diff options
Diffstat (limited to 'arch/tile/kernel/vdso.c')
| -rw-r--r-- | arch/tile/kernel/vdso.c | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/arch/tile/kernel/vdso.c b/arch/tile/kernel/vdso.c new file mode 100644 index 000000000..5bc51d7df --- /dev/null +++ b/arch/tile/kernel/vdso.c @@ -0,0 +1,197 @@ +/* + * Copyright 2012 Tilera Corporation. All Rights Reserved. + * + * 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, version 2. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or + * NON INFRINGEMENT. See the GNU General Public License for + * more details. + */ + +#include <linux/binfmts.h> +#include <linux/compat.h> +#include <linux/elf.h> +#include <linux/mm.h> +#include <linux/pagemap.h> + +#include <asm/vdso.h> +#include <asm/mman.h> +#include <asm/sections.h> + +#include <arch/sim.h> + +/* The alignment of the vDSO. */ +#define VDSO_ALIGNMENT PAGE_SIZE + + +static unsigned int vdso_pages; +static struct page **vdso_pagelist; + +#ifdef CONFIG_COMPAT +static unsigned int vdso32_pages; +static struct page **vdso32_pagelist; +#endif +static int vdso_ready; + +/* + * 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; + +static unsigned int __read_mostly vdso_enabled = 1; + +static struct page **vdso_setup(void *vdso_kbase, unsigned int pages) +{ + int i; + struct page **pagelist; + + pagelist = kzalloc(sizeof(struct page *) * (pages + 1), GFP_KERNEL); + BUG_ON(pagelist == NULL); + for (i = 0; i < pages - 1; i++) { + struct page *pg = virt_to_page(vdso_kbase + i*PAGE_SIZE); + ClearPageReserved(pg); + pagelist[i] = pg; + } + pagelist[pages - 1] = virt_to_page(vdso_data); + pagelist[pages] = NULL; + + return pagelist; +} + +static int __init vdso_init(void) +{ + int data_pages = sizeof(vdso_data_store) >> PAGE_SHIFT; + + /* + * We can disable vDSO support generally, but we need to retain + * one page to support the two-bundle (16-byte) rt_sigreturn path. + */ + if (!vdso_enabled) { + size_t offset = (unsigned long)&__vdso_rt_sigreturn; + static struct page *sigret_page; + sigret_page = alloc_page(GFP_KERNEL | __GFP_ZERO); + BUG_ON(sigret_page == NULL); + vdso_pagelist = &sigret_page; + vdso_pages = 1; + BUG_ON(offset >= PAGE_SIZE); + memcpy(page_address(sigret_page) + offset, + vdso_start + offset, 16); +#ifdef CONFIG_COMPAT + vdso32_pages = vdso_pages; + vdso32_pagelist = vdso_pagelist; +#endif + vdso_ready = 1; + return 0; + } + + vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT; + vdso_pages += data_pages; + vdso_pagelist = vdso_setup(vdso_start, vdso_pages); + +#ifdef CONFIG_COMPAT + vdso32_pages = (vdso32_end - vdso32_start) >> PAGE_SHIFT; + vdso32_pages += data_pages; + vdso32_pagelist = vdso_setup(vdso32_start, vdso32_pages); +#endif + + smp_wmb(); + vdso_ready = 1; + + return 0; +} +arch_initcall(vdso_init); + +const char *arch_vma_name(struct vm_area_struct *vma) +{ + if (vma->vm_mm && vma->vm_start == VDSO_BASE) + return "[vdso]"; +#ifndef __tilegx__ + if (vma->vm_start == MEM_USER_INTRPT) + return "[intrpt]"; +#endif + return NULL; +} + +int setup_vdso_pages(void) +{ + struct page **pagelist; + unsigned long pages; + struct mm_struct *mm = current->mm; + unsigned long vdso_base = 0; + int retval = 0; + + if (!vdso_ready) + return 0; + + mm->context.vdso_base = 0; + + pagelist = vdso_pagelist; + pages = vdso_pages; +#ifdef CONFIG_COMPAT + if (is_compat_task()) { + pagelist = vdso32_pagelist; + pages = vdso32_pages; + } +#endif + + /* + * vDSO has a problem and was disabled, just don't "enable" it for the + * process. + */ + if (pages == 0) + return 0; + + vdso_base = get_unmapped_area(NULL, vdso_base, + (pages << PAGE_SHIFT) + + ((VDSO_ALIGNMENT - 1) & PAGE_MASK), + 0, 0); + if (IS_ERR_VALUE(vdso_base)) { + retval = vdso_base; + return retval; + } + + /* Add required alignment. */ + vdso_base = ALIGN(vdso_base, VDSO_ALIGNMENT); + + /* + * 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). + */ + 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 + */ + retval = install_special_mapping(mm, vdso_base, + pages << PAGE_SHIFT, + VM_READ|VM_EXEC | + VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC, + pagelist); + if (retval) + mm->context.vdso_base = 0; + + return retval; +} + +static __init int vdso_func(char *s) +{ + return kstrtouint(s, 0, &vdso_enabled); +} +__setup("vdso=", vdso_func); |