283 lines
7.0 KiB
C
283 lines
7.0 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* unaligned.c: Unaligned load/store trap handling with special
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* cases for the kernel to do them more quickly.
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*
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* Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
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* Copyright (C) 1996 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
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*/
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#include <linux/kernel.h>
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#include <linux/sched/signal.h>
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#include <linux/mm.h>
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#include <asm/ptrace.h>
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#include <asm/processor.h>
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#include <linux/uaccess.h>
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#include <linux/smp.h>
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#include <linux/perf_event.h>
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#include <linux/extable.h>
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#include <asm/setup.h>
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#include "kernel.h"
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enum direction {
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load, /* ld, ldd, ldh, ldsh */
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store, /* st, std, sth, stsh */
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both, /* Swap, ldstub, etc. */
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fpload,
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fpstore,
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invalid,
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};
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static inline enum direction decode_direction(unsigned int insn)
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{
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unsigned long tmp = (insn >> 21) & 1;
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if(!tmp)
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return load;
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else {
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if(((insn>>19)&0x3f) == 15)
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return both;
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else
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return store;
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}
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}
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/* 8 = double-word, 4 = word, 2 = half-word */
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static inline int decode_access_size(unsigned int insn)
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{
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insn = (insn >> 19) & 3;
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if(!insn)
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return 4;
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else if(insn == 3)
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return 8;
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else if(insn == 2)
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return 2;
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else {
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printk("Impossible unaligned trap. insn=%08x\n", insn);
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die_if_kernel("Byte sized unaligned access?!?!", current->thread.kregs);
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return 4; /* just to keep gcc happy. */
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}
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}
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/* 0x400000 = signed, 0 = unsigned */
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static inline int decode_signedness(unsigned int insn)
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{
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return (insn & 0x400000);
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}
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static inline void maybe_flush_windows(unsigned int rs1, unsigned int rs2,
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unsigned int rd)
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{
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if(rs2 >= 16 || rs1 >= 16 || rd >= 16) {
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/* Wheee... */
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__asm__ __volatile__("save %sp, -0x40, %sp\n\t"
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"save %sp, -0x40, %sp\n\t"
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"save %sp, -0x40, %sp\n\t"
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"save %sp, -0x40, %sp\n\t"
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"save %sp, -0x40, %sp\n\t"
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"save %sp, -0x40, %sp\n\t"
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"save %sp, -0x40, %sp\n\t"
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"restore; restore; restore; restore;\n\t"
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"restore; restore; restore;\n\t");
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}
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}
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static inline int sign_extend_imm13(int imm)
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{
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return imm << 19 >> 19;
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}
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static inline unsigned long fetch_reg(unsigned int reg, struct pt_regs *regs)
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{
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struct reg_window32 *win;
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if(reg < 16)
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return (!reg ? 0 : regs->u_regs[reg]);
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/* Ho hum, the slightly complicated case. */
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win = (struct reg_window32 *) regs->u_regs[UREG_FP];
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return win->locals[reg - 16]; /* yes, I know what this does... */
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}
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static inline unsigned long safe_fetch_reg(unsigned int reg, struct pt_regs *regs)
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{
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struct reg_window32 __user *win;
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unsigned long ret;
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if (reg < 16)
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return (!reg ? 0 : regs->u_regs[reg]);
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/* Ho hum, the slightly complicated case. */
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win = (struct reg_window32 __user *) regs->u_regs[UREG_FP];
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if ((unsigned long)win & 3)
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return -1;
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if (get_user(ret, &win->locals[reg - 16]))
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return -1;
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return ret;
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}
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static inline unsigned long *fetch_reg_addr(unsigned int reg, struct pt_regs *regs)
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{
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struct reg_window32 *win;
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if(reg < 16)
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return ®s->u_regs[reg];
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win = (struct reg_window32 *) regs->u_regs[UREG_FP];
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return &win->locals[reg - 16];
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}
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static unsigned long compute_effective_address(struct pt_regs *regs,
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unsigned int insn)
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{
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unsigned int rs1 = (insn >> 14) & 0x1f;
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unsigned int rs2 = insn & 0x1f;
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unsigned int rd = (insn >> 25) & 0x1f;
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if(insn & 0x2000) {
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maybe_flush_windows(rs1, 0, rd);
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return (fetch_reg(rs1, regs) + sign_extend_imm13(insn));
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} else {
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maybe_flush_windows(rs1, rs2, rd);
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return (fetch_reg(rs1, regs) + fetch_reg(rs2, regs));
