463 lines
11 KiB
C
Executable file
463 lines
11 KiB
C
Executable file
// SPDX-License-Identifier: GPL-2.0
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/*
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* fault.c: Page fault handlers for the Sparc.
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*
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* Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
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* Copyright (C) 1996 Eddie C. Dost (ecd@skynet.be)
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* Copyright (C) 1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
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*/
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#include <asm/head.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/sched.h>
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#include <linux/ptrace.h>
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#include <linux/mman.h>
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#include <linux/threads.h>
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#include <linux/kernel.h>
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#include <linux/signal.h>
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#include <linux/mm.h>
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#include <linux/smp.h>
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#include <linux/perf_event.h>
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#include <linux/interrupt.h>
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#include <linux/kdebug.h>
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#include <linux/uaccess.h>
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#include <asm/page.h>
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#include <asm/pgtable.h>
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#include <asm/openprom.h>
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#include <asm/oplib.h>
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#include <asm/setup.h>
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#include <asm/smp.h>
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#include <asm/traps.h>
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#include "mm_32.h"
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int show_unhandled_signals = 1;
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static void __noreturn unhandled_fault(unsigned long address,
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struct task_struct *tsk,
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struct pt_regs *regs)
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{
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if ((unsigned long) address < PAGE_SIZE) {
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printk(KERN_ALERT
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"Unable to handle kernel NULL pointer dereference\n");
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} else {
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printk(KERN_ALERT "Unable to handle kernel paging request at virtual address %08lx\n",
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address);
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}
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printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n",
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(tsk->mm ? tsk->mm->context : tsk->active_mm->context));
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printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n",
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(tsk->mm ? (unsigned long) tsk->mm->pgd :
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(unsigned long) tsk->active_mm->pgd));
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die_if_kernel("Oops", regs);
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}
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asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc,
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unsigned long address)
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{
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struct pt_regs regs;
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unsigned long g2;
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unsigned int insn;
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int i;
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i = search_extables_range(ret_pc, &g2);
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switch (i) {
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case 3:
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/* load & store will be handled by fixup */
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return 3;
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case 1:
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/* store will be handled by fixup, load will bump out */
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/* for _to_ macros */
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insn = *((unsigned int *) pc);
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if ((insn >> 21) & 1)
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return 1;
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break;
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case 2:
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/* load will be handled by fixup, store will bump out */
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/* for _from_ macros */
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insn = *((unsigned int *) pc);
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if (!((insn >> 21) & 1) || ((insn>>19)&0x3f) == 15)
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return 2;
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break;
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default:
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break;
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}
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memset(®s, 0, sizeof(regs));
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regs.pc = pc;
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regs.npc = pc + 4;
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__asm__ __volatile__(
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"rd %%psr, %0\n\t"
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"nop\n\t"
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"nop\n\t"
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"nop\n" : "=r" (regs.psr));
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unhandled_fault(address, current, ®s);
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/* Not reached */
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return 0;
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}
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static inline void
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show_signal_msg(struct pt_regs *regs, int sig, int code,
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unsigned long address, struct task_struct *tsk)
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{
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if (!unhandled_signal(tsk, sig))
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return;
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if (!printk_ratelimit())
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return;
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printk("%s%s[%d]: segfault at %lx ip %px (rpc %px) sp %px error %x",
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task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
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tsk->comm, task_pid_nr(tsk), address,
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(void *)regs->pc, (void *)regs->u_regs[UREG_I7],
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(void *)regs->u_regs[UREG_FP], code);
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print_vma_addr(KERN_CONT " in ", regs->pc);
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printk(KERN_CONT "\n");
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}
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static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs,
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unsigned long addr)
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{
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if (unlikely(show_unhandled_signals))
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show_signal_msg(regs, sig, code,
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addr, current);
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force_sig_fault(sig, code, (void __user *) addr, 0, current);
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}
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static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
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{
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unsigned int insn;
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if (text_fault)
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return regs->pc;
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if (regs->psr & PSR_PS)
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insn = *(unsigned int *) regs->pc;
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else
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__get_user(insn, (unsigned int *) regs->pc);
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return safe_compute_effective_address(regs, insn);
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}
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static noinline void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
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int text_fault)
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{
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unsigned long addr = compute_si_addr(regs, text_fault);
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__do_fault_siginfo(code, sig, regs, addr);
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}
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asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
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unsigned long address)
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{
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struct vm_area_struct *vma;
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struct task_struct *tsk = current;
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struct mm_struct *mm = tsk->mm;
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unsigned int fixup;
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unsigned long g2;
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int from_user = !(regs->psr & PSR_PS);
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int code;
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vm_fault_t fault;
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unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
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if (text_fault)
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address = regs->pc;
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/*
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* We fault-in kernel-space virtual memory on-demand. The
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* 'reference' page table is init_mm.pgd.
