cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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traps.c (4173B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Traps/Non-MMU Exception handling for ARC
      4 *
      5 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
      6 *
      7 * vineetg: May 2011
      8 *  -user-space unaligned access emulation
      9 *
     10 * Rahul Trivedi: Codito Technologies 2004
     11 */
     12
     13#include <linux/sched/signal.h>
     14#include <linux/kdebug.h>
     15#include <linux/uaccess.h>
     16#include <linux/ptrace.h>
     17#include <linux/kprobes.h>
     18#include <linux/kgdb.h>
     19#include <asm/setup.h>
     20#include <asm/unaligned.h>
     21#include <asm/kprobes.h>
     22
     23void die(const char *str, struct pt_regs *regs, unsigned long address)
     24{
     25	show_kernel_fault_diag(str, regs, address);
     26
     27	/* DEAD END */
     28	__asm__("flag 1");
     29}
     30
     31/*
     32 * Helper called for bulk of exceptions NOT needing specific handling
     33 *  -for user faults enqueues requested signal
     34 *  -for kernel, chk if due to copy_(to|from)_user, otherwise die()
     35 */
     36static noinline int
     37unhandled_exception(const char *str, struct pt_regs *regs,
     38		    int signo, int si_code, void __user *addr)
     39{
     40	if (user_mode(regs)) {
     41		struct task_struct *tsk = current;
     42
     43		tsk->thread.fault_address = (__force unsigned int)addr;
     44
     45		force_sig_fault(signo, si_code, addr);
     46
     47	} else {
     48		/* If not due to copy_(to|from)_user, we are doomed */
     49		if (fixup_exception(regs))
     50			return 0;
     51
     52		die(str, regs, (unsigned long)addr);
     53	}
     54
     55	return 1;
     56}
     57
     58#define DO_ERROR_INFO(signr, str, name, sicode) \
     59int name(unsigned long address, struct pt_regs *regs) \
     60{								\
     61	return unhandled_exception(str, regs, signr, sicode,	\
     62				   (void __user *)address);	\
     63}
     64
     65/*
     66 * Entry points for exceptions NOT needing specific handling
     67 */
     68DO_ERROR_INFO(SIGILL, "Priv Op/Disabled Extn", do_privilege_fault, ILL_PRVOPC)
     69DO_ERROR_INFO(SIGILL, "Invalid Extn Insn", do_extension_fault, ILL_ILLOPC)
     70DO_ERROR_INFO(SIGILL, "Illegal Insn (or Seq)", insterror_is_error, ILL_ILLOPC)
     71DO_ERROR_INFO(SIGBUS, "Invalid Mem Access", __weak do_memory_error, BUS_ADRERR)
     72DO_ERROR_INFO(SIGTRAP, "Breakpoint Set", trap_is_brkpt, TRAP_BRKPT)
     73DO_ERROR_INFO(SIGBUS, "Misaligned Access", do_misaligned_error, BUS_ADRALN)
     74DO_ERROR_INFO(SIGSEGV, "gcc generated __builtin_trap", do_trap5_error, 0)
     75
     76/*
     77 * Entry Point for Misaligned Data access Exception, for emulating in software
     78 */
     79int do_misaligned_access(unsigned long address, struct pt_regs *regs,
     80			 struct callee_regs *cregs)
     81{
     82	/* If emulation not enabled, or failed, kill the task */
     83	if (misaligned_fixup(address, regs, cregs) != 0)
     84		return do_misaligned_error(address, regs);
     85
     86	return 0;
     87}
     88
     89/*
     90 * Entry point for miscll errors such as Nested Exceptions
     91 *  -Duplicate TLB entry is handled seperately though
     92 */
     93void do_machine_check_fault(unsigned long address, struct pt_regs *regs)
     94{
     95	die("Unhandled Machine Check Exception", regs, address);
     96}
     97
     98
     99/*
    100 * Entry point for traps induced by ARCompact TRAP_S <n> insn
    101 * This is same family as TRAP0/SWI insn (use the same vector).
    102 * The only difference being SWI insn take no operand, while TRAP_S does
    103 * which reflects in ECR Reg as 8 bit param.
    104 * Thus TRAP_S <n> can be used for specific purpose
    105 *  -1 used for software breakpointing (gdb)
    106 *  -2 used by kprobes
    107 *  -5 __builtin_trap() generated by gcc (2018.03 onwards) for toggle such as
    108 *     -fno-isolate-erroneous-paths-dereference
    109 */
    110void do_non_swi_trap(unsigned long address, struct pt_regs *regs)
    111{
    112	unsigned int param = regs->ecr_param;
    113
    114	switch (param) {
    115	case 1:
    116		trap_is_brkpt(address, regs);
    117		break;
    118
    119	case 2:
    120		trap_is_kprobe(address, regs);
    121		break;
    122
    123	case 3:
    124	case 4:
    125		kgdb_trap(regs);
    126		break;
    127
    128	case 5:
    129		do_trap5_error(address, regs);
    130		break;
    131	default:
    132		break;
    133	}
    134}
    135
    136/*
    137 * Entry point for Instruction Error Exception
    138 *  -For a corner case, ARC kprobes implementation resorts to using
    139 *   this exception, hence the check
    140 */
    141void do_insterror_or_kprobe(unsigned long address, struct pt_regs *regs)
    142{
    143	int rc;
    144
    145	/* Check if this exception is caused by kprobes */
    146	rc = notify_die(DIE_IERR, "kprobe_ierr", regs, address, 0, SIGILL);
    147	if (rc == NOTIFY_STOP)
    148		return;
    149
    150	insterror_is_error(address, regs);
    151}
    152
    153/*
    154 * abort() call generated by older gcc for __builtin_trap()
    155 */
    156void abort(void)
    157{
    158	__asm__ __volatile__("trap_s  5\n");
    159}