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Linux/arch/tile/kernel/machine_kexec.c

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  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_warn("%s: detected attempt to kexec with num_online_cpus() > 1\n",
 81                         __func__);
 82                 return -ENOSYS;
 83         }
 84         if (image->type != KEXEC_TYPE_DEFAULT) {
 85                 pr_warn("%s: detected attempt to kexec with unsupported type: %d\n",
 86                         __func__, image->type);
 87                 return -ENOSYS;
 88         }
 89         return 0;
 90 }
 91 
 92 void machine_kexec_cleanup(struct kimage *image)
 93 {
 94         /*
 95          * We did nothing in machine_kexec_prepare,
 96          * so we have nothing to do here.
 97          */
 98 }
 99 
100 /*
101  * If we can find elf boot notes on this page, return the command
102  * line.  Otherwise, silently return null.  Somewhat kludgy, but no
103  * good way to do this without significantly rearchitecting the
104  * architecture-independent kexec code.
105  */
106 
107 static unsigned char *kexec_bn2cl(void *pg)
108 {
109         struct Elf32_Bhdr *bhdrp;
110         Elf32_Nhdr *nhdrp;
111         unsigned char *desc;
112         unsigned char *command_line;
113         __sum16 csum;
114 
115         bhdrp = (struct Elf32_Bhdr *) pg;
116 
117         /*
118          * This routine is invoked for every source page, so make
119          * sure to quietly ignore every impossible page.
120          */
121         if (bhdrp->b_signature != ELF_BOOT_MAGIC ||
122             bhdrp->b_size > PAGE_SIZE)
123                 return 0;
124 
125         /*
126          * If we get a checksum mismatch, warn with the checksum
127          * so we can diagnose better.
128          */
129         csum = ip_compute_csum(pg, bhdrp->b_size);
130         if (csum != 0) {
131                 pr_warn("%s: bad checksum %#x (size %d)\n",
132                         __func__, csum, bhdrp->b_size);
133                 return 0;
134         }
135 
136         nhdrp = (Elf32_Nhdr *) (bhdrp + 1);
137 
138         while (nhdrp->n_type != EBN_COMMAND_LINE) {
139 
140                 desc = (unsigned char *) (nhdrp + 1);
141                 desc += roundupsz(nhdrp->n_descsz);
142 
143                 nhdrp = (Elf32_Nhdr *) desc;
144 
145                 /* still in bounds? */
146                 if ((unsigned char *) (nhdrp + 1) >
147                     ((unsigned char *) pg) + bhdrp->b_size) {
148 
149                         pr_info("%s: out of bounds\n", __func__);
150                         return 0;
151                 }
152         }
153 
154         command_line = (unsigned char *) (nhdrp + 1);
155         desc = command_line;
156 
157         while (*desc != '\0') {
158                 desc++;
159                 if (((unsigned long)desc & PAGE_MASK) != (unsigned long)pg) {
160                         pr_info("%s: ran off end of page\n", __func__);
161                         return 0;
162                 }
163         }
164 
165         return command_line;
166 }
167 
168 static void kexec_find_and_set_command_line(struct kimage *image)
169 {
170         kimage_entry_t *ptr, entry;
171 
172         unsigned char *command_line = 0;
173         unsigned char *r;
174         HV_Errno hverr;
175 
176         for (ptr = &image->head;
177              (entry = *ptr) && !(entry & IND_DONE);
178              ptr = (entry & IND_INDIRECTION) ?
179                      phys_to_virt((entry & PAGE_MASK)) : ptr + 1) {
180 
181                 if ((entry & IND_SOURCE)) {
182                         void *va =
183                                 kmap_atomic_pfn(entry >> PAGE_SHIFT);
184                         r = kexec_bn2cl(va);
185                         if (r) {
186                                 command_line = r;
187                                 break;
188                         }
189                         kunmap_atomic(va);
190                 }
191         }
192 
193         if (command_line != 0) {
194                 pr_info("setting new command line to \"%s\"\n", command_line);
195 
196                 hverr = hv_set_command_line(
197                         (HV_VirtAddr) command_line, strlen(command_line));
198                 kunmap_atomic(command_line);
199         } else {
200                 pr_info("%s: no command line found; making empty\n", __func__);
201                 hverr = hv_set_command_line((HV_VirtAddr) command_line, 0);
202         }
203         if (hverr)
204                 pr_warn("%s: hv_set_command_line returned error: %d\n",
205                         __func__, hverr);
206 }
207 
208 /*
209  * The kexec code range-checks all its PAs, so to avoid having it run
210  * amok and allocate memory and then sequester it from every other
211  * controller, we force it to come from controller zero.  We also
212  * disable the oom-killer since if we do end up running out of memory,
213  * that almost certainly won't help.
