diff options
Diffstat (limited to 'arch/ppc/kernel/module.c')
| -rw-r--r-- | arch/ppc/kernel/module.c | 320 |
1 files changed, 320 insertions, 0 deletions
diff --git a/arch/ppc/kernel/module.c b/arch/ppc/kernel/module.c new file mode 100644 index 000000000000..92f4e5f64f02 --- /dev/null +++ b/arch/ppc/kernel/module.c @@ -0,0 +1,320 @@ +/* Kernel module help for PPC. + Copyright (C) 2001 Rusty Russell. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA +*/ +#include <linux/module.h> +#include <linux/moduleloader.h> +#include <linux/elf.h> +#include <linux/vmalloc.h> +#include <linux/fs.h> +#include <linux/string.h> +#include <linux/kernel.h> +#include <linux/cache.h> + +#if 0 +#define DEBUGP printk +#else +#define DEBUGP(fmt , ...) +#endif + +LIST_HEAD(module_bug_list); + +void *module_alloc(unsigned long size) +{ + if (size == 0) + return NULL; + return vmalloc(size); +} + +/* Free memory returned from module_alloc */ +void module_free(struct module *mod, void *module_region) +{ + vfree(module_region); + /* FIXME: If module_region == mod->init_region, trim exception + table entries. */ +} + +/* Count how many different relocations (different symbol, different + addend) */ +static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num) +{ + unsigned int i, j, ret = 0; + + /* Sure, this is order(n^2), but it's usually short, and not + time critical */ + for (i = 0; i < num; i++) { + for (j = 0; j < i; j++) { + /* If this addend appeared before, it's + already been counted */ + if (ELF32_R_SYM(rela[i].r_info) + == ELF32_R_SYM(rela[j].r_info) + && rela[i].r_addend == rela[j].r_addend) + break; + } + if (j == i) ret++; + } + return ret; +} + +/* Get the potential trampolines size required of the init and + non-init sections */ +static unsigned long get_plt_size(const Elf32_Ehdr *hdr, + const Elf32_Shdr *sechdrs, + const char *secstrings, + int is_init) +{ + unsigned long ret = 0; + unsigned i; + + /* Everything marked ALLOC (this includes the exported + symbols) */ + for (i = 1; i < hdr->e_shnum; i++) { + /* If it's called *.init*, and we're not init, we're + not interested */ + if ((strstr(secstrings + sechdrs[i].sh_name, ".init") != 0) + != is_init) + continue; + + /* We don't want to look at debug sections. */ + if (strstr(secstrings + sechdrs[i].sh_name, ".debug") != 0) + continue; + + if (sechdrs[i].sh_type == SHT_RELA) { + DEBUGP("Found relocations in section %u\n", i); + DEBUGP("Ptr: %p. Number: %u\n", + (void *)hdr + sechdrs[i].sh_offset, + sechdrs[i].sh_size / sizeof(Elf32_Rela)); + ret += count_relocs((void *)hdr + + sechdrs[i].sh_offset, + sechdrs[i].sh_size + / sizeof(Elf32_Rela)) + * sizeof(struct ppc_plt_entry); + } + } + + return ret; +} + +int module_frob_arch_sections(Elf32_Ehdr *hdr, + Elf32_Shdr *sechdrs, + char *secstrings, + struct module *me) +{ + unsigned int i; + + /* Find .plt and .init.plt sections */ + for (i = 0; i < hdr->e_shnum; i++) { + if (strcmp(secstrings + sechdrs[i].sh_name, ".init.plt") == 0) + me->arch.init_plt_section = i; + else if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0) + me->arch.core_plt_section = i; + } + if (!me->arch.core_plt_section || !me->arch.init_plt_section) { + printk("Module doesn't contain .plt or .init.plt sections.\n"); + return -ENOEXEC; + } + + /* Override their sizes */ + sechdrs[me->arch.core_plt_section].sh_size + = get_plt_size(hdr, sechdrs, secstrings, 0); + sechdrs[me->arch.init_plt_section].sh_size + = get_plt_size(hdr, sechdrs, secstrings, 1); + return 0; +} + +int apply_relocate(Elf32_Shdr *sechdrs, + const char *strtab, + unsigned int symindex, + unsigned int relsec, + struct module *module) +{ + printk(KERN_ERR "%s: Non-ADD RELOCATION unsupported\n", + module->name); + return -ENOEXEC; +} + +static inline int entry_matches(struct ppc_plt_entry *entry, Elf32_Addr val) +{ + if (entry->jump[0] == 0x3d600000 + ((val + 0x8000) >> 16) + && entry->jump[1] == 0x396b0000 + (val & 0xffff)) + return 1; + return 0; +} + +/* Set up a trampoline in the PLT to bounce us to the distant function */ +static uint32_t do_plt_call(void *location, + Elf32_Addr val, + Elf32_Shdr *sechdrs, + struct module *mod) +{ + struct ppc_plt_entry *entry; + + DEBUGP("Doing plt for call to 0x%x at 0x%x\n", val, (unsigned int)location); + /* Init, or