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module.c
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1 /*
2  * linux/arch/arm/kernel/module.c
3  *
4  * Copyright (C) 2002 Russell King.
5  * Modified for nommu by Hyok S. Choi
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License version 2 as
9  * published by the Free Software Foundation.
10  *
11  * Module allocation method suggested by Andi Kleen.
12  */
13 #include <linux/module.h>
14 #include <linux/moduleloader.h>
15 #include <linux/kernel.h>
16 #include <linux/mm.h>
17 #include <linux/elf.h>
18 #include <linux/vmalloc.h>
19 #include <linux/fs.h>
20 #include <linux/string.h>
21 #include <linux/gfp.h>
22 
23 #include <asm/pgtable.h>
24 #include <asm/sections.h>
25 #include <asm/smp_plat.h>
26 #include <asm/unwind.h>
27 
28 #ifdef CONFIG_XIP_KERNEL
29 /*
30  * The XIP kernel text is mapped in the module area for modules and
31  * some other stuff to work without any indirect relocations.
32  * MODULES_VADDR is redefined here and not in asm/memory.h to avoid
33  * recompiling the whole kernel when CONFIG_XIP_KERNEL is turned on/off.
34  */
35 #undef MODULES_VADDR
36 #define MODULES_VADDR (((unsigned long)_etext + ~PMD_MASK) & PMD_MASK)
37 #endif
38 
39 #ifdef CONFIG_MMU
40 void *module_alloc(unsigned long size)
41 {
42  return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
43  GFP_KERNEL, PAGE_KERNEL_EXEC, -1,
44  __builtin_return_address(0));
45 }
46 #endif
47 
48 int
49 apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
50  unsigned int relindex, struct module *module)
51 {
52  Elf32_Shdr *symsec = sechdrs + symindex;
53  Elf32_Shdr *relsec = sechdrs + relindex;
54  Elf32_Shdr *dstsec = sechdrs + relsec->sh_info;
55  Elf32_Rel *rel = (void *)relsec->sh_addr;
56  unsigned int i;
57 
58  for (i = 0; i < relsec->sh_size / sizeof(Elf32_Rel); i++, rel++) {
59  unsigned long loc;
60  Elf32_Sym *sym;
61  const char *symname;
62  s32 offset;
63 #ifdef CONFIG_THUMB2_KERNEL
64  u32 upper, lower, sign, j1, j2;
65 #endif
66 
67  offset = ELF32_R_SYM(rel->r_info);
68  if (offset < 0 || offset > (symsec->sh_size / sizeof(Elf32_Sym))) {
69  pr_err("%s: section %u reloc %u: bad relocation sym offset\n",
70  module->name, relindex, i);
71  return -ENOEXEC;
72  }
73 
74  sym = ((Elf32_Sym *)symsec->sh_addr) + offset;
75  symname = strtab + sym->st_name;
76 
77  if (rel->r_offset < 0 || rel->r_offset > dstsec->sh_size - sizeof(u32)) {
78  pr_err("%s: section %u reloc %u sym '%s': out of bounds relocation, offset %d size %u\n",
79  module->name, relindex, i, symname,
80  rel->r_offset, dstsec->sh_size);
81  return -ENOEXEC;
82  }
83 
84  loc = dstsec->sh_addr + rel->r_offset;
85 
86  switch (ELF32_R_TYPE(rel->r_info)) {
87  case R_ARM_NONE:
88  /* ignore */
89  break;
90 
91  case R_ARM_ABS32:
92  *(u32 *)loc += sym->st_value;
93  break;
94 
95  case R_ARM_PC24:
96  case R_ARM_CALL:
97  case R_ARM_JUMP24:
98  offset = (*(u32 *)loc & 0x00ffffff) << 2;
99  if (offset & 0x02000000)
100  offset -= 0x04000000;
101 
102  offset += sym->st_value - loc;
103  if (offset & 3 ||
104  offset <= (s32)0xfe000000 ||
105  offset >= (s32)0x02000000) {
106  pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
107  module->name, relindex, i, symname,
108  ELF32_R_TYPE(rel->r_info), loc,
109  sym->st_value);
110  return -ENOEXEC;
111  }
112 
113  offset >>= 2;
114 
115  *(u32 *)loc &= 0xff000000;
116  *(u32 *)loc |= offset & 0x00ffffff;
117  break;
118 
119  case R_ARM_V4BX:
120  /* Preserve Rm and the condition code. Alter
121  * other bits to re-code instruction as
122  * MOV PC,Rm.
