Root/arch/s390/kernel/module.c

1/*
2 * arch/s390/kernel/module.c - Kernel module help for s390.
3 *
4 * S390 version
5 * Copyright (C) 2002, 2003 IBM Deutschland Entwicklung GmbH,
6 * IBM Corporation
7 * Author(s): Arnd Bergmann (arndb@de.ibm.com)
8 * Martin Schwidefsky (schwidefsky@de.ibm.com)
9 *
10 * based on i386 version
11 * Copyright (C) 2001 Rusty Russell.
12 *
13 * This program is free software; you can redistribute it and/or modify
14 * it under the terms of the GNU General Public License as published by
15 * the Free Software Foundation; either version 2 of the License, or
16 * (at your option) any later version.
17 *
18 * This program is distributed in the hope that it will be useful,
19 * but WITHOUT ANY WARRANTY; without even the implied warranty of
20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21 * GNU General Public License for more details.
22 *
23 * You should have received a copy of the GNU General Public License
24 * along with this program; if not, write to the Free Software
25 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
26 */
27#include <linux/module.h>
28#include <linux/elf.h>
29#include <linux/vmalloc.h>
30#include <linux/fs.h>
31#include <linux/string.h>
32#include <linux/kernel.h>
33#include <linux/moduleloader.h>
34#include <linux/bug.h>
35
36#if 0
37#define DEBUGP printk
38#else
39#define DEBUGP(fmt , ...)
40#endif
41
42#ifndef CONFIG_64BIT
43#define PLT_ENTRY_SIZE 12
44#else /* CONFIG_64BIT */
45#define PLT_ENTRY_SIZE 20
46#endif /* CONFIG_64BIT */
47
48void *module_alloc(unsigned long size)
49{
50    if (size == 0)
51        return NULL;
52    return vmalloc(size);
53}
54
55/* Free memory returned from module_alloc */
56void module_free(struct module *mod, void *module_region)
57{
58    if (mod) {
59        vfree(mod->arch.syminfo);
60        mod->arch.syminfo = NULL;
61    }
62    vfree(module_region);
63}
64
65static void
66check_rela(Elf_Rela *rela, struct module *me)
67{
68    struct mod_arch_syminfo *info;
69
70    info = me->arch.syminfo + ELF_R_SYM (rela->r_info);
71    switch (ELF_R_TYPE (rela->r_info)) {
72    case R_390_GOT12: /* 12 bit GOT offset. */
73    case R_390_GOT16: /* 16 bit GOT offset. */
74    case R_390_GOT20: /* 20 bit GOT offset. */
75    case R_390_GOT32: /* 32 bit GOT offset. */
76    case R_390_GOT64: /* 64 bit GOT offset. */
77    case R_390_GOTENT: /* 32 bit PC rel. to GOT entry shifted by 1. */
78    case R_390_GOTPLT12: /* 12 bit offset to jump slot. */
79    case R_390_GOTPLT16: /* 16 bit offset to jump slot. */
80    case R_390_GOTPLT20: /* 20 bit offset to jump slot. */
81    case R_390_GOTPLT32: /* 32 bit offset to jump slot. */
82    case R_390_GOTPLT64: /* 64 bit offset to jump slot. */
83    case R_390_GOTPLTENT: /* 32 bit rel. offset to jump slot >> 1. */
84        if (info->got_offset == -1UL) {
85            info->got_offset = me->arch.got_size;
86            me->arch.got_size += sizeof(void*);
87        }
88        break;
89    case R_390_PLT16DBL: /* 16 bit PC rel. PLT shifted by 1. */
90    case R_390_PLT32DBL: /* 32 bit PC rel. PLT shifted by 1. */
91    case R_390_PLT32: /* 32 bit PC relative PLT address. */
92    case R_390_PLT64: /* 64 bit PC relative PLT address. */
93    case R_390_PLTOFF16: /* 16 bit offset from GOT to PLT. */
94    case R_390_PLTOFF32: /* 32 bit offset from GOT to PLT. */
95    case R_390_PLTOFF64: /* 16 bit offset from GOT to PLT. */
96        if (info->plt_offset == -1UL) {
97            info->plt_offset = me->arch.plt_size;
98            me->arch.plt_size += PLT_ENTRY_SIZE;
99        }
100        break;
101    case R_390_COPY:
102    case R_390_GLOB_DAT:
103    case R_390_JMP_SLOT:
104    case R_390_RELATIVE:
105        /* Only needed if we want to support loading of
106           modules linked with -shared. */
107        break;
108    }
109}
110
111/*
112 * Account for GOT and PLT relocations. We can't add sections for
113 * got and plt but we can increase the core module size.