core PLT? */ + if (location >= mod->module_core + && location < mod->module_core + mod->core_size) + entry = (void *)sechdrs[mod->arch.core_plt_section].sh_addr; + else + entry = (void *)sechdrs[mod->arch.init_plt_section].sh_addr; + + /* Find this entry, or if that fails, the next avail. entry */ + while (entry->jump[0]) { + if (entry_matches(entry, val)) return (uint32_t)entry; + entry++; + } + + /* Stolen from Paul Mackerras as well... */ + entry->jump[0] = 0x3d600000+((val+0x8000)>>16); /* lis r11,sym@ha */ + entry->jump[1] = 0x396b0000 + (val&0xffff); /* addi r11,r11,sym@l*/ + entry->jump[2] = 0x7d6903a6; /* mtctr r11 */ + entry->jump[3] = 0x4e800420; /* bctr */ + + DEBUGP("Initialized plt for 0x%x at %p\n", val, entry); + return (uint32_t)entry; +} + +int apply_relocate_add(Elf32_Shdr *sechdrs, + const char *strtab, + unsigned int symindex, + unsigned int relsec, + struct module *module) +{ + unsigned int i; + Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr; + Elf32_Sym *sym; + uint32_t *location; + uint32_t value; + + DEBUGP("Applying ADD relocate section %u to %u\n", relsec, + sechdrs[relsec].sh_info); + for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) { + /* This is where to make the change */ + location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr + + rela[i].r_offset; + /* This is the symbol it is referring to. Note that all + undefined symbols have been resolved. */ + sym = (Elf32_Sym *)sechdrs[symindex].sh_addr + + ELF32_R_SYM(rela[i].r_info); + /* `Everything is relative'. */ + value = sym->st_value + rela[i].r_addend; + + switch (ELF32_R_TYPE(rela[i].r_info)) { + case R_PPC_ADDR32: + /* Simply set it */ + *(uint32_t *)location = value; + break; + + case R_PPC_ADDR16_LO: + /* Low half of the symbol */ + *(uint16_t *)location = value; + break; + + case R_PPC_ADDR16_HA: + /* Sign-adjusted lower 16 bits: PPC ELF ABI says: + (((x >> 16) + ((x & 0x8000) ? 1 : 0))) & 0xFFFF. + This is the same, only sane. + */ + *(uint16_t *)location = (value + 0x8000) >> 16; + break; + + case R_PPC_REL24: + if ((int)(value - (uint32_t)location) < -0x02000000 + || (int)(value - (uint32_t)location) >= 0x02000000) + value = do_plt_call(location, value, + sechdrs, module); + + /* Only replace bits 2 through 26 */ + DEBUGP("REL24 value = %08X. location = %08X\n", + value, (uint32_t)location); + DEBUGP("Location before: %08X.\n", + *(uint32_t *)location); + *(uint32_t *)location + = (*(uint32_t *)location & ~0x03fffffc) + | ((value - (uint32_t)location) + & 0x03fffffc); + DEBUGP("Location after: %08X.\n", + *(uint32_t *)location); + DEBUGP("ie. jump to %08X+%08X = %08X\n", + *(uint32_t *)location & 0x03fffffc, + (uint32_t)location, + (*(uint32_t *)location & 0x03fffffc) + + (uint32_t)location); + break; + + case R_PPC_REL32: + /* 32-bit relative jump. */ + *(uint32_t *)location = value - (uint32_t)location; + break; + + default: + printk("%s: unknown ADD relocation: %u\n", + module->name, + ELF32_R_TYPE(rela[i].r_info)); + return -ENOEXEC; + } + } + return 0; +} + +int module_finalize(const Elf_Ehdr *hdr, + const Elf_Shdr *sechdrs, + struct module *me) +{ + char *secstrings; + unsigned int i; + + me->arch.bug_table = NULL; + me->arch.num_bugs = 0; + + /* Find the __bug_table section, if present */ + secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; + for (i = 1; i < hdr->e_shnum; i++) { + if (strcmp(secstrings+sechdrs[i].sh_name, "__bug_table")) + continue; + me->arch.bug_table = (void *) sechdrs[i].sh_addr; + me->arch.num_bugs = sechdrs[i].sh_size / sizeof(struct bug_entry); + break; + } + + /* + * Strictly speaking this should have a spinlock to protect against + * traversals, but since we only traverse on BUG()s, a spinlock + * could potentially lead to deadlock and thus be counter-productive. + */ + list_add(&me->arch.bug_list, &module_bug_list); + + return 0; +} + +void module_arch_cleanup(struct module *mod) +{ + list_del(&mod->arch.bug_list); +} + +struct bug_entry *module_find_bug(unsigned long bugaddr) +{ + struct mod_arch_specific *mod; + unsigned int i; + struct bug_entry *bug; + + list_for_each_entry(mod, &module_bug_list, bug_list) { + bug = mod->bug_table; + for (i = 0; i < mod->num_bugs; ++i, ++bug) + if (bugaddr == bug->bug_addr) + return bug; + } + return NULL; +} |