diff options
Diffstat (limited to '')
-rw-r--r-- | arch/hexagon/kernel/vdso.c | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/arch/hexagon/kernel/vdso.c b/arch/hexagon/kernel/vdso.c new file mode 100644 index 000000000..3ea968415 --- /dev/null +++ b/arch/hexagon/kernel/vdso.c @@ -0,0 +1,101 @@ +/* + * vDSO implementation for Hexagon + * + * Copyright (c) 2011, The Linux Foundation. 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 version 2 and + * only version 2 as published by the Free Software Foundation. + * + * 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. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA + * 02110-1301, USA. + */ + +#include <linux/err.h> +#include <linux/mm.h> +#include <linux/vmalloc.h> +#include <linux/binfmts.h> + +#include <asm/vdso.h> + +static struct page *vdso_page; + +/* Create a vDSO page holding the signal trampoline. + * We want this for a non-executable stack. + */ +static int __init vdso_init(void) +{ + struct hexagon_vdso *vdso; + + vdso_page = alloc_page(GFP_KERNEL); + if (!vdso_page) + panic("Cannot allocate vdso"); + + vdso = vmap(&vdso_page, 1, 0, PAGE_KERNEL); + if (!vdso) + panic("Cannot map vdso"); + clear_page(vdso); + + /* Install the signal trampoline; currently looks like this: + * r6 = #__NR_rt_sigreturn; + * trap0(#1); + */ + vdso->rt_signal_trampoline[0] = __rt_sigtramp_template[0]; + vdso->rt_signal_trampoline[1] = __rt_sigtramp_template[1]; + + vunmap(vdso); + + return 0; +} +arch_initcall(vdso_init); + +/* + * Called from binfmt_elf. Create a VMA for the vDSO page. + */ +int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) +{ + int ret; + unsigned long vdso_base; + struct mm_struct *mm = current->mm; + + if (down_write_killable(&mm->mmap_sem)) + return -EINTR; + + /* Try to get it loaded right near ld.so/glibc. */ + vdso_base = STACK_TOP; + + vdso_base = get_unmapped_area(NULL, vdso_base, PAGE_SIZE, 0, 0); + if (IS_ERR_VALUE(vdso_base)) { + ret = vdso_base; + goto up_fail; + } + + /* MAYWRITE to allow gdb to COW and set breakpoints. */ + ret = install_special_mapping(mm, vdso_base, PAGE_SIZE, + VM_READ|VM_EXEC| + VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, + &vdso_page); + + if (ret) + goto up_fail; + + mm->context.vdso = (void *)vdso_base; + +up_fail: + up_write(&mm->mmap_sem); + return ret; +} + +const char *arch_vma_name(struct vm_area_struct *vma) +{ + if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso) + return "[vdso]"; + return NULL; +} |