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authorHelge Deller <deller@gmx.de>2009-01-01 16:25:30 -0500
committerRusty Russell <rusty@rustcorp.com.au>2009-01-04 17:10:14 -0500
commitc298be74492bece102f3379d14015638f1fd1fac (patch)
tree92b314dff5ebc41e1eeb5d6d41f84db3a393e668 /arch
parent088af9a6e05d51e7c3dc85d45d8b7a52c3ee08d7 (diff)
parisc: fix module loading failure of large kernel modules
On 32bit (and sometimes 64bit) and with big kernel modules like xfs or ipv6 the relocation types R_PARISC_PCREL17F and R_PARISC_PCREL22F may fail to reach their PLT stub if we only create one big stub array for all sections at the beginning of the core or init section. With this patch we now instead add individual PLT stub entries directly in front of the code sections where the stubs are actually called. This reduces the distance between the PCREL location and the stub entry so that the relocations can be fulfilled. While calculating the final layout of the kernel module in memory, the kernel module loader calls arch_mod_section_prepend() to request the to be reserved amount of memory in front of each individual section. Tested with 32- and 64bit kernels. Signed-off-by: Helge Deller <deller@gmx.de> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'arch')
-rw-r--r--arch/parisc/include/asm/module.h6
-rw-r--r--arch/parisc/kernel/module.c216
2 files changed, 139 insertions, 83 deletions
diff --git a/arch/parisc/include/asm/module.h b/arch/parisc/include/asm/module.h
index c2cb49e934c1..1f4123427ea0 100644
--- a/arch/parisc/include/asm/module.h
+++ b/arch/parisc/include/asm/module.h
@@ -23,8 +23,10 @@ struct mod_arch_specific
23{ 23{
24 unsigned long got_offset, got_count, got_max; 24 unsigned long got_offset, got_count, got_max;
25 unsigned long fdesc_offset, fdesc_count, fdesc_max; 25 unsigned long fdesc_offset, fdesc_count, fdesc_max;
26 unsigned long stub_offset, stub_count, stub_max; 26 struct {
27 unsigned long init_stub_offset, init_stub_count, init_stub_max; 27 unsigned long stub_offset;
28 unsigned int stub_entries;
29 } *section;
28 int unwind_section; 30 int unwind_section;
29 struct unwind_table *unwind; 31 struct unwind_table *unwind;
30}; 32};
diff --git a/arch/parisc/kernel/module.c b/arch/parisc/kernel/module.c
index 44138c3e6ea7..9013243cecca 100644
--- a/arch/parisc/kernel/module.c
+++ b/arch/parisc/kernel/module.c
@@ -6,6 +6,7 @@
6 * 6 *
7 * Linux/PA-RISC Project (http://www.parisc-linux.org/) 7 * Linux/PA-RISC Project (http://www.parisc-linux.org/)
8 * Copyright (C) 2003 Randolph Chung <tausq at debian . org> 8 * Copyright (C) 2003 Randolph Chung <tausq at debian . org>
9 * Copyright (C) 2008 Helge Deller <deller@gmx.de>
9 * 10 *
10 * 11 *
11 * This program is free software; you can redistribute it and/or modify 12 * This program is free software; you can redistribute it and/or modify
@@ -24,6 +25,19 @@
24 * 25 *
25 * 26 *
26 * Notes: 27 * Notes:
28 * - PLT stub handling
29 * On 32bit (and sometimes 64bit) and with big kernel modules like xfs or
30 * ipv6 the relocation types R_PARISC_PCREL17F and R_PARISC_PCREL22F may
31 * fail to reach their PLT stub if we only create one big stub array for
32 * all sections at the beginning of the core or init section.
33 * Instead we now insert individual PLT stub entries directly in front of
34 * of the code sections where the stubs are actually called.
35 * This reduces the distance between the PCREL location and the stub entry
36 * so that the relocations can be fulfilled.