114 */
115int
116module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
117              char *secstrings, struct module *me)
118{
119    Elf_Shdr *symtab;
120    Elf_Sym *symbols;
121    Elf_Rela *rela;
122    char *strings;
123    int nrela, i, j;
124
125    /* Find symbol table and string table. */
126    symtab = NULL;
127    for (i = 0; i < hdr->e_shnum; i++)
128        switch (sechdrs[i].sh_type) {
129        case SHT_SYMTAB:
130            symtab = sechdrs + i;
131            break;
132        }
133    if (!symtab) {
134        printk(KERN_ERR "module %s: no symbol table\n", me->name);
135        return -ENOEXEC;
136    }
137
138    /* Allocate one syminfo structure per symbol. */
139    me->arch.nsyms = symtab->sh_size / sizeof(Elf_Sym);
140    me->arch.syminfo = vmalloc(me->arch.nsyms *
141                   sizeof(struct mod_arch_syminfo));
142    if (!me->arch.syminfo)
143        return -ENOMEM;
144    symbols = (void *) hdr + symtab->sh_offset;
145    strings = (void *) hdr + sechdrs[symtab->sh_link].sh_offset;
146    for (i = 0; i < me->arch.nsyms; i++) {
147        if (symbols[i].st_shndx == SHN_UNDEF &&
148            strcmp(strings + symbols[i].st_name,
149               "_GLOBAL_OFFSET_TABLE_") == 0)
150            /* "Define" it as absolute. */
151            symbols[i].st_shndx = SHN_ABS;
152        me->arch.syminfo[i].got_offset = -1UL;
153        me->arch.syminfo[i].plt_offset = -1UL;
154        me->arch.syminfo[i].got_initialized = 0;
155        me->arch.syminfo[i].plt_initialized = 0;
156    }
157
158    /* Search for got/plt relocations. */
159    me->arch.got_size = me->arch.plt_size = 0;
160    for (i = 0; i < hdr->e_shnum; i++) {
161        if (sechdrs[i].sh_type != SHT_RELA)
162            continue;
163        nrela = sechdrs[i].sh_size / sizeof(Elf_Rela);
164        rela = (void *) hdr + sechdrs[i].sh_offset;
165        for (j = 0; j < nrela; j++)
166            check_rela(rela + j, me);
167    }
168
169    /* Increase core size by size of got & plt and set start
170       offsets for got and plt. */
171    me->core_size = ALIGN(me->core_size, 4);
172    me->arch.got_offset = me->core_size;
173    me->core_size += me->arch.got_size;
174    me->arch.plt_offset = me->core_size;
175    me->core_size += me->arch.plt_size;
176    return 0;
177}
178
179int
180apply_relocate(Elf_Shdr *sechdrs, const char *strtab, unsigned int symindex,
181           unsigned int relsec, struct module *me)
182{
183    printk(KERN_ERR "module %s: RELOCATION unsupported\n",
184           me->name);
185    return -ENOEXEC;
186}
187
188static int
189apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
190       struct module *me)
191{
192    struct mod_arch_syminfo *info;
193    Elf_Addr loc, val;
194    int r_type, r_sym;
195
196    /* This is where to make the change */
197    loc = base + rela->r_offset;
198    /* This is the symbol it is referring to. Note that all
199       undefined symbols have been resolved. */
200    r_sym = ELF_R_SYM(rela->r_info);
201    r_type = ELF_R_TYPE(rela->r_info);
202    info = me->arch.syminfo + r_sym;
203    val = symtab[r_sym].st_value;
204
205    switch (r_type) {
206    case R_390_8: /* Direct 8 bit. */
207    case R_390_12: /* Direct 12 bit. */
208    case R_390_16: /* Direct 16 bit. */
209    case R_390_20: /* Direct 20 bit. */
210    case R_390_32: /* Direct 32 bit. */
211    case R_390_64: /* Direct 64 bit. */
212        val += rela->r_addend;
213        if (r_type == R_390_8)
214            *(unsigned char *) loc = val;
215        else if (r_type == R_390_12)
216            *(unsigned short *) loc = (val & 0xfff) |
217                (*(unsigned short *) loc & 0xf000);
218        else if (r_type == R_390_16)
219            *(unsigned short *) loc = val;
220        else if (r_type == R_390_20)
221            *(unsigned int *) loc =
222                (*(unsigned int *) loc & 0xf00000ff) |
223                (val & 0xfff) << 16 | (val & 0xff000) >> 4;
224        else if (r_type == R_390_32)
