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