123  */
124  *(u32 *)loc &= 0xf000000f;
125  *(u32 *)loc |= 0x01a0f000;
126  break;
127 
128  case R_ARM_PREL31:
129  offset = *(u32 *)loc + sym->st_value - loc;
130  *(u32 *)loc = offset & 0x7fffffff;
131  break;
132 
133  case R_ARM_MOVW_ABS_NC:
134  case R_ARM_MOVT_ABS:
135  offset = *(u32 *)loc;
136  offset = ((offset & 0xf0000) >> 4) | (offset & 0xfff);
137  offset = (offset ^ 0x8000) - 0x8000;
138 
139  offset += sym->st_value;
140  if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_ABS)
141  offset >>= 16;
142 
143  *(u32 *)loc &= 0xfff0f000;
144  *(u32 *)loc |= ((offset & 0xf000) << 4) |
145  (offset & 0x0fff);
146  break;
147 
148 #ifdef CONFIG_THUMB2_KERNEL
149  case R_ARM_THM_CALL:
150  case R_ARM_THM_JUMP24:
151  upper = *(u16 *)loc;
152  lower = *(u16 *)(loc + 2);
153 
154  /*
155  * 25 bit signed address range (Thumb-2 BL and B.W
156  * instructions):
157  * S:I1:I2:imm10:imm11:0
158  * where:
159  * S = upper[10] = offset[24]
160  * I1 = ~(J1 ^ S) = offset[23]
161  * I2 = ~(J2 ^ S) = offset[22]
162  * imm10 = upper[9:0] = offset[21:12]
163  * imm11 = lower[10:0] = offset[11:1]
164  * J1 = lower[13]
165  * J2 = lower[11]
166  */
167  sign = (upper >> 10) & 1;
168  j1 = (lower >> 13) & 1;
169  j2 = (lower >> 11) & 1;
170  offset = (sign << 24) | ((~(j1 ^ sign) & 1) << 23) |
171  ((~(j2 ^ sign) & 1) << 22) |
172  ((upper & 0x03ff) << 12) |
173  ((lower & 0x07ff) << 1);
174  if (offset & 0x01000000)
175  offset -= 0x02000000;
176  offset += sym->st_value - loc;
177 
178  /*
179  * For function symbols, only Thumb addresses are
180  * allowed (no interworking).
181  *
182  * For non-function symbols, the destination
183  * has no specific ARM/Thumb disposition, so
184  * the branch is resolved under the assumption
185  * that interworking is not required.
186  */
187  if ((ELF32_ST_TYPE(sym->st_info) == STT_FUNC &&
188  !(offset & 1)) ||
189  offset <= (s32)0xff000000 ||
190  offset >= (s32)0x01000000) {
191  pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
192  module->name, relindex, i, symname,
193  ELF32_R_TYPE(rel->r_info), loc,
194  sym->st_value);
195  return -ENOEXEC;
196  }
197 
198  sign = (offset >> 24) & 1;
199  j1 = sign ^ (~(offset >> 23) & 1);
200  j2 = sign ^ (~(offset >> 22) & 1);
201  *(u16 *)loc = (u16)((upper & 0xf800) | (sign << 10) |
202  ((offset >> 12) & 0x03ff));
203  *(u16 *)(loc + 2) = (u16)((lower & 0xd000) |
204  (j1 << 13) | (j2 << 11) |
205  ((offset >> 1) & 0x07ff));
206  break;
207 
208  case R_ARM_THM_MOVW_ABS_NC:
209  case R_ARM_THM_MOVT_ABS:
210  upper = *(u16 *)loc;
211  lower = *(u16 *)(loc + 2);
212 
213  /*
214  * MOVT/MOVW instructions encoding in Thumb-2:
215  *
216  * i = upper[10]
217  * imm4 = upper[3:0]
218  * imm3 = lower[14:12]
219  * imm8 = lower[7:0]
220  *
221  * imm16 = imm4:i:imm3:imm8
222  */
223  offset = ((upper & 0x000f) << 12) |
224  ((upper & 0x0400) << 1) |
225  ((lower & 0x7000) >> 4) | (lower & 0x00ff);
226  offset = (offset ^ 0x8000) - 0x8000;
227  offset += sym->st_value;
228 
229  if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_ABS)
230  offset >>= 16;
231 
232  *(u16 *)loc = (u16)((upper & 0xfbf0) |
233  ((offset & 0xf000) >> 12) |
234  ((offset & 0x0800) >> 1));
235  *(u16 *)(loc + 2) = (u16)((lower & 0x8f00) |
