/* * linux/arch/ppc64/kernel/vdso.c * * Copyright (C) 2004 Benjamin Herrenschmidt, IBM Corp. * <benh@kernel.crashing.org> * * 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. */ #include <linux/config.h> #include <linux/module.h> #include <linux/errno.h> #include <linux/sched.h> #include <linux/kernel.h> #include <linux/mm.h> #include <linux/smp.h> #include <linux/smp_lock.h> #include <linux/stddef.h> #include <linux/unistd.h> #include <linux/slab.h> #include <linux/user.h> #include <linux/elf.h> #include <linux/security.h> #include <linux/bootmem.h> #include <asm/pgtable.h> #include <asm/system.h> #include <asm/processor.h> #include <asm/mmu.h> #include <asm/mmu_context.h> #include <asm/machdep.h> #include <asm/cputable.h> #include <asm/sections.h> #include <asm/vdso.h> #undef DEBUG #ifdef DEBUG #define DBG(fmt...) printk(fmt) #else #define DBG(fmt...) #endif /* * The vDSOs themselves are here */ extern char vdso64_start, vdso64_end; extern char vdso32_start, vdso32_end; static void *vdso64_kbase = &vdso64_start; static void *vdso32_kbase = &vdso32_start; unsigned int vdso64_pages; unsigned int vdso32_pages; /* Signal trampolines user addresses */ unsigned long vdso64_rt_sigtramp; unsigned long vdso32_sigtramp; unsigned long vdso32_rt_sigtramp; /* Format of the patch table */ struct vdso_patch_def { u32 pvr_mask, pvr_value; const char *gen_name; const char *fix_name; }; /* Table of functions to patch based on the CPU type/revision * * TODO: Improve by adding whole lists for each entry */ static struct vdso_patch_def vdso_patches[] = { { 0xffff0000, 0x003a0000, /* POWER5 */ "__kernel_sync_dicache", "__kernel_sync_dicache_p5" }, { 0xffff0000, 0x003b0000, /* POWER5 */ "__kernel_sync_dicache", "__kernel_sync_dicache_p5" }, }; /* * Some infos carried around for each of them during parsing at * boot time. */ struct lib32_elfinfo { Elf32_Ehdr *hdr; /* ptr to ELF */ Elf32_Sym *dynsym; /* ptr to .dynsym section */ unsigned long dynsymsize; /* size of .dynsym section */ char *dynstr; /* ptr to .dynstr section */ unsigned long text; /* offset of .text section in .so */ }; struct lib64_elfinfo { Elf64_Ehdr *hdr; Elf64_Sym *dynsym; unsigned long dynsymsize; char *dynstr; unsigned long text; }; #ifdef __DEBUG static void dump_one_vdso_page(struct page *pg, struct page *upg) { printk("kpg: %p (c:%d,f:%08lx)", __va(page_to_pfn(pg) << PAGE_SHIFT), page_count(pg), pg->flags); if (upg/* && pg != upg*/) { printk(" upg: %p (c:%d,f:%08lx)", __va(page_to_pfn(upg) << PAGE_SHIFT), page_count(upg), upg->flags); } printk("\n"); } static void dump_vdso_pages(struct vm_area_struct * vma) { int i; if (!vma || test_thread_flag(TIF_32BIT)) { printk("vDSO32 @ %016lx:\n", (unsigned long)vdso32_kbase); for (i=0; i<vdso32_pages; i++) { struct page *pg = virt_to_page(vdso32_kbase + i*PAGE_SIZE); struct page *upg = (vma && vma->vm_mm) ? follow_page(vma->vm_mm, vma->vm_start + i*PAGE_SIZE, 0) : NULL; dump_one_vdso_page(pg, upg); } } if (!vma || !test_thread_flag(TIF_32BIT)) { printk("vDSO64 @ %016lx:\n", (unsigned long)vdso64_kbase); for (i=0; i<vdso64_pages; i++) { struct page *pg = virt_to_page(vdso64_kbase + i*PAGE_SIZE); struct page *upg = (vma && vma->vm_mm) ? follow_page(vma->vm_mm, vma->vm_start + i*PAGE_SIZE, 0) : NULL; dump_one_vdso_page(pg, upg); } } } #endif /* DEBUG */ /* * Keep a dummy vma_close for now, it will prevent VMA merging. */ static void vdso_vma_close(struct vm_area_struct * vma) { } /* * Our nopage() function, maps in the actual vDSO kernel pages, they will * be mapped read-only by do_no_page(), and eventually COW'ed, either * right away for an initial write access, or by do_wp_page(). */ static struct page * vdso_vma_nopage(struct vm_area_struct * vma, unsigned long address, int *type) { unsigned long offset = address - vma->vm_start; struct page *pg; void *vbase = test_thread_flag(TIF_32BIT) ? vdso32_kbase : vdso64_kbase; DBG("vdso_vma_nopage(current: %s, address: %016lx, off: %lx)\n", current->comm, address, offset); if (address < vma->vm_start || address > vma->vm_end) return NOPAGE_SIGBUS; /* * Last page is systemcfg, special handling here, no get_page() a * this is a reserved page */ if ((vma->vm_end - address) <= PAGE_SIZE) return virt_to_page(systemcfg); pg = virt_to_page(vbase + offset); get_page(pg); DBG(" ->page count: %d\n", page_count(pg)); return pg; } static struct vm_operations_struct vdso_vmops = { .close = vdso_vma_close, .nopage = vdso_vma_nopage, }; /* * This is called from binfmt_elf, we create the special vma for the * vDSO and insert it into the mm struct tree */ int arch_setup_additional_pages(struct linux_binprm *bprm, int executable_stack) { struct mm_struct *mm = current->mm; struct vm_area_struct *vma; unsigned long vdso_pages; unsigned long vdso_base; if (test_thread_flag(TIF_32BIT)) { vdso_pages = vdso32_pages; vdso_base = VDSO32_MBASE; } else { vdso_pages = vdso64_pages; vdso_base = VDSO64_MBASE; } current->thread.vdso_base = 0; /* vDSO has a problem and was disabled, just don't "enable" it for the * process */ if (vdso_pages == 0) return 0; vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL); if (vma == NULL) return -ENOMEM; if (security_vm_enough_memory(vdso_pages)) { kmem_cache_free(vm_area_cachep, vma); return -ENOMEM; } memset(vma, 0, sizeof(*vma)); /* * pick a base address for the vDSO in process space. We try to put it * at vdso_base which is the "natural" base for it, but we might fail * and end up putting it elsewhere. */ vdso_base = get_unmapped_area(NULL, vdso_base, vdso_pages << PAGE_SHIFT, 0, 0); if (vdso_base & ~PAGE_MASK) return (int)vdso_base; current->thread.vdso_base = vdso_base; vma->vm_mm = mm; vma->vm_start = current->thread.vdso_base; /* * the VMA size is one page more than the vDSO since systemcfg * is mapped in the last one */ vma->vm_end = vma->vm_start + ((vdso_pages + 1) << PAGE_SHIFT); /* * our vma flags don't have VM_WRITE so by default, the process isn't allowed * to write those pages. * gdb can break that with ptrace interface, and thus trigger COW on those * pages but it's then your responsibility to never do that on the "data" page * of the vDSO or you'll stop getting kernel updates and your nice userland * gettimeofday will be totally dead. It's fine to use that for setting * breakpoints in the vDSO code pages though */ vma->vm_flags = VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; vma->vm_flags |= mm->def_flags; vma->vm_page_prot = protection_map[vma->vm_flags & 0x7]; vma->vm_ops = &vdso_vmops; down_write(&mm->mmap_sem); insert_vm_struct(mm, vma); mm->total_vm += (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; up_write(&mm->mmap_sem); return 0; } static void * __init find_section32(Elf32_Ehdr *ehdr, const char *secname, unsigned long *size) { Elf32_Shdr *sechdrs; unsigned int i; char *secnames; /* Grab section headers and strings so we can tell who is who */ sechdrs = (void *)ehdr + ehdr->e_shoff; secnames = (void *)ehdr + sechdrs[ehdr->e_shstrndx].sh_offset; /* Find the section they want */ for (i = 1; i < ehdr->e_shnum; i++) { if (strcmp(secnames+sechdrs[i].sh_name, secname) == 0) { if (size) *size = sechdrs[i].sh_size; return (void *)ehdr + sechdrs[i].sh_offset; } } *size = 0; return NULL; } static void * __init find_section64(Elf64_Ehdr *ehdr, const char *secname, unsigned long *size) { Elf64_Shdr *sechdrs; unsigned int i; char *secnames; /* Grab section headers and strings so we can tell who is who */ sechdrs = (void *)ehdr + ehdr->e_shoff; secnames = (void *)ehdr + sechdrs[ehdr->e_shstrndx].sh_offset; /* Find the