225            *(unsigned int *) loc = val;
226        else if (r_type == R_390_64)
227            *(unsigned long *) loc = val;
228        break;
229    case R_390_PC16: /* PC relative 16 bit. */
230    case R_390_PC16DBL: /* PC relative 16 bit shifted by 1. */
231    case R_390_PC32DBL: /* PC relative 32 bit shifted by 1. */
232    case R_390_PC32: /* PC relative 32 bit. */
233    case R_390_PC64: /* PC relative 64 bit. */
234        val += rela->r_addend - loc;
235        if (r_type == R_390_PC16)
236            *(unsigned short *) loc = val;
237        else if (r_type == R_390_PC16DBL)
238            *(unsigned short *) loc = val >> 1;
239        else if (r_type == R_390_PC32DBL)
240            *(unsigned int *) loc = val >> 1;
241        else if (r_type == R_390_PC32)
242            *(unsigned int *) loc = val;
243        else if (r_type == R_390_PC64)
244            *(unsigned long *) loc = val;
245        break;
246    case R_390_GOT12: /* 12 bit GOT offset. */
247    case R_390_GOT16: /* 16 bit GOT offset. */
248    case R_390_GOT20: /* 20 bit GOT offset. */
249    case R_390_GOT32: /* 32 bit GOT offset. */
250    case R_390_GOT64: /* 64 bit GOT offset. */
251    case R_390_GOTENT: /* 32 bit PC rel. to GOT entry shifted by 1. */
252    case R_390_GOTPLT12: /* 12 bit offset to jump slot. */
253    case R_390_GOTPLT20: /* 20 bit offset to jump slot. */
254    case R_390_GOTPLT16: /* 16 bit offset to jump slot. */
255    case R_390_GOTPLT32: /* 32 bit offset to jump slot. */
256    case R_390_GOTPLT64: /* 64 bit offset to jump slot. */
257    case R_390_GOTPLTENT: /* 32 bit rel. offset to jump slot >> 1. */
258        if (info->got_initialized == 0) {
259            Elf_Addr *gotent;
260
261            gotent = me->module_core + me->arch.got_offset +
262                info->got_offset;
263            *gotent = val;
264            info->got_initialized = 1;
265        }
266        val = info->got_offset + rela->r_addend;
267        if (r_type == R_390_GOT12 ||
268            r_type == R_390_GOTPLT12)
269            *(unsigned short *) loc = (val & 0xfff) |
270                (*(unsigned short *) loc & 0xf000);
271        else if (r_type == R_390_GOT16 ||
272             r_type == R_390_GOTPLT16)
273            *(unsigned short *) loc = val;
274        else if (r_type == R_390_GOT20 ||
275             r_type == R_390_GOTPLT20)
276            *(unsigned int *) loc =
277                (*(unsigned int *) loc & 0xf00000ff) |
278                (val & 0xfff) << 16 | (val & 0xff000) >> 4;
279        else if (r_type == R_390_GOT32 ||
280             r_type == R_390_GOTPLT32)
281            *(unsigned int *) loc = val;
282        else if (r_type == R_390_GOTENT ||
283             r_type == R_390_GOTPLTENT)
284            *(unsigned int *) loc =
285                (val + (Elf_Addr) me->module_core - loc) >> 1;
286        else if (r_type == R_390_GOT64 ||
287             r_type == R_390_GOTPLT64)
288            *(unsigned long *) loc = val;
289        break;
290    case R_390_PLT16DBL: /* 16 bit PC rel. PLT shifted by 1. */
291    case R_390_PLT32DBL: /* 32 bit PC rel. PLT shifted by 1. */
292    case R_390_PLT32: /* 32 bit PC relative PLT address. */
293    case R_390_PLT64: /* 64 bit PC relative PLT address. */
294    case R_390_PLTOFF16: /* 16 bit offset from GOT to PLT. */
295    case R_390_PLTOFF32: /* 32 bit offset from GOT to PLT. */
296    case R_390_PLTOFF64: /* 16 bit offset from GOT to PLT. */
297        if (info->plt_initialized == 0) {
298            unsigned int *ip;
299            ip = me->module_core + me->arch.plt_offset +
300                info->plt_offset;
301#ifndef CONFIG_64BIT
302            ip[0] = 0x0d105810; /* basr 1,0; l 1,6(1); br 1 */
303            ip[1] = 0x100607f1;
304            ip[2] = val;
305#else /* CONFIG_64BIT */
306            ip[0] = 0x0d10e310; /* basr 1,0; lg 1,10(1); br 1 */
307            ip[1] = 0x100a0004;
308            ip[2] = 0x07f10000;
