  84         }
  85         if (image->type != KEXEC_TYPE_DEFAULT) {
  86                 pr_warning("%s: detected attempt to kexec "
  87                        "with unsupported type: %d\n",
  88                        __func__,
  89                        image->type);
  90                 return -ENOSYS;
  91         }
  92         return 0;
  93 }
  94
  95 void machine_kexec_cleanup(struct kimage *image)
  96 {
  97         /*
  98          * We did nothing in machine_kexec_prepare,
  99          * so we have nothing to do here.
 100          */
 101 }
 102
 103 /*
 104  * If we can find elf boot notes on this page, return the command
 105  * line.  Otherwise, silently return null.  Somewhat kludgy, but no
 106  * good way to do this without significantly rearchitecting the
 107  * architecture-independent kexec code.
 108  */
 109
 110 static unsigned char *kexec_bn2cl(void *pg)
 111 {
 112         struct Elf32_Bhdr *bhdrp;
 113         Elf32_Nhdr *nhdrp;
 114         unsigned char *desc;
 115         unsigned char *command_line;
 116         __sum16 csum;
 117
 118         bhdrp = (struct Elf32_Bhdr *) pg;
 119
 120         /*
 121          * This routine is invoked for every source page, so make
 122          * sure to quietly ignore every impossible page.
 123          */
 124         if (bhdrp->b_signature != ELF_BOOT_MAGIC ||
 125             bhdrp->b_size > PAGE_SIZE)
 126                 return 0;
 127
 128         /*
 129          * If we get a checksum mismatch, warn with the checksum
 130          * so we can diagnose better.
 131          */
 132         csum = ip_compute_csum(pg, bhdrp->b_size);
 133         if (csum != 0) {
 134                 pr_warning("%s: bad checksum %#x (size %d)\n",
 135                            __func__, csum, bhdrp->b_size);
 136                 return 0;
 137         }
 138
 139         nhdrp = (Elf32_Nhdr *) (bhdrp + 1);
 140
 141         while (nhdrp->n_type != EBN_COMMAND_LINE) {
 142
 143                 desc = (unsigned char *) (nhdrp + 1);
 144                 desc += roundupsz(nhdrp->n_descsz);
 145
 146                 nhdrp = (Elf32_Nhdr *) desc;
 147
 148                 /* still in bounds? */
 149                 if ((unsigned char *) (nhdrp + 1) >
 150                     ((unsigned char *) pg) + bhdrp->b_size) {
 151
 152                         pr_info("%s: out of bounds\n", __func__);
 153                         return 0;
 154                 }
 155         }
 156
 157         command_line = (unsigned char *) (nhdrp + 1);
 158         desc = command_line;
 159
 160         while (*desc != '\0') {
 161                 desc++;
 162                 if (((unsigned long)desc & PAGE_MASK) != (unsigned long)pg) {
 163                         pr_info("%s: ran off end of page\n",
 164                                __func__);
 165                         return 0;
 166                 }
 167         }
 168
 169         return command_line;
 170 }
 171
 172 static void kexec_find_and_set_command_line(struct kimage *image)
 173 {
 174         kimage_entry_t *ptr, entry;
 175
 176         unsigned char *command_line = 0;
 177         unsigned char *r;
 178         HV_Errno hverr;
 179
 180         for (ptr = &image->head;
 181              (entry = *ptr) && !(entry & IND_DONE);
 182              ptr = (entry & IND_INDIRECTION) ?
 183                      phys_to_virt((entry & PAGE_MASK)) : ptr + 1) {
 184
 185                 if ((entry & IND_SOURCE)) {
 186                         void *va =
 187                                 kmap_atomic_pfn(entry >> PAGE_SHIFT);
 188                         r = kexec_bn2cl(va);
 189                         if (r) {
 190                                 command_line = r;
 191                                 break;
 192                         }
 193                         kunmap_atomic(va);
 194                 }
 195         }
 196
 197         if (command_line != 0) {
 198                 pr_info("setting new command line to \"%s\"\n",
 199                        command_line);
 200
 201                 hverr = hv_set_command_line(
 202                         (HV_VirtAddr) command_line, strlen(command_line));
 203                 kunmap_atomic(command_line);
 204         } else {
 205                 pr_info("%s: no command line found; making empty\n",
 206                        __func__);
 207                 hverr = hv_set_command_line((HV_VirtAddr) command_line, 0);
 208         }
 209         if (hverr)
 210                 pr_warning("%s: hv_set_command_line returned error: %d\n",
 211                            __func__, hverr);
 212 }
 213
 214 /*
 215  * The kexec code range-checks all its PAs, so to avoid having it run
 216  * amok and allocate memory and then sequester it from every other
 217  * controller, we force it to come from controller zero.  We also
 218  * disable the oom-killer since if we do end up running out of memory,
 219  * that almost certainly won't help.
