1 files changed, 158 insertions, 0 deletions
diff --git a/arch/arc/kernel/traps.c b/arch/arc/kernel/traps.c
new file mode 100644
index 0000000000..9b9570b793
--- /dev/null
+++ b/arch/arc/kernel/traps.c
@@ -0,0 +1,158 @@
+// 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");
+}