arch/s390/mm/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 #include <asm/fpu.h>
  11
  12 const struct exception_table_entry *s390_search_extables(unsigned long addr)
  13 {
  14         const struct exception_table_entry *fixup;
  15         size_t num;
  16
  17         fixup = search_exception_tables(addr);
  18         if (fixup)
  19                 return fixup;
  20         num = __stop_amode31_ex_table - __start_amode31_ex_table;
  21         return search_extable(__start_amode31_ex_table, num, addr);
  22 }
  23
  24 static bool ex_handler_fixup(const struct exception_table_entry *ex, struct pt_regs *regs)
  25 {
  26         regs->psw.addr = extable_fixup(ex);
  27         return true;
  28 }
  29
  30 static bool ex_handler_ua_fault(const struct exception_table_entry *ex, struct pt_regs *regs)
  31 {
  32         unsigned int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
  33
  34         regs->gprs[reg_err] = -EFAULT;
  35         regs->psw.addr = extable_fixup(ex);
  36         return true;
  37 }
  38
  39 static bool ex_handler_ua_load_reg(const struct exception_table_entry *ex,
  40                                    bool pair, struct pt_regs *regs)
  41 {
  42         unsigned int reg_zero = FIELD_GET(EX_DATA_REG_ADDR, ex->data);
  43         unsigned int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
  44
  45         regs->gprs[reg_err] = -EFAULT;
  46         regs->gprs[reg_zero] = 0;
  47         if (pair)
  48                 regs->gprs[reg_zero + 1] = 0;
  49         regs->psw.addr = extable_fixup(ex);
  50         return true;
  51 }
  52
  53 static bool ex_handler_zeropad(const struct exception_table_entry *ex, struct pt_regs *regs)
  54 {
  55         unsigned int reg_addr = FIELD_GET(EX_DATA_REG_ADDR, ex->data);
  56         unsigned int reg_data = FIELD_GET(EX_DATA_REG_ERR, ex->data);
  57         unsigned long data, addr, offset;
  58
  59         addr = regs->gprs[reg_addr];
  60         offset = addr & (sizeof(unsigned long) - 1);
  61         addr &= ~(sizeof(unsigned long) - 1);
  62         data = *(unsigned long *)addr;
  63         data <<= BITS_PER_BYTE * offset;
  64         regs->gprs[reg_data] = data;
  65         regs->psw.addr = extable_fixup(ex);
  66         return true;
  67 }
  68
  69 static bool ex_handler_fpc(const struct exception_table_entry *ex, struct pt_regs *regs)
  70 {
  71         fpu_sfpc(0);
  72         regs->psw.addr = extable_fixup(ex);
  73         return true;
  74 }
  75
  76 bool fixup_exception(struct pt_regs *regs)
  77 {
  78         const struct exception_table_entry *ex;
  79
  80         ex = s390_search_extables(instruction_pointer(regs));
  81         if (!ex)
  82                 return false;
  83         switch (ex->type) {
  84         case EX_TYPE_FIXUP:
  85                 return ex_handler_fixup(ex, regs);
  86         case EX_TYPE_BPF:
  87                 return ex_handler_bpf(ex, regs);
  88         case EX_TYPE_UA_FAULT:
  89                 return ex_handler_ua_fault(ex, regs);
  90         case EX_TYPE_UA_LOAD_REG:
  91                 return ex_handler_ua_load_reg(ex, false, regs);
  92         case EX_TYPE_UA_LOAD_REGPAIR:
  93                 return ex_handler_ua_load_reg(ex, true, regs);
  94         case EX_TYPE_ZEROPAD:
  95                 return ex_handler_zeropad(ex, regs);
  96         case EX_TYPE_FPC:
  97                 return ex_handler_fpc(ex, regs);
  98         }
  99         panic("invalid exception table entry");
 100 }