159 lines
3.7 KiB
C
159 lines
3.7 KiB
C
#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/sched.h>
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#include <linux/user.h>
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#include <asm/uaccess.h>
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#include <asm/desc.h>
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#include <asm/system.h>
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#include <asm/ldt.h>
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#include <asm/processor.h>
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#include <asm/proto.h>
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/*
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* sys_alloc_thread_area: get a yet unused TLS descriptor index.
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*/
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static int get_free_idx(void)
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{
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struct thread_struct *t = ¤t->thread;
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int idx;
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for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++)
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if (desc_empty((struct n_desc_struct *)(t->tls_array) + idx))
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return idx + GDT_ENTRY_TLS_MIN;
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return -ESRCH;
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}
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/*
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* Set a given TLS descriptor:
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* When you want addresses > 32bit use arch_prctl()
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*/
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int do_set_thread_area(struct thread_struct *t, struct user_desc __user *u_info)
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{
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struct user_desc info;
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struct n_desc_struct *desc;
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int cpu, idx;
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if (copy_from_user(&info, u_info, sizeof(info)))
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return -EFAULT;
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idx = info.entry_number;
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/*
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* index -1 means the kernel should try to find and
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* allocate an empty descriptor:
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*/
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if (idx == -1) {
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idx = get_free_idx();
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if (idx < 0)
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return idx;
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if (put_user(idx, &u_info->entry_number))
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return -EFAULT;
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}
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if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
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return -EINVAL;
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desc = ((struct n_desc_struct *)t->tls_array) + idx - GDT_ENTRY_TLS_MIN;
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/*
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* We must not get preempted while modifying the TLS.
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*/
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cpu = get_cpu();
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if (LDT_empty(&info)) {
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desc->a = 0;
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desc->b = 0;
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} else {
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desc->a = LDT_entry_a(&info);
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desc->b = LDT_entry_b(&info);
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}
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if (t == ¤t->thread)
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load_TLS(t, cpu);
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put_cpu();
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return 0;
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}
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asmlinkage long sys32_set_thread_area(struct user_desc __user *u_info)
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{
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return do_set_thread_area(¤t->thread, u_info);
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}
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/*
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* Get the current Thread-Local Storage area:
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*/
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#define GET_LIMIT(desc) ( \
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((desc)->a & 0x0ffff) | \
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((desc)->b & 0xf0000) )
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#define GET_32BIT(desc) (((desc)->b >> 22) & 1)
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#define GET_CONTENTS(desc) (((desc)->b >> 10) & 3)
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#define GET_WRITABLE(desc) (((desc)->b >> 9) & 1)
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#define GET_LIMIT_PAGES(desc) (((desc)->b >> 23) & 1)
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#define GET_PRESENT(desc) (((desc)->b >> 15) & 1)
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#define GET_USEABLE(desc) (((desc)->b >> 20) & 1)
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#define GET_LONGMODE(desc) (((desc)->b >> 21) & 1)
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int do_get_thread_area(struct thread_struct *t, struct user_desc __user *u_info)
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{
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struct user_desc info;
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struct n_desc_struct *desc;
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int idx;
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if (get_user(idx, &u_info->entry_number))
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return -EFAULT;
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if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
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return -EINVAL;
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desc = ((struct n_desc_struct *)t->tls_array) + idx - GDT_ENTRY_TLS_MIN;
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memset(&info, 0, sizeof(struct user_desc));
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info.entry_number = idx;
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info.base_addr = get_desc_base(desc);
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info.limit = GET_LIMIT(desc);
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info.seg_32bit = GET_32BIT(desc);
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info.contents = GET_CONTENTS(desc);
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info.read_exec_only = !GET_WRITABLE(desc);
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info.limit_in_pages = GET_LIMIT_PAGES(desc);
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info.seg_not_present = !GET_PRESENT(desc);
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info.useable = GET_USEABLE(desc);
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info.lm = GET_LONGMODE(desc);
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if (copy_to_user(u_info, &info, sizeof(info)))
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return -EFAULT;
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return 0;
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}
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asmlinkage long sys32_get_thread_area(struct user_desc __user *u_info)
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{
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return do_get_thread_area(¤t->thread, u_info);
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}
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int ia32_child_tls(struct task_struct *p, struct pt_regs *childregs)
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{
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struct n_desc_struct *desc;
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struct user_desc info;
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struct user_desc __user *cp;
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int idx;
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cp = (void __user *)childregs->rsi;
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if (copy_from_user(&info, cp, sizeof(info)))
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return -EFAULT;
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if (LDT_empty(&info))
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return -EINVAL;
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idx = info.entry_number;
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if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
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return -EINVAL;
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desc = (struct n_desc_struct *)(p->thread.tls_array) + idx - GDT_ENTRY_TLS_MIN;
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desc->a = LDT_entry_a(&info);
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desc->b = LDT_entry_b(&info);
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return 0;
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}
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