diff options
author | David Woodhouse <dwmw2@shinybook.infradead.org> | 2005-07-13 15:25:59 +0100 |
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committer | David Woodhouse <dwmw2@shinybook.infradead.org> | 2005-07-13 15:25:59 +0100 |
commit | 30beab1491f0b96b2f23d3fb68af01fd921a16d8 (patch) | |
tree | c580bdc0846269fbb10feeda901ecec1a48ee2ef /arch/um/kernel/skas/mmu.c | |
parent | 21af6c4f2aa5f63138871b4ddd77d7ebf2588c9d (diff) | |
parent | c32511e2718618f0b53479eb36e07439aa363a74 (diff) |
Merge with /shiny/git/linux-2.6/.git
Diffstat (limited to 'arch/um/kernel/skas/mmu.c')
-rw-r--r-- | arch/um/kernel/skas/mmu.c | 141 |
1 files changed, 119 insertions, 22 deletions
diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c index 6cb9a6d028a..d232daa42c3 100644 --- a/arch/um/kernel/skas/mmu.c +++ b/arch/um/kernel/skas/mmu.c @@ -3,46 +3,143 @@ * Licensed under the GPL */ +#include "linux/config.h" #include "linux/sched.h" #include "linux/list.h" #include "linux/spinlock.h" #include "linux/slab.h" +#include "linux/errno.h" +#include "linux/mm.h" #include "asm/current.h" #include "asm/segment.h" #include "asm/mmu.h" +#include "asm/pgalloc.h" +#include "asm/pgtable.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; + + spin_lock(&mm->page_table_lock); + 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, pmd, proc); + if (!pte) + goto out_pte; + + /* There's an interaction between the skas0 stub pages, stack + * randomization, and the BUG at the end of exit_mmap. exit_mmap + * checks that the number of page tables freed is the same as had + * been allocated. If the stack is on the last page table page, + * then the stack pte page will be freed, and if not, it won't. To + * avoid having to know where the stack is, or if the process mapped + * something at the top of its address space for some other reason, + * we set TASK_SIZE to end at the start of the last page table. + * This keeps exit_mmap off the last page, but introduces a leak + * of that page. So, we hang onto it here and free it in + * destroy_context_skas. + */ + + mm->context.skas.last_page_table = pmd_page_kernel(*pmd); + + *pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT)); + *pte = pte_mkexec(*pte); + *pte = pte_wrprotect(*pte); + spin_unlock(&mm->page_table_lock); + return(0); + + out_pmd: + pud_free(pud); + out_pte: + pmd_free(pmd); + out: + spin_unlock(&mm->page_table_lock); + return(-ENOMEM); +} + int init_new_context_skas(struct task_struct *task, struct mm_struct *mm) { - int from; + struct mm_struct *cur_mm = current->mm; + struct mm_id *cur_mm_id = &cur_mm->context.skas.id; + struct mm_id *mm_id = &mm->context.skas.id; + unsigned long stack; + int from, ret; - if((current->mm != NULL) && (current->mm != &init_mm)) - from = current->mm->context.skas.mm_fd; - else from = -1; + if(proc_mm){ + if((cur_mm != NULL) && (cur_mm != &init_mm)) + from = cur_mm->context.skas.id.u.mm_fd; + else from = -1; - mm->context.skas.mm_fd = new_mm(from); - if(mm->context.skas.mm_fd < 0){ - printk("init_new_context_skas - new_mm failed, errno = %d\n", - mm->context.skas.mm_fd); - return(mm->context.skas.mm_fd); + ret = new_mm(from); + if(ret < 0){ + printk("init_new_context_skas - new_mm failed, " + "errno = %d\n", ret); + return ret; + } + mm_id->u.mm_fd = ret; } + else { + /* This zeros the entry that pgd_alloc didn't, needed since + * we are about to reinitialize it, and want mm.nr_ptes to + * be accurate. + */ + mm->pgd[USER_PTRS_PER_PGD] = __pgd(0); - return(0); + ret = init_stub_pte(mm, CONFIG_STUB_CODE, + (unsigned long) &__syscall_stub_start); + if(ret) + goto out; + + ret = -ENOMEM; + stack = get_zeroed_page(GFP_KERNEL); + if(stack == 0) + goto out; + mm_id->stack = stack; + + ret = init_stub_pte(mm, CONFIG_STUB_DATA, stack); + if(ret) + goto out_free; + + mm->nr_ptes--; + + if((cur_mm != NULL) && (cur_mm != &init_mm)) + mm_id->u.pid = copy_context_skas0(stack, + cur_mm_id->u.pid); + else mm_id->u.pid = start_userspace(stack); + } + + return 0; + + out_free: + free_page(mm_id->stack); + out: + return ret; } void destroy_context_skas(struct mm_struct *mm) { - os_close_file(mm->context.skas.mm_fd); -} + struct mmu_context_skas *mmu = &mm->context.skas; -/* - * Overrides for Emacs so that we follow Linus's tabbing style. - * Emacs will notice this stuff at the end of the file and automatically - * adjust the settings for this buffer only. This must remain at the end - * of the file. - * --------------------------------------------------------------------------- - * Local variables: - * c-file-style: "linux" - * End: - */ + if(proc_mm) + os_close_file(mmu->id.u.mm_fd); + else { + os_kill_ptraced_process(mmu->id.u.pid, 1); + free_page(mmu->id.stack); + free_page(mmu->last_page_table); + } +} |