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282 lines
7.0 KiB
282 lines
7.0 KiB
// 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 ([email protected]) |
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* Copyright (C) 1996 Jakub Jelinek ([email protected]) |
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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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0, current); |
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}
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