1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
4 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
8 #include <linux/sched/signal.h>
9 #include <linux/slab.h>
11 #include <asm/pgalloc.h>
12 #include <asm/sections.h>
13 #include <as-layout.h>
17 static int init_stub_pte(struct mm_struct *mm, unsigned long proc,
26 pgd = pgd_offset(mm, proc);
28 p4d = p4d_alloc(mm, pgd, proc);
32 pud = pud_alloc(mm, p4d, proc);
36 pmd = pmd_alloc(mm, pud, proc);
40 pte = pte_alloc_map(mm, pmd, proc);
44 *pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT));
45 *pte = pte_mkread(*pte);
58 int init_new_context(struct task_struct *task, struct mm_struct *mm)
60 struct mm_context *from_mm = NULL;
61 struct mm_context *to_mm = &mm->context;
62 unsigned long stack = 0;
65 stack = get_zeroed_page(GFP_KERNEL);
69 to_mm->id.stack = stack;
70 if (current->mm != NULL && current->mm != &init_mm)
71 from_mm = ¤t->mm->context;
73 block_signals_trace();
75 to_mm->id.u.pid = copy_context_skas0(stack,
77 else to_mm->id.u.pid = start_userspace(stack);
78 unblock_signals_trace();
80 if (to_mm->id.u.pid < 0) {
81 ret = to_mm->id.u.pid;
85 ret = init_new_ldt(to_mm, from_mm);
87 printk(KERN_ERR "init_new_context_skas - init_ldt"
88 " failed, errno = %d\n", ret);
95 if (to_mm->id.stack != 0)
96 free_page(to_mm->id.stack);
101 void uml_setup_stubs(struct mm_struct *mm)
105 ret = init_stub_pte(mm, STUB_CODE,
106 (unsigned long) __syscall_stub_start);
110 ret = init_stub_pte(mm, STUB_DATA, mm->context.id.stack);
114 mm->context.stub_pages[0] = virt_to_page(__syscall_stub_start);
115 mm->context.stub_pages[1] = virt_to_page(mm->context.id.stack);
117 /* dup_mmap already holds mmap_sem */
118 err = install_special_mapping(mm, STUB_START, STUB_END - STUB_START,
119 VM_READ | VM_MAYREAD | VM_EXEC |
120 VM_MAYEXEC | VM_DONTCOPY | VM_PFNMAP,
121 mm->context.stub_pages);
123 printk(KERN_ERR "install_special_mapping returned %d\n", err);
129 force_sigsegv(SIGSEGV);
132 void arch_exit_mmap(struct mm_struct *mm)
136 pte = virt_to_pte(mm, STUB_CODE);
138 pte_clear(mm, STUB_CODE, pte);
140 pte = virt_to_pte(mm, STUB_DATA);
144 pte_clear(mm, STUB_DATA, pte);
147 void destroy_context(struct mm_struct *mm)
149 struct mm_context *mmu = &mm->context;
152 * If init_new_context wasn't called, this will be
153 * zero, resulting in a kill(0), which will result in the
154 * whole UML suddenly dying. Also, cover negative and
155 * 1 cases, since they shouldn't happen either.
157 if (mmu->id.u.pid < 2) {
158 printk(KERN_ERR "corrupt mm_context - pid = %d\n",
162 os_kill_ptraced_process(mmu->id.u.pid, 1);
164 free_page(mmu->id.stack);