From 9b802d1f43978869fcd98e92b854fd8785cefee7 Mon Sep 17 00:00:00 2001 From: James Hogan Date: Tue, 9 Oct 2012 10:55:00 +0100 Subject: [PATCH] metag: Module support Signed-off-by: James Hogan --- arch/metag/include/asm/module.h | 37 +++++ arch/metag/kernel/module.c | 284 ++++++++++++++++++++++++++++++++ 2 files changed, 321 insertions(+) create mode 100644 arch/metag/include/asm/module.h create mode 100644 arch/metag/kernel/module.c diff --git a/arch/metag/include/asm/module.h b/arch/metag/include/asm/module.h new file mode 100644 index 000000000000..e47e60941b2b --- /dev/null +++ b/arch/metag/include/asm/module.h @@ -0,0 +1,37 @@ +#ifndef _ASM_METAG_MODULE_H +#define _ASM_METAG_MODULE_H + +#include + +struct metag_plt_entry { + /* Indirect jump instruction sequence. */ + unsigned long tramp[2]; +}; + +struct mod_arch_specific { + /* Indices of PLT sections within module. */ + unsigned int core_plt_section, init_plt_section; +}; + +#if defined CONFIG_METAG_META12 +#define MODULE_PROC_FAMILY "META 1.2 " +#elif defined CONFIG_METAG_META21 +#define MODULE_PROC_FAMILY "META 2.1 " +#else +#define MODULE_PROC_FAMILY "" +#endif + +#ifdef CONFIG_4KSTACKS +#define MODULE_STACKSIZE "4KSTACKS " +#else +#define MODULE_STACKSIZE "" +#endif + +#define MODULE_ARCH_VERMAGIC MODULE_PROC_FAMILY MODULE_STACKSIZE + +#ifdef MODULE +asm(".section .plt,\"ax\",@progbits; .balign 8; .previous"); +asm(".section .init.plt,\"ax\",@progbits; .balign 8; .previous"); +#endif + +#endif /* _ASM_METAG_MODULE_H */ diff --git a/arch/metag/kernel/module.c b/arch/metag/kernel/module.c new file mode 100644 index 000000000000..986331cd0a52 --- /dev/null +++ b/arch/metag/kernel/module.c @@ -0,0 +1,284 @@ +/* Kernel module help for Meta. + + 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. +*/ +#include +#include +#include +#include +#include +#include +#include + +#include + +/* Count how many different relocations (different symbol, different + addend) */ +static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num) +{ + unsigned int i, r_info, r_addend, _count_relocs; + + _count_relocs = 0; + r_info = 0; + r_addend = 0; + for (i = 0; i < num; i++) + /* Only count relbranch relocs, others don't need stubs */ + if (ELF32_R_TYPE(rela[i].r_info) == R_METAG_RELBRANCH && + (r_info != ELF32_R_SYM(rela[i].r_info) || + r_addend != rela[i].r_addend)) { + _count_relocs++; + r_info = ELF32_R_SYM(rela[i].r_info); + r_addend = rela[i].r_addend; + } + + return _count_relocs; +} + +static int relacmp(const void *_x, const void *_y) +{ + const Elf32_Rela *x, *y; + + y = (Elf32_Rela *)_x; + x = (Elf32_Rela *)_y; + + /* Compare the entire r_info (as opposed to ELF32_R_SYM(r_info) only) to + * make the comparison cheaper/faster. It won't affect the sorting or + * the counting algorithms' performance + */ + if (x->r_info < y->r_info) + return -1; + else if (x->r_info > y->r_info) + return 1; + else if (x->r_addend < y->r_addend) + return -1; + else if (x->r_addend > y->r_addend) + return 1; + else + return 0; +} + +static void relaswap(void *_x, void *_y, int size) +{ + uint32_t *x, *y, tmp; + int i; + + y = (uint32_t *)_x; + x = (uint32_t *)_y; + + for (i = 0; i < sizeof(Elf32_Rela) / sizeof(uint32_t); i++) { + tmp = x[i]; + x[i] = y[i]; + y[i] = tmp; + } +} + +/* 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") != NULL) + != is_init) + continue; + + /* We don't want to look at debug sections. */ + if (strstr(secstrings + sechdrs[i].sh_name, ".debug") != NULL) + continue; + + if (sechdrs[i].sh_type == SHT_RELA) { + pr_debug("Found relocations in section %u\n", i); + pr_debug("Ptr: %p. Number: %u\n", + (void *)hdr + sechdrs[i].sh_offset, + sechdrs[i].sh_size / sizeof(Elf32_Rela)); + + /* Sort the relocation information based on a symbol and + * addend key. This is a stable O(n*log n) complexity + * alogrithm but it will reduce the complexity of + * count_relocs() to linear complexity O(n) + */ + sort((void *)hdr + sechdrs[i].sh_offset, + sechdrs[i].sh_size / sizeof(Elf32_Rela), + sizeof(Elf32_Rela), relacmp, relaswap); + + ret += count_relocs((void *)hdr + + sechdrs[i].sh_offset, + sechdrs[i].sh_size + / sizeof(Elf32_Rela)) + * sizeof(struct metag_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) { + pr_err("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.core_plt_section].sh_type = SHT_NOBITS; + sechdrs[me->arch.init_plt_section].sh_size + = get_plt_size(hdr, sechdrs, secstrings, 1); + sechdrs[me->arch.init_plt_section].sh_type = SHT_NOBITS; + 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 metag_plt_entry *entry; + /* Instructions used to do the indirect jump. */ + uint32_t tramp[2]; + + /* We have to trash a register, so we assume that any control + transfer more than 21-bits away must be a function call + (so we can use a call-clobbered register). */ + + /* MOVT D0Re0,#HI(v) */ + tramp[0] = 0x02000005 | (((val & 0xffff0000) >> 16) << 3); + /* JUMP D0Re0,#LO(v) */ + tramp[1] = 0xac000001 | ((val & 0x0000ffff) << 3); + + /* 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->tramp[0]) + if (entry->tramp[0] == tramp[0] && entry->tramp[1] == tramp[1]) + return (uint32_t)entry; + else + entry++; + + entry->tramp[0] = tramp[0]; + entry->tramp[1] = tramp[1]; + + return (uint32_t)entry; +} + +int apply_relocate_add(Elf32_Shdr *sechdrs, + const char *strtab, + unsigned int symindex, + unsigned int relsec, + struct module *me) +{ + unsigned int i; + Elf32_Rela *rel = (void *)sechdrs[relsec].sh_addr; + Elf32_Sym *sym; + Elf32_Addr relocation; + uint32_t *location; + int32_t value; + + pr_debug("Applying relocate section %u to %u\n", relsec, + sechdrs[relsec].sh_info); + for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) { + /* This is where to make the change */ + location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr + + rel[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(rel[i].r_info); + relocation = sym->st_value + rel[i].r_addend; + + switch (ELF32_R_TYPE(rel[i].r_info)) { + case R_METAG_NONE: + break; + case R_METAG_HIADDR16: + relocation >>= 16; + case R_METAG_LOADDR16: + *location = (*location & 0xfff80007) | + ((relocation & 0xffff) << 3); + break; + case R_METAG_ADDR32: + /* + * Packed data structures may cause a misaligned + * R_METAG_ADDR32 to be emitted. + */ + put_unaligned(relocation, location); + break; + case R_METAG_GETSETOFF: + *location += ((relocation & 0xfff) << 7); + break; + case R_METAG_RELBRANCH: + if (*location & (0x7ffff << 5)) { + pr_err("bad relbranch relocation\n"); + break; + } + + /* This jump is too big for the offset slot. Build + * a PLT to jump through to get to where we want to go. + * NB: 21bit check - not scaled to 19bit yet + */ + if (((int32_t)(relocation - + (uint32_t)location) > 0xfffff) || + ((int32_t)(relocation - + (uint32_t)location) < -0xfffff)) { + relocation = do_plt_call(location, relocation, + sechdrs, me); + } + + value = relocation - (uint32_t)location; + + /* branch instruction aligned */ + value /= 4; + + if ((value > 0x7ffff) || (value < -0x7ffff)) { + /* + * this should have been caught by the code + * above! + */ + pr_err("overflow of relbranch reloc\n"); + } + + *location = (*location & (~(0x7ffff << 5))) | + ((value & 0x7ffff) << 5); + break; + + default: + pr_err("module %s: Unknown relocation: %u\n", + me->name, ELF32_R_TYPE(rel[i].r_info)); + return -ENOEXEC; + } + } + return 0; +} -- GitLab