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![Heiko Carstens](/assets/img/avatar_default.png)
We use the user_mode() helper already at several places but also have the open coded variant at other places. Convert the code to always use the helper function. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
672 lines
17 KiB
C
672 lines
17 KiB
C
/*
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* S390 version
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* Copyright IBM Corp. 1999
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* Author(s): Hartmut Penner (hp@de.ibm.com)
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* Ulrich Weigand (uweigand@de.ibm.com)
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*
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* Derived from "arch/i386/mm/fault.c"
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* Copyright (C) 1995 Linus Torvalds
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*/
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#include <linux/kernel_stat.h>
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#include <linux/perf_event.h>
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#include <linux/signal.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/ptrace.h>
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#include <linux/mman.h>
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#include <linux/mm.h>
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#include <linux/compat.h>
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#include <linux/smp.h>
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#include <linux/kdebug.h>
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#include <linux/init.h>
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#include <linux/console.h>
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#include <linux/module.h>
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#include <linux/hardirq.h>
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#include <linux/kprobes.h>
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#include <linux/uaccess.h>
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#include <linux/hugetlb.h>
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#include <asm/asm-offsets.h>
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#include <asm/pgtable.h>
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#include <asm/irq.h>
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#include <asm/mmu_context.h>
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#include <asm/facility.h>
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#include "../kernel/entry.h"
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#ifndef CONFIG_64BIT
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#define __FAIL_ADDR_MASK 0x7ffff000
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#define __SUBCODE_MASK 0x0200
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#define __PF_RES_FIELD 0ULL
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#else /* CONFIG_64BIT */
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#define __FAIL_ADDR_MASK -4096L
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#define __SUBCODE_MASK 0x0600
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#define __PF_RES_FIELD 0x8000000000000000ULL
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#endif /* CONFIG_64BIT */
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#define VM_FAULT_BADCONTEXT 0x010000
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#define VM_FAULT_BADMAP 0x020000
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#define VM_FAULT_BADACCESS 0x040000
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#define VM_FAULT_SIGNAL 0x080000
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static unsigned long store_indication;
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void fault_init(void)
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{
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if (test_facility(2) && test_facility(75))
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store_indication = 0xc00;
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}
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static inline int notify_page_fault(struct pt_regs *regs)
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{
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int ret = 0;
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/* kprobe_running() needs smp_processor_id() */
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if (kprobes_built_in() && !user_mode(regs)) {
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preempt_disable();
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if (kprobe_running() && kprobe_fault_handler(regs, 14))
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ret = 1;
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preempt_enable();
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}
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return ret;
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}
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/*
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* Unlock any spinlocks which will prevent us from getting the
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* message out.
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*/
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void bust_spinlocks(int yes)
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{
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if (yes) {
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oops_in_progress = 1;
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} else {
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int loglevel_save = console_loglevel;
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console_unblank();
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oops_in_progress = 0;
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/*
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* OK, the message is on the console. Now we call printk()
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* without oops_in_progress set so that printk will give klogd
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* a poke. Hold onto your hats...
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*/
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console_loglevel = 15;
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printk(" ");
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console_loglevel = loglevel_save;
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}
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}
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/*
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* Returns the address space associated with the fault.
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* Returns 0 for kernel space and 1 for user space.
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*/
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static inline int user_space_fault(unsigned long trans_exc_code)
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{
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/*
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* The lowest two bits of the translation exception
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* identification indicate which paging table was used.
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*/
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trans_exc_code &= 3;
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if (trans_exc_code == 2)
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/* Access via secondary space, set_fs setting decides */
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return current->thread.mm_segment.ar4;
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if (addressing_mode == HOME_SPACE_MODE)
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/* User space if the access has been done via home space. */
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return trans_exc_code == 3;
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/*
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* If the user space is not the home space the kernel runs in home
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* space. Access via secondary space has already been covered,
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* access via primary space or access register is from user space
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* and access via home space is from the kernel.
