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// SPDX-License-Identifier: GPL-2.0-only
/*
* Traps/Non-MMU Exception handling for ARC
*
* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
*
* vineetg: May 2011
* -user-space unaligned access emulation
*
* Rahul Trivedi: Codito Technologies 2004
*/
#include <linux/sched/signal.h>
#include <linux/kdebug.h>
#include <linux/uaccess.h>
#include <linux/ptrace.h>
#include <linux/kprobes.h>
#include <linux/kgdb.h>
#include <asm/entry.h>
#include <asm/setup.h>
#include <asm/unaligned.h>
#include <asm/kprobes.h>
void die(const char *str, struct pt_regs *regs, unsigned long address)
{
show_kernel_fault_diag(str, regs, address);
/* DEAD END */
__asm__("flag 1");
}
/*
* Helper called for bulk of exceptions NOT needing specific handling
* -for user faults enqueues requested signal
* -for kernel, chk if due to copy_(to|from)_user, otherwise die()
*/
static noinline int
unhandled_exception(const char *str, struct pt_regs *regs,
int signo, int si_code, void __user *addr)
{
if (user_mode(regs)) {
struct task_struct *tsk = current;
tsk->thread.fault_address = (__force unsigned int)addr;
force_sig_fault(signo, si_code, addr);
} else {
/* If not due to copy_(to|from)_user, we are doomed */
if (fixup_exception(regs))
return 0;
die(str, regs, (unsigned long)addr);
}
return 1;
}
#define DO_ERROR_INFO(signr, str, name, sicode) \
int name(unsigned long address, struct pt_regs *regs) \
{ \
return unhandled_exception(str, regs, signr, sicode, \
(void __user *)address); \
}
/*
* Entry points for exceptions NOT needing specific handling
*/
DO_ERROR_INFO(SIGILL, "Priv Op/Disabled Extn", do_privilege_fault, ILL_PRVOPC)
DO_ERROR_INFO(SIGILL, "Invalid Extn Insn", do_extension_fault, ILL_ILLOPC)
DO_ERROR_INFO(SIGILL, "Illegal Insn (or Seq)", insterror_is_error, ILL_ILLOPC)
DO_ERROR_INFO(SIGBUS, "Invalid Mem Access", __weak do_memory_error, BUS_ADRERR)
DO_ERROR_INFO(SIGTRAP, "Breakpoint Set", trap_is_brkpt, TRAP_BRKPT)
DO_ERROR_INFO(SIGBUS, "Misaligned Access", do_misaligned_error, BUS_ADRALN)
DO_ERROR_INFO(SIGSEGV, "gcc generated __builtin_trap", do_trap5_error, 0)
/*
* Entry Point for Misaligned Data access Exception, for emulating in software
*/
int do_misaligned_access(unsigned long address, struct pt_regs *regs,
struct callee_regs *cregs)
{
/* If emulation not enabled, or failed, kill the task */
if (misaligned_fixup(address, regs, cregs) != 0)
return do_misaligned_error(address, regs);
return 0;
}
/*
* Entry point for miscll errors such as Nested Exceptions
* -Duplicate TLB entry is handled seperately though
*/
void do_machine_check_fault(unsigned long address, struct pt_regs *regs)
{
die("Unhandled Machine Check Exception", regs, address);
}
/*
* Entry point for traps induced by ARCompact TRAP_S <n> insn
* This is same family as TRAP0/SWI insn (use the same vector).
* The only difference being SWI insn take no operand, while TRAP_S does
* which reflects in ECR Reg as 8 bit param.
* Thus TRAP_S <n> can be used for specific purpose
* -1 used for software breakpointing (gdb)
* -2 used by kprobes
* -5 __builtin_trap() generated by gcc (2018.03 onwards) for toggle such as
* -fno-isolate-erroneous-paths-dereference
*/
void do_non_swi_trap(unsigned long address, struct pt_regs *regs)
{
switch (regs->ecr.param) {
case 1:
trap_is_brkpt(address, regs);
break;
case 2:
trap_is_kprobe(address, regs);
break;
case 3:
case 4:
kgdb_trap(regs);
break;
case 5:
do_trap5_error(address, regs);
break;
default:
break;
}
}
/*
* Entry point for Instruction Error Exception
* -For a corner case, ARC kprobes implementation resorts to using
* this exception, hence the check
*/
void do_insterror_or_kprobe(unsigned long address, struct pt_regs *regs)
{
int rc;
/* Check if this exception is caused by kprobes */
rc = notify_die(DIE_IERR, "kprobe_ierr", regs, address, 0, SIGILL);
if (rc == NOTIFY_STOP)
return;
insterror_is_error(address, regs);
}
/*
* abort() call generated by older gcc for __builtin_trap()
*/
void abort(void)
{
__asm__ __volatile__("trap_s 5\n");
}
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