334 строки
8.2 KiB
C
334 строки
8.2 KiB
C
/*
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* vdso setup for s390
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*
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* Copyright IBM Corp. 2008
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* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License (version 2 only)
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* as published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/errno.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/smp.h>
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#include <linux/stddef.h>
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#include <linux/unistd.h>
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#include <linux/slab.h>
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#include <linux/user.h>
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#include <linux/elf.h>
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#include <linux/security.h>
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#include <linux/bootmem.h>
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#include <linux/compat.h>
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#include <asm/asm-offsets.h>
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#include <asm/pgtable.h>
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#include <asm/processor.h>
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#include <asm/mmu.h>
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#include <asm/mmu_context.h>
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#include <asm/sections.h>
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#include <asm/vdso.h>
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#include <asm/facility.h>
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#if defined(CONFIG_32BIT) || defined(CONFIG_COMPAT)
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extern char vdso32_start, vdso32_end;
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static void *vdso32_kbase = &vdso32_start;
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static unsigned int vdso32_pages;
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static struct page **vdso32_pagelist;
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#endif
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#ifdef CONFIG_64BIT
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extern char vdso64_start, vdso64_end;
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static void *vdso64_kbase = &vdso64_start;
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static unsigned int vdso64_pages;
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static struct page **vdso64_pagelist;
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#endif /* CONFIG_64BIT */
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/*
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* Should the kernel map a VDSO page into processes and pass its
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* address down to glibc upon exec()?
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*/
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unsigned int __read_mostly vdso_enabled = 1;
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static int __init vdso_setup(char *s)
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{
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unsigned long val;
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int rc;
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rc = 0;
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if (strncmp(s, "on", 3) == 0)
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vdso_enabled = 1;
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else if (strncmp(s, "off", 4) == 0)
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vdso_enabled = 0;
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else {
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rc = strict_strtoul(s, 0, &val);
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vdso_enabled = rc ? 0 : !!val;
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}
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return !rc;
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}
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__setup("vdso=", vdso_setup);
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/*
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* The vdso data page
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*/
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static union {
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struct vdso_data data;
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u8 page[PAGE_SIZE];
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} vdso_data_store __page_aligned_data;
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struct vdso_data *vdso_data = &vdso_data_store.data;
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/*
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* Setup vdso data page.
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*/
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static void vdso_init_data(struct vdso_data *vd)
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{
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vd->ectg_available = user_mode != HOME_SPACE_MODE && test_facility(31);
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}
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#ifdef CONFIG_64BIT
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/*
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* Allocate/free per cpu vdso data.
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*/
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#define SEGMENT_ORDER 2
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int vdso_alloc_per_cpu(struct _lowcore *lowcore)
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{
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unsigned long segment_table, page_table, page_frame;
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u32 *psal, *aste;
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int i;
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lowcore->vdso_per_cpu_data = __LC_PASTE;
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if (user_mode == HOME_SPACE_MODE || !vdso_enabled)
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return 0;
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segment_table = __get_free_pages(GFP_KERNEL, SEGMENT_ORDER);
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page_table = get_zeroed_page(GFP_KERNEL | GFP_DMA);
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page_frame = get_zeroed_page(GFP_KERNEL);
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if (!segment_table || !page_table || !page_frame)
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goto out;
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clear_table((unsigned long *) segment_table, _SEGMENT_ENTRY_EMPTY,
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PAGE_SIZE << SEGMENT_ORDER);
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clear_table((unsigned long *) page_table, _PAGE_TYPE_EMPTY,
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256*sizeof(unsigned long));
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*(unsigned long *) segment_table = _SEGMENT_ENTRY + page_table;
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*(unsigned long *) page_table = _PAGE_RO + page_frame;
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psal = (u32 *) (page_table + 256*sizeof(unsigned long));
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aste = psal + 32;
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for (i = 4; i < 32; i += 4)
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psal[i] = 0x80000000;
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lowcore->paste[4] = (u32)(addr_t) psal;
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psal[0] = 0x20000000;
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psal[2] = (u32)(addr_t) aste;
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*(unsigned long *) (aste + 2) = segment_table +
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_ASCE_TABLE_LENGTH + _ASCE_USER_BITS + _ASCE_TYPE_SEGMENT;
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aste[4] = (u32)(addr_t) psal;
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lowcore->vdso_per_cpu_data = page_frame;
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return 0;
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out:
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free_page(page_frame);
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free_page(page_table);
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free_pages(segment_table, SEGMENT_ORDER);
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return -ENOMEM;
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}
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void vdso_free_per_cpu(struct _lowcore *lowcore)
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{
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unsigned long segment_table, page_table, page_frame;
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u32 *psal, *aste;
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if (user_mode == HOME_SPACE_MODE || !vdso_enabled)
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return;
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psal = (u32 *)(addr_t) lowcore->paste[4];
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aste = (u32 *)(addr_t) psal[2];
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segment_table = *(unsigned long *)(aste + 2) & PAGE_MASK;
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page_table = *(unsigned long *) segment_table;
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page_frame = *(unsigned long *) page_table;
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free_page(page_frame);
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free_page(page_table);
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free_pages(segment_table, SEGMENT_ORDER);
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}
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static void vdso_init_cr5(void)
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{
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unsigned long cr5;
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if (user_mode == HOME_SPACE_MODE || !vdso_enabled)
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return;
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cr5 = offsetof(struct _lowcore, paste);
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__ctl_load(cr5, 5, 5);
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}
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#endif /* CONFIG_64BIT */
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/*
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* This is called from binfmt_elf, we create the special vma for the
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* vDSO and insert it into the mm struct tree
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*/
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int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
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{
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struct mm_struct *mm = current->mm;
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struct page **vdso_pagelist;
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unsigned long vdso_pages;
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unsigned long vdso_base;
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int rc;
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if (!vdso_enabled)
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return 0;
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/*
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* Only map the vdso for dynamically linked elf binaries.
