diff options
Diffstat (limited to 'arch/x86/kernel/tls.c')
| -rw-r--r-- | arch/x86/kernel/tls.c | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/arch/x86/kernel/tls.c b/arch/x86/kernel/tls.c new file mode 100644 index 00000000000..5291596f19b --- /dev/null +++ b/arch/x86/kernel/tls.c @@ -0,0 +1,158 @@ +#include <linux/kernel.h> +#include <linux/errno.h> +#include <linux/sched.h> +#include <linux/user.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> + +/* + * 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((struct n_desc_struct *)(t->tls_array) + idx)) + return idx + GDT_ENTRY_TLS_MIN; + return -ESRCH; +} + +/* + * Set a given TLS descriptor: + * When you want addresses > 32bit use arch_prctl() + */ +int do_set_thread_area(struct thread_struct *t, struct user_desc __user *u_info) +{ + struct user_desc info; + struct n_desc_struct *desc; + int cpu, idx; + + if (copy_from_user(&info, u_info, sizeof(info))) + return -EFAULT; + + idx = info.entry_number; + + /* + * index -1 means the kernel should try to find and + * allocate an empty descriptor: + */ + if (idx == -1) { + 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; + + desc = ((struct n_desc_struct *)t->tls_array) + idx - GDT_ENTRY_TLS_MIN; + + /* + * We must not get preempted while modifying the TLS. + */ + cpu = get_cpu(); + + if (LDT_empty(&info)) { + desc->a = 0; + desc->b = 0; + } else { + desc->a = LDT_entry_a(&info); + desc->b = LDT_entry_b(&info); + } + if (t == ¤t->thread) + load_TLS(t, cpu); + + put_cpu(); + return 0; +} + +asmlinkage long sys32_set_thread_area(struct user_desc __user *u_info) +{ + return do_set_thread_area(¤t->thread, u_info); +} + + +/* + * Get the current Thread-Local Storage area: + */ + +#define GET_LIMIT(desc) ( \ + ((desc)->a & 0x0ffff) | \ + ((desc)->b & 0xf0000) ) + +#define GET_32BIT(desc) (((desc)->b >> 22) & 1) +#define GET_CONTENTS(desc) (((desc)->b >> 10) & 3) +#define GET_WRITABLE(desc) (((desc)->b >> 9) & 1) +#define GET_LIMIT_PAGES(desc) (((desc)->b >> 23) & 1) +#define GET_PRESENT(desc) (((desc)->b >> 15) & 1) +#define GET_USEABLE(desc) (((desc)->b >> 20) & 1) +#define GET_LONGMODE(desc) (((desc)->b >> 21) & 1) + +int do_get_thread_area(struct thread_struct *t, struct user_desc __user *u_info) +{ + struct user_desc info; + struct n_desc_struct *desc; + int idx; + + if (get_user(idx, &u_info->entry_number)) + return -EFAULT; + if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) + return -EINVAL; + + desc = ((struct n_desc_struct *)t->tls_array) + idx - GDT_ENTRY_TLS_MIN; + + memset(&info, 0, sizeof(struct user_desc)); + info.entry_number = idx; + info.base_addr = get_desc_base(desc); + info.limit = GET_LIMIT(desc); + info.seg_32bit = GET_32BIT(desc); + info.contents = GET_CONTENTS(desc); + info.read_exec_only = !GET_WRITABLE(desc); + info.limit_in_pages = GET_LIMIT_PAGES(desc); + info.seg_not_present = !GET_PRESENT(desc); + info.useable = GET_USEABLE(desc); + info.lm = GET_LONGMODE(desc); + + if (copy_to_user(u_info, &info, sizeof(info))) + return -EFAULT; + return 0; +} + +asmlinkage long sys32_get_thread_area(struct user_desc __user *u_info) +{ + return do_get_thread_area(¤t->thread, u_info); +} + + +int ia32_child_tls(struct task_struct *p, struct pt_regs *childregs) +{ + struct n_desc_struct *desc; + struct user_desc info; + struct user_desc __user *cp; + int idx; + + cp = (void __user *)childregs->rsi; + if (copy_from_user(&info, cp, sizeof(info))) + return -EFAULT; + if (LDT_empty(&info)) + return -EINVAL; + + idx = info.entry_number; + if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) + return -EINVAL; + + desc = (struct n_desc_struct *)(p->thread.tls_array) + idx - GDT_ENTRY_TLS_MIN; + desc->a = LDT_entry_a(&info); + desc->b = LDT_entry_b(&info); + + return 0; +} |