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*/
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return trans_exc_code != 3;
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}
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static inline void report_user_fault(struct pt_regs *regs, long signr)
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{
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if ((task_pid_nr(current) > 1) && !show_unhandled_signals)
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return;
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if (!unhandled_signal(current, signr))
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return;
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if (!printk_ratelimit())
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return;
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printk(KERN_ALERT "User process fault: interruption code 0x%X ",
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regs->int_code);
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print_vma_addr(KERN_CONT "in ", regs->psw.addr & PSW_ADDR_INSN);
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printk(KERN_CONT "\n");
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printk(KERN_ALERT "failing address: %lX\n",
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regs->int_parm_long & __FAIL_ADDR_MASK);
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show_regs(regs);
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}
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/*
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* Send SIGSEGV to task. This is an external routine
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* to keep the stack usage of do_page_fault small.
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*/
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static noinline void do_sigsegv(struct pt_regs *regs, int si_code)
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{
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struct siginfo si;
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report_user_fault(regs, SIGSEGV);
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si.si_signo = SIGSEGV;
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si.si_code = si_code;
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si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
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force_sig_info(SIGSEGV, &si, current);
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}
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static noinline void do_no_context(struct pt_regs *regs)
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{
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const struct exception_table_entry *fixup;
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unsigned long address;
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/* Are we prepared to handle this kernel fault? */
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fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
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if (fixup) {
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regs->psw.addr = fixup->fixup | PSW_ADDR_AMODE;
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return;
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}
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/*
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* Oops. The kernel tried to access some bad page. We'll have to
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* terminate things with extreme prejudice.
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*/
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address = regs->int_parm_long & __FAIL_ADDR_MASK;
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if (!user_space_fault(regs->int_parm_long))
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printk(KERN_ALERT "Unable to handle kernel pointer dereference"
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" at virtual kernel address %p\n", (void *)address);
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else
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printk(KERN_ALERT "Unable to handle kernel paging request"
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" at virtual user address %p\n", (void *)address);
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die(regs, "Oops");
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do_exit(SIGKILL);
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}
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static noinline void do_low_address(struct pt_regs *regs)
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{
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/* Low-address protection hit in kernel mode means
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NULL pointer write access in kernel mode. */
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if (regs->psw.mask & PSW_MASK_PSTATE) {
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/* Low-address protection hit in user mode 'cannot happen'. */
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die (regs, "Low-address protection");
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do_exit(SIGKILL);
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}
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do_no_context(regs);
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}
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static noinline void do_sigbus(struct pt_regs *regs)
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{
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struct task_struct *tsk = current;
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struct siginfo si;
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/*
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* Send a sigbus, regardless of whether we were in kernel
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* or user mode.
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*/
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si.si_signo = SIGBUS;
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si.si_errno = 0;
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si.si_code = BUS_ADRERR;
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si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
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force_sig_info(SIGBUS, &si, tsk);
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}
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static noinline void do_fault_error(struct pt_regs *regs, int fault)
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{
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int si_code;
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switch (fault) {
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case VM_FAULT_BADACCESS:
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case VM_FAULT_BADMAP:
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/* Bad memory access. Check if it is kernel or user space. */
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if (user_mode(regs)) {
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/* User mode accesses just cause a SIGSEGV */
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si_code = (fault == VM_FAULT_BADMAP) ?
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SEGV_MAPERR : SEGV_ACCERR;
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do_sigsegv(regs, si_code);
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return;
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}
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case VM_FAULT_BADCONTEXT:
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do_no_context(regs);
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break;
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case VM_FAULT_SIGNAL:
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if (!user_mode(regs))
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do_no_context(regs);
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break;
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default: /* fault & VM_FAULT_ERROR */
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if (fault & VM_FAULT_OOM) {
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if (!user_mode(regs))
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do_no_context(regs);
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else
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pagefault_out_of_memory();
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} else if (fault & VM_FAULT_SIGBUS) {
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/* Kernel mode? Handle exceptions or die */
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if (!user_mode(regs))
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do_no_context(regs);
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else
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do_sigbus(regs);
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} else
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BUG();
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break;
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}
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}
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/*
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* This routine handles page faults. It determines the address,
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* and the problem, and then passes it off to one of the appropriate
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* routines.
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*
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* interruption code (int_code):
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* 04 Protection -> Write-Protection (suprression)
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* 10 Segment translation -> Not present (nullification)
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* 11 Page translation -> Not present (nullification)
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* 3b Region third trans. -> Not present (nullification)
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*/
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static inline int do_exception(struct pt_regs *regs, int access)
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{
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struct task_struct *tsk;
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struct mm_struct *mm;
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struct vm_area_struct *vma;
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unsigned long trans_exc_code;
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unsigned long address;
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unsigned int flags;
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int fault;
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if (notify_page_fault(regs))
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return 0;
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tsk = current;
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mm = tsk->mm;
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trans_exc_code = regs->int_parm_long;
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/*
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* Verify that the fault happened in user space, that
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* we are not in an interrupt and that there is a
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* user context.