37 * While calculating the final layout of the kernel module in memory, the
38 * kernel module loader calls arch_mod_section_prepend() to request the
39 * to be reserved amount of memory in front of each individual section.
40 *
27 * - SEGREL32 handling 41 * - SEGREL32 handling
28 * We are not doing SEGREL32 handling correctly. According to the ABI, we 42 * We are not doing SEGREL32 handling correctly. According to the ABI, we
29 * should do a value offset, like this: 43 * should do a value offset, like this:
@@ -58,9 +72,13 @@
58#define DEBUGP(fmt...) 72#define DEBUGP(fmt...)
59#endif 73#endif
60 74
75#define RELOC_REACHABLE(val, bits) \
76 (( ( !((val) & (1<<((bits)-1))) && ((val)>>(bits)) != 0 ) || \
77 ( ((val) & (1<<((bits)-1))) && ((val)>>(bits)) != (((__typeof__(val))(~0))>>((bits)+2)))) ? \
78 0 : 1)
79
61#define CHECK_RELOC(val, bits) \ 80#define CHECK_RELOC(val, bits) \
62 if ( ( !((val) & (1<<((bits)-1))) && ((val)>>(bits)) != 0 ) || \ 81 if (!RELOC_REACHABLE(val, bits)) { \
63 ( ((val) & (1<<((bits)-1))) && ((val)>>(bits)) != (((__typeof__(val))(~0))>>((bits)+2)))) { \
64 printk(KERN_ERR "module %s relocation of symbol %s is out of range (0x%lx in %d bits)\n", \ 82 printk(KERN_ERR "module %s relocation of symbol %s is out of range (0x%lx in %d bits)\n", \
65 me->name, strtab + sym->st_name, (unsigned long)val, bits); \ 83 me->name, strtab + sym->st_name, (unsigned long)val, bits); \
66 return -ENOEXEC; \ 84 return -ENOEXEC; \
@@ -92,13 +110,6 @@ static inline int in_local(struct module *me, void *loc)
92 return in_init(me, loc) || in_core(me, loc); 110 return in_init(me, loc) || in_core(me, loc);
93} 111}
94 112
95static inline int in_local_section(struct module *me, void *loc, void *dot)
96{
97 return (in_init(me, loc) && in_init(me, dot)) ||
98 (in_core(me, loc) && in_core(me, dot));
99}
100
101
102#ifndef CONFIG_64BIT 113#ifndef CONFIG_64BIT
103struct got_entry { 114struct got_entry {
104 Elf32_Addr addr; 115 Elf32_Addr addr;
@@ -258,23 +269,42 @@ static inline unsigned long count_stubs(const Elf_Rela *rela, unsigned long n)
258/* Free memory returned from module_alloc */ 269/* Free memory returned from module_alloc */
259void module_free(struct module *mod, void *module_region) 270void module_free(struct module *mod, void *module_region)
260{ 271{
272 kfree(mod->arch.section);
273 mod->arch.section = NULL;
274
261 vfree(module_region); 275 vfree(module_region);
262 /* FIXME: If module_region == mod->init_region, trim exception 276 /* FIXME: If module_region == mod->init_region, trim exception
263 table entries. */ 277 table entries. */
264} 278}
265 279
280/* Additional bytes needed in front of individual sections */
281unsigned int arch_mod_section_prepend(struct module *mod,
282 unsigned int section)
283{
284 /* size needed for all stubs of this section (including
285 * one additional for correct alignment of the stubs) */
286 return (mod->arch.section[section].stub_entries + 1)
287 * sizeof(struct stub_entry);
288}
289
266#define CONST 290#define CONST
267int module_frob_arch_sections(CONST Elf_Ehdr *hdr, 291int module_frob_arch_sections(CONST Elf_Ehdr *hdr,
268 CONST Elf_Shdr *sechdrs, 292 CONST Elf_Shdr *sechdrs,
