> In message <20030207001006.A19306@flint.arm.linux.org.uk> you write:
> > And I'll promptly provide you with the other view. I'm still trying to
> > sort out the best thing to do for ARM. We have the choice of:
Actually, I must be really confused. I thought ARM was already
complete.
Anyway, here's a version which simply does what the usermode one did,
if you decide to take the "fix it later" approach.
Cheers!
Rusty.
PS. I did this in the usermode test framework, so not live tested.
-- Anyone who quotes me in their sig is an idiot. -- Rusty Russell.diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal linux-2.5.59/arch/arm/kernel/module.c working-2.5.59-armmodule/arch/arm/kernel/module.c --- linux-2.5.59/arch/arm/kernel/module.c 2003-02-07 19:21:51.000000000 +1100 +++ working-2.5.59-armmodule/arch/arm/kernel/module.c 2003-02-07 19:04:12.000000000 +1100 @@ -2,6 +2,7 @@ * linux/arch/arm/kernel/module.c * * Copyright (C) 2002 Russell King. + * Dumbed down by Rusty Russell. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as @@ -17,54 +18,74 @@ #include <linux/fs.h> #include <linux/string.h> -#include <asm/pgtable.h> +#if 0 +#define DEBUGP printk +#else +#define DEBUGP(fmt , ...) +#endif -void *module_alloc(unsigned long size) +/* This is a beautiful architecture. --RR */ +struct arm_plt_entry { - struct vm_struct *area; - struct page **pages; - unsigned int array_size, i; - - size = PAGE_ALIGN(size); - if (!size) - goto out_null; + u32 ldr_pc; /* ldr pc,[pc,#-4] */ + u32 location; /* sym@ */ +}; - area = __get_vm_area(size, VM_ALLOC, MODULE_START, MODULE_END); - if (!area) - goto out_null; +void *module_alloc(unsigned long size) +{ + if (size == 0) + return NULL; + return vmalloc(size); +} - area->nr_pages = size >> PAGE_SHIFT; - array_size = area->nr_pages * sizeof(struct page *); - area->pages = pages = kmalloc(array_size, GFP_KERNEL); - if (!area->pages) { - remove_vm_area(area->addr); - kfree(area); - goto out_null; - } +/* Free memory returned from module_alloc */ +void module_free(struct module *mod, void *module_region) +{ + vfree(module_region); +} - memset(pages, 0, array_size); +/* Count how many different PC24 relocations (different symbol) */ +static unsigned int count_relocs(const Elf32_Rel *rel, unsigned int num) +{ + unsigned int i, j, ret = 0; - for (i = 0; i < area->nr_pages; i++) { - pages[i] = alloc_page(GFP_KERNEL); - if (unlikely(!pages[i])) { - area->nr_pages = i; - goto out_no_pages; + /* Sure, this is order(n^2), but it's usually short, and not + time critical */ + for (i = 0; i < num; i++) { + if (ELF32_R_TYPE(rel[i].r_info) != R_ARM_PC24) + continue; + for (j = 0; j < i; j++) { + if (ELF32_R_TYPE(rel[j].r_info) != R_ARM_PC24) + continue; + /* If this addend appeared before, it's + already been counted */ + if (ELF32_R_SYM(rel[i].r_info) + == ELF32_R_SYM(rel[j].r_info)) + break; } + if (j == i) ret++; } - - if (map_vm_area(area, PAGE_KERNEL, &pages)) - goto out_no_pages; - return area->addr; - - out_no_pages: - vfree(area->addr); - out_null: - return NULL; + return ret; } -void module_free(struct module *module, void *region) +/* Get the potential trampolines size required sections */ +static unsigned long get_plt_size(const Elf32_Ehdr *hdr, + const Elf32_Shdr *sechdrs, + const char *secstrings) { - vfree(region); + unsigned long ret = 0; + unsigned i; + + /* Everything marked ALLOC (this includes the exported + symbols) */ + for (i = 1; i < hdr->e_shnum; i++) { + if (sechdrs[i].sh_type != SHT_REL) + continue; + ret += count_relocs((void *)hdr + sechdrs[i].sh_offset, + sechdrs[i].sh_size / sizeof(Elf32_Rel)); + } + + return ret * sizeof(struct arm_plt_entry); } int module_frob_arch_sections(Elf_Ehdr *hdr, @@ -72,9 +93,55 @@ int module_frob_arch_sections(Elf_Ehdr * char *secstrings, struct module *mod) { + unsigned int i; + char *p; + + /* Find .plt section, and rename .init sections, which we + don't handle */ + for (i = 1; i < hdr->e_shnum; i++) { + if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0) + mod->arch.plt_section = i; + while ((p = strstr(secstrings + sechdrs[i].sh_name, ".init"))) + p[0] = '_'; + } + if (!mod->arch.plt_section) { + printk("Module doesn't contain .plt section.