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eb35bdd7bc
Nathan reports that we leak TLS information from the parent context
during an exec, as we don't clear the TLS registers when flushing the
thread state.
This patch updates the flushing code so that we:
(1) Unconditionally zero the tpidr_el0 register (since this is fully
context switched for native tasks and zeroed for compat tasks)
(2) Zero the tp_value state in thread_info before clearing the
tpidrr0_el0 register for compat tasks (since this is only writable
by the set_tls compat syscall and therefore not fully switched).
A missing compiler barrier is also added to the compat set_tls syscall.
Cc: <stable@vger.kernel.org>
Acked-by: Nathan Lynch <Nathan_Lynch@mentor.com>
Reported-by: Nathan Lynch <Nathan_Lynch@mentor.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
95 lines
2.7 KiB
C
95 lines
2.7 KiB
C
/*
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* Based on arch/arm/kernel/sys_arm.c
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*
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* Copyright (C) People who wrote linux/arch/i386/kernel/sys_i386.c
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* Copyright (C) 1995, 1996 Russell King.
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* Copyright (C) 2012 ARM Ltd.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/compat.h>
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#include <linux/personality.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/syscalls.h>
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#include <linux/uaccess.h>
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#include <asm/cacheflush.h>
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#include <asm/unistd.h>
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static inline void
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do_compat_cache_op(unsigned long start, unsigned long end, int flags)
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{
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struct mm_struct *mm = current->active_mm;
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struct vm_area_struct *vma;
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if (end < start || flags)
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return;
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down_read(&mm->mmap_sem);
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vma = find_vma(mm, start);
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if (vma && vma->vm_start < end) {
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if (start < vma->vm_start)
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start = vma->vm_start;
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if (end > vma->vm_end)
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end = vma->vm_end;
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up_read(&mm->mmap_sem);
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__flush_cache_user_range(start & PAGE_MASK, PAGE_ALIGN(end));
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return;
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}
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up_read(&mm->mmap_sem);
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}
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/*
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* Handle all unrecognised system calls.
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*/
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long compat_arm_syscall(struct pt_regs *regs)
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{
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unsigned int no = regs->regs[7];
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switch (no) {
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/*
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* Flush a region from virtual address 'r0' to virtual address 'r1'
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* _exclusive_. There is no alignment requirement on either address;
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* user space does not need to know the hardware cache layout.
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*
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* r2 contains flags. It should ALWAYS be passed as ZERO until it
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* is defined to be something else. For now we ignore it, but may
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* the fires of hell burn in your belly if you break this rule. ;)
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*
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* (at a later date, we may want to allow this call to not flush
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* various aspects of the cache. Passing '0' will guarantee that
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* everything necessary gets flushed to maintain consistency in
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* the specified region).
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*/
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case __ARM_NR_compat_cacheflush:
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do_compat_cache_op(regs->regs[0], regs->regs[1], regs->regs[2]);
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return 0;
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case __ARM_NR_compat_set_tls:
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current->thread.tp_value = regs->regs[0];
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/*
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* Protect against register corruption from context switch.
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* See comment in tls_thread_flush.
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*/
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barrier();
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asm ("msr tpidrro_el0, %0" : : "r" (regs->regs[0]));
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return 0;
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default:
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return -ENOSYS;
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}
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}
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