1/* 2 * S390 kdump implementation 3 * 4 * Copyright IBM Corp. 2011 5 * Author(s): Michael Holzheu <holzheu@linux.vnet.ibm.com> 6 */ 7 8#include <linux/crash_dump.h> 9#include <asm/lowcore.h> 10#include <linux/kernel.h> 11#include <linux/module.h> 12#include <linux/gfp.h> 13#include <linux/slab.h> 14#include <linux/bootmem.h> 15#include <linux/elf.h> 16#include <linux/memblock.h> 17#include <asm/os_info.h> 18#include <asm/elf.h> 19#include <asm/ipl.h> 20#include <asm/sclp.h> 21 22#define PTR_ADD(x, y) (((char *) (x)) + ((unsigned long) (y))) 23#define PTR_SUB(x, y) (((char *) (x)) - ((unsigned long) (y))) 24#define PTR_DIFF(x, y) ((unsigned long)(((char *) (x)) - ((unsigned long) (y)))) 25 26static struct memblock_region oldmem_region; 27 28static struct memblock_type oldmem_type = { 29 .cnt = 1, 30 .max = 1, 31 .total_size = 0, 32 .regions = &oldmem_region, 33}; 34 35#define for_each_dump_mem_range(i, nid, p_start, p_end, p_nid) \ 36 for (i = 0, __next_mem_range(&i, nid, &memblock.physmem, \ 37 &oldmem_type, p_start, \ 38 p_end, p_nid); \ 39 i != (u64)ULLONG_MAX; \ 40 __next_mem_range(&i, nid, &memblock.physmem, \ 41 &oldmem_type, \ 42 p_start, p_end, p_nid)) 43 44struct dump_save_areas dump_save_areas; 45 46/* 47 * Allocate and add a save area for a CPU 48 */ 49struct save_area_ext *dump_save_area_create(int cpu) 50{ 51 struct save_area_ext **save_areas, *save_area; 52 53 save_area = kmalloc(sizeof(*save_area), GFP_KERNEL); 54 if (!save_area) 55 return NULL; 56 if (cpu + 1 > dump_save_areas.count) { 57 dump_save_areas.count = cpu + 1; 58 save_areas = krealloc(dump_save_areas.areas, 59 dump_save_areas.count * sizeof(void *), 60 GFP_KERNEL | __GFP_ZERO); 61 if (!save_areas) { 62 kfree(save_area); 63 return NULL; 64 } 65 dump_save_areas.areas = save_areas; 66 } 67 dump_save_areas.areas[cpu] = save_area; 68 return save_area; 69} 70 71/* 72 * Return physical address for virtual address 73 */ 74static inline void *load_real_addr(void *addr) 75{ 76 unsigned long real_addr; 77 78 asm volatile( 79 " lra %0,0(%1)\n" 80 " jz 0f\n" 81 " la %0,0\n" 82 "0:" 83 : "=a" (real_addr) : "a" (addr) : "cc"); 84 return (void *)real_addr; 85} 86 87/* 88 * Copy real to virtual or real memory 89 */ 90static int copy_from_realmem(void *dest, void *src, size_t count) 91{ 92 unsigned long size; 93 94 if (!count) 95 return 0; 96 if (!is_vmalloc_or_module_addr(dest)) 97 return memcpy_real(dest, src, count); 98 do { 99 size = min(count, PAGE_SIZE - (__pa(dest) & ~PAGE_MASK)); 100 if (memcpy_real(load_real_addr(dest), src, size)) 101 return -EFAULT; 102 count -= size; 103 dest += size; 104 src += size; 105 } while (count); 106 return 0; 107} 108 109/* 110 * Pointer to ELF header in new kernel 111 */ 112static void *elfcorehdr_newmem; 113 114/* 115 * Copy one page from zfcpdump "oldmem" 116 * 117 * For pages below HSA size memory from the HSA is copied. Otherwise 118 * real memory copy is used. 119 */ 120static ssize_t copy_oldmem_page_zfcpdump(char *buf, size_t csize, 121 unsigned long src, int