/* * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #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) { unsigned long val; int rc; rc = 0; if (strncmp(s, "on", 3) == 0) vdso_enabled = 1; else if (strncmp(s, "off", 4) == 0) vdso_enabled = 0; else { rc = strict_strtoul(s, 0, &val); vdso_enabled = rc ? 0 : !!val; } return !rc; } __setup("vdso=", vdso_setup); /* * The vdso data page */ static union { struct vdso_data data; u8 page[PAGE_SIZE]; } vdso_data_store __page_aligned_data; struct vdso_data *vdso_data = &vdso_data_store.data; /* * Setup vdso data page. */ static void vdso_init_data(struct vdso_data *vd) { vd->ectg_available = user_mode != HOME_SPACE_MODE && test_facility(31); } #ifdef CONFIG_64BIT /* * Setup per cpu vdso data page. */ static void vdso_init_per_cpu_data(int cpu, struct vdso_per_cpu_data *vpcd) { } /* * Allocate/free per cpu vdso data. */ #define SEGMENT_ORDER 2 int vdso_alloc_per_cpu(int cpu, struct _lowcore *lowcore) { unsigned long segment_table, page_table, page_frame; u32 *psal, *aste; int i; lowcore->vdso_per_cpu_data = __LC_PASTE; if (user_mode == HOME_SPACE_MODE || !vdso_enabled) return 0; segment_table = __get_free_pages(GFP_KERNEL, SEGMENT_ORDER); page_table = get_zeroed_page(GFP_KERNEL | GFP_DMA); page_frame = get_zeroed_page(GFP_KERNEL); if (!segment_table || !page_table || !page_frame) goto out; clear_table((unsigned long *) segment_table, _SEGMENT_ENTRY_EMPTY, PAGE_SIZE << SEGMENT_ORDER); clear_table((unsigned long *) page_table, _PAGE_TYPE_EMPTY, 256*sizeof(unsigned long)); *(unsigned long *) segment_table = _SEGMENT_ENTRY + page_table; *(unsigned long *) page_table = _PAGE_RO + page_frame; psal = (u32 *) (page_table + 256*sizeof(unsigned long)); aste = psal + 32; for (i = 4; i < 32; i += 4) psal[i] = 0x80000000; lowcore->paste[4] = (u32)(addr_t) psal; psal[0] = 0x20000000; psal[2] = (u32)(addr_t) aste; *(unsigned long *) (aste + 2) = segment_table + _ASCE_TABLE_LENGTH + _ASCE_USER_BITS + _ASCE_TYPE_SEGMENT; aste[4] = (u32)(addr_t) psal; lowcore->vdso_per_cpu_data = page_frame; vdso_init_per_cpu_data(cpu, (struct vdso_per_cpu_data *) page_frame); return 0; out: free_page(page_frame); free_page(page_table); free_pages(segment_table, SEGMENT_ORDER); return -ENOMEM; } void vdso_free_per_cpu(int cpu, struct _lowcore *lowcore) { unsigned long segment_table, page_table, page_frame; u32 *psal, *aste; if (user_mode == HOME_SPACE_MODE || !vdso_enabled) return; psal = (u32 *)(addr_t) lowcore->paste[4]; aste = (u32 *)(addr_t) psal[2]; segment_table = *(unsigned long *)(aste + 2) & PAGE_MASK; page_table = *(unsigned long *) segment_table; page_frame = *(unsigned long *) page_table; free_page(page_frame); free_page(page_table); free_pages(segment_table, SEGMENT_ORDER); } static void __vdso_init_cr5(void *dummy) { unsigned long cr5; cr5 = offsetof(struct _lowcore, paste); __ctl_load(cr5, 5, 5); } static void vdso_init_cr5(void) { if (user_mode != HOME_SPACE_MODE && vdso_enabled) on_each_cpu(__vdso_init_cr5, NULL, 1); } #endif /* CONFIG_64BIT */ /* * 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; #ifdef CONFIG_64BIT vdso_pagelist = vdso64_pagelist; vdso_pages = vdso64_pages; #ifdef CONFIG_COMPAT if (is_compat_task()) { 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, 0, vdso_pages << PAGE_SHIFT, 0, 0); if (IS_ERR_VALUE(vdso_base)) { rc = vdso_base; goto out_up; } /* * Put vDSO base into mm struct. We need to do this before calling * install_special_mapping or the perf counter mmap tracking code * will fail to recognise it as a vDSO (since arch_vma_name fails). */ current->mm->context.vdso_base = vdso_base; /* * 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) current->mm->context.vdso_base = 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 (!vdso_enabled) return 0; vdso_init_data(vdso_data); #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; #ifndef CONFIG_SMP if (vdso_alloc_per_cpu(0, &S390_lowcore)) BUG(); #endif vdso_init_cr5(); #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 mm_struct *mm) { return NULL; }