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/arch/alpha/kernel/module.c

https://bitbucket.org/evzijst/gittest
C | 311 lines | 242 code | 31 blank | 38 comment | 43 complexity | 3420be347909bd4fc62be7911f8ec647 MD5 | raw file
  1/*  Kernel module help for Alpha.
  2    Copyright (C) 2002 Richard Henderson.
  3
  4    This program is free software; you can redistribute it and/or modify
  5    it under the terms of the GNU General Public License as published by
  6    the Free Software Foundation; either version 2 of the License, or
  7    (at your option) any later version.
  8
  9    This program is distributed in the hope that it will be useful,
 10    but WITHOUT ANY WARRANTY; without even the implied warranty of
 11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 12    GNU General Public License for more details.
 13
 14    You should have received a copy of the GNU General Public License
 15    along with this program; if not, write to the Free Software
 16    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 17*/
 18#include <linux/moduleloader.h>
 19#include <linux/elf.h>
 20#include <linux/vmalloc.h>
 21#include <linux/fs.h>
 22#include <linux/string.h>
 23#include <linux/kernel.h>
 24#include <linux/slab.h>
 25
 26#if 0
 27#define DEBUGP printk
 28#else
 29#define DEBUGP(fmt...)
 30#endif
 31
 32void *
 33module_alloc(unsigned long size)
 34{
 35	if (size == 0)
 36		return NULL;
 37	return vmalloc(size);
 38}
 39
 40void
 41module_free(struct module *mod, void *module_region)
 42{
 43	vfree(module_region);
 44}
 45
 46/* Allocate the GOT at the end of the core sections.  */
 47
 48struct got_entry {
 49	struct got_entry *next;
 50	Elf64_Addr r_offset;
 51	int got_offset;
 52};
 53
 54static inline void
 55process_reloc_for_got(Elf64_Rela *rela,
 56		      struct got_entry *chains, Elf64_Xword *poffset)
 57{
 58	unsigned long r_sym = ELF64_R_SYM (rela->r_info);
 59	unsigned long r_type = ELF64_R_TYPE (rela->r_info);
 60	Elf64_Addr r_offset = rela->r_offset;
 61	struct got_entry *g;
 62
 63	if (r_type != R_ALPHA_LITERAL)
 64		return;
 65
 66	for (g = chains + r_sym; g ; g = g->next)
 67		if (g->r_offset == r_offset) {
 68			if (g->got_offset == 0) {
 69				g->got_offset = *poffset;
 70				*poffset += 8;
 71			}
 72			goto found_entry;
 73		}
 74
 75	g = kmalloc (sizeof (*g), GFP_KERNEL);
 76	g->next = chains[r_sym].next;
 77	g->r_offset = r_offset;
 78	g->got_offset = *poffset;
 79	*poffset += 8;
 80	chains[r_sym].next = g;
 81
 82 found_entry:
 83	/* Trick: most of the ELF64_R_TYPE field is unused.  There are
 84	   42 valid relocation types, and a 32-bit field.  Co-opt the
 85	   bits above 256 to store the got offset for this reloc.  */
 86	rela->r_info |= g->got_offset << 8;
 87}
 88
 89int
 90module_frob_arch_sections(Elf64_Ehdr *hdr, Elf64_Shdr *sechdrs,
 91			  char *secstrings, struct module *me)
 92{
 93	struct got_entry *chains;
 94	Elf64_Rela *rela;
 95	Elf64_Shdr *esechdrs, *symtab, *s, *got;
 96	unsigned long nsyms, nrela, i;
 97
 98	esechdrs = sechdrs + hdr->e_shnum;
 99	symtab = got = NULL;
100
101	/* Find out how large the symbol table is.  Allocate one got_entry
102	   head per symbol.  Normally this will be enough, but not always.
103	   We'll chain different offsets for the symbol down each head.  */
104	for (s = sechdrs; s < esechdrs; ++s)
105		if (s->sh_type == SHT_SYMTAB)
106			symtab = s;
107		else if (!strcmp(".got", secstrings + s->sh_name)) {
108			got = s;
109			me->arch.gotsecindex = s - sechdrs;
110		}
111
112	if (!symtab) {
113		printk(KERN_ERR "module %s: no symbol table\n", me->name);
114		return -ENOEXEC;
115	}
116	if (!got) {
117		printk(KERN_ERR "module %s: no got section\n", me->name);
118		return -ENOEXEC;
119	}
120
121	nsyms = symtab->sh_size / sizeof(Elf64_Sym);
122	chains = kmalloc(nsyms * sizeof(struct got_entry), GFP_KERNEL);
123	memset(chains, 0, nsyms * sizeof(struct got_entry));
124
125	got->sh_size = 0;
126	got->sh_addralign = 8;
127	got->sh_type = SHT_NOBITS;
128
129	/* Examine all LITERAL relocations to find out what GOT entries
130	   are required.  This sizes the GOT section as well.  */
131	for (s = sechdrs; s < esechdrs; ++s)
132		if (s->sh_type == SHT_RELA) {
133			nrela = s->sh_size / sizeof(Elf64_Rela);
134			rela = (void *)hdr + s->sh_offset;
135			for (i = 0; i < nrela; ++i)
136				process_reloc_for_got(rela+i, chains,
137						      &got->sh_size);
138		}
139
140	/* Free the memory we allocated.  */
141	for (i = 0; i < nsyms; ++i) {
142		struct got_entry *g, *n;
143		for (g = chains[i].next; g ; g = n) {
144			n = g->next;
145			kfree(g);
146		}
147	}
148	kfree(chains);
149
150	return 0;
151}
152
153int
154apply_relocate(Elf64_Shdr *sechdrs, const char *strtab, unsigned int symindex,
155	       unsigned int relsec, struct module *me)
156{
157	printk(KERN_ERR "module %s: REL relocation unsupported\n", me->name);
158	return -ENOEXEC;
159}
160
161int
162apply_relocate_add(Elf64_Shdr *sechdrs, const char *strtab,
163		   unsigned int symindex, unsigned int relsec,
164		   struct module *me)
165{
166	Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
167	unsigned long i, n = sechdrs[relsec].sh_size / sizeof(*rela);
168	Elf64_Sym *symtab, *sym;
169	void *base, *location;
170	unsigned long got, gp;
171
172	DEBUGP("Applying relocate section %u to %u\n", relsec,
173	       sechdrs[relsec].sh_info);
174
175	base = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr;
176	symtab = (Elf64_Sym *)sechdrs[symindex].sh_addr;
177
178	/* The small sections were sorted to the end of the segment.