section they want */ for (i = 1; i < ehdr->e_shnum; i++) { if (strcmp(secnames+sechdrs[i].sh_name, secname) == 0) { if (size) *size = sechdrs[i].sh_size; return (void *)ehdr + sechdrs[i].sh_offset; } } if (size) *size = 0; return NULL; } static Elf32_Sym * __init find_symbol32(struct lib32_elfinfo *lib, const char *symname) { unsigned int i; char name[32], *c; for (i = 0; i < (lib->dynsymsize / sizeof(Elf32_Sym)); i++) { if (lib->dynsym[i].st_name == 0) continue; strlcpy(name, lib->dynstr + lib->dynsym[i].st_name, 32); c = strchr(name, '@'); if (c) *c = 0; if (strcmp(symname, name) == 0) return &lib->dynsym[i]; } return NULL; } static Elf64_Sym * __init find_symbol64(struct lib64_elfinfo *lib, const char *symname) { unsigned int i; char name[32], *c; for (i = 0; i < (lib->dynsymsize / sizeof(Elf64_Sym)); i++) { if (lib->dynsym[i].st_name == 0) continue; strlcpy(name, lib->dynstr + lib->dynsym[i].st_name, 32); c = strchr(name, '@'); if (c) *c = 0; if (strcmp(symname, name) == 0) return &lib->dynsym[i]; } return NULL; } /* Note that we assume the section is .text and the symbol is relative to * the library base */ static unsigned long __init find_function32(struct lib32_elfinfo *lib, const char *symname) { Elf32_Sym *sym = find_symbol32(lib, symname); if (sym == NULL) { printk(KERN_WARNING "vDSO32: function %s not found !\n", symname); return 0; } return sym->st_value - VDSO32_LBASE; } /* Note that we assume the section is .text and the symbol is relative to * the library base */ static unsigned long __init find_function64(struct lib64_elfinfo *lib, const char *symname) { Elf64_Sym *sym = find_symbol64(lib, symname); if (sym == NULL) { printk(KERN_WARNING "vDSO64: function %s not found !\n", symname); return 0; } #ifdef VDS64_HAS_DESCRIPTORS return *((u64 *)(vdso64_kbase + sym->st_value - VDSO64_LBASE)) - VDSO64_LBASE; #else return sym->st_value - VDSO64_LBASE; #endif } static __init int vdso_do_find_sections(struct lib32_elfinfo *v32, struct lib64_elfinfo *v64) { void *sect; /* * Locate symbol tables & text section */ v32->dynsym = find_section32(v32->hdr, ".dynsym", &v32->dynsymsize); v32->dynstr = find_section32(v32->hdr, ".dynstr", NULL); if (v32->dynsym == NULL || v32->dynstr == NULL) { printk(KERN_ERR "vDSO32: a required symbol section was not found\n"); return -1; } sect = find_section32(v32->hdr, ".text", NULL); if (sect == NULL) { printk(KERN_ERR "vDSO32: the .text section was not found\n"); return -1; } v32->text = sect - vdso32_kbase; v64->dynsym = find_section64(v64->hdr, ".dynsym", &v64->dynsymsize); v64->dynstr = find_section64(v64->hdr, ".dynstr", NULL); if (v64->dynsym == NULL || v64->dynstr == NULL) { printk(KERN_ERR "vDSO64: a required symbol section was not found\n"); return -1; } sect = find_section64(v64->hdr, ".text", NULL); if (sect == NULL) { printk(KERN_ERR "vDSO64: the .text section was not found\n"); return -1; } v64->text = sect - vdso64_kbase; return 0; } static __init void vdso_setup_trampolines(struct lib32_elfinfo *v32, struct lib64_elfinfo *v64) { /* * Find signal trampolines */ vdso64_rt_sigtramp = find_function64(v64, "__kernel_sigtramp_rt64"); vdso32_sigtramp = find_function32(v32, "__kernel_sigtramp32"); vdso32_rt_sigtramp = find_function32(v32, "__kernel_sigtramp_rt32"); } static __init int vdso_fixup_datapage(struct lib32_elfinfo *v32, struct lib64_elfinfo *v64) { Elf32_Sym *sym32; Elf64_Sym *sym64; sym32 = find_symbol32(v32, "__kernel_datapage_offset"); if (sym32 == NULL) { printk(KERN_ERR "vDSO32: Can't find symbol __kernel_datapage_offset !\n"); return -1; } *((int *)(vdso32_kbase + (sym32->st_value - VDSO32_LBASE))) = (vdso32_pages << PAGE_SHIFT) - (sym32->st_value - VDSO32_LBASE); sym64 = find_symbol64(v64, "__kernel_datapage_offset"); if (sym64 == NULL) { printk(KERN_ERR "vDSO64: Can't find symbol __kernel_datapage_offset !