extable.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 #include <linux/bitfield.h>
   4 #include <linux/extable.h>
   5 #include <linux/string.h>
   6 #include <linux/errno.h>
   7 #include <linux/panic.h>
   8 #include <asm/asm-extable.h>
   9 #include <asm/extable.h>
  10
  11 const struct exception_table_entry *s390_search_extables(unsigned long addr)
  12 {
  13         const struct exception_table_entry *fixup;
  14         size_t num;
  15
  16         fixup = search_exception_tables(addr);
  17         if (fixup)
  18                 return fixup;
  19         num = __stop_amode31_ex_table - __start_amode31_ex_table;
  20         return search_extable(__start_amode31_ex_table, num, addr);
  21 }
  22
  23 static bool ex_handler_fixup(const struct exception_table_entry *ex, struct pt_regs *regs)
  24 {
  25         regs->psw.addr = extable_fixup(ex);
  26         return true;
  27 }
  28
  29 static bool ex_handler_ua_store(const struct exception_table_entry *ex, struct pt_regs *regs)
  30 {
  31         unsigned int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
  32
  33         regs->gprs[reg_err] = -EFAULT;
  34         regs->psw.addr = extable_fixup(ex);
  35         return true;
  36 }
  37
  38 static bool ex_handler_ua_load_mem(const struct exception_table_entry *ex, struct pt_regs *regs)
  39 {
  40         unsigned int reg_addr = FIELD_GET(EX_DATA_REG_ADDR, ex->data);
  41         unsigned int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
  42         size_t len = FIELD_GET(EX_DATA_LEN, ex->data);
  43
  44         regs->gprs[reg_err] = -EFAULT;
  45         memset((void *)regs->gprs[reg_addr], 0, len);
  46         regs->psw.addr = extable_fixup(ex);
  47         return true;
  48 }
  49
  50 static bool ex_handler_ua_load_reg(const struct exception_table_entry *ex,
  51                                    bool pair, struct pt_regs *regs)
  52 {
  53         unsigned int reg_zero = FIELD_GET(EX_DATA_REG_ADDR, ex->data);
  54         unsigned int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
  55
  56         regs->gprs[reg_err] = -EFAULT;
  57         regs->gprs[reg_zero] = 0;
  58         if (pair)
  59                 regs->gprs[reg_zero + 1] = 0;
  60         regs->psw.addr = extable_fixup(ex);
  61         return true;
  62 }
  63
  64 static bool ex_handler_zeropad(const struct exception_table_entry *ex, struct pt_regs *regs)
  65 {
  66         unsigned int reg_addr = FIELD_GET(EX_DATA_REG_ADDR, ex->data);
  67         unsigned int reg_data = FIELD_GET(EX_DATA_REG_ERR, ex->data);
  68         unsigned long data, addr, offset;
  69
  70         addr = regs->gprs[reg_addr];
  71         offset = addr & (sizeof(unsigned long) - 1);
  72         addr &= ~(sizeof(unsigned long) - 1);
  73         data = *(unsigned long *)addr;
  74         data <<= BITS_PER_BYTE * offset;
  75         regs->gprs[reg_data] = data;
  76         regs->psw.addr = extable_fixup(ex);
  77         return true;
  78 }
  79
  80 bool fixup_exception(struct pt_regs *regs)
  81 {
  82         const struct exception_table_entry *ex;
  83
  84         ex = s390_search_extables(instruction_pointer(regs));
  85         if (!ex)
  86                 return false;
  87         switch (ex->type) {
  88         case EX_TYPE_FIXUP:
  89                 return ex_handler_fixup(ex, regs);
  90         case EX_TYPE_BPF:
  91                 return ex_handler_bpf(ex, regs);
  92         case EX_TYPE_UA_STORE:
  93                 return ex_handler_ua_store(ex, regs);
  94         case EX_TYPE_UA_LOAD_MEM:
  95                 return ex_handler_ua_load_mem(ex, regs);
  96         case EX_TYPE_UA_LOAD_REG:
  97                 return ex_handler_ua_load_reg(ex, false, regs);
  98         case EX_TYPE_UA_LOAD_REGPAIR:
  99                 return ex_handler_ua_load_reg(ex, true, regs);
 100         case EX_TYPE_ZEROPAD:
 101                 return ex_handler_zeropad(ex, regs);
 102         }
 103         panic("invalid exception table entry");
 104 }