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*
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* NOTE! We MUST NOT take any locks for this case. We may
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* be in an interrupt or a critical region, and should
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* only copy the information from the master page table,
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* nothing more.
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*/
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code = SEGV_MAPERR;
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if (address >= TASK_SIZE)
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goto vmalloc_fault;
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/*
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* If we're in an interrupt or have no user
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* context, we must not take the fault..
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*/
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if (pagefault_disabled() || !mm)
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goto no_context;
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perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
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retry:
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down_read(&mm->mmap_sem);
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if (!from_user && address >= PAGE_OFFSET)
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goto bad_area;
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vma = find_vma(mm, address);
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if (!vma)
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goto bad_area;
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if (vma->vm_start <= address)
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goto good_area;
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if (!(vma->vm_flags & VM_GROWSDOWN))
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goto bad_area;
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if (expand_stack(vma, address))
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goto bad_area;
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/*
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* Ok, we have a good vm_area for this memory access, so
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* we can handle it..
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*/
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good_area:
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code = SEGV_ACCERR;
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if (write) {
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if (!(vma->vm_flags & VM_WRITE))
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goto bad_area;
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} else {
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/* Allow reads even for write-only mappings */
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if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
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goto bad_area;
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}
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if (from_user)
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flags |= FAULT_FLAG_USER;
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if (write)
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flags |= FAULT_FLAG_WRITE;
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/*
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* If for any reason at all we couldn't handle the fault,
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* make sure we exit gracefully rather than endlessly redo
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* the fault.
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*/
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fault = handle_mm_fault(vma, address, flags);
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if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
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return;
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if (unlikely(fault & VM_FAULT_ERROR)) {
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if (fault & VM_FAULT_OOM)
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goto out_of_memory;
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else if (fault & VM_FAULT_SIGSEGV)
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goto bad_area;
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else if (fault & VM_FAULT_SIGBUS)
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goto do_sigbus;
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BUG();
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}
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if (flags & FAULT_FLAG_ALLOW_RETRY) {
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if (fault & VM_FAULT_MAJOR) {
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current->maj_flt++;
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perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ,
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1, regs, address);
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} else {
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current->min_flt++;
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perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN,
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1, regs, address);
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}
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if (fault & VM_FAULT_RETRY) {
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags |= FAULT_FLAG_TRIED;
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/* No need to up_read(&mm->mmap_sem) as we would
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* have already released it in __lock_page_or_retry
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* in mm/filemap.c.
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*/
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goto retry;
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}
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}
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up_read(&mm->mmap_sem);
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return;
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/*
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* Something tried to access memory that isn't in our memory map..
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* Fix it, but check if it's kernel or user first..
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*/
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bad_area:
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up_read(&mm->mmap_sem);
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bad_area_nosemaphore:
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/* User mode accesses just cause a SIGSEGV */
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if (from_user) {
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do_fault_siginfo(code, SIGSEGV, regs, text_fault);
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return;
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}
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/* Is this in ex_table? */
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no_context:
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g2 = regs->u_regs[UREG_G2];
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if (!from_user) {
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fixup = search_extables_range(regs->pc, &g2);
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/* Values below 10 are reserved for other things */
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if (fixup > 10) {
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extern const unsigned int __memset_start[];
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extern const unsigned int __memset_end[];
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extern const unsigned int __csum_partial_copy_start[];
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extern const unsigned int __csum_partial_copy_end[];
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#ifdef DEBUG_EXCEPTIONS
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printk("Exception: PC<%08lx> faddr<%08lx>\n",
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regs->pc, address);
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printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
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regs->pc, fixup, g2);
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#endif
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if ((regs->pc >= (unsigned long)__memset_start &&
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regs->pc < (unsigned long)__memset_end) ||
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(regs->pc >= (unsigned long)__csum_partial_copy_start &&
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regs->pc < (unsigned long)__csum_partial_copy_end)) {
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regs->u_regs[UREG_I4] = address;
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regs->u_regs[UREG_I5] = regs->pc;
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}
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regs->u_regs[UREG_G2] = g2;
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regs->pc = fixup;
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regs->npc = regs->pc + 4;
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return;
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}
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}
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unhandled_fault(address, tsk, regs);
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do_exit(SIGKILL);
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/*
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* We ran out of memory, or some other thing happened to us that made
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* us unable to handle the page fault gracefully.