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*/
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if (!uses_interp)
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return 0;
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#ifdef CONFIG_64BIT
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vdso_pagelist = vdso64_pagelist;
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vdso_pages = vdso64_pages;
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#ifdef CONFIG_COMPAT
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if (is_compat_task()) {
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vdso_pagelist = vdso32_pagelist;
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vdso_pages = vdso32_pages;
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}
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#endif
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#else
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vdso_pagelist = vdso32_pagelist;
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vdso_pages = vdso32_pages;
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#endif
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/*
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* vDSO has a problem and was disabled, just don't "enable" it for
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* the process
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*/
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if (vdso_pages == 0)
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return 0;
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current->mm->context.vdso_base = 0;
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/*
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* pick a base address for the vDSO in process space. We try to put
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* it at vdso_base which is the "natural" base for it, but we might
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* fail and end up putting it elsewhere.
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*/
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down_write(&mm->mmap_sem);
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vdso_base = get_unmapped_area(NULL, 0, vdso_pages << PAGE_SHIFT, 0, 0);
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if (IS_ERR_VALUE(vdso_base)) {
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rc = vdso_base;
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goto out_up;
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}
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/*
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* Put vDSO base into mm struct. We need to do this before calling
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* install_special_mapping or the perf counter mmap tracking code
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* will fail to recognise it as a vDSO (since arch_vma_name fails).
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*/
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current->mm->context.vdso_base = vdso_base;
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/*
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* our vma flags don't have VM_WRITE so by default, the process
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* isn't allowed to write those pages.
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* gdb can break that with ptrace interface, and thus trigger COW
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* on those pages but it's then your responsibility to never do that
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* on the "data" page of the vDSO or you'll stop getting kernel
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* updates and your nice userland gettimeofday will be totally dead.
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* It's fine to use that for setting breakpoints in the vDSO code
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* pages though.
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*/
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rc = install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
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VM_READ|VM_EXEC|
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VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
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vdso_pagelist);
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if (rc)
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current->mm->context.vdso_base = 0;
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out_up:
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up_write(&mm->mmap_sem);
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return rc;
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}
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const char *arch_vma_name(struct vm_area_struct *vma)
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{
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if (vma->vm_mm && vma->vm_start == vma->vm_mm->context.vdso_base)
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return "[vdso]";
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return NULL;
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}
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static int __init vdso_init(void)
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{
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int i;
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if (!vdso_enabled)
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return 0;
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vdso_init_data(vdso_data);
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#if defined(CONFIG_32BIT) || defined(CONFIG_COMPAT)
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/* Calculate the size of the 32 bit vDSO */
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vdso32_pages = ((&vdso32_end - &vdso32_start
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+ PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;
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/* Make sure pages are in the correct state */
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vdso32_pagelist = kzalloc(sizeof(struct page *) * (vdso32_pages + 1),
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GFP_KERNEL);
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BUG_ON(vdso32_pagelist == NULL);
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for (i = 0; i < vdso32_pages - 1; i++) {
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struct page *pg = virt_to_page(vdso32_kbase + i*PAGE_SIZE);
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ClearPageReserved(pg);
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get_page(pg);
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vdso32_pagelist[i] = pg;
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}
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vdso32_pagelist[vdso32_pages - 1] = virt_to_page(vdso_data);
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vdso32_pagelist[vdso32_pages] = NULL;
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#endif
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#ifdef CONFIG_64BIT
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/* Calculate the size of the 64 bit vDSO */
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vdso64_pages = ((&vdso64_end - &vdso64_start
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+ PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;
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/* Make sure pages are in the correct state */
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vdso64_pagelist = kzalloc(sizeof(struct page *) * (vdso64_pages + 1),
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GFP_KERNEL);
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BUG_ON(vdso64_pagelist == NULL);
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for (i = 0; i < vdso64_pages - 1; i++) {
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struct page *pg = virt_to_page(vdso64_kbase + i*PAGE_SIZE);
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ClearPageReserved(pg);
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get_page(pg);
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vdso64_pagelist[i] = pg;
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}
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vdso64_pagelist[vdso64_pages - 1] = virt_to_page(vdso_data);
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vdso64_pagelist[vdso64_pages] = NULL;
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if (vdso_alloc_per_cpu(&S390_lowcore))
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BUG();
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vdso_init_cr5();
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#endif /* CONFIG_64BIT */
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get_page(virt_to_page(vdso_data));
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smp_wmb();
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return 0;
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}
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early_initcall(vdso_init);
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int in_gate_area_no_mm(unsigned long addr)
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{
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return 0;
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}
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int in_gate_area(struct mm_struct *mm, unsigned long addr)
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{
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return 0;
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}
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struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
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{
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return NULL;
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}
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