1 /* Kernel module help for PPC.
2 Copyright (C) 2001 Rusty Russell.
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.
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.
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
18 #include <linux/module.h>
19 #include <linux/moduleloader.h>
20 #include <linux/elf.h>
21 #include <linux/vmalloc.h>
23 #include <linux/string.h>
24 #include <linux/kernel.h>
25 #include <linux/cache.h>
26 #include <linux/bug.h>
27 #include <linux/sort.h>
34 #define DEBUGP(fmt , ...)
37 /* Count how many different relocations (different symbol, different
39 static unsigned int count_relocs(const Elf32_Rela
*rela
, unsigned int num
)
41 unsigned int i
, r_info
, r_addend
, _count_relocs
;
46 for (i
= 0; i
< num
; i
++)
47 /* Only count 24-bit relocs, others don't need stubs */
48 if (ELF32_R_TYPE(rela
[i
].r_info
) == R_PPC_REL24
&&
49 (r_info
!= ELF32_R_SYM(rela
[i
].r_info
) ||
50 r_addend
!= rela
[i
].r_addend
)) {
52 r_info
= ELF32_R_SYM(rela
[i
].r_info
);
53 r_addend
= rela
[i
].r_addend
;
59 static int relacmp(const void *_x
, const void *_y
)
61 const Elf32_Rela
*x
, *y
;
66 /* Compare the entire r_info (as opposed to ELF32_R_SYM(r_info) only) to
67 * make the comparison cheaper/faster. It won't affect the sorting or
68 * the counting algorithms' performance
70 if (x
->r_info
< y
->r_info
)
72 else if (x
->r_info
> y
->r_info
)
74 else if (x
->r_addend
< y
->r_addend
)
76 else if (x
->r_addend
> y
->r_addend
)
82 static void relaswap(void *_x
, void *_y
, int size
)
90 for (i
= 0; i
< sizeof(Elf32_Rela
) / sizeof(uint32_t); i
++) {
97 /* Get the potential trampolines size required of the init and
99 static unsigned long get_plt_size(const Elf32_Ehdr
*hdr
,
100 const Elf32_Shdr
*sechdrs
,
101 const char *secstrings
,
104 unsigned long ret
= 0;
107 /* Everything marked ALLOC (this includes the exported
109 for (i
= 1; i
< hdr
->e_shnum
; i
++) {
110 /* If it's called *.init*, and we're not init, we're
112 if ((strstr(secstrings
+ sechdrs
[i
].sh_name
, ".init") != 0)
116 /* We don't want to look at debug sections. */
117 if (strstr(secstrings
+ sechdrs
[i
].sh_name
, ".debug") != 0)
120 if (sechdrs
[i
].sh_type
== SHT_RELA
) {
121 DEBUGP("Found relocations in section %u\n", i
);
122 DEBUGP("Ptr: %p. Number: %u\n",
123 (void *)hdr
+ sechdrs
[i
].sh_offset
,
124 sechdrs
[i
].sh_size
/ sizeof(Elf32_Rela
));
126 /* Sort the relocation information based on a symbol and
127 * addend key. This is a stable O(n*log n) complexity
128 * alogrithm but it will reduce the complexity of
129 * count_relocs() to linear complexity O(n)
131 sort((void *)hdr
+ sechdrs
[i
].sh_offset
,
132 sechdrs
[i
].sh_size
/ sizeof(Elf32_Rela
),
133 sizeof(Elf32_Rela
), relacmp
, relaswap
);
135 ret
+= count_relocs((void *)hdr
136 + sechdrs
[i
].sh_offset
,
138 / sizeof(Elf32_Rela
))
139 * sizeof(struct ppc_plt_entry
);
146 int module_frob_arch_sections(Elf32_Ehdr
*hdr
,
153 /* Find .plt and .init.plt sections */
154 for (i
= 0; i
< hdr
->e_shnum
; i
++) {
155 if (strcmp(secstrings
+ sechdrs
[i
].sh_name
, ".init.plt") == 0)
156 me
->arch
.init_plt_section
= i
;
157 else if (strcmp(secstrings
+ sechdrs
[i
].sh_name
, ".plt") == 0)
158 me
->arch
.core_plt_section
= i
;
160 if (!me
->arch
.core_plt_section
|| !me
->arch
.init_plt_section
) {
161 printk("Module doesn't contain .plt or .init.plt sections.\n");
165 /* Override their sizes */
166 sechdrs
[me
->arch
.core_plt_section
].sh_size
167 = get_plt_size(hdr
, sechdrs
, secstrings
, 0);
168 sechdrs
[me
->arch
.init_plt_section
].sh_size
169 = get_plt_size(hdr
