diff options
Diffstat (limited to 'arch/ppc64/kernel/module.c')
| -rw-r--r-- | arch/ppc64/kernel/module.c | 442 |
1 files changed, 442 insertions, 0 deletions
diff --git a/arch/ppc64/kernel/module.c b/arch/ppc64/kernel/module.c new file mode 100644 index 000000000000..c683bf88e690 --- /dev/null +++ b/arch/ppc64/kernel/module.c @@ -0,0 +1,442 @@ +/* Kernel module help for PPC64. + Copyright (C) 2001, 2003 Rusty Russell IBM Corporation. + + 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/elf.h> +#include <linux/moduleloader.h> +#include <linux/err.h> +#include <linux/vmalloc.h> +#include <asm/module.h> +#include <asm/uaccess.h> + +/* FIXME: We don't do .init separately. To do this, we'd need to have + a separate r2 value in the init and core section, and stub between + them, too. + + Using a magic allocator which places modules within 32MB solves + this, and makes other things simpler. Anton? + --RR. */ +#if 0 +#define DEBUGP printk +#else +#define DEBUGP(fmt , ...) +#endif + +/* There's actually a third entry here, but it's unused */ +struct ppc64_opd_entry +{ + unsigned long funcaddr; + unsigned long r2; +}; + +/* Like PPC32, we need little trampolines to do > 24-bit jumps (into + the kernel itself). But on PPC64, these need to be used for every + jump, actually, to reset r2 (TOC+0x8000). */ +struct ppc64_stub_entry +{ + /* 28 byte jump instruction sequence (7 instructions) */ + unsigned char jump[28]; + unsigned char unused[4]; + /* Data for the above code */ + struct ppc64_opd_entry opd; +}; + +/* We use a stub to fix up r2 (TOC ptr) and to jump to the (external) + function which may be more than 24-bits away. We could simply + patch the new r2 value and function pointer into the stub, but it's + significantly shorter to put these values at the end of the stub + code, and patch the stub address (32-bits relative to the TOC ptr, + r2) into the stub. */ +static struct ppc64_stub_entry ppc64_stub = +{ .jump = { + 0x3d, 0x82, 0x00, 0x00, /* addis r12,r2, <high> */ + 0x39, 0x8c, 0x00, 0x00, /* addi r12,r12, <low> */ + /* Save current r2 value in magic place on the stack. */ + 0xf8, 0x41, 0x00, 0x28, /* std r2,40(r1) */ + 0xe9, 0x6c, 0x00, 0x20, /* ld r11,32(r12) */ + 0xe8, 0x4c, 0x00, 0x28, /* ld r2,40(r12) */ + 0x7d, 0x69, 0x03, 0xa6, /* mtctr r11 */ + 0x4e, 0x80, 0x04, 0x20 /* bctr */ +} }; + +/* Count how many different 24-bit relocations (different symbol, + different addend) */ +static unsigned int count_relocs(const Elf64_Rela *rela, unsigned int num) +{ + unsigned int i, j, ret = 0; + + /* FIXME: Only count external ones --RR */ + /* Sure, this is order(n^2), but it's usually short, and not + time critical */ + for (i = 0; i < num; i++) { + /* Only count 24-bit relocs, others don't need stubs */ + if (ELF64_R_TYPE(rela[i].r_info) != R_PPC_REL24) + continue; + for (j = 0; j < i; j++) { + /* If this addend appeared before, it's + already been counted */ + if (rela[i].r_info == rela[j].r_info + && rela[i].r_addend == rela[j].r_addend) + break; + } + if (j == i) ret++; + } + return ret; +} + +void *module_alloc(unsigned long size) +{ + if (size == 0) + return NULL; + + return vmalloc_exec(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. */ +} + +/* Get size of potential trampolines required. */ +static unsigned long get_stubs_size(const Elf64_Ehdr *hdr, + const Elf64_Shdr *sechdrs) +{ + /* One extra reloc so it's always 0-funcaddr terminated */ + unsigned long relocs = 1; + unsigned i; + + /* Every relocated section... */ + for (i = 1; i < hdr->e_shnum; i++) { + if (sechdrs[i].sh_type == SHT_RELA) { + DEBUGP("Found