269 CONST char *secstrings, 293 CONST char *secstrings,
270 struct module *me) 294 struct module *me)
271{ 295{
272 unsigned long gots = 0, fdescs = 0, stubs = 0, init_stubs = 0; 296 unsigned long gots = 0, fdescs = 0, len;
273 unsigned int i; 297 unsigned int i;
274 298
299 len = hdr->e_shnum * sizeof(me->arch.section[0]);
300 me->arch.section = kzalloc(len, GFP_KERNEL);
301 if (!me->arch.section)
302 return -ENOMEM;
303
275 for (i = 1; i < hdr->e_shnum; i++) { 304 for (i = 1; i < hdr->e_shnum; i++) {
276 const Elf_Rela *rels = (void *)hdr + sechdrs[i].sh_offset; 305 const Elf_Rela *rels = (void *)sechdrs[i].sh_addr;
277 unsigned long nrels = sechdrs[i].sh_size / sizeof(*rels); 306 unsigned long nrels = sechdrs[i].sh_size / sizeof(*rels);
307 unsigned int count, s;
278 308
279 if (strncmp(secstrings + sechdrs[i].sh_name, 309 if (strncmp(secstrings + sechdrs[i].sh_name,
280 ".PARISC.unwind", 14) == 0) 310 ".PARISC.unwind", 14) == 0)
@@ -290,11 +320,23 @@ int module_frob_arch_sections(CONST Elf_Ehdr *hdr,
290 */ 320 */
291 gots += count_gots(rels, nrels); 321 gots += count_gots(rels, nrels);
292 fdescs += count_fdescs(rels, nrels); 322 fdescs += count_fdescs(rels, nrels);
293 if(strncmp(secstrings + sechdrs[i].sh_name, 323
294 ".rela.init", 10) == 0) 324 /* XXX: By sorting the relocs and finding duplicate entries
295 init_stubs += count_stubs(rels, nrels); 325 * we could reduce the number of necessary stubs and save
296 else 326 * some memory. */
297 stubs += count_stubs(rels, nrels); 327 count = count_stubs(rels, nrels);
328 if (!count)
329 continue;
330
331 /* so we need relocation stubs. reserve necessary memory. */
332 /* sh_info gives the section for which we need to add stubs. */
333 s = sechdrs[i].sh_info;
334
335 /* each code section should only have one relocation section */
336 WARN_ON(me->arch.section[s].stub_entries);
337
338 /* store number of stubs we need for this section */
339 me->arch.section[s].stub_entries += count;
298 } 340 }
299 341
300 /* align things a bit */ 342 /* align things a bit */
@@ -306,18 +348,8 @@ int module_frob_arch_sections(CONST Elf_Ehdr *hdr,
306 me->arch.fdesc_offset = me->core_size; 348 me->arch.fdesc_offset = me->core_size;
307 me->core_size += fdescs * sizeof(Elf_Fdesc); 349 me->core_size += fdescs * sizeof(Elf_Fdesc);
308 350
309 me->core_size = ALIGN(me->core_size, 16);
310 me->arch.stub_offset = me->core_size;
311 me->core_size += stubs * sizeof(struct stub_entry);
312
313 me->init_size = ALIGN(me->init_size, 16);
314 me->arch.init_stub_offset = me->init_size;
315 me->init_size += init_stubs * sizeof(struct stub_entry);
316
317 me->arch.got_max = gots; 351 me->arch.got_max = gots;
318 me->arch.fdesc_max = fdescs; 352 me->arch.fdesc_max = fdescs;
319 me->arch.stub_max = stubs;
320 me->arch.init_stub_max = init_stubs;
321 353
322 return 0; 354 return 0;
323} 355}
@@ -380,23 +412,27 @@ enum elf_stub_type {
380}; 412};
381 413
382static Elf_Addr get_stub(struct module *me, unsigned long value, long addend, 414static Elf_Addr get_stub(struct module *me, unsigned long value, long addend,
383 enum elf_stub_type stub_type, int init_section) 415 enum elf_stub_type stub_type, Elf_Addr loc0, unsigned int targetsec)