309            ip[3] = (unsigned int) (val >> 32);
310            ip[4] = (unsigned int) val;
311#endif /* CONFIG_64BIT */
312            info->plt_initialized = 1;
313        }
314        if (r_type == R_390_PLTOFF16 ||
315            r_type == R_390_PLTOFF32 ||
316            r_type == R_390_PLTOFF64)
317            val = me->arch.plt_offset - me->arch.got_offset +
318                info->plt_offset + rela->r_addend;
319        else {
320            if (!((r_type == R_390_PLT16DBL &&
321                   val - loc + 0xffffUL < 0x1ffffeUL) ||
322                  (r_type == R_390_PLT32DBL &&
323                   val - loc + 0xffffffffULL < 0x1fffffffeULL)))
324                val = (Elf_Addr) me->module_core +
325                    me->arch.plt_offset +
326                    info->plt_offset;
327            val += rela->r_addend - loc;
328        }
329        if (r_type == R_390_PLT16DBL)
330            *(unsigned short *) loc = val >> 1;
331        else if (r_type == R_390_PLTOFF16)
332            *(unsigned short *) loc = val;
333        else if (r_type == R_390_PLT32DBL)
334            *(unsigned int *) loc = val >> 1;
335        else if (r_type == R_390_PLT32 ||
336             r_type == R_390_PLTOFF32)
337            *(unsigned int *) loc = val;
338        else if (r_type == R_390_PLT64 ||
339             r_type == R_390_PLTOFF64)
340            *(unsigned long *) loc = val;
341        break;
342    case R_390_GOTOFF16: /* 16 bit offset to GOT. */
343    case R_390_GOTOFF32: /* 32 bit offset to GOT. */
344    case R_390_GOTOFF64: /* 64 bit offset to GOT. */
345        val = val + rela->r_addend -
346            ((Elf_Addr) me->module_core + me->arch.got_offset);
347        if (r_type == R_390_GOTOFF16)
348            *(unsigned short *) loc = val;
349        else if (r_type == R_390_GOTOFF32)
350            *(unsigned int *) loc = val;
351        else if (r_type == R_390_GOTOFF64)
352            *(unsigned long *) loc = val;
353        break;
354    case R_390_GOTPC: /* 32 bit PC relative offset to GOT. */
355    case R_390_GOTPCDBL: /* 32 bit PC rel. off. to GOT shifted by 1. */
356        val = (Elf_Addr) me->module_core + me->arch.got_offset +
357            rela->r_addend - loc;
358        if (r_type == R_390_GOTPC)
359            *(unsigned int *) loc = val;
360        else if (r_type == R_390_GOTPCDBL)
361            *(unsigned int *) loc = val >> 1;
362        break;
363    case R_390_COPY:
364    case R_390_GLOB_DAT: /* Create GOT entry. */
365    case R_390_JMP_SLOT: /* Create PLT entry. */
366    case R_390_RELATIVE: /* Adjust by program base. */
367        /* Only needed if we want to support loading of
368           modules linked with -shared. */
369        break;
370    default:
371        printk(KERN_ERR "module %s: Unknown relocation: %u\n",
372               me->name, r_type);
373        return -ENOEXEC;
374    }
375    return 0;
376}
377
378int
379apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
380           unsigned int symindex, unsigned int relsec,
381           struct module *me)
382{
383    Elf_Addr base;
384    Elf_Sym *symtab;
385    Elf_Rela *rela;
386    unsigned long i, n;
387    int rc;
388
389    DEBUGP("Applying relocate section %u to %u\n",
390           relsec, sechdrs[relsec].sh_info);
391    base = sechdrs[sechdrs[relsec].sh_info].sh_addr;
392    symtab = (Elf_Sym *) sechdrs[symindex].sh_addr;
393    rela = (Elf_Rela *) sechdrs[relsec].sh_addr;
394    n = sechdrs[relsec].sh_size / sizeof(Elf_Rela);
395
396    for (i = 0; i < n; i++, rela++) {
397        rc = apply_rela(rela, base, symtab, me);
398        if (rc)
399            return rc;
400    }
401    return 0;
402}
403
404int module_finalize(const Elf_Ehdr *hdr,
405            const Elf_Shdr *sechdrs,
406            struct module *me)
407{
408    vfree(me->arch.syminfo);
409    me->arch.syminfo = NULL;
410    return 0;
411}
412
413void module_arch_cleanup(struct module *mod)
414{
415}
416

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