\n"); return -1; } *((int *)(vdso64_kbase + sym64->st_value - VDSO64_LBASE)) = (vdso64_pages << PAGE_SHIFT) - (sym64->st_value - VDSO64_LBASE); return 0; } static int vdso_do_func_patch32(struct lib32_elfinfo *v32, struct lib64_elfinfo *v64, const char *orig, const char *fix) { Elf32_Sym *sym32_gen, *sym32_fix; sym32_gen = find_symbol32(v32, orig); if (sym32_gen == NULL) { printk(KERN_ERR "vDSO32: Can't find symbol %s !\n", orig); return -1; } sym32_fix = find_symbol32(v32, fix); if (sym32_fix == NULL) { printk(KERN_ERR "vDSO32: Can't find symbol %s !\n", fix); return -1; } sym32_gen->st_value = sym32_fix->st_value; sym32_gen->st_size = sym32_fix->st_size; sym32_gen->st_info = sym32_fix->st_info; sym32_gen->st_other = sym32_fix->st_other; sym32_gen->st_shndx = sym32_fix->st_shndx; return 0; } static int vdso_do_func_patch64(struct lib32_elfinfo *v32, struct lib64_elfinfo *v64, const char *orig, const char *fix) { Elf64_Sym *sym64_gen, *sym64_fix; sym64_gen = find_symbol64(v64, orig); if (sym64_gen == NULL) { printk(KERN_ERR "vDSO64: Can't find symbol %s !\n", orig); return -1; } sym64_fix = find_symbol64(v64, fix); if (sym64_fix == NULL) { printk(KERN_ERR "vDSO64: Can't find symbol %s !\n", fix); return -1; } sym64_gen->st_value = sym64_fix->st_value; sym64_gen->st_size = sym64_fix->st_size; sym64_gen->st_info = sym64_fix->st_info; sym64_gen->st_other = sym64_fix->st_other; sym64_gen->st_shndx = sym64_fix->st_shndx; return 0; } static __init int vdso_fixup_alt_funcs(struct lib32_elfinfo *v32, struct lib64_elfinfo *v64) { u32 pvr; int i; pvr = mfspr(SPRN_PVR); for (i = 0; i < ARRAY_SIZE(vdso_patches); i++) { struct vdso_patch_def *patch = &vdso_patches[i]; int match = (pvr & patch->pvr_mask) == patch->pvr_value; DBG("patch %d (mask: %x, pvr: %x) : %s\n", i, patch->pvr_mask, patch->pvr_value, match ? "match" : "skip"); if (!match) continue; DBG("replacing %s with %s...\n", patch->gen_name, patch->fix_name); /* * Patch the 32 bits and 64 bits symbols. Note that we do not patch * the "." symbol on 64 bits. It would be easy to do, but doesn't * seem to be necessary, patching the OPD symbol is enough. */ vdso_do_func_patch32(v32, v64, patch->gen_name, patch->fix_name); vdso_do_func_patch64(v32, v64, patch->gen_name, patch->fix_name); } return 0; } static __init int vdso_setup(void) { struct lib32_elfinfo v32; struct lib64_elfinfo v64; v32.hdr = vdso32_kbase; v64.hdr = vdso64_kbase; if (vdso_do_find_sections(&v32, &v64)) return -1; if (vdso_fixup_datapage(&v32, &v64)) return -1; if (vdso_fixup_alt_funcs(&v32, &v64)) return -1; vdso_setup_trampolines(&v32, &v64); return 0; } void __init vdso_init(void) { int i; vdso64_pages = (&vdso64_end - &vdso64_start) >> PAGE_SHIFT; vdso32_pages = (&vdso32_end - &vdso32_start) >> PAGE_SHIFT; DBG("vdso64_kbase: %p, 0x%x pages, vdso32_kbase: %p, 0x%x pages\n", vdso64_kbase, vdso64_pages, vdso32_kbase, vdso32_pages); /* * Initialize the vDSO images in memory, that is do necessary * fixups of vDSO symbols, locate trampolines, etc... */ if (vdso_setup()) { printk(KERN_ERR "vDSO setup failure, not enabled !\n"); /* XXX should free pages here ? */ vdso64_pages = vdso32_pages = 0; return; } /* Make sure pages are in the correct state */ for (i = 0; i < vdso64_pages; i++) { struct page *pg = virt_to_page(vdso64_kbase + i*PAGE_SIZE); ClearPageReserved(pg); get_page(pg); } for (i = 0; i < vdso32_pages; i++) { struct page *pg = virt_to_page(vdso32_kbase + i*PAGE_SIZE); ClearPageReserved(pg); get_page(pg); } } int in_gate_area_no_task(unsigned long addr) { return 0; } int in_gate_area(struct task_struct *task, unsigned long addr) { return 0; } struct vm_area_struct *get_gate_vma(struct task_struct *tsk) { return NULL; }