userbuf) 122{ 123 int rc; 124 125 if (src < sclp_get_hsa_size()) { 126 rc = memcpy_hsa(buf, src, csize, userbuf); 127 } else { 128 if (userbuf) 129 rc = copy_to_user_real((void __force __user *) buf, 130 (void *) src, csize); 131 else 132 rc = memcpy_real(buf, (void *) src, csize); 133 } 134 return rc ? rc : csize; 135} 136 137/* 138 * Copy one page from kdump "oldmem" 139 * 140 * For the kdump reserved memory this functions performs a swap operation: 141 * - [OLDMEM_BASE - OLDMEM_BASE + OLDMEM_SIZE] is mapped to [0 - OLDMEM_SIZE]. 142 * - [0 - OLDMEM_SIZE] is mapped to [OLDMEM_BASE - OLDMEM_BASE + OLDMEM_SIZE] 143 */ 144static ssize_t copy_oldmem_page_kdump(char *buf, size_t csize, 145 unsigned long src, int userbuf) 146 147{ 148 int rc; 149 150 if (src < OLDMEM_SIZE) 151 src += OLDMEM_BASE; 152 else if (src > OLDMEM_BASE && 153 src < OLDMEM_BASE + OLDMEM_SIZE) 154 src -= OLDMEM_BASE; 155 if (userbuf) 156 rc = copy_to_user_real((void __force __user *) buf, 157 (void *) src, csize); 158 else 159 rc = copy_from_realmem(buf, (void *) src, csize); 160 return (rc == 0) ? rc : csize; 161} 162 163/* 164 * Copy one page from "oldmem" 165 */ 166ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize, 167 unsigned long offset, int userbuf) 168{ 169 unsigned long src; 170 171 if (!csize) 172 return 0; 173 src = (pfn << PAGE_SHIFT) + offset; 174 if (OLDMEM_BASE) 175 return copy_oldmem_page_kdump(buf, csize, src, userbuf); 176 else 177 return copy_oldmem_page_zfcpdump(buf, csize, src, userbuf); 178} 179 180/* 181 * Remap "oldmem" for kdump 182 * 183 * For the kdump reserved memory this functions performs a swap operation: 184 * [0 - OLDMEM_SIZE] is mapped to [OLDMEM_BASE - OLDMEM_BASE + OLDMEM_SIZE] 185 */ 186static int remap_oldmem_pfn_range_kdump(struct vm_area_struct *vma, 187 unsigned long from, unsigned long pfn, 188 unsigned long size, pgprot_t prot) 189{ 190 unsigned long size_old; 191 int rc; 192 193 if (pfn < OLDMEM_SIZE >> PAGE_SHIFT) { 194 size_old = min(size, OLDMEM_SIZE - (pfn << PAGE_SHIFT)); 195 rc = remap_pfn_range(vma, from, 196 pfn + (OLDMEM_BASE >> PAGE_SHIFT), 197 size_old, prot); 198 if (rc || size == size_old) 199 return rc; 200 size -= size_old; 201 from += size_old; 202 pfn += size_old >> PAGE_SHIFT; 203 } 204 return remap_pfn_range(vma, from, pfn, size, prot); 205} 206 207/* 208 * Remap "oldmem" for zfcpdump 209 * 210 * We only map available memory above HSA size. Memory below HSA size 211 * is read on demand using the copy_oldmem_page() function. 212 */ 213static int remap_oldmem_pfn_range_zfcpdump(struct vm_area_struct *vma, 214 unsigned long from, 215 unsigned long pfn, 216 unsigned long size, pgprot_t prot) 217{ 218 unsigned long hsa_end = sclp_get_hsa_size(); 219 unsigned long size_hsa; 220 221 if (pfn < hsa_end >> PAGE_SHIFT) { 222 size_hsa = min(size, hsa_end - (pfn << PAGE_SHIFT)); 223 if (size == size_hsa) 224 return 0; 225 size -= size_hsa; 226 from += size_hsa; 227 pfn += size_hsa >> PAGE_SHIFT; 228 } 229 return remap_pfn_range(vma, from, pfn, size, prot); 