179	   The following should definitely cover them.  */
180	gp = (u64)me->module_core + me->core_size - 0x8000;
181	got = sechdrs[me->arch.gotsecindex].sh_addr;
182
183	for (i = 0; i < n; i++) {
184		unsigned long r_sym = ELF64_R_SYM (rela[i].r_info);
185		unsigned long r_type = ELF64_R_TYPE (rela[i].r_info);
186		unsigned long r_got_offset = r_type >> 8;
187		unsigned long value, hi, lo;
188		r_type &= 0xff;
189
190		/* This is where to make the change.  */
191		location = base + rela[i].r_offset;
192
193		/* This is the symbol it is referring to.  Note that all
194		   unresolved symbols have been resolved.  */
195		sym = symtab + r_sym;
196		value = sym->st_value + rela[i].r_addend;
197
198		switch (r_type) {
199		case R_ALPHA_NONE:
200			break;
201		case R_ALPHA_REFQUAD:
202			/* BUG() can produce misaligned relocations. */
203			((u32 *)location)[0] = value;
204			((u32 *)location)[1] = value >> 32;
205			break;
206		case R_ALPHA_GPREL32:
207			value -= gp;
208			if ((int)value != value)
209				goto reloc_overflow;
210			*(u32 *)location = value;
211			break;
212		case R_ALPHA_LITERAL:
213			hi = got + r_got_offset;
214			lo = hi - gp;
215			if ((short)lo != lo)
216				goto reloc_overflow;
217			*(u16 *)location = lo;
218			*(u64 *)hi = value;
219			break;
220		case R_ALPHA_LITUSE:
221			break;
222		case R_ALPHA_GPDISP:
223			value = gp - (u64)location;
224			lo = (short)value;
225			hi = (int)(value - lo);
226			if (hi + lo != value)
227				goto reloc_overflow;
228			*(u16 *)location = hi >> 16;
229			*(u16 *)(location + rela[i].r_addend) = lo;
230			break;
231		case R_ALPHA_BRSGP:
232			/* BRSGP is only allowed to bind to local symbols.
233			   If the section is undef, this means that the
234			   value was resolved from somewhere else.  */
235			if (sym->st_shndx == SHN_UNDEF)
236				goto reloc_overflow;
237			if ((sym->st_other & STO_ALPHA_STD_GPLOAD) ==
238			    STO_ALPHA_STD_GPLOAD)
239				/* Omit the prologue. */
240				value += 8;
241			/* FALLTHRU */
242		case R_ALPHA_BRADDR:
243			value -= (u64)location + 4;
244			if (value & 3)
245				goto reloc_overflow;
246			value = (long)value >> 2;
247			if (value + (1<<21) >= 1<<22)
248				goto reloc_overflow;
249			value &= 0x1fffff;
250			value |= *(u32 *)location & ~0x1fffff;
251			*(u32 *)location = value;
252			break;
253		case R_ALPHA_HINT:
254			break;
255		case R_ALPHA_SREL32:
256			value -= (u64)location;
257			if ((int)value != value)
258				goto reloc_overflow;
259			*(u32 *)location = value;
260			break;
261		case R_ALPHA_SREL64:
262			value -= (u64)location;
263			*(u64 *)location = value;
264			break;
265		case R_ALPHA_GPRELHIGH:
266			value = (long)(value - gp + 0x8000) >> 16;
267			if ((short) value != value)
268				goto reloc_overflow;
269			*(u16 *)location = value;
270			break;
271		case R_ALPHA_GPRELLOW:
272			value -= gp;
273			*(u16 *)location = value;
274			break;
275		case R_ALPHA_GPREL16:
276			value -= gp;
277			if ((short) value != value)
278				goto reloc_overflow;
279			*(u16 *)location = value;
280			break;
281		default:
282			printk(KERN_ERR "module %s: Unknown relocation: %lu\n",
283			       me->name, r_type);
284			return -ENOEXEC;
285		reloc_overflow:
286			if (ELF64_ST_TYPE (sym->st_info) == STT_SECTION)
287			  printk(KERN_ERR
288			         "module %s: Relocation overflow vs section %d\n",
289			         me->name, sym->st_shndx);
290			else
291			  printk(KERN_ERR
292			         "module %s: Relocation overflow vs %s\n",
293			         me->name, strtab + sym->st_name);
294			return -ENOEXEC;
295		}
296	}
297
298	return 0;
299}
300
301int
302module_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
303		struct module *me)
304{
305	return 0;
306}
307
308void
309module_arch_cleanup(struct module *mod)
310{
311}