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*/
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fault = VM_FAULT_BADCONTEXT;
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if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm))
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goto out;
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address = trans_exc_code & __FAIL_ADDR_MASK;
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perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
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flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
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if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400)
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flags |= FAULT_FLAG_WRITE;
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down_read(&mm->mmap_sem);
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#ifdef CONFIG_PGSTE
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if ((current->flags & PF_VCPU) && S390_lowcore.gmap) {
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address = __gmap_fault(address,
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(struct gmap *) S390_lowcore.gmap);
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if (address == -EFAULT) {
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fault = VM_FAULT_BADMAP;
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goto out_up;
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}
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if (address == -ENOMEM) {
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fault = VM_FAULT_OOM;
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goto out_up;
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}
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}
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#endif
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retry:
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fault = VM_FAULT_BADMAP;
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vma = find_vma(mm, address);
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if (!vma)
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goto out_up;
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if (unlikely(vma->vm_start > address)) {
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if (!(vma->vm_flags & VM_GROWSDOWN))
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goto out_up;
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if (expand_stack(vma, address))
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goto out_up;
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}
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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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fault = VM_FAULT_BADACCESS;
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if (unlikely(!(vma->vm_flags & access)))
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goto out_up;
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if (is_vm_hugetlb_page(vma))
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address &= HPAGE_MASK;
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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(mm, vma, address, flags);
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/* No reason to continue if interrupted by SIGKILL. */
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if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) {
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fault = VM_FAULT_SIGNAL;
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goto out;
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}
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if (unlikely(fault & VM_FAULT_ERROR))
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goto out_up;
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/*
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* Major/minor page fault accounting is only done on the
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* initial attempt. If we go through a retry, it is extremely
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* likely that the page will be found in page cache at that point.
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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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tsk->maj_flt++;
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perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
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regs, address);
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} else {
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tsk->min_flt++;
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perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
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regs, address);
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}
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if (fault & VM_FAULT_RETRY) {
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/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
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* of starvation. */
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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down_read(&mm->mmap_sem);
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goto retry;
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}
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}
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/*
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* The instruction that caused the program check will
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* be repeated. Don't signal single step via SIGTRAP.
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*/
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clear_tsk_thread_flag(tsk, TIF_PER_TRAP);
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fault = 0;
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out_up:
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up_read(&mm->mmap_sem);
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out:
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return fault;
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}
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void __kprobes do_protection_exception(struct pt_regs *regs)
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{
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unsigned long trans_exc_code;
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int fault;
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trans_exc_code = regs->int_parm_long;
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/* Protection exception is suppressing, decrement psw address. */
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regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16);
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/*
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* Check for low-address protection. This needs to be treated
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* as a special case because the translation exception code
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* field is not guaranteed to contain valid data in this case.
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*/
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if (unlikely(!(trans_exc_code & 4))) {
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do_low_address(regs);
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return;
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}
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fault = do_exception(regs, VM_WRITE);
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if (unlikely(fault))
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do_fault_error(regs, fault);
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}
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void __kprobes do_dat_exception(struct pt_regs *regs)
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{
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int access, fault;
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access = VM_READ | VM_EXEC | VM_WRITE;
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fault = do_exception(regs, access);
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if (unlikely(fault))
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do_fault_error(regs, fault);
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}
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#ifdef CONFIG_64BIT
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void __kprobes do_asce_exception(struct pt_regs *regs)
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{
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struct mm_struct *mm = current->mm;
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struct vm_area_struct *vma;
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unsigned long trans_exc_code;
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trans_exc_code = regs->int_parm_long;
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if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm))
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goto no_context;
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down_read(&mm->mmap_sem);
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vma = find_vma(mm, trans_exc_code & __FAIL_ADDR_MASK);
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up_read(&mm->mmap_sem);
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if (vma) {
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update_mm(mm, current);
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return;
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}
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/* User mode accesses just cause a SIGSEGV */
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if (user_mode(regs)) {
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do_sigsegv(regs, SEGV_MAPERR);
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return;
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}
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no_context:
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do_no_context(regs);
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}
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#endif
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int __handle_fault(unsigned long uaddr, unsigned long pgm_int_code, int write)
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{
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struct pt_regs regs;
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int access, fault;
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/* Emulate a uaccess fault from kernel mode. */
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regs.psw.mask = psw_kernel_bits | PSW_MASK_DAT | PSW_MASK_MCHECK;
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if (!irqs_disabled())
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regs.psw.mask |= PSW_MASK_IO | PSW_MASK_EXT;
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regs.psw.addr = (unsigned long) __builtin_return_address(0);
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regs.psw.addr |= PSW_ADDR_AMODE;
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regs.int_code = pgm_int_code;
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regs.int_parm_long = (uaddr & PAGE_MASK) | 2;
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access = write ? VM_WRITE : VM_READ;
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fault = do_exception(®s, access);
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/*
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* Since the fault happened in kernel mode while performing a uaccess
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* all we need to do now is emulating a fixup in case "fault" is not
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* zero.
