diff options
Diffstat (limited to 'arch/um/kernel/skas/mmu.c')
| -rw-r--r-- | arch/um/kernel/skas/mmu.c | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c new file mode 100644 index 000000000..d9961163d --- /dev/null +++ b/arch/um/kernel/skas/mmu.c @@ -0,0 +1,166 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de) + * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) + */ + +#include <linux/mm.h> +#include <linux/sched/signal.h> +#include <linux/slab.h> + +#include <asm/pgalloc.h> +#include <asm/sections.h> +#include <as-layout.h> +#include <os.h> +#include <skas.h> + +static int init_stub_pte(struct mm_struct *mm, unsigned long proc, + unsigned long kernel) +{ + pgd_t *pgd; + p4d_t *p4d; + pud_t *pud; + pmd_t *pmd; + pte_t *pte; + + pgd = pgd_offset(mm, proc); + + p4d = p4d_alloc(mm, pgd, proc); + if (!p4d) + goto out; + + pud = pud_alloc(mm, p4d, proc); + if (!pud) + goto out_pud; + + pmd = pmd_alloc(mm, pud, proc); + if (!pmd) + goto out_pmd; + + pte = pte_alloc_map(mm, 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_pud: + p4d_free(mm, p4d); + 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; + + block_signals_trace(); + 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); + unblock_signals_trace(); + + 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_lock */ + 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); +} + +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); +} |