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}
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}
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unsigned long safe_compute_effective_address(struct pt_regs *regs,
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unsigned int insn)
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{
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unsigned int rs1 = (insn >> 14) & 0x1f;
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unsigned int rs2 = insn & 0x1f;
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unsigned int rd = (insn >> 25) & 0x1f;
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if(insn & 0x2000) {
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maybe_flush_windows(rs1, 0, rd);
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return (safe_fetch_reg(rs1, regs) + sign_extend_imm13(insn));
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} else {
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maybe_flush_windows(rs1, rs2, rd);
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return (safe_fetch_reg(rs1, regs) + safe_fetch_reg(rs2, regs));
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}
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}
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/* This is just to make gcc think panic does return... */
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static void unaligned_panic(char *str)
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{
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panic("%s", str);
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}
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/* una_asm.S */
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extern int do_int_load(unsigned long *dest_reg, int size,
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unsigned long *saddr, int is_signed);
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extern int __do_int_store(unsigned long *dst_addr, int size,
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unsigned long *src_val);
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static int do_int_store(int reg_num, int size, unsigned long *dst_addr,
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struct pt_regs *regs)
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{
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unsigned long zero[2] = { 0, 0 };
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unsigned long *src_val;
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if (reg_num)
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src_val = fetch_reg_addr(reg_num, regs);
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else {
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src_val = &zero[0];
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if (size == 8)
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zero[1] = fetch_reg(1, regs);
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}
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return __do_int_store(dst_addr, size, src_val);
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}
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extern void smp_capture(void);
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extern void smp_release(void);
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static inline void advance(struct pt_regs *regs)
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{
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regs->pc = regs->npc;
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regs->npc += 4;
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}
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static inline int floating_point_load_or_store_p(unsigned int insn)
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{
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return (insn >> 24) & 1;
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}
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static inline int ok_for_kernel(unsigned int insn)
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{
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return !floating_point_load_or_store_p(insn);
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}
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static void kernel_mna_trap_fault(struct pt_regs *regs, unsigned int insn)
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{
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const struct exception_table_entry *entry;
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entry = search_exception_tables(regs->pc);
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if (!entry) {
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unsigned long address = compute_effective_address(regs, insn);
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if(address < PAGE_SIZE) {
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printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference in mna handler");
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} else
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printk(KERN_ALERT "Unable to handle kernel paging request in mna handler");
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printk(KERN_ALERT " at virtual address %08lx\n",address);
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printk(KERN_ALERT "current->{mm,active_mm}->context = %08lx\n",
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(current->mm ? current->mm->context :
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current->active_mm->context));
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printk(KERN_ALERT "current->{mm,active_mm}->pgd = %08lx\n",
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(current->mm ? (unsigned long) current->mm->pgd :
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(unsigned long) current->active_mm->pgd));
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die_if_kernel("Oops", regs);
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/* Not reached */
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}
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regs->pc = entry->fixup;
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regs->npc = regs->pc + 4;
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}
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asmlinkage void kernel_unaligned_trap(struct pt_regs *regs, unsigned int insn)
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{
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enum direction dir = decode_direction(insn);
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int size = decode_access_size(insn);
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if(!ok_for_kernel(insn) || dir == both) {
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printk("Unsupported unaligned load/store trap for kernel at <%08lx>.\n",
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regs->pc);
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unaligned_panic("Wheee. Kernel does fpu/atomic unaligned load/store.");
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} else {
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unsigned long addr = compute_effective_address(regs, insn);
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int err;
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perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, regs, addr);
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switch (dir) {
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case load:
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err = do_int_load(fetch_reg_addr(((insn>>25)&0x1f),
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regs),
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size, (unsigned long *) addr,
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decode_signedness(insn));
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break;
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case store:
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err = do_int_store(((insn>>25)&0x1f), size,
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(unsigned long *) addr, regs);
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break;
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default:
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panic("Impossible kernel unaligned trap.");
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/* Not reached... */
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}
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if (err)
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kernel_mna_trap_fault(regs, insn);
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else
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advance(regs);
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}
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}
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asmlinkage void user_unaligned_trap(struct pt_regs *regs, unsigned int insn)
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{
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send_sig_fault(SIGBUS, BUS_ADRALN,
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(void __user *)safe_compute_effective_address(regs, insn),
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current);
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}
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