1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Copyright (C) 2009 Sunplus Core Technology Co., Ltd. 4 * Lennox Wu <lennox.wu@sunplusct.com> 5 * Chen Liqin <liqin.chen@sunplusct.com> 6 * Copyright (C) 2013 Regents of the University of California 7 */ 8 9 10 #include <linux/bitfield.h> 11 #include <linux/extable.h> 12 #include <linux/module.h> 13 #include <linux/uaccess.h> 14 #include <asm/asm-extable.h> 15 #include <asm/ptrace.h> 16 17 static inline unsigned long 18 get_ex_fixup(const struct exception_table_entry *ex) 19 { 20 return ((unsigned long)&ex->fixup + ex->fixup); 21 } 22 23 static bool ex_handler_fixup(const struct exception_table_entry *ex, 24 struct pt_regs *regs) 25 { 26 regs->epc = get_ex_fixup(ex); 27 return true; 28 } 29 30 static inline unsigned long regs_get_gpr(struct pt_regs *regs, unsigned int offset) 31 { 32 if (unlikely(!offset || offset > MAX_REG_OFFSET)) 33 return 0; 34 35 return *(unsigned long *)((unsigned long)regs + offset); 36 } 37 38 static inline void regs_set_gpr(struct pt_regs *regs, unsigned int offset, 39 unsigned long val) 40 { 41 if (unlikely(offset > MAX_REG_OFFSET)) 42 return; 43 44 if (offset) 45 *(unsigned long *)((unsigned long)regs + offset) = val; 46 } 47 48 static bool ex_handler_uaccess_err_zero(const struct exception_table_entry *ex, 49 struct pt_regs *regs) 50 { 51 int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data); 52 int reg_zero = FIELD_GET(EX_DATA_REG_ZERO, ex->data); 53 54 regs_set_gpr(regs, reg_err * sizeof(unsigned long), -EFAULT); 55 regs_set_gpr(regs, reg_zero * sizeof(unsigned long), 0); 56 57 regs->epc = get_ex_fixup(ex); 58 return true; 59 } 60 61 static bool 62 ex_handler_load_unaligned_zeropad(const struct exception_table_entry *ex, 63 struct pt_regs *regs) 64 { 65 int reg_data = FIELD_GET(EX_DATA_REG_DATA, ex->data); 66 int reg_addr = FIELD_GET(EX_DATA_REG_ADDR, ex->data); 67 unsigned long data, addr, offset; 68 69 addr = regs_get_gpr(regs, reg_addr * sizeof(unsigned long)); 70 71 offset = addr & 0x7UL; 72 addr &= ~0x7UL; 73 74 data = *(unsigned long *)addr >> (offset * 8); 75 76 regs_set_gpr(regs, reg_data * sizeof(unsigned long), data); 77 78 regs->epc = get_ex_fixup(ex); 79 return true; 80 } 81 82 bool fixup_exception(struct pt_regs *regs) 83 { 84 const struct exception_table_entry *ex; 85 86 ex = search_exception_tables(regs->epc); 87 if (!ex) 88 return false; 89 90 switch (ex->type) { 91 case EX_TYPE_FIXUP: 92 return ex_handler_fixup(ex, regs); 93 case EX_TYPE_BPF: 94 return ex_handler_bpf(ex, regs); 95 case EX_TYPE_UACCESS_ERR_ZERO: 96 return ex_handler_uaccess_err_zero(ex, regs); 97 case EX_TYPE_LOAD_UNALIGNED_ZEROPAD: 98 return ex_handler_load_unaligned_zeropad(ex, regs); 99 } 100 101 BUG(); 102 } 103