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// SPDX-License-Identifier: GPL-2.0
#include <linux/bitfield.h>
#include <linux/extable.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/panic.h>
#include <asm/asm-extable.h>
#include <asm/extable.h>
#include <asm/fpu.h>
const struct exception_table_entry *s390_search_extables(unsigned long addr)
{
const struct exception_table_entry *fixup;
size_t num;
fixup = search_exception_tables(addr);
if (fixup)
return fixup;
num = __stop_amode31_ex_table - __start_amode31_ex_table;
return search_extable(__start_amode31_ex_table, num, addr);
}
static bool ex_handler_fixup(const struct exception_table_entry *ex, struct pt_regs *regs)
{
regs->psw.addr = extable_fixup(ex);
return true;
}
static bool ex_handler_ua_fault(const struct exception_table_entry *ex, struct pt_regs *regs)
{
unsigned int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
regs->gprs[reg_err] = -EFAULT;
regs->psw.addr = extable_fixup(ex);
return true;
}
static bool ex_handler_ua_load_reg(const struct exception_table_entry *ex,
bool pair, struct pt_regs *regs)
{
unsigned int reg_zero = FIELD_GET(EX_DATA_REG_ADDR, ex->data);
unsigned int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
regs->gprs[reg_err] = -EFAULT;
regs->gprs[reg_zero] = 0;
if (pair)
regs->gprs[reg_zero + 1] = 0;
regs->psw.addr = extable_fixup(ex);
return true;
}
static bool ex_handler_zeropad(const struct exception_table_entry *ex, struct pt_regs *regs)
{
unsigned int reg_addr = FIELD_GET(EX_DATA_REG_ADDR, ex->data);
unsigned int reg_data = FIELD_GET(EX_DATA_REG_ERR, ex->data);
unsigned long data, addr, offset;
addr = regs->gprs[reg_addr];
offset = addr & (sizeof(unsigned long) - 1);
addr &= ~(sizeof(unsigned long) - 1);
data = *(unsigned long *)addr;
data <<= BITS_PER_BYTE * offset;
regs->gprs[reg_data] = data;
regs->psw.addr = extable_fixup(ex);
return true;
}
static bool ex_handler_fpc(const struct exception_table_entry *ex, struct pt_regs *regs)
{
fpu_sfpc(0);
regs->psw.addr = extable_fixup(ex);
return true;
}
struct insn_ssf {
u64 opc1 : 8;
u64 r3 : 4;
u64 opc2 : 4;
u64 b1 : 4;
u64 d1 : 12;
u64 b2 : 4;
u64 d2 : 12;
} __packed;
static bool ex_handler_ua_mvcos(const struct exception_table_entry *ex,
bool from, struct pt_regs *regs)
{
unsigned long uaddr, remainder;
struct insn_ssf *insn;
/*
* If the faulting user space access crossed a page boundary retry by
* limiting the access to the first page (adjust length accordingly).
* Then the mvcos instruction will either complete with condition code
* zero, or generate another fault where the user space access did not
* cross a page boundary.
* If the faulting user space access did not cross a page boundary set
* length to zero and retry. In this case no user space access will
* happen, and the mvcos instruction will complete with condition code
* zero.
* In both cases the instruction will complete with condition code
* zero (copying finished), and the register which contains the
* length, indicates the number of bytes copied.
*/
regs->psw.addr = extable_fixup(ex);
insn = (struct insn_ssf *)regs->psw.addr;
if (from)
uaddr = regs->gprs[insn->b2] + insn->d2;
else
uaddr = regs->gprs[insn->b1] + insn->d1;
remainder = PAGE_SIZE - (uaddr & (PAGE_SIZE - 1));
if (regs->gprs[insn->r3] <= remainder)
remainder = 0;
regs->gprs[insn->r3] = remainder;
return true;
}
bool fixup_exception(struct pt_regs *regs)
{
const struct exception_table_entry *ex;
ex = s390_search_extables(instruction_pointer(regs));
if (!ex)
return false;
switch (ex->type) {
case EX_TYPE_FIXUP:
return ex_handler_fixup(ex, regs);
case EX_TYPE_BPF:
return ex_handler_bpf(ex, regs);
case EX_TYPE_UA_FAULT:
return ex_handler_ua_fault(ex, regs);
case EX_TYPE_UA_LOAD_REG:
return ex_handler_ua_load_reg(ex, false, regs);
case EX_TYPE_UA_LOAD_REGPAIR:
return ex_handler_ua_load_reg(ex, true, regs);
case EX_TYPE_ZEROPAD:
return ex_handler_zeropad(ex, regs);
case EX_TYPE_FPC:
return ex_handler_fpc(ex, regs);
case EX_TYPE_UA_MVCOS_TO:
return ex_handler_ua_mvcos(ex, false, regs);
case EX_TYPE_UA_MVCOS_FROM:
return ex_handler_ua_mvcos(ex, true, regs);
}
panic("invalid exception table entry");
}
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