diff options
Diffstat (limited to 'xenolinux-2.4.23-sparse/arch/xeno/kernel/ldt.c')
| -rw-r--r-- | xenolinux-2.4.23-sparse/arch/xeno/kernel/ldt.c | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/xenolinux-2.4.23-sparse/arch/xeno/kernel/ldt.c b/xenolinux-2.4.23-sparse/arch/xeno/kernel/ldt.c new file mode 100644 index 0000000000..501ce94484 --- /dev/null +++ b/xenolinux-2.4.23-sparse/arch/xeno/kernel/ldt.c @@ -0,0 +1,182 @@ +/* + * linux/kernel/ldt.c + * + * Copyright (C) 1992 Krishna Balasubramanian and Linus Torvalds + * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com> + */ + +#include <linux/errno.h> +#include <linux/sched.h> +#include <linux/string.h> +#include <linux/mm.h> +#include <linux/smp.h> +#include <linux/smp_lock.h> +#include <linux/vmalloc.h> + +#include <asm/uaccess.h> +#include <asm/system.h> +#include <asm/ldt.h> +#include <asm/desc.h> + +/* + * read_ldt() is not really atomic - this is not a problem since + * synchronization of reads and writes done to the LDT has to be + * assured by user-space anyway. Writes are atomic, to protect + * the security checks done on new descriptors. + */ +static int read_ldt(void * ptr, unsigned long bytecount) +{ + int err; + unsigned long size; + struct mm_struct * mm = current->mm; + + err = 0; + if (!mm->context.segments) + goto out; + + size = LDT_ENTRIES*LDT_ENTRY_SIZE; + if (size > bytecount) + size = bytecount; + + err = size; + if (copy_to_user(ptr, mm->context.segments, size)) + err = -EFAULT; + out: + return err; +} + +static int read_default_ldt(void * ptr, unsigned long bytecount) +{ + int err; + unsigned long size; + void *address; + + err = 0; + address = &default_ldt[0]; + size = sizeof(struct desc_struct); + if (size > bytecount) + size = bytecount; + + err = size; + if (copy_to_user(ptr, address, size)) + err = -EFAULT; + + return err; +} + +static int write_ldt(void * ptr, unsigned long bytecount, int oldmode) +{ + struct mm_struct * mm = current->mm; + __u32 entry_1, entry_2, *lp; + unsigned long phys_lp, max_limit; + int error; + struct modify_ldt_ldt_s ldt_info; + + error = -EINVAL; + if (bytecount != sizeof(ldt_info)) + goto out; + error = -EFAULT; + if (copy_from_user(&ldt_info, ptr, sizeof(ldt_info))) + goto out; + + error = -EINVAL; + if (ldt_info.entry_number >= LDT_ENTRIES) + goto out; + if (ldt_info.contents == 3) { + if (oldmode) + goto out; + if (ldt_info.seg_not_present == 0) + goto out; + } + + /* + * This makes our tests for overlap with Xen space easier. There's no good + * reason to have a user segment starting this high anyway. + */ + if (ldt_info.base_addr >= PAGE_OFFSET) + goto out; + + down_write(&mm->mmap_sem); + if (!mm->context.segments) { + void * segments = vmalloc(LDT_ENTRIES*LDT_ENTRY_SIZE); + error = -ENOMEM; + if (!segments) + goto out_unlock; + memset(segments, 0, LDT_ENTRIES*LDT_ENTRY_SIZE); + make_pages_readonly(segments, (LDT_ENTRIES*LDT_ENTRY_SIZE)/PAGE_SIZE); + wmb(); + mm->context.segments = segments; + mm->context.cpuvalid = 1UL << smp_processor_id(); + load_LDT(mm); + flush_page_update_queue(); + } + + lp = (__u32 *)((ldt_info.entry_number<<3) + (char *)mm->context.segments); + phys_lp = arbitrary_virt_to_phys(lp); + + /* Allow LDTs to be cleared by the user. */ + if (ldt_info.base_addr == 0 && ldt_info.limit == 0) { + if (oldmode || + (ldt_info.contents == 0 && + ldt_info.read_exec_only == 1 && + ldt_info.seg_32bit == 0 && + ldt_info.limit_in_pages == 0 && + ldt_info.seg_not_present == 1 && + ldt_info.useable == 0 )) { + entry_1 = 0; + entry_2 = 0; + goto install; + } + } + + max_limit = HYPERVISOR_VIRT_START - ldt_info.base_addr; + if ( ldt_info.limit_in_pages ) + max_limit >>= PAGE_SHIFT; + max_limit--; + if ( (ldt_info.limit & 0xfffff) > (max_limit & 0xfffff) ) + ldt_info.limit = max_limit; + + entry_1 = ((ldt_info.base_addr & 0x0000ffff) << 16) | + (ldt_info.limit & 0x0ffff); + entry_2 = (ldt_info.base_addr & 0xff000000) | + ((ldt_info.base_addr & 0x00ff0000) >> 16) | + (ldt_info.limit & 0xf0000) | + ((ldt_info.read_exec_only ^ 1) << 9) | + (ldt_info.contents << 10) | + ((ldt_info.seg_not_present ^ 1) << 15) | + (ldt_info.seg_32bit << 22) | + (ldt_info.limit_in_pages << 23) | + 0x7000; + if (!oldmode) + entry_2 |= (ldt_info.useable << 20); + + /* Install the new entry ... */ + install: + error = HYPERVISOR_update_descriptor(phys_lp, entry_1, entry_2); + + out_unlock: + up_write(&mm->mmap_sem); + out: + return error; +} + +asmlinkage int sys_modify_ldt(int func, void *ptr, unsigned long bytecount) +{ + int ret = -ENOSYS; + + switch (func) { + case 0: + ret = read_ldt(ptr, bytecount); + break; + case 1: + ret = write_ldt(ptr, bytecount, 1); + break; + case 2: + ret = read_default_ldt(ptr, bytecount); + break; + case 0x11: + ret = write_ldt(ptr, bytecount, 0); + break; + } + return ret; +} |