230} 231 232/* 233 * Remap "oldmem" for kdump or zfcpdump 234 */ 235int remap_oldmem_pfn_range(struct vm_area_struct *vma, unsigned long from, 236 unsigned long pfn, unsigned long size, pgprot_t prot) 237{ 238 if (OLDMEM_BASE) 239 return remap_oldmem_pfn_range_kdump(vma, from, pfn, size, prot); 240 else 241 return remap_oldmem_pfn_range_zfcpdump(vma, from, pfn, size, 242 prot); 243} 244 245/* 246 * Copy memory from old kernel 247 */ 248int copy_from_oldmem(void *dest, void *src, size_t count) 249{ 250 unsigned long copied = 0; 251 int rc; 252 253 if (OLDMEM_BASE) { 254 if ((unsigned long) src < OLDMEM_SIZE) { 255 copied = min(count, OLDMEM_SIZE - (unsigned long) src); 256 rc = copy_from_realmem(dest, src + OLDMEM_BASE, copied); 257 if (rc) 258 return rc; 259 } 260 } else { 261 unsigned long hsa_end = sclp_get_hsa_size(); 262 if ((unsigned long) src < hsa_end) { 263 copied = min(count, hsa_end - (unsigned long) src); 264 rc = memcpy_hsa(dest, (unsigned long) src, copied, 0); 265 if (rc) 266 return rc; 267 } 268 } 269 return copy_from_realmem(dest + copied, src + copied, count - copied); 270} 271 272/* 273 * Alloc memory and panic in case of ENOMEM 274 */ 275static void *kzalloc_panic(int len) 276{ 277 void *rc; 278 279 rc = kzalloc(len, GFP_KERNEL); 280 if (!rc) 281 panic("s390 kdump kzalloc (%d) failed", len); 282 return rc; 283} 284 285/* 286 * Initialize ELF note 287 */ 288static void *nt_init(void *buf, Elf64_Word type, void *desc, int d_len, 289 const char *name) 290{ 291 Elf64_Nhdr *note; 292 u64 len; 293 294 note = (Elf64_Nhdr *)buf; 295 note->n_namesz = strlen(name) + 1; 296 note->n_descsz = d_len; 297 note->n_type = type; 298 len = sizeof(Elf64_Nhdr); 299 300 memcpy(buf + len, name, note->n_namesz); 301 len = roundup(len + note->n_namesz, 4); 302 303 memcpy(buf + len, desc, note->n_descsz); 304 len = roundup(len + note->n_descsz, 4); 305 306 return PTR_ADD(buf, len); 307} 308 309/* 310 * Initialize prstatus note 311 */ 312static void *nt_prstatus(void *ptr, struct save_area *sa) 313{ 314 struct elf_prstatus nt_prstatus; 315 static int cpu_nr = 1; 316 317 memset(&nt_prstatus, 0, sizeof(nt_prstatus)); 318 memcpy(&nt_prstatus.pr_reg.gprs, sa->gp_regs, sizeof(sa->gp_regs)); 319 memcpy(&nt_prstatus.pr_reg.psw, sa->psw, sizeof(sa->psw)); 320 memcpy(&nt_prstatus.pr_reg.acrs, sa->acc_regs, sizeof(sa->acc_regs)); 321 nt_prstatus.pr_pid = cpu_nr; 322 cpu_nr++; 323 324 return nt_init(ptr, NT_PRSTATUS, &nt_prstatus, sizeof(nt_prstatus), 325 "CORE"); 326} 327 328/* 329 * Initialize fpregset (floating point) note 330 */ 331static void *nt_fpregset(void *ptr, struct save_area *sa) 332{ 333 elf_fpregset_t nt_fpregset; 334 335 memset(&nt_fpregset, 0, sizeof(nt_fpregset)); 336 memcpy(&nt_fpregset.fpc, &sa->fp_ctrl_reg, sizeof(sa->fp_ctrl_reg)); 337 memcpy(&nt_fpregset.fprs, &sa->fp_regs, sizeof(sa->fp_regs)); 338 339 return nt_init(ptr, NT_PRFPREG, &nt_fpregset, sizeof(nt_fpregset), 340 "CORE"); 341} 342 343/* 344 * Initialize timer note 345 */ 346static void *nt_s390_timer(void *ptr, struct save_area *sa) 347{ 348 return nt_init(ptr, NT_S390_TIMER, &sa->timer, sizeof(sa->timer), 349 KEXEC_CORE_NOTE_NAME); 350} 351 352/* 353 * Initialize TOD clock comparator note 354 */ 355static void *nt_s390_tod_cmp(void *ptr, struct save_area *sa) 356{ 357 return nt_init(ptr, NT_S390_TODCMP, &sa->clk_cmp, 358 sizeof(sa->clk_cmp), KEXEC_CORE_NOTE_NAME); 359} 360 361/* 362 * Initialize TOD programmable register note 363 */ 364static void *nt_s390_tod_preg(void *ptr, struct save_area *sa) 365{ 366 return nt_init(ptr, NT_S390_TODPREG, &sa->tod_reg, 367 sizeof(sa->tod_reg), KEXEC_CORE_NOTE_NAME); 368} 369 370/* 371 * Initialize control register note 372 */ 373static void *nt_s390_ctrs(void *ptr, struct save_area *sa) 374{ 375 return nt_init(ptr, NT_S390_CTRS, &sa->ctrl_regs, 376 sizeof(sa->ctrl_regs), KEXEC_CORE_NOTE_NAME); 377} 378 379/* 380 * Initialize prefix register note 381 */ 382static void *nt_s390_prefix(void *ptr, struct save_area *sa) 383{ 384 return nt_init(ptr, NT_S390_PREFIX, &sa->pref_reg, 385 sizeof(sa->pref_reg), KEXEC_CORE_NOTE_NAME); 386} 387 388/* 389 * Initialize vxrs high note (full 128 bit VX registers 16-31) 390 */ 391static void *nt_s390_vx_high(void *ptr, __vector128 *vx_regs) 392{ 393 return nt_init(ptr, NT_S390_VXRS_HIGH, &vx_regs[16], 394 16 * sizeof(__vector128), KEXEC_CORE_NOTE_NAME); 395} 396 397/* 398 * Initialize vxrs low note (lower halves of VX registers 0-15) 399 */ 400static void *nt_s390_vx_low(void *ptr, __vector128 *vx_regs) 401{ 402 Elf64_Nhdr *note; 403 u64 len; 404 int i; 405 406 note = (Elf64_Nhdr *)ptr; 407 note->n_namesz = strlen(KEXEC_CORE_NOTE_NAME) + 1; 408 note->n_descsz = 16 * 8; 409 note->n_type = NT_S390_VXRS_LOW; 410 len = sizeof(Elf64_Nhdr); 411 412 memcpy(ptr + len, KEXEC_CORE_NOTE_NAME, note->n_namesz); 413 len = roundup(len + note->n_namesz, 4); 414 415 ptr += len; 416 /* Copy lower halves of SIMD registers 0-15 */ 417 for (i = 0; i < 16; i++) { 418 memcpy(ptr, &vx_regs[i], 8); 419 ptr += 8; 420 } 421 return ptr; 422} 423 424/* 425 * Fill ELF notes for one CPU with save area registers 426 */ 427void *fill_cpu_elf_notes(void *ptr, struct save_area *sa, __vector128 *vx_regs) 428{ 429 ptr = nt_prstatus(ptr, sa); 430 ptr = nt_fpregset(ptr, sa); 431 ptr = nt_s390_timer(ptr, sa); 432 ptr = nt_s390_tod_cmp(ptr, sa); 433 ptr = nt_s390_tod_preg(ptr, sa); 434 ptr = nt_s390_ctrs(ptr, sa); 435 ptr = nt_s390_prefix(ptr, sa); 436 if (MACHINE_HAS_VX && vx_regs) { 437 ptr = nt_s390_vx_low(ptr, vx_regs); 438 ptr = nt_s390_vx_high(ptr, vx_regs); 439 } 440 return ptr; 441} 442 443/* 444 * Initialize prpsinfo note (new kernel) 445 */ 446static void *nt_prpsinfo(void *ptr) 447{ 448 struct elf_prpsinfo prpsinfo; 449 450 memset(&prpsinfo, 0, sizeof(prpsinfo)); 451 prpsinfo.pr_sname = 'R'; 452 strcpy(prpsinfo.pr_fname, "vmlinux"); 453 return nt_init(ptr, NT_PRPSINFO, &prpsinfo, sizeof(prpsinfo), 454 KEXEC_CORE_NOTE_NAME); 455} 456 457/* 458 * Get vmcoreinfo using lowcore->vmcore_info (new kernel) 459 */ 460static void *get_vmcoreinfo_old(unsigned long *size) 461{ 462 char nt_name[11], *vmcoreinfo; 463 Elf64_Nhdr note; 464 void *addr; 465 466 if (copy_from_oldmem(&addr, &S390_lowcore.vmcore_info, sizeof(addr))) 467 return NULL; 468 memset(nt_name, 0, sizeof(nt_name)); 469 if (copy_from_oldmem(¬e, addr, sizeof(note))) 470 return NULL; 471 if (copy_from_oldmem(nt_name, addr + sizeof(note), sizeof(nt_name) - 1)) 472 return NULL; 473 if (strcmp(nt_name, "VMCOREINFO") != 0) 474 return NULL; 475 vmcoreinfo = kzalloc_panic(note.n_descsz); 476 if (copy_from_oldmem(vmcoreinfo, addr + 24, note.n_descsz)) 477 return NULL; 478 *size = note.n_descsz; 479 return vmcoreinfo; 480} 481 482/* 483 * Initialize vmcoreinfo note (new kernel) 484 */ 485static void *nt_vmcoreinfo(void *ptr) 486{ 487 unsigned long size; 488 void *vmcoreinfo; 489 490 vmcoreinfo = os_info_old_entry(OS_INFO_VMCOREINFO, &size); 491 if (!vmcoreinfo) 492 vmcoreinfo = get_vmcoreinfo_old(&size); 493 if (!vmcoreinfo) 494 return ptr; 495 return nt_init(ptr, 0, vmcoreinfo, size, "VMCOREINFO"); 496} 497 498/* 499 * Initialize ELF header (new kernel) 500 */ 501static void *ehdr_init(Elf64_Ehdr *ehdr, int mem_chunk_cnt) 502{ 503 memset(ehdr, 0, sizeof(*ehdr)); 504 memcpy(ehdr->e_ident, ELFMAG, SELFMAG); 505 ehdr->e_ident[EI_CLASS] = ELFCLASS64; 506 ehdr->e_ident[EI_DATA] = ELFDATA2MSB; 507 ehdr->e_ident[EI_VERSION] = EV_CURRENT; 508 memset(ehdr->e_ident + EI_PAD, 0, EI_NIDENT - EI_PAD); 509 ehdr->e_type = ET_CORE; 510 ehdr->e_machine = EM_S390; 511 ehdr->e_version = EV_CURRENT; 512 ehdr->e_phoff = sizeof(Elf64_Ehdr); 513 ehdr->e_ehsize = sizeof(Elf64_Ehdr); 514 ehdr->e_phentsize = sizeof(Elf64_Phdr); 515 ehdr->e_phnum = mem_chunk_cnt + 1; 516 return ehdr + 1; 517} 518 519/* 520 * Return CPU count for ELF header (new kernel) 521 */ 522static int get_cpu_cnt(void) 523{ 524 int i, cpus = 0; 525 526 for (i = 0; i < dump_save_areas.count; i++) { 527 if (dump_save_areas.areas[i]->sa.pref_reg == 0) 528 continue; 529 cpus++; 530 } 531 return cpus; 532} 533 534/* 535 * Return memory chunk count for ELF header (new kernel) 536 */ 537static int get_mem_chunk_cnt(void) 538{ 539 int cnt = 0; 540 u64 idx; 541 542 for_each_dump_mem_range(idx, NUMA_NO_NODE, NULL, NULL, NULL) 543 cnt++; 544 return cnt; 545} 546 547/* 548 * Initialize ELF loads (new kernel) 549 */ 550static void loads_init(Elf64_Phdr *phdr, u64 loads_offset) 551{ 552 phys_addr_t start, end; 553 u64 idx; 554 555 for_each_dump_mem_range(idx, NUMA_NO_NODE, &start, &end, NULL) { 556 phdr->p_filesz = end - start; 557 phdr->p_type = PT_LOAD; 558 phdr->p_offset = start; 559 phdr->p_vaddr = start; 560 phdr->p_paddr = start; 561 phdr->p_memsz = end - start; 562 phdr->p_flags = PF_R | PF_W | PF_X; 563 phdr->p_align = PAGE_SIZE; 564 phdr++; 565 } 566} 567 568/* 569 * Initialize notes (new kernel) 570 */ 571static void *notes_init(Elf64_Phdr *phdr, void *ptr, u64 notes_offset) 572{ 573 struct save_area_ext *sa_ext; 574 void *ptr_start = ptr; 575 int i; 576 577 ptr = nt_prpsinfo(ptr); 