forked from Minki/linux
efd1ca52d0
This consolidates the four different places that implemented the same encoding magic for the GDT-slot 32-bit TLS support. The old tls32.c was renamed and is now only slightly modified to be the shared implementation. Signed-off-by: Roland McGrath <roland@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Zachary Amsden <zach@vmware.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
137 lines
3.2 KiB
C
137 lines
3.2 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(&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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*/
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int do_set_thread_area(struct task_struct *p, int idx,
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struct user_desc __user *u_info,
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int can_allocate)
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{
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struct thread_struct *t = &p->thread;
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struct user_desc info;
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u32 *desc;
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int cpu;
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if (copy_from_user(&info, u_info, sizeof(info)))
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return -EFAULT;
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if (idx == -1)
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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 && can_allocate) {
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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 = (u32 *) &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[0] = 0;
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desc[1] = 0;
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} else {
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desc[0] = LDT_entry_a(&info);
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desc[1] = 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 int sys_set_thread_area(struct user_desc __user *u_info)
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{
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return do_set_thread_area(current, -1, u_info, 1);
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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) (((desc)[0] & 0x0ffff) | ((desc)[1] & 0xf0000))
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#define GET_32BIT(desc) (((desc)[1] >> 22) & 1)
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#define GET_CONTENTS(desc) (((desc)[1] >> 10) & 3)
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#define GET_WRITABLE(desc) (((desc)[1] >> 9) & 1)
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#define GET_LIMIT_PAGES(desc) (((desc)[1] >> 23) & 1)
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#define GET_PRESENT(desc) (((desc)[1] >> 15) & 1)
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#define GET_USEABLE(desc) (((desc)[1] >> 20) & 1)
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#define GET_LONGMODE(desc) (((desc)[1] >> 21) & 1)
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int do_get_thread_area(struct task_struct *p, int idx,
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struct user_desc __user *u_info)
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{
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struct thread_struct *t = &p->thread;
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struct user_desc info;
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u32 *desc;
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if (idx == -1 && 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 = (u32 *) &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((void *)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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#ifdef CONFIG_X86_64
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info.lm = GET_LONGMODE(desc);
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#endif
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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 int sys_get_thread_area(struct user_desc __user *u_info)
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{
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return do_get_thread_area(current, -1, u_info);
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}
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