384{ 416{
385 unsigned long i;
386 struct stub_entry *stub; 417 struct stub_entry *stub;
387 418
388 if(init_section) { 419 /* initialize stub_offset to point in front of the section */
389 i = me->arch.init_stub_count++; 420 if (!me->arch.section[targetsec].stub_offset) {
390 BUG_ON(me->arch.init_stub_count > me->arch.init_stub_max); 421 loc0 -= (me->arch.section[targetsec].stub_entries + 1) *
391 stub = me->module_init + me->arch.init_stub_offset + 422 sizeof(struct stub_entry);
392 i * sizeof(struct stub_entry); 423 /* get correct alignment for the stubs */
393 } else { 424 loc0 = ALIGN(loc0, sizeof(struct stub_entry));
394 i = me->arch.stub_count++; 425 me->arch.section[targetsec].stub_offset = loc0;
395 BUG_ON(me->arch.stub_count > me->arch.stub_max);
396 stub = me->module_core + me->arch.stub_offset +
397 i * sizeof(struct stub_entry);
398 } 426 }
399 427
428 /* get address of stub entry */
429 stub = (void *) me->arch.section[targetsec].stub_offset;
430 me->arch.section[targetsec].stub_offset += sizeof(struct stub_entry);
431
432 /* do not write outside available stub area */
433 BUG_ON(0 == me->arch.section[targetsec].stub_entries--);
434
435
400#ifndef CONFIG_64BIT 436#ifndef CONFIG_64BIT
401/* for 32-bit the stub looks like this: 437/* for 32-bit the stub looks like this:
402 * ldil L'XXX,%r1 438 * ldil L'XXX,%r1
@@ -489,15 +525,19 @@ int apply_relocate_add(Elf_Shdr *sechdrs,
489 Elf32_Addr val; 525 Elf32_Addr val;
490 Elf32_Sword addend; 526 Elf32_Sword addend;
491 Elf32_Addr dot; 527 Elf32_Addr dot;
528 Elf_Addr loc0;
529 unsigned int targetsec = sechdrs[relsec].sh_info;
492 //unsigned long dp = (unsigned long)$global$; 530 //unsigned long dp = (unsigned long)$global$;
493 register unsigned long dp asm ("r27"); 531 register unsigned long dp asm ("r27");
494 532
495 DEBUGP("Applying relocate section %u to %u\n", relsec, 533 DEBUGP("Applying relocate section %u to %u\n", relsec,
496 sechdrs[relsec].sh_info); 534 targetsec);
497 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) { 535 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
498 /* This is where to make the change */ 536 /* This is where to make the change */
499 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr 537 loc = (void *)sechdrs[targetsec].sh_addr
500 + rel[i].r_offset; 538 + rel[i].r_offset;
539 /* This is the start of the target section */
540 loc0 = sechdrs[targetsec].sh_addr;
501 /* This is the symbol it is referring to */ 541 /* This is the symbol it is referring to */
502 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr 542 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
503 + ELF32_R_SYM(rel[i].r_info); 543 + ELF32_R_SYM(rel[i].r_info);
@@ -569,19 +609,32 @@ int apply_relocate_add(Elf_Shdr *sechdrs,
569 break; 609 break;
570 case R_PARISC_PCREL17F: 610 case R_PARISC_PCREL17F:
571 /* 17-bit PC relative address */ 611 /* 17-bit PC relative address */
572 val = get_stub(me, val, addend, ELF_STUB_GOT, in_init(me, loc)); 612 /* calculate direct call offset */
613 val += addend;
573 val = (val - dot - 8)/4; 614 val = (val - dot - 8)/4;
574 CHECK_RELOC(val, 17) 615 if (!RELOC_REACHABLE(val, 17)) {