214  */
215 struct page *kimage_alloc_pages_arch(gfp_t gfp_mask, unsigned int order)
216 {
217         gfp_mask |= __GFP_THISNODE | __GFP_NORETRY;
218         return alloc_pages_node(0, gfp_mask, order);
219 }
220 
221 /*
222  * Address range in which pa=va mapping is set in setup_quasi_va_is_pa().
223  * For tilepro, PAGE_OFFSET is used since this is the largest possbile value
224  * for tilepro, while for tilegx, we limit it to entire middle level page
225  * table which we assume has been allocated and is undoubtedly large enough.
226  */
227 #ifndef __tilegx__
228 #define QUASI_VA_IS_PA_ADDR_RANGE PAGE_OFFSET
229 #else
230 #define QUASI_VA_IS_PA_ADDR_RANGE PGDIR_SIZE
231 #endif
232 
233 static void setup_quasi_va_is_pa(void)
234 {
235         HV_PTE pte;
236         unsigned long i;
237 
238         /*
239          * Flush our TLB to prevent conflicts between the previous contents
240          * and the new stuff we're about to add.
241          */
242         local_flush_tlb_all();
243 
244         /*
245          * setup VA is PA, at least up to QUASI_VA_IS_PA_ADDR_RANGE.
246          * Note here we assume that level-1 page table is defined by
247          * HPAGE_SIZE.
248          */
249         pte = hv_pte(_PAGE_KERNEL | _PAGE_HUGE_PAGE);
250         pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_NO_L3);
251         for (i = 0; i < (QUASI_VA_IS_PA_ADDR_RANGE >> HPAGE_SHIFT); i++) {
252                 unsigned long vaddr = i << HPAGE_SHIFT;
253                 pgd_t *pgd = pgd_offset(current->mm, vaddr);
254                 pud_t *pud = pud_offset(pgd, vaddr);
255                 pte_t *ptep = (pte_t *) pmd_offset(pud, vaddr);
256                 unsigned long pfn = i << (HPAGE_SHIFT - PAGE_SHIFT);
257 
258                 if (pfn_valid(pfn))
259                         __set_pte(ptep, pfn_pte(pfn, pte));
260         }
261 }
262 
263 
264 void machine_kexec(struct kimage *image)
265 {
266         void *reboot_code_buffer;
267         pte_t *ptep;
268         void (*rnk)(unsigned long, void *, unsigned long)
269                 __noreturn;
270 
271         /* Mask all interrupts before starting to reboot. */
272         interrupt_mask_set_mask(~0ULL);
273 
274         kexec_find_and_set_command_line(image);
275 
276         /*
277          * Adjust the home caching of the control page to be cached on
278          * this cpu, and copy the assembly helper into the control
279          * code page, which we map in the vmalloc area.
280          */
281         homecache_change_page_home(image->control_code_page, 0,
282                                    smp_processor_id());
283         reboot_code_buffer = page_address(image->control_code_page);
284         BUG_ON(reboot_code_buffer == NULL);
285         ptep = virt_to_pte(NULL, (unsigned long)reboot_code_buffer);
286         __set_pte(ptep, pte_mkexec(*ptep));
287         memcpy(reboot_code_buffer, relocate_new_kernel,
288                relocate_new_kernel_size);
289         __flush_icache_range(
290                 (unsigned long) reboot_code_buffer,
291                 (unsigned long) reboot_code_buffer + relocate_new_kernel_size);
292 
293         setup_quasi_va_is_pa();
294 
295         /* now call it */
296         rnk = reboot_code_buffer;
297         (*rnk)(image->head, reboot_code_buffer, image->start);
298 }
299 

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