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* For the calling uaccess functions this results always in -EFAULT.
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*/
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return fault ? -EFAULT : 0;
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}
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#ifdef CONFIG_PFAULT
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/*
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* 'pfault' pseudo page faults routines.
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*/
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static int pfault_disable;
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static int __init nopfault(char *str)
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{
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pfault_disable = 1;
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return 1;
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}
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__setup("nopfault", nopfault);
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struct pfault_refbk {
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u16 refdiagc;
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u16 reffcode;
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u16 refdwlen;
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u16 refversn;
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u64 refgaddr;
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u64 refselmk;
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u64 refcmpmk;
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u64 reserved;
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} __attribute__ ((packed, aligned(8)));
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int pfault_init(void)
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{
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struct pfault_refbk refbk = {
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.refdiagc = 0x258,
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.reffcode = 0,
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.refdwlen = 5,
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.refversn = 2,
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.refgaddr = __LC_CURRENT_PID,
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.refselmk = 1ULL << 48,
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.refcmpmk = 1ULL << 48,
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.reserved = __PF_RES_FIELD };
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int rc;
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if (pfault_disable)
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return -1;
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asm volatile(
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" diag %1,%0,0x258\n"
|
|
"0: j 2f\n"
|
|
"1: la %0,8\n"
|
|
"2:\n"
|
|
EX_TABLE(0b,1b)
|
|
: "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc");
|
|
return rc;
|
|
}
|
|
|
|
void pfault_fini(void)
|
|
{
|
|
struct pfault_refbk refbk = {
|
|
.refdiagc = 0x258,
|
|
.reffcode = 1,
|
|
.refdwlen = 5,
|
|
.refversn = 2,
|
|
};
|
|
|
|
if (pfault_disable)
|
|
return;
|
|
asm volatile(
|
|
" diag %0,0,0x258\n"
|
|
"0:\n"
|
|
EX_TABLE(0b,0b)
|
|
: : "a" (&refbk), "m" (refbk) : "cc");
|
|
}
|
|
|
|
static DEFINE_SPINLOCK(pfault_lock);
|
|
static LIST_HEAD(pfault_list);
|
|
|
|
static void pfault_interrupt(struct ext_code ext_code,
|
|
unsigned int param32, unsigned long param64)
|
|
{
|
|
struct task_struct *tsk;
|
|
__u16 subcode;
|
|
pid_t pid;
|
|
|
|
/*
|
|
* Get the external interruption subcode & pfault
|
|
* initial/completion signal bit. VM stores this
|
|
* in the 'cpu address' field associated with the
|
|
* external interrupt.