relocations in section %u\n", i); + DEBUGP("Ptr: %p. Number: %lu\n", + (void *)sechdrs[i].sh_addr, + sechdrs[i].sh_size / sizeof(Elf64_Rela)); + relocs += count_relocs((void *)sechdrs[i].sh_addr, + sechdrs[i].sh_size + / sizeof(Elf64_Rela)); + } + } + + DEBUGP("Looks like a total of %lu stubs, max\n", relocs); + return relocs * sizeof(struct ppc64_stub_entry); +} + +static void dedotify_versions(struct modversion_info *vers, + unsigned long size) +{ + struct modversion_info *end; + + for (end = (void *)vers + size; vers < end; vers++) + if (vers->name[0] == '.') + memmove(vers->name, vers->name+1, strlen(vers->name)); +} + +/* Undefined symbols which refer to .funcname, hack to funcname */ +static void dedotify(Elf64_Sym *syms, unsigned int numsyms, char *strtab) +{ + unsigned int i; + + for (i = 1; i < numsyms; i++) { + if (syms[i].st_shndx == SHN_UNDEF) { + char *name = strtab + syms[i].st_name; + if (name[0] == '.') + memmove(name, name+1, strlen(name)); + } + } +} + +int module_frob_arch_sections(Elf64_Ehdr *hdr, + Elf64_Shdr *sechdrs, + char *secstrings, + struct module *me) +{ + unsigned int i; + + /* Find .toc and .stubs sections, symtab and strtab */ + for (i = 1; i < hdr->e_shnum; i++) { + char *p; + if (strcmp(secstrings + sechdrs[i].sh_name, ".stubs") == 0) + me->arch.stubs_section = i; + else if (strcmp(secstrings + sechdrs[i].sh_name, ".toc") == 0) + me->arch.toc_section = i; + else if (strcmp(secstrings+sechdrs[i].sh_name,"__versions")==0) + dedotify_versions((void *)hdr + sechdrs[i].sh_offset, + sechdrs[i].sh_size); + + /* We don't handle .init for the moment: rename to _init */ + while ((p = strstr(secstrings + sechdrs[i].sh_name, ".init"))) + p[0] = '_'; + + if (sechdrs[i].sh_type == SHT_SYMTAB) + dedotify((void *)hdr + sechdrs[i].sh_offset, + sechdrs[i].sh_size / sizeof(Elf64_Sym), + (void *)hdr + + sechdrs[sechdrs[i].sh_link].sh_offset); + } + if (!me->arch.stubs_section || !me->arch.toc_section) { + printk("%s: doesn't contain .toc or .stubs.\n", me->name); + return -ENOEXEC; + } + + /* Override the stubs size */ + sechdrs[me->arch.stubs_section].sh_size = get_stubs_size(hdr, sechdrs); + return 0; +} + +int apply_relocate(Elf64_Shdr *sechdrs, + const char *strtab, + unsigned int symindex, + unsigned int relsec, + struct module *me) +{ + printk(KERN_ERR "%s: Non-ADD RELOCATION unsupported\n", me->name); + return -ENOEXEC; +} + +/* r2 is the TOC pointer: it actually points 0x8000 into the TOC (this + gives the value maximum span in an instruction which uses a signed + offset) */ +static inline unsigned long my_r2(Elf64_Shdr *sechdrs, struct module *me) +{ + return sechdrs[me->arch.toc_section].sh_addr + 0x8000; +} + +/* Both low and high 16 bits are added as SIGNED additions, so if low + 16 bits has high bit set, high 16 bits must be adjusted. These + macros do that (stolen from binutils). */ +#define PPC_LO(v) ((v) & 0xffff) +#define PPC_HI(v) (((v) >> 16) & 0xffff) +#define PPC_HA(v) PPC_HI ((v) + 0x8000) + +/* Patch stub to reference function and correct r2 value. */ +static inline int create_stub(Elf64_Shdr *sechdrs, + struct ppc64_stub_entry *entry, + struct ppc64_opd_entry *opd, + struct module *me) +{ + Elf64_Half *loc1, *loc2; + long reladdr; + + *entry = ppc64_stub; + + loc1 = (Elf64_Half *)&entry->jump[2]; + loc2 = (Elf64_Half *)&entry->jump[6]; + + /* Stub uses address relative to r2. */ + reladdr = (unsigned long)entry - my_r2(sechdrs, me); + if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) { + printk("%s: Address %p of stub out of range of %p.