2 * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
3 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4 * Licensed under the GPL
8 #include <linux/sched/signal.h>
9 #include <linux/slab.h>
11 #include <asm/pgalloc.h>
12 #include <asm/pgtable.h>
13 #include <asm/sections.h>
14 #include <as-layout.h>
18 static int init_stub_pte(struct mm_struct *mm, unsigned long proc,
26 pgd = pgd_offset(mm, proc);
27 pud = pud_alloc(mm, pgd, proc);
31 pmd = pmd_alloc(mm, pud, proc);
35 pte = pte_alloc_map(mm, pmd, proc);
39 *pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT));
40 *pte = pte_mkread(*pte);
51 int init_new_context(struct task_struct *task, struct mm_struct *mm)
53 struct mm_context *from_mm = NULL;
54 struct mm_context *to_mm = &mm->context;
55 unsigned long stack = 0;
58 stack = get_zeroed_page(GFP_KERNEL);
62 to_mm->id.stack = stack;
63 if (current->mm != NULL && current->mm != &init_mm)
64 from_mm = ¤t->mm->context;
68 to_mm->id.u.pid = copy_context_skas0(stack,
70 else to_mm->id.u.pid = start_userspace(stack);
73 if (to_mm->id.u.pid < 0) {
74 ret = to_mm->id.u.pid;
78 ret = init_new_ldt(to_mm, from_mm);
80 printk(KERN_ERR "init_new_context_skas - init_ldt"
81 " failed, errno = %d\n", ret);
88 if (to_mm->id.stack != 0)
89 free_page(to_mm->id.stack);
94 void uml_setup_stubs(struct mm_struct *mm)
98 ret = init_stub_pte(mm, STUB_CODE,
99 (unsigned long) __syscall_stub_start);
103 ret = init_stub_pte(mm, STUB_DATA, mm->context.id.stack);
107 mm->context.stub_pages[0] = virt_to_page(__syscall_stub_start);
108 mm->context.stub_pages[1] = virt_to_page(mm->context.id.stack);
110 /* dup_mmap already holds mmap_sem */
111 err = install_special_mapping(mm, STUB_START, STUB_END - STUB_START,
112 VM_READ | VM_MAYREAD | VM_EXEC |
113 VM_MAYEXEC | VM_DONTCOPY | VM_PFNMAP,
114 mm->context.stub_pages);
116 printk(KERN_ERR "install_special_mapping returned %d\n", err);
122 force_sigsegv(SIGSEGV, current);
125 void arch_exit_mmap(struct mm_struct *mm)
129 pte = virt_to_pte(mm, STUB_CODE);
131 pte_clear(mm, STUB_CODE, pte);
133 pte = virt_to_pte(mm, STUB_DATA);
137 pte_clear(mm, STUB_DATA, pte);
140 void destroy_context(struct mm_struct *mm)
142 struct mm_context *mmu = &mm->context;
145 * If init_new_context wasn't called, this will be
146 * zero, resulting in a kill(0), which will result in the
147 * whole UML suddenly dying. Also, cover negative and
148 * 1 cases, since they shouldn't happen either.
150 if (mmu->id.u.pid < 2) {
151 printk(KERN_ERR "corrupt mm_context - pid = %d\n",
155 os_kill_ptraced_process(mmu->id.u.pid, 1);
157 free_page(mmu->id.stack);