|
|
*/
|
|
subcode = ext_code.subcode;
|
|
if ((subcode & 0xff00) != __SUBCODE_MASK)
|
|
return;
|
|
kstat_cpu(smp_processor_id()).irqs[EXTINT_PFL]++;
|
|
/* Get the token (= pid of the affected task). */
|
|
pid = sizeof(void *) == 4 ? param32 : param64;
|
|
rcu_read_lock();
|
|
tsk = find_task_by_pid_ns(pid, &init_pid_ns);
|
|
if (tsk)
|
|
get_task_struct(tsk);
|
|
rcu_read_unlock();
|
|
if (!tsk)
|
|
return;
|
|
spin_lock(&pfault_lock);
|
|
if (subcode & 0x0080) {
|
|
/* signal bit is set -> a page has been swapped in by VM */
|
|
if (tsk->thread.pfault_wait == 1) {
|
|
/* Initial interrupt was faster than the completion
|
|
* interrupt. pfault_wait is valid. Set pfault_wait
|
|
* back to zero and wake up the process. This can
|
|
* safely be done because the task is still sleeping
|
|
* and can't produce new pfaults. */
|
|
tsk->thread.pfault_wait = 0;
|
|
list_del(&tsk->thread.list);
|
|
wake_up_process(tsk);
|
|
put_task_struct(tsk);
|
|
} else {
|
|
/* Completion interrupt was faster than initial
|
|
* interrupt. Set pfault_wait to -1 so the initial
|
|
* interrupt doesn't put the task to sleep.
|
|
* If the task is not running, ignore the completion
|
|
* interrupt since it must be a leftover of a PFAULT
|
|
* CANCEL operation which didn't remove all pending
|
|
* completion interrupts. */
|
|
if (tsk->state == TASK_RUNNING)
|
|
tsk->thread.pfault_wait = -1;
|
|
}
|
|
} else {
|
|
/* signal bit not set -> a real page is missing. */
|
|
if (WARN_ON_ONCE(tsk != current))
|
|
goto out;
|
|
if (tsk->thread.pfault_wait == 1) {
|
|
/* Already on the list with a reference: put to sleep */
|
|
__set_task_state(tsk, TASK_UNINTERRUPTIBLE);
|
|
set_tsk_need_resched(tsk);
|
|
} else if (tsk->thread.pfault_wait == -1) {
|
|
/* Completion interrupt was faster than the initial
|
|
* interrupt (pfault_wait == -1). Set pfault_wait
|
|
* back to zero and exit. */
|
|
tsk->thread.pfault_wait = 0;
|
|
} else {
|
|
/* Initial interrupt arrived before completion
|
|
* interrupt. Let the task sleep.
|
|
* An extra task reference is needed since a different
|
|
* cpu may set the task state to TASK_RUNNING again
|
|
* before the scheduler is reached. */
|
|
get_task_struct(tsk);
|
|
tsk->thread.pfault_wait = 1;
|
|
list_add(&tsk->thread.list, &pfault_list);
|
|
__set_task_state(tsk, TASK_UNINTERRUPTIBLE);
|
|
set_tsk_need_resched(tsk);
|
|
}
|
|
}
|
|
out:
|
|
spin_unlock(&pfault_lock);
|
|
put_task_struct(tsk);
|
|
}
|
|
|
|
static int __cpuinit pfault_cpu_notify(struct notifier_block *self,
|
|
unsigned long action, void *hcpu)
|
|
{
|
|
struct thread_struct *thread, *next;
|
|
struct task_struct *tsk;
|
|
|
|
switch (action) {
|
|
case CPU_DEAD:
|
|
case CPU_DEAD_FROZEN:
|
|
spin_lock_irq(&pfault_lock);
|
|
list_for_each_entry_safe(thread, next, &pfault_list, list) {
|
|
thread->pfault_wait = 0;
|
|
list_del(&thread->list);
|
|
tsk = container_of(thread, struct task_struct, thread);
|
|
wake_up_process(tsk);
|
|
put_task_struct(tsk);
|
|
}
|
|
spin_unlock_irq(&pfault_lock);
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
return NOTIFY_OK;
|
|
}
|
|
|
|
static int __init pfault_irq_init(void)
|
|
{
|
|
int rc;
|
|
|
|
rc = register_external_interrupt(0x2603, pfault_interrupt);
|
|
if (rc)
|
|
goto out_extint;
|
|
rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP;
|
|
if (rc)
|
|
goto out_pfault;
|
|
service_subclass_irq_register();
|
|
hotcpu_notifier(pfault_cpu_notify, 0);
|
|
return 0;
|
|
|
|
out_pfault:
|
|
unregister_external_interrupt(0x2603, pfault_interrupt);
|
|
out_extint:
|
|
pfault_disable = 1;
|
|
return rc;
|
|
}
|
|
early_initcall(pfault_irq_init);
|
|
|
|
#endif /* CONFIG_PFAULT */
|