616 /* direct distance too far, create
617 * stub entry instead */
618 val = get_stub(me, sym->st_value, addend,
619 ELF_STUB_DIRECT, loc0, targetsec);
620 val = (val - dot - 8)/4;
621 CHECK_RELOC(val, 17);
622 }
575 *loc = (*loc & ~0x1f1ffd) | reassemble_17(val); 623 *loc = (*loc & ~0x1f1ffd) | reassemble_17(val);
576 break; 624 break;
577 case R_PARISC_PCREL22F: 625 case R_PARISC_PCREL22F:
578 /* 22-bit PC relative address; only defined for pa20 */ 626 /* 22-bit PC relative address; only defined for pa20 */
579 val = get_stub(me, val, addend, ELF_STUB_GOT, in_init(me, loc)); 627 /* calculate direct call offset */
580 DEBUGP("STUB FOR %s loc %lx+%lx at %lx\n", 628 val += addend;
581 strtab + sym->st_name, (unsigned long)loc, addend,
582 val)
583 val = (val - dot - 8)/4; 629 val = (val - dot - 8)/4;
584 CHECK_RELOC(val, 22); 630 if (!RELOC_REACHABLE(val, 22)) {
631 /* direct distance too far, create
632 * stub entry instead */
633 val = get_stub(me, sym->st_value, addend,
634 ELF_STUB_DIRECT, loc0, targetsec);
635 val = (val - dot - 8)/4;
636 CHECK_RELOC(val, 22);
637 }
585 *loc = (*loc & ~0x3ff1ffd) | reassemble_22(val); 638 *loc = (*loc & ~0x3ff1ffd) | reassemble_22(val);
586 break; 639 break;
587 640
@@ -610,13 +663,17 @@ int apply_relocate_add(Elf_Shdr *sechdrs,
610 Elf64_Addr val; 663 Elf64_Addr val;
611 Elf64_Sxword addend; 664 Elf64_Sxword addend;
612 Elf64_Addr dot; 665 Elf64_Addr dot;
666 Elf_Addr loc0;
667 unsigned int targetsec = sechdrs[relsec].sh_info;
613 668
614 DEBUGP("Applying relocate section %u to %u\n", relsec, 669 DEBUGP("Applying relocate section %u to %u\n", relsec,
615 sechdrs[relsec].sh_info); 670 targetsec);
616 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) { 671 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
617 /* This is where to make the change */ 672 /* This is where to make the change */
618 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr 673 loc = (void *)sechdrs[targetsec].sh_addr
619 + rel[i].r_offset; 674 + rel[i].r_offset;
675 /* This is the start of the target section */
676 loc0 = sechdrs[targetsec].sh_addr;
620 /* This is the symbol it is referring to */ 677 /* This is the symbol it is referring to */
621 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr 678 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
622 + ELF64_R_SYM(rel[i].r_info); 679 + ELF64_R_SYM(rel[i].r_info);
@@ -672,42 +729,40 @@ int apply_relocate_add(Elf_Shdr *sechdrs,
672 DEBUGP("PCREL22F Symbol %s loc %p val %lx\n", 729 DEBUGP("PCREL22F Symbol %s loc %p val %lx\n",
673 strtab + sym->st_name, 730 strtab + sym->st_name,
674 loc, val); 731 loc, val);
732 val += addend;
675 /* can we reach it locally? */ 733 /* can we reach it locally? */
676 if(!in_local_section(me, (void *)val, (void *)dot)) { 734 if (in_local(me, (void *)val)) {
677 735 /* this is the case where the symbol is local
678 if (in_local(me, (void *)val)) 736 * to the module, but in a different section,
679 /* this is the case where the 737 * so stub the jump in case it's more than 22
680 * symbol is local to the 738 * bits away */
681 * module, but in a different 739 val = (val - dot - 8)/4;
