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