\n"); + return -ENOEXEC; + } + + /* Override its size */ + sechdrs[mod->arch.plt_section].sh_size + = get_plt_size(hdr, sechdrs, secstrings); + /* Override its type and flags: in asm statement doesn't work 8( */ + sechdrs[mod->arch.plt_section].sh_type = SHT_NOBITS; + sechdrs[mod->arch.plt_section].sh_flags = (SHF_EXECINSTR | SHF_ALLOC); return 0; } +/* Allocate (or find) the PLT entry for this function. */ +static u32 make_plt(Elf32_Shdr *sechdrs, struct module *module, u32 funcaddr) +{ + struct arm_plt_entry *plt; + unsigned int i, num_plts; + + plt = (void *)sechdrs[module->arch.plt_section].sh_addr; + num_plts = sechdrs[module->arch.plt_section].sh_size / sizeof(*plt); + + for (i = 0; i < num_plts; i++) { + if (!plt[i].ldr_pc) { + /* New one. Fill in. */ + plt[i].ldr_pc = 0xe51ff004; + plt[i].location = funcaddr; + } + if (plt[i].location == funcaddr) { + DEBUGP("Made plt %u for %p at %p\n", + i, (void *)funcaddr, &plt[i]); + return (u32)&plt[i]; + } + } + BUG(); +} + int apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex, unsigned int relindex, struct module *module) @@ -86,7 +153,7 @@ apply_relocate(Elf32_Shdr *sechdrs, cons unsigned int i; for (i = 0; i < relsec->sh_size / sizeof(Elf32_Rel); i++, rel++) { - unsigned long loc; + unsigned long loc, addend; Elf32_Sym *sym; s32 offset; @@ -98,6 +165,11 @@ apply_relocate(Elf32_Shdr *sechdrs, cons } sym = ((Elf32_Sym *)symsec->sh_addr) + offset; + if (!sym->st_value) { + printk(KERN_WARNING "%s: unknown symbol %s\n", + module->name, strtab + sym->st_name); + return -ENOENT; + } if (rel->r_offset < 0 || rel->r_offset > dstsec->sh_size - sizeof(u32)) { printk(KERN_ERR "%s: out of bounds relocation, " @@ -115,24 +187,26 @@ apply_relocate(Elf32_Shdr *sechdrs, cons break; case R_ARM_PC24: - offset = (*(u32 *)loc & 0x00ffffff) << 2; - if (offset & 0x02000000) - offset -= 0x04000000; + /* Pull addend from location */ + addend = (*(u32 *)loc & 0x00ffffff) << 2; + if (addend & 0x02000000) + addend -= 0x04000000; + offset = sym->st_value + addend - loc; - offset += sym->st_value - loc; - if (offset & 3 || - offset <= (s32)0xfc000000 || - offset >= (s32)0x04000000) { + /* if the target is too far away, use plt. */ + if (offset < -0x02000000 || offset >= 0x02000000) + offset = make_plt(sechdrs,module,sym->st_value) + + addend - loc; + + if (offset & 3) { printk(KERN_ERR "%s: unable to fixup " - "relocation: out of range\n", - module->name); + "relocation: %u out of range\n", + module->name, offset); return -ENOEXEC; } - offset >>= 2; - *(u32 *)loc &= 0xff000000; - *(u32 *)loc |= offset & 0x00ffffff; + *(u32 *)loc |= (offset >> 2) & 0x00ffffff; break; default: diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal linux-2.5.59/include/asm-arm/module.h working-2.5.59-armmodule/include/asm-arm/module.h --- linux-2.5.59/include/asm-arm/module.h 2003-02-07 19:16:25.000000000 +1100 +++ working-2.5.59-armmodule/include/asm-arm/module.h 2003-02-07 19:04:03.000000000 +1100 @@ -3,11 +3,16 @@ struct mod_arch_specific { - int foo; + /* Index of PLT section within module. */ + unsigned int plt_section; }; #define Elf_Shdr Elf32_Shdr #define Elf_Sym Elf32_Sym #define Elf_Ehdr Elf32_Ehdr +/* Make empty sections for module_frob_arch_sections to expand. */ +#ifdef MODULE +asm(".section .plt; .align 3; .previous"); +#endif #endif /* _ASM_ARM_MODULE_H */ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Fri Feb 07 2003 - 22:00:23 EST