682 * section, so stub the jump 740 if (!RELOC_REACHABLE(val, 22)) {
683 * in case it's more than 22 741 /* direct distance too far, create
684 * bits away */ 742 * stub entry instead */
685 val = get_stub(me, val, addend, ELF_STUB_DIRECT, 743 val = get_stub(me, sym->st_value,
686 in_init(me, loc)); 744 addend, ELF_STUB_DIRECT,
687 else if (strncmp(strtab + sym->st_name, "$$", 2) 745 loc0, targetsec);
746 } else {
747 /* Ok, we can reach it directly. */
748 val = sym->st_value;
749 val += addend;
750 }
751 } else {
752 val = sym->st_value;
753 if (strncmp(strtab + sym->st_name, "$$", 2)
688 == 0) 754 == 0)
689 val = get_stub(me, val, addend, ELF_STUB_MILLI, 755 val = get_stub(me, val, addend, ELF_STUB_MILLI,
690 in_init(me, loc)); 756 loc0, targetsec);
691 else 757 else
692 val = get_stub(me, val, addend, ELF_STUB_GOT, 758 val = get_stub(me, val, addend, ELF_STUB_GOT,
693 in_init(me, loc)); 759 loc0, targetsec);
694 } 760 }
695 DEBUGP("STUB FOR %s loc %lx, val %lx+%lx at %lx\n", 761 DEBUGP("STUB FOR %s loc %lx, val %lx+%lx at %lx\n",
696 strtab + sym->st_name, loc, sym->st_value, 762 strtab + sym->st_name, loc, sym->st_value,
697 addend, val); 763 addend, val);
698 /* FIXME: local symbols work as long as the
699 * core and init pieces aren't separated too
700 * far. If this is ever broken, you will trip
701 * the check below. The way to fix it would
702 * be to generate local stubs to go between init
703 * and core */
704 if((Elf64_Sxword)(val - dot - 8) > 0x800000 -1 ||
705 (Elf64_Sxword)(val - dot - 8) < -0x800000) {
706 printk(KERN_ERR "Module %s, symbol %s is out of range for PCREL22F relocation\n",
707 me->name, strtab + sym->st_name);
708 return -ENOEXEC;
709 }
710 val = (val - dot - 8)/4; 764 val = (val - dot - 8)/4;
765 CHECK_RELOC(val, 22);
711 *loc = (*loc & ~0x3ff1ffd) | reassemble_22(val); 766 *loc = (*loc & ~0x3ff1ffd) | reassemble_22(val);
712 break; 767 break;
713 case R_PARISC_DIR64: 768 case R_PARISC_DIR64:
@@ -794,12 +849,8 @@ int module_finalize(const Elf_Ehdr *hdr,
794 addr = (u32 *)entry->addr; 849 addr = (u32 *)entry->addr;
795 printk("INSNS: %x %x %x %x\n", 850 printk("INSNS: %x %x %x %x\n",
796 addr[0], addr[1], addr[2], addr[3]); 851 addr[0], addr[1], addr[2], addr[3]);
797 printk("stubs used %ld, stubs max %ld\n" 852 printk("got entries used %ld, gots max %ld\n"
798 "init_stubs used %ld, init stubs max %ld\n"
799 "got entries used %ld, gots max %ld\n"
800 "fdescs used %ld, fdescs max %ld\n", 853 "fdescs used %ld, fdescs max %ld\n",
801 me->arch.stub_count, me->arch.stub_max,
802 me->arch.init_stub_count, me->arch.init_stub_max,
803 me->arch.got_count, me->arch.got_max, 854 me->arch.got_count, me->arch.got_max,
804 me->arch.fdesc_count, me->arch.fdesc_max); 855 me->arch.fdesc_count, me->arch.fdesc_max);
805#endif 856#endif
@@ -829,7 +880,10 @@ int module_finalize(const Elf_Ehdr *hdr,
829 me->name, me->arch.got_count, MAX_GOTS); 880 me->name, me->arch.got_count, MAX_GOTS);
830 return -EINVAL; 881 return -EINVAL;
831 } 882 }
832 883
884 kfree(me->arch.section);
885 me->arch.section = NULL;
886
833 /* no symbol table */ 887 /* no symbol table */
834 if(symhdr == NULL) 888 if(symhdr == NULL)
835 return 0; 889 return 0;