1 /* 2 * This file is subject to the terms and conditions of the GNU General Public 3 * License. See the file "COPYING" in the main directory of this archive 4 * for more details. 5 * 6 * Copyright (C) 2009, 2010 Cavium Networks, Inc. 7 */ 8 9 10 #include <linux/kernel.h> 11 #include <linux/err.h> 12 #include <linux/sched.h> 13 #include <linux/mm.h> 14 #include <linux/init.h> 15 #include <linux/binfmts.h> 16 #include <linux/elf.h> 17 #include <linux/vmalloc.h> 18 #include <linux/unistd.h> 19 #include <linux/random.h> 20 21 #include <asm/vdso.h> 22 #include <asm/uasm.h> 23 #include <asm/processor.h> 24 25 /* 26 * Including <asm/unistd.h> would give use the 64-bit syscall numbers ... 27 */ 28 #define __NR_O32_sigreturn 4119 29 #define __NR_O32_rt_sigreturn 4193 30 #define __NR_N32_rt_sigreturn 6211 31 32 static struct page *vdso_page; 33 34 static void __init install_trampoline(u32 *tramp, unsigned int sigreturn) 35 { 36 uasm_i_addiu(&tramp, 2, 0, sigreturn); /* li v0, sigreturn */ 37 uasm_i_syscall(&tramp, 0); 38 } 39 40 static int __init init_vdso(void) 41 { 42 struct mips_vdso *vdso; 43 44 vdso_page = alloc_page(GFP_KERNEL); 45 if (!vdso_page) 46 panic("Cannot allocate vdso"); 47 48 vdso = vmap(&vdso_page, 1, 0, PAGE_KERNEL); 49 if (!vdso) 50 panic("Cannot map vdso"); 51 clear_page(vdso); 52 53 install_trampoline(vdso->rt_signal_trampoline, __NR_rt_sigreturn); 54 #ifdef CONFIG_32BIT 55 install_trampoline(vdso->signal_trampoline, __NR_sigreturn); 56 #else 57 install_trampoline(vdso->n32_rt_signal_trampoline, 58 __NR_N32_rt_sigreturn); 59 install_trampoline(vdso->o32_signal_trampoline, __NR_O32_sigreturn); 60 install_trampoline(vdso->o32_rt_signal_trampoline, 61 __NR_O32_rt_sigreturn); 62 #endif 63 64 vunmap(vdso); 65 66 return 0; 67 } 68 subsys_initcall(init_vdso); 69 70 static unsigned long vdso_addr(unsigned long start) 71 { 72 unsigned long offset = 0UL; 73 74 if (current->flags & PF_RANDOMIZE) { 75 offset = get_random_int(); 76 offset <<= PAGE_SHIFT; 77 if (TASK_IS_32BIT_ADDR) 78 offset &= 0xfffffful; 79 else 80 offset &= 0xffffffful; 81 } 82 83 return STACK_TOP + offset; 84 } 85 86 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 87 { 88 int ret; 89 unsigned long addr; 90 struct mm_struct *mm = current->mm; 91 92 down_write(&mm->mmap_sem); 93 94 addr = vdso_addr(mm->start_stack); 95 96 addr = get_unmapped_area(NULL, addr, PAGE_SIZE, 0, 0); 97 if (IS_ERR_VALUE(addr)) { 98 ret = addr; 99 goto up_fail; 100 } 101 102 ret = install_special_mapping(mm, addr, PAGE_SIZE, 103 VM_READ|VM_EXEC| 104 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, 105 &vdso_page); 106 107 if (ret) 108 goto up_fail; 109 110 mm->context.vdso = (void *)addr; 111 112 up_fail: 113 up_write(&mm->mmap_sem); 114 return ret; 115 } 116 117 const char *arch_vma_name(struct vm_area_struct *vma) 118 { 119 if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso) 120 return "[vdso]"; 121 return NULL; 122 } 123