 220  */
 221 struct page *kimage_alloc_pages_arch(gfp_t gfp_mask, unsigned int order)
 222 {
 223         gfp_mask |= __GFP_THISNODE | __GFP_NORETRY;
 224         return alloc_pages_node(0, gfp_mask, order);
 225 }
 226
 227 /*
 228  * Address range in which pa=va mapping is set in setup_quasi_va_is_pa().
 229  * For tilepro, PAGE_OFFSET is used since this is the largest possbile value
 230  * for tilepro, while for tilegx, we limit it to entire middle level page
 231  * table which we assume has been allocated and is undoubtedly large enough.
 232  */
 233 #ifndef __tilegx__
 234 #define QUASI_VA_IS_PA_ADDR_RANGE PAGE_OFFSET
 235 #else
 236 #define QUASI_VA_IS_PA_ADDR_RANGE PGDIR_SIZE
 237 #endif
 238
 239 static void setup_quasi_va_is_pa(void)
 240 {
 241         HV_PTE pte;
 242         unsigned long i;
 243
 244         /*
 245          * Flush our TLB to prevent conflicts between the previous contents
 246          * and the new stuff we're about to add.
 247          */
 248         local_flush_tlb_all();
 249
 250         /*
 251          * setup VA is PA, at least up to QUASI_VA_IS_PA_ADDR_RANGE.
 252          * Note here we assume that level-1 page table is defined by
 253          * HPAGE_SIZE.
 254          */
 255         pte = hv_pte(_PAGE_KERNEL | _PAGE_HUGE_PAGE);
 256         pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_NO_L3);
 257         for (i = 0; i < (QUASI_VA_IS_PA_ADDR_RANGE >> HPAGE_SHIFT); i++) {
 258                 unsigned long vaddr = i << HPAGE_SHIFT;
 259                 pgd_t *pgd = pgd_offset(current->mm, vaddr);
 260                 pud_t *pud = pud_offset(pgd, vaddr);
 261                 pte_t *ptep = (pte_t *) pmd_offset(pud, vaddr);
 262                 unsigned long pfn = i << (HPAGE_SHIFT - PAGE_SHIFT);
 263
 264                 if (pfn_valid(pfn))
 265                         __set_pte(ptep, pfn_pte(pfn, pte));
 266         }
 267 }
 268
 269
 270 void machine_kexec(struct kimage *image)
 271 {
 272         void *reboot_code_buffer;
 273         pte_t *ptep;
 274         void (*rnk)(unsigned long, void *, unsigned long)
 275                 __noreturn;
 276
 277         /* Mask all interrupts before starting to reboot. */
 278         interrupt_mask_set_mask(~0ULL);
 279
 280         kexec_find_and_set_command_line(image);
 281
 282         /*
 283          * Adjust the home caching of the control page to be cached on
 284          * this cpu, and copy the assembly helper into the control
 285          * code page, which we map in the vmalloc area.
 286          */
 287         homecache_change_page_home(image->control_code_page, 0,
 288                                    smp_processor_id());
 289         reboot_code_buffer = page_address(image->control_code_page);
 290         BUG_ON(reboot_code_buffer == NULL);
 291         ptep = virt_to_pte(NULL, (unsigned long)reboot_code_buffer);
 292         __set_pte(ptep, pte_mkexec(*ptep));
 293         memcpy(reboot_code_buffer, relocate_new_kernel,
 294                relocate_new_kernel_size);
 295         __flush_icache_range(
 296                 (unsigned long) reboot_code_buffer,
 297                 (unsigned long) reboot_code_buffer + relocate_new_kernel_size);
 298
 299         setup_quasi_va_is_pa();
 300
 301         /* now call it */
 302         rnk = reboot_code_buffer;
 303         (*rnk)(image->head, reboot_code_buffer, image->start);
 304 }