, sechdrs
, secstrings
, 1);
173 int apply_relocate(Elf32_Shdr
*sechdrs
,
175 unsigned int symindex
,
177 struct module
*module
)
179 printk(KERN_ERR
"%s: Non-ADD RELOCATION unsupported\n",
184 static inline int entry_matches(struct ppc_plt_entry
*entry
, Elf32_Addr val
)
186 if (entry
->jump
[0] == 0x3d600000 + ((val
+ 0x8000) >> 16)
187 && entry
->jump
[1] == 0x396b0000 + (val
& 0xffff))
192 /* Set up a trampoline in the PLT to bounce us to the distant function */
193 static uint32_t do_plt_call(void *location
,
198 struct ppc_plt_entry
*entry
;
200 DEBUGP("Doing plt for call to 0x%x at 0x%x\n", val
, (unsigned int)location
);
201 /* Init, or core PLT? */
202 if (location
>= mod
->module_core
203 && location
< mod
->module_core
+ mod
->core_size
)
204 entry
= (void *)sechdrs
[mod
->arch
.core_plt_section
].sh_addr
;
206 entry
= (void *)sechdrs
[mod
->arch
.init_plt_section
].sh_addr
;
208 /* Find this entry, or if that fails, the next avail. entry */
209 while (entry
->jump
[0]) {
210 if (entry_matches(entry
, val
)) return (uint32_t)entry
;
214 /* Stolen from Paul Mackerras as well... */
215 entry
->jump
[0] = 0x3d600000+((val
+0x8000)>>16); /* lis r11,sym@ha */
216 entry
->jump
[1] = 0x396b0000 + (val
&0xffff); /* addi r11,r11,sym@l*/
217 entry
->jump
[2] = 0x7d6903a6; /* mtctr r11 */
218 entry
->jump
[3] = 0x4e800420; /* bctr */
220 DEBUGP("Initialized plt for 0x%x at %p\n", val
, entry
);
221 return (uint32_t)entry
;
224 int apply_relocate_add(Elf32_Shdr
*sechdrs
,
226 unsigned int symindex
,
228 struct module
*module
)
231 Elf32_Rela
*rela
= (void *)sechdrs
[relsec
].sh_addr
;
236 DEBUGP("Applying ADD relocate section %u to %u\n", relsec
,
237 sechdrs
[relsec
].sh_info
);
238 for (i
= 0; i
< sechdrs
[relsec
].sh_size
/ sizeof(*rela
); i
++) {
239 /* This is where to make the change */
240 location
= (void *)sechdrs
[sechdrs
[relsec
].sh_info
].sh_addr
242 /* This is the symbol it is referring to. Note that all
243 undefined symbols have been resolved. */
244 sym
= (Elf32_Sym
*)sechdrs
[symindex
].sh_addr
245 + ELF32_R_SYM(rela
[i
].r_info
);
246 /* `Everything is relative'. */
247 value
= sym
->st_value
+ rela
[i
].r_addend
;
249 switch (ELF32_R_TYPE(rela
[i
].r_info
)) {
252 *(uint32_t *)location
= value
;
255 case R_PPC_ADDR16_LO
:
256 /* Low half of the symbol */
257 *(uint16_t *)location
= value
;
260 case R_PPC_ADDR16_HI
:
261 /* Higher half of the symbol */
262 *(uint16_t *)location
= (value
>> 16);
265 case R_PPC_ADDR16_HA
:
266 /* Sign-adjusted lower 16 bits: PPC ELF ABI says:
267 (((x >> 16) + ((x & 0x8000) ? 1 : 0))) & 0xFFFF.
268 This is the same, only sane.
270 *(uint16_t *)location
= (value
+ 0x8000) >> 16;
274 if ((int)(value
- (uint32_t)location
) < -0x02000000
275 || (int)(value
- (uint32_t)location
) >= 0x02000000)
276 value
= do_plt_call(location
, value
,
279 /* Only replace bits 2 through 26 */
280 DEBUGP("REL24 value = %08X. location = %08X\n",
281 value
, (uint32_t)location
);
282 DEBUGP("Location before: %08X.\n",
283 *(uint32_t *)location
);
284 *(uint32_t *)location
285 = (*(uint32_t *)location
& ~0x03fffffc)
286 | ((value
- (uint32_t)location
)
288 DEBUGP("Location after: %08X.\n",
289 *(uint32_t *)location
);
290 DEBUGP("ie. jump to %08X+%08X = %08X\n",
291 *(uint32_t *)location
& 0x03fffffc,
293 (*(uint32_t *)location
& 0x03fffffc)
294 + (uint32_t)location
);
298 /* 32-bit relative jump. */
299 *(uint32_t *)location
= value
- (uint32_t)location
;
303 printk("%s: unknown ADD relocation: %u\n",
305 ELF32_R_TYPE(rela
[i
].r_info
));
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