236  ((offset & 0x0700) << 4) |
237  (offset & 0x00ff));
238  break;
239 #endif
240 
241  default:
242  printk(KERN_ERR "%s: unknown relocation: %u\n",
243  module->name, ELF32_R_TYPE(rel->r_info));
244  return -ENOEXEC;
245  }
246  }
247  return 0;
248 }
249 
250 struct mod_unwind_map {
251  const Elf_Shdr *unw_sec;
252  const Elf_Shdr *txt_sec;
253 };
254 
255 static const Elf_Shdr *find_mod_section(const Elf32_Ehdr *hdr,
256  const Elf_Shdr *sechdrs, const char *name)
257 {
258  const Elf_Shdr *s, *se;
259  const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
260 
261  for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++)
262  if (strcmp(name, secstrs + s->sh_name) == 0)
263  return s;
264 
265  return NULL;
266 }
267 
268 extern void fixup_pv_table(const void *, unsigned long);
269 extern void fixup_smp(const void *, unsigned long);
270 
271 int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
272  struct module *mod)
273 {
274  const Elf_Shdr *s = NULL;
275 #ifdef CONFIG_ARM_UNWIND
276  const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
277  const Elf_Shdr *sechdrs_end = sechdrs + hdr->e_shnum;
278  struct mod_unwind_map maps[ARM_SEC_MAX];
279  int i;
280 
281  memset(maps, 0, sizeof(maps));
282 
283  for (s = sechdrs; s < sechdrs_end; s++) {
284  const char *secname = secstrs + s->sh_name;
285 
286  if (!(s->sh_flags & SHF_ALLOC))
287  continue;
288 
289  if (strcmp(".ARM.exidx.init.text", secname) == 0)
290  maps[ARM_SEC_INIT].unw_sec = s;
291  else if (strcmp(".ARM.exidx.devinit.text", secname) == 0)
292  maps[ARM_SEC_DEVINIT].unw_sec = s;
293  else if (strcmp(".ARM.exidx", secname) == 0)
294  maps[ARM_SEC_CORE].unw_sec = s;
295  else if (strcmp(".ARM.exidx.exit.text", secname) == 0)
296  maps[ARM_SEC_EXIT].unw_sec = s;
297  else if (strcmp(".ARM.exidx.devexit.text", secname) == 0)
298  maps[ARM_SEC_DEVEXIT].unw_sec = s;
299  else if (strcmp(".init.text", secname) == 0)
300  maps[ARM_SEC_INIT].txt_sec = s;
301  else if (strcmp(".devinit.text", secname) == 0)
302  maps[ARM_SEC_DEVINIT].txt_sec = s;
303  else if (strcmp(".text", secname) == 0)
304  maps[ARM_SEC_CORE].txt_sec = s;
305  else if (strcmp(".exit.text", secname) == 0)
306  maps[ARM_SEC_EXIT].txt_sec = s;
307  else if (strcmp(".devexit.text", secname) == 0)
308  maps[ARM_SEC_DEVEXIT].txt_sec = s;
309  }
310 
311  for (i = 0; i < ARM_SEC_MAX; i++)
312  if (maps[i].unw_sec && maps[i].txt_sec)
313  mod->arch.unwind[i] =
314  unwind_table_add(maps[i].unw_sec->sh_addr,
315  maps[i].unw_sec->sh_size,
316  maps[i].txt_sec->sh_addr,
317  maps[i].txt_sec->sh_size);
318 #endif
319 #ifdef CONFIG_ARM_PATCH_PHYS_VIRT
320  s = find_mod_section(hdr, sechdrs, ".pv_table");
321  if (s)
322  fixup_pv_table((void *)s->sh_addr, s->sh_size);
323 #endif
324  s = find_mod_section(hdr, sechdrs, ".alt.smp.init");
325  if (s && !is_smp())
326 #ifdef CONFIG_SMP_ON_UP
327  fixup_smp((void *)s->sh_addr, s->sh_size);
328 #else
329  return -EINVAL;
330 #endif
331  return 0;
332 }
333 
334 void
335 module_arch_cleanup(struct module *mod)
336 {
337 #ifdef CONFIG_ARM_UNWIND
338  int i;
339 
340  for (i = 0; i < ARM_SEC_MAX; i++)
341  if (mod->arch.unwind[i])
342  unwind_table_del(mod->arch.unwind[i]);
343 #endif
344 }
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