/* * vdso setup for s390 * * Copyright IBM Corp. 2008 * Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com) * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License (version 2 only) * as published by the Free Software Foundation. */ #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/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/sections.h> #include <asm/vdso.h> /* Max supported size for symbol names */ #define MAX_SYMNAME 64 #if defined(CONFIG_32BIT) || defined(CONFIG_COMPAT) extern char vdso32_start, vdso32_end; static void *vdso32_kbase = &vdso32_start; static unsigned int vdso32_pages; static struct page **vdso32_pagelist; #endif #ifdef CONFIG_64BIT extern char vdso64_start, vdso64_end; static void *vdso64_kbase = &vdso64_start; static unsigned int vdso64_pages; static struct page **vdso64_pagelist; #endif /* CONFIG_64BIT */ /* * Should the kernel map a VDSO page into processes and pass its * address down to glibc upon exec()? */ unsigned int __read_mostly vdso_enabled = 1; static int __init vdso_setup(char *s) { vdso_enabled = simple_strtoul(s, NULL, 0); return 1; } __setup("vdso=", vdso_setup); /* * The vdso data page */ static union { struct vdso_data data; u8 page[PAGE_SIZE]; } vdso_data_store __attribute__((__section__(".data.page_aligned"))); struct vdso_data *vdso_data = &vdso_data_store.data; /* * 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 uses_interp) { struct mm_struct *mm = current->mm; struct page **vdso_pagelist; unsigned long vdso_pages; unsigned long vdso_base; int rc; if (!vdso_enabled) return 0; /* * Only map the vdso for dynamically linked elf binaries. */ if (!uses_interp) return 0; vdso_base = mm->mmap_base; #ifdef CONFIG_64BIT vdso_pagelist = vdso64_pagelist; vdso_pages = vdso64_pages; #ifdef CONFIG_COMPAT if (test_thread_flag(TIF_31BIT)) { vdso_pagelist = vdso32_pagelist; vdso_pages = vdso32_pages; } #endif #else vdso_pagelist = vdso32_pagelist; vdso_pages = vdso32_pages; #endif /* * vDSO has a problem and was disabled, just don't "enable" it for * the process */ if (vdso_pages == 0) return 0; current->mm->context.vdso_base = 0; /* * 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. */ down_write(&mm->mmap_sem); vdso_base = get_unmapped_area(NULL, vdso_base, vdso_pages << PAGE_SHIFT, 0, 0); if (IS_ERR_VALUE(vdso_base)) { rc = vdso_base; goto out_up; } /* * 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 * * Make sure the vDSO gets into every core dump. * Dumping its contents makes post-mortem fully interpretable later * without matching up the same kernel and hardware config to see * what PC values meant. */ rc = install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT, VM_READ|VM_EXEC| VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC| VM_ALWAYSDUMP, vdso_pagelist); if (rc) goto out_up; /* Put vDSO base into mm struct */ current->mm->context.vdso_base = vdso_base; up_write(&mm->mmap_sem); return 0; out_up: up_write(&mm->mmap_sem); return rc; } const char *arch_vma_name(struct vm_area_struct *vma) { if (vma->vm_mm && vma->vm_start == vma->vm_mm->context.vdso_base) return "[vdso]"; return NULL; } static int __init vdso_init(void) { int i; #if defined(CONFIG_32BIT) || defined(CONFIG_COMPAT) /* Calculate the size of the 32 bit vDSO */ vdso32_pages = ((&vdso32_end - &vdso32_start + PAGE_SIZE - 1) >> PAGE_SHIFT) + 1; /* Make sure pages are in the correct state */ vdso32_pagelist = kzalloc(sizeof(struct page *) * (vdso32_pages + 1), GFP_KERNEL); BUG_ON(vdso32_pagelist == NULL); for (i = 0; i < vdso32_pages - 1; i++) { struct page *pg = virt_to_page(vdso32_kbase + i*PAGE_SIZE); ClearPageReserved(pg); get_page(pg); vdso32_pagelist[i] = pg; } vdso32_pagelist[vdso32_pages - 1] = virt_to_page(vdso_data); vdso32_pagelist[vdso32_pages] = NULL; #endif #ifdef CONFIG_64BIT /* Calculate the size of the 64 bit vDSO */ vdso64_pages = ((&vdso64_end - &vdso64_start + PAGE_SIZE - 1) >> PAGE_SHIFT) + 1; /* Make sure pages are in the correct state */ vdso64_pagelist = kzalloc(sizeof(struct page *) * (vdso64_pages + 1), GFP_KERNEL); BUG_ON(vdso64_pagelist == NULL); for (i = 0; i < vdso64_pages - 1; i++) { struct page *pg = virt_to_page(vdso64_kbase + i*PAGE_SIZE); ClearPageReserved(pg); get_page(pg); vdso64_pagelist[i] = pg; } vdso64_pagelist[vdso64_pages - 1] = virt_to_page(vdso_data); vdso64_pagelist[vdso64_pages] = NULL; #endif /* CONFIG_64BIT */ get_page(virt_to_page(vdso_data)); smp_wmb(); return 0; } arch_initcall(vdso_init); 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; }