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*/
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out_of_memory:
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up_read(&mm->mmap_sem);
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if (from_user) {
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pagefault_out_of_memory();
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return;
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}
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goto no_context;
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do_sigbus:
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up_read(&mm->mmap_sem);
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do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault);
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if (!from_user)
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goto no_context;
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vmalloc_fault:
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{
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/*
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* Synchronize this task's top level page-table
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* with the 'reference' page table.
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*/
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int offset = pgd_index(address);
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pgd_t *pgd, *pgd_k;
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pmd_t *pmd, *pmd_k;
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pgd = tsk->active_mm->pgd + offset;
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pgd_k = init_mm.pgd + offset;
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if (!pgd_present(*pgd)) {
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if (!pgd_present(*pgd_k))
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goto bad_area_nosemaphore;
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pgd_val(*pgd) = pgd_val(*pgd_k);
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return;
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}
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pmd = pmd_offset(pgd, address);
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pmd_k = pmd_offset(pgd_k, address);
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if (pmd_present(*pmd) || !pmd_present(*pmd_k))
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goto bad_area_nosemaphore;
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*pmd = *pmd_k;
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return;
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}
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}
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/* This always deals with user addresses. */
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static void force_user_fault(unsigned long address, int write)
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{
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struct vm_area_struct *vma;
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struct task_struct *tsk = current;
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struct mm_struct *mm = tsk->mm;
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unsigned int flags = FAULT_FLAG_USER;
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int code;
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code = SEGV_MAPERR;
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down_read(&mm->mmap_sem);
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vma = find_vma(mm, address);
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if (!vma)
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goto bad_area;
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if (vma->vm_start <= address)
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goto good_area;
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if (!(vma->vm_flags & VM_GROWSDOWN))
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goto bad_area;
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if (expand_stack(vma, address))
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goto bad_area;
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good_area:
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code = SEGV_ACCERR;
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if (write) {
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if (!(vma->vm_flags & VM_WRITE))
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goto bad_area;
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flags |= FAULT_FLAG_WRITE;
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} else {
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if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
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goto bad_area;
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}
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switch (handle_mm_fault(vma, address, flags)) {
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case VM_FAULT_SIGBUS:
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case VM_FAULT_OOM:
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goto do_sigbus;
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}
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up_read(&mm->mmap_sem);
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return;
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bad_area:
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up_read(&mm->mmap_sem);
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__do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address);
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return;
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do_sigbus:
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up_read(&mm->mmap_sem);
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__do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address);
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}
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static void check_stack_aligned(unsigned long sp)
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{
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if (sp & 0x7UL)
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force_sig(SIGILL, current);
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}
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void window_overflow_fault(void)
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{
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unsigned long sp;
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sp = current_thread_info()->rwbuf_stkptrs[0];
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if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
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force_user_fault(sp + 0x38, 1);
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force_user_fault(sp, 1);
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check_stack_aligned(sp);
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}
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void window_underflow_fault(unsigned long sp)
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{
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if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
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force_user_fault(sp + 0x38, 0);
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force_user_fault(sp, 0);
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check_stack_aligned(sp);
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}
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void window_ret_fault(struct pt_regs *regs)
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{
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unsigned long sp;
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sp = regs->u_regs[UREG_FP];
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if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
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force_user_fault(sp + 0x38, 0);
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force_user_fault(sp, 0);
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check_stack_aligned(sp);
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}
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