diff options
Diffstat (limited to 'arch/x86/kernel/tls.c')
| -rw-r--r-- | arch/x86/kernel/tls.c | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/arch/x86/kernel/tls.c b/arch/x86/kernel/tls.c new file mode 100644 index 00000000000..6dfd4e76661 --- /dev/null +++ b/arch/x86/kernel/tls.c @@ -0,0 +1,213 @@ +#include <linux/kernel.h> +#include <linux/errno.h> +#include <linux/sched.h> +#include <linux/user.h> +#include <linux/regset.h> + +#include <asm/uaccess.h> +#include <asm/desc.h> +#include <asm/system.h> +#include <asm/ldt.h> +#include <asm/processor.h> +#include <asm/proto.h> + +#include "tls.h" + +/* + * sys_alloc_thread_area: get a yet unused TLS descriptor index. + */ +static int get_free_idx(void) +{ + struct thread_struct *t = ¤t->thread; + int idx; + + for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++) + if (desc_empty(&t->tls_array[idx])) + return idx + GDT_ENTRY_TLS_MIN; + return -ESRCH; +} + +static void set_tls_desc(struct task_struct *p, int idx, + const struct user_desc *info, int n) +{ + struct thread_struct *t = &p->thread; + struct desc_struct *desc = &t->tls_array[idx - GDT_ENTRY_TLS_MIN]; + int cpu; + + /* + * We must not get preempted while modifying the TLS. + */ + cpu = get_cpu(); + + while (n-- > 0) { + if (LDT_empty(info)) + desc->a = desc->b = 0; + else + fill_ldt(desc, info); + ++info; + ++desc; + } + + if (t == ¤t->thread) + load_TLS(t, cpu); + + put_cpu(); +} + +/* + * Set a given TLS descriptor: + */ +int do_set_thread_area(struct task_struct *p, int idx, + struct user_desc __user *u_info, + int can_allocate) +{ + struct user_desc info; + + if (copy_from_user(&info, u_info, sizeof(info))) + return -EFAULT; + + if (idx == -1) + idx = info.entry_number; + + /* + * index -1 means the kernel should try to find and + * allocate an empty descriptor: + */ + if (idx == -1 && can_allocate) { + idx = get_free_idx(); + if (idx < 0) + return idx; + if (put_user(idx, &u_info->entry_number)) + return -EFAULT; + } + + if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) + return -EINVAL; + + set_tls_desc(p, idx, &info, 1); + + return 0; +} + +asmlinkage int sys_set_thread_area(struct user_desc __user *u_info) +{ + return do_set_thread_area(current, -1, u_info, 1); +} + + +/* + * Get the current Thread-Local Storage area: + */ + +static void fill_user_desc(struct user_desc *info, int idx, + const struct desc_struct *desc) + +{ + memset(info, 0, sizeof(*info)); + info->entry_number = idx; + info->base_addr = get_desc_base(desc); + info->limit = get_desc_limit(desc); + info->seg_32bit = desc->d; + info->contents = desc->type >> 2; + info->read_exec_only = !(desc->type & 2); + info->limit_in_pages = desc->g; + info->seg_not_present = !desc->p; + info->useable = desc->avl; +#ifdef CONFIG_X86_64 + info->lm = desc->l; +#endif +} + +int do_get_thread_area(struct task_struct *p, int idx, + struct user_desc __user *u_info) +{ + struct user_desc info; + + if (idx == -1 && get_user(idx, &u_info->entry_number)) + return -EFAULT; + + if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) + return -EINVAL; + + fill_user_desc(&info, idx, + &p->thread.tls_array[idx - GDT_ENTRY_TLS_MIN]); + + if (copy_to_user(u_info, &info, sizeof(info))) + return -EFAULT; + return 0; +} + +asmlinkage int sys_get_thread_area(struct user_desc __user *u_info) +{ + return do_get_thread_area(current, -1, u_info); +} + +int regset_tls_active(struct task_struct *target, + const struct user_regset *regset) +{ + struct thread_struct *t = &target->thread; + int n = GDT_ENTRY_TLS_ENTRIES; + while (n > 0 && desc_empty(&t->tls_array[n - 1])) + --n; + return n; +} + +int regset_tls_get(struct task_struct *target, const struct user_regset *regset, + unsigned int pos, unsigned int count, + void *kbuf, void __user *ubuf) +{ + const struct desc_struct *tls; + + if (pos > GDT_ENTRY_TLS_ENTRIES * sizeof(struct user_desc) || + (pos % sizeof(struct user_desc)) != 0 || + (count % sizeof(struct user_desc)) != 0) + return -EINVAL; + + pos /= sizeof(struct user_desc); + count /= sizeof(struct user_desc); + + tls = &target->thread.tls_array[pos]; + + if (kbuf) { + struct user_desc *info = kbuf; + while (count-- > 0) + fill_user_desc(info++, GDT_ENTRY_TLS_MIN + pos++, + tls++); + } else { + struct user_desc __user *u_info = ubuf; + while (count-- > 0) { + struct user_desc info; + fill_user_desc(&info, GDT_ENTRY_TLS_MIN + pos++, tls++); + if (__copy_to_user(u_info++, &info, sizeof(info))) + return -EFAULT; + } + } + + return 0; +} + +int regset_tls_set(struct task_struct *target, const struct user_regset *regset, + unsigned int pos, unsigned int count, + const void *kbuf, const void __user *ubuf) +{ + struct user_desc infobuf[GDT_ENTRY_TLS_ENTRIES]; + const struct user_desc *info; + + if (pos > GDT_ENTRY_TLS_ENTRIES * sizeof(struct user_desc) || + (pos % sizeof(struct user_desc)) != 0 || + (count % sizeof(struct user_desc)) != 0) + return -EINVAL; + + if (kbuf) + info = kbuf; + else if (__copy_from_user(infobuf, ubuf, count)) + return -EFAULT; + else + info = infobuf; + + set_tls_desc(target, + GDT_ENTRY_TLS_MIN + (pos / sizeof(struct user_desc)), + info, count / sizeof(struct user_desc)); + + return 0; +} |