578 579 for (i = 0; i < dump_save_areas.count; i++) { 580 sa_ext = dump_save_areas.areas[i]; 581 if (sa_ext->sa.pref_reg == 0) 582 continue; 583 ptr = fill_cpu_elf_notes(ptr, &sa_ext->sa, sa_ext->vx_regs); 584 } 585 ptr = nt_vmcoreinfo(ptr); 586 memset(phdr, 0, sizeof(*phdr)); 587 phdr->p_type = PT_NOTE; 588 phdr->p_offset = notes_offset; 589 phdr->p_filesz = (unsigned long) PTR_SUB(ptr, ptr_start); 590 phdr->p_memsz = phdr->p_filesz; 591 return ptr; 592} 593 594/* 595 * Create ELF core header (new kernel) 596 */ 597int elfcorehdr_alloc(unsigned long long *addr, unsigned long long *size) 598{ 599 Elf64_Phdr *phdr_notes, *phdr_loads; 600 int mem_chunk_cnt; 601 void *ptr, *hdr; 602 u32 alloc_size; 603 u64 hdr_off; 604 605 /* If we are not in kdump or zfcpdump mode return */ 606 if (!OLDMEM_BASE && ipl_info.type != IPL_TYPE_FCP_DUMP) 607 return 0; 608 /* If elfcorehdr= has been passed via cmdline, we use that one */ 609 if (elfcorehdr_addr != ELFCORE_ADDR_MAX) 610 return 0; 611 /* If we cannot get HSA size for zfcpdump return error */ 612 if (ipl_info.type == IPL_TYPE_FCP_DUMP && !sclp_get_hsa_size()) 613 return -ENODEV; 614 615 /* For kdump, exclude previous crashkernel memory */ 616 if (OLDMEM_BASE) { 617 oldmem_region.base = OLDMEM_BASE; 618 oldmem_region.size = OLDMEM_SIZE; 619 oldmem_type.total_size = OLDMEM_SIZE; 620 } 621 622 mem_chunk_cnt = get_mem_chunk_cnt(); 623 624 alloc_size = 0x1000 + get_cpu_cnt() * 0x4a0 + 625 mem_chunk_cnt * sizeof(Elf64_Phdr); 626 hdr = kzalloc_panic(alloc_size); 627 /* Init elf header */ 628 ptr = ehdr_init(hdr, mem_chunk_cnt); 629 /* Init program headers */ 630 phdr_notes = ptr; 631 ptr = PTR_ADD(ptr, sizeof(Elf64_Phdr)); 632 phdr_loads = ptr; 633 ptr = PTR_ADD(ptr, sizeof(Elf64_Phdr) * mem_chunk_cnt); 634 /* Init notes */ 635 hdr_off = PTR_DIFF(ptr, hdr); 636 ptr = notes_init(phdr_notes, ptr, ((unsigned long) hdr) + hdr_off); 637 /* Init loads */ 638 hdr_off = PTR_DIFF(ptr, hdr); 639 loads_init(phdr_loads, hdr_off); 640 *addr = (unsigned long long) hdr; 641 elfcorehdr_newmem = hdr; 642 *size = (unsigned long long) hdr_off; 643 BUG_ON(elfcorehdr_size > alloc_size); 644 return 0; 645} 646 647/* 648 * Free ELF core header (new kernel) 649 */ 650void elfcorehdr_free(unsigned long long addr) 651{ 652 if (!elfcorehdr_newmem) 653 return; 654 kfree((void *)(unsigned long)addr); 655} 656 657/* 658 * Read from ELF header 659 */ 660ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos) 661{ 662 void *src = (void *)(unsigned long)*ppos; 663 664 src = elfcorehdr_newmem ? src : src - OLDMEM_BASE; 665 memcpy(buf, src, count); 666 *ppos += count; 667 return count; 668} 669 670/* 671 * Read from ELF notes data 672 */ 673ssize_t elfcorehdr_read_notes(char *buf, size_t count, u64 *ppos) 674{ 675 void *src = (void *)(unsigned long)*ppos; 676 int rc; 677 678 if (elfcorehdr_newmem) { 679 memcpy(buf, src, count); 680 } else { 681 rc = copy_from_oldmem(buf, src, count); 682 if (rc) 683 return rc; 684 } 685 *ppos += count; 686 return count; 687} 688