\n", + me->name, (void *)reladdr, (void *)my_r2); + return 0; + } + DEBUGP("Stub %p get data from reladdr %li\n", entry, reladdr); + + *loc1 = PPC_HA(reladdr); + *loc2 = PPC_LO(reladdr); + entry->opd.funcaddr = opd->funcaddr; + entry->opd.r2 = opd->r2; + return 1; +} + +/* Create stub to jump to function described in this OPD: we need the + stub to set up the TOC ptr (r2) for the function. */ +static unsigned long stub_for_addr(Elf64_Shdr *sechdrs, + unsigned long opdaddr, + struct module *me) +{ + struct ppc64_stub_entry *stubs; + struct ppc64_opd_entry *opd = (void *)opdaddr; + unsigned int i, num_stubs; + + num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*stubs); + + /* Find this stub, or if that fails, the next avail. entry */ + stubs = (void *)sechdrs[me->arch.stubs_section].sh_addr; + for (i = 0; stubs[i].opd.funcaddr; i++) { + BUG_ON(i >= num_stubs); + + if (stubs[i].opd.funcaddr == opd->funcaddr) + return (unsigned long)&stubs[i]; + } + + if (!create_stub(sechdrs, &stubs[i], opd, me)) + return 0; + + return (unsigned long)&stubs[i]; +} + +/* We expect a noop next: if it is, replace it with instruction to + restore r2. */ +static int restore_r2(u32 *instruction, struct module *me) +{ + if (*instruction != 0x60000000) { + printk("%s: Expect noop after relocate, got %08x\n", + me->name, *instruction); + return 0; + } + *instruction = 0xe8410028; /* ld r2,40(r1) */ + return 1; +} + +int apply_relocate_add(Elf64_Shdr *sechdrs, + const char *strtab, + unsigned int symindex, + unsigned int relsec, + struct module *me) +{ + unsigned int i; + Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr; + Elf64_Sym *sym; + unsigned long *location; + unsigned long 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 */ + sym = (Elf64_Sym *)sechdrs[symindex].sh_addr + + ELF64_R_SYM(rela[i].r_info); + + DEBUGP("RELOC at %p: %li-type as %s (%lu) + %li\n", + location, (long)ELF64_R_TYPE(rela[i].r_info), + strtab + sym->st_name, (unsigned long)sym->st_value, + (long)rela[i].r_addend); + + /* `Everything is relative'. */ + value = sym->st_value + rela[i].r_addend; + + switch (ELF64_R_TYPE(rela[i].r_info)) { + case R_PPC64_ADDR32: + /* Simply set it */ + *(u32 *)location = value; + break; + + case R_PPC64_ADDR64: + /* Simply set it */ + *(unsigned long *)location = value; + break; + + case R_PPC64_TOC: + *(unsigned long *)location = my_r2(sechdrs, me); + break; + + case R_PPC64_TOC16_DS: + /* Subtact TOC pointer */ + value -= my_r2(sechdrs, me); + if ((value & 3) != 0 || value + 0x8000 > 0xffff) { + printk("%s: bad TOC16_DS relocation (%lu)\n", + me->name, value); + return -ENOEXEC; + } + *((uint16_t *) location) + = (*((uint16_t *) location) & ~0xfffc) + | (value & 0xfffc); + break; + + case R_PPC_REL24: + /* FIXME: Handle weak symbols here --RR */ + if (sym->st_shndx == SHN_UNDEF) { + /* External: go via stub */ + value = stub_for_addr(sechdrs, value, me); + if (!value) + return -ENOENT; + if (!restore_r2((u32 *)location + 1, me)) + return -ENOEXEC; + } + + /* Convert value to relative */ + value -= (unsigned long)location; + if (value + 0x2000000 > 0x3ffffff || (value & 3) != 0){ + printk("%s: REL24 %li out of range!\n", + me->name, (long int)value); + return -ENOEXEC; + } + + /* Only replace bits 2 through 26 */ + *(uint32_t *)location + = (*(uint32_t *)location & ~0x03fffffc) + | (value & 0x03fffffc); + break; + + default: + printk("%s: Unknown ADD relocation: %lu\n", + me->name, + (unsigned long)ELF64_R_TYPE(rela[i].r_info)); + return -ENOEXEC; + } + } + + return 0; +} + +LIST_HEAD(module_bug_list); + +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; +} |