160 lines
3.3 KiB
C
160 lines
3.3 KiB
C
/*
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* Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
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* Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
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* Licensed under the GPL
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*/
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#include <linux/mm.h>
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#include <linux/sched/signal.h>
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#include <linux/slab.h>
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#include <asm/pgalloc.h>
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#include <asm/pgtable.h>
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#include <asm/sections.h>
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#include <as-layout.h>
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#include <os.h>
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#include <skas.h>
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static int init_stub_pte(struct mm_struct *mm, unsigned long proc,
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unsigned long kernel)
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{
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pgd_t *pgd;
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pud_t *pud;
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pmd_t *pmd;
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pte_t *pte;
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pgd = pgd_offset(mm, proc);
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pud = pud_alloc(mm, pgd, proc);
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if (!pud)
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goto out;
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pmd = pmd_alloc(mm, pud, proc);
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if (!pmd)
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goto out_pmd;
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pte = pte_alloc_map(mm, pmd, proc);
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if (!pte)
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goto out_pte;
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*pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT));
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*pte = pte_mkread(*pte);
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return 0;
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out_pte:
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pmd_free(mm, pmd);
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out_pmd:
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pud_free(mm, pud);
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out:
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return -ENOMEM;
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}
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int init_new_context(struct task_struct *task, struct mm_struct *mm)
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{
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struct mm_context *from_mm = NULL;
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struct mm_context *to_mm = &mm->context;
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unsigned long stack = 0;
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int ret = -ENOMEM;
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stack = get_zeroed_page(GFP_KERNEL);
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if (stack == 0)
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goto out;
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to_mm->id.stack = stack;
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if (current->mm != NULL && current->mm != &init_mm)
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from_mm = ¤t->mm->context;
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block_signals();
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if (from_mm)
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to_mm->id.u.pid = copy_context_skas0(stack,
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from_mm->id.u.pid);
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else to_mm->id.u.pid = start_userspace(stack);
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unblock_signals();
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if (to_mm->id.u.pid < 0) {
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ret = to_mm->id.u.pid;
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goto out_free;
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}
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ret = init_new_ldt(to_mm, from_mm);
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if (ret < 0) {
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printk(KERN_ERR "init_new_context_skas - init_ldt"
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" failed, errno = %d\n", ret);
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goto out_free;
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}
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return 0;
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out_free:
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if (to_mm->id.stack != 0)
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free_page(to_mm->id.stack);
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out:
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return ret;
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}
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void uml_setup_stubs(struct mm_struct *mm)
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{
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int err, ret;
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ret = init_stub_pte(mm, STUB_CODE,
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(unsigned long) __syscall_stub_start);
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if (ret)
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goto out;
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ret = init_stub_pte(mm, STUB_DATA, mm->context.id.stack);
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if (ret)
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goto out;
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mm->context.stub_pages[0] = virt_to_page(__syscall_stub_start);
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mm->context.stub_pages[1] = virt_to_page(mm->context.id.stack);
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/* dup_mmap already holds mmap_sem */
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err = install_special_mapping(mm, STUB_START, STUB_END - STUB_START,
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VM_READ | VM_MAYREAD | VM_EXEC |
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VM_MAYEXEC | VM_DONTCOPY | VM_PFNMAP,
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mm->context.stub_pages);
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if (err) {
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printk(KERN_ERR "install_special_mapping returned %d\n", err);
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goto out;
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}
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return;
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out:
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force_sigsegv(SIGSEGV, current);
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}
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void arch_exit_mmap(struct mm_struct *mm)
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{
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pte_t *pte;
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pte = virt_to_pte(mm, STUB_CODE);
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if (pte != NULL)
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pte_clear(mm, STUB_CODE, pte);
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pte = virt_to_pte(mm, STUB_DATA);
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if (pte == NULL)
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return;
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pte_clear(mm, STUB_DATA, pte);
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}
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void destroy_context(struct mm_struct *mm)
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{
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struct mm_context *mmu = &mm->context;
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/*
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* If init_new_context wasn't called, this will be
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* zero, resulting in a kill(0), which will result in the
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* whole UML suddenly dying. Also, cover negative and
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* 1 cases, since they shouldn't happen either.
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*/
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if (mmu->id.u.pid < 2) {
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printk(KERN_ERR "corrupt mm_context - pid = %d\n",
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mmu->id.u.pid);
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return;
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}
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os_kill_ptraced_process(mmu->id.u.pid, 1);
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free_page(mmu->id.stack);
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free_ldt(mmu);
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}
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