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1ca1443570
These registers are saved/restored together with the other general
registers using ptrace. In arch_set_tls we then just need to set the
register and it will be synced back normally.
Most of this logic was introduced in commit f355559cf7 ("[PATCH] uml:
x86_64 thread fixes"). However, at least today we can rely on ptrace to
restore the base registers for us. As such, only the part of the patch
that tracks the FS register for use as thread local storage is actually
needed.
Signed-off-by: Benjamin Berg <benjamin@sipsolutions.net>
Signed-off-by: Richard Weinberger <richard@nod.at>
65 lines
1.5 KiB
C
65 lines
1.5 KiB
C
/*
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* Copyright (C) 2003 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
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* Copyright 2003 PathScale, Inc.
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*
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* Licensed under the GPL
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*/
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#include <linux/sched.h>
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#include <linux/sched/mm.h>
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#include <linux/syscalls.h>
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#include <linux/uaccess.h>
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#include <asm/prctl.h> /* XXX This should get the constants from libc */
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#include <registers.h>
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#include <os.h>
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long arch_prctl(struct task_struct *task, int option,
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unsigned long __user *arg2)
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{
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long ret = -EINVAL;
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switch (option) {
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case ARCH_SET_FS:
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current->thread.regs.regs.gp[FS_BASE / sizeof(unsigned long)] =
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(unsigned long) arg2;
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ret = 0;
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break;
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case ARCH_SET_GS:
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current->thread.regs.regs.gp[GS_BASE / sizeof(unsigned long)] =
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(unsigned long) arg2;
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ret = 0;
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break;
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case ARCH_GET_FS:
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ret = put_user(current->thread.regs.regs.gp[FS_BASE / sizeof(unsigned long)], arg2);
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break;
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case ARCH_GET_GS:
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ret = put_user(current->thread.regs.regs.gp[GS_BASE / sizeof(unsigned long)], arg2);
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break;
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}
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return ret;
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}
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SYSCALL_DEFINE2(arch_prctl, int, option, unsigned long, arg2)
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{
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return arch_prctl(current, option, (unsigned long __user *) arg2);
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}
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void arch_switch_to(struct task_struct *to)
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{
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/*
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* Nothing needs to be done on x86_64.
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* The FS_BASE/GS_BASE registers are saved in the ptrace register set.
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*/
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}
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SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
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unsigned long, prot, unsigned long, flags,
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unsigned long, fd, unsigned long, off)
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{
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if (off & ~PAGE_MASK)
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return -EINVAL;
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return ksys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
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}
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