1 files changed, 378 insertions, 0 deletions
diff --git a/arch/sh/kernel/kgdb.c b/arch/sh/kernel/kgdb.c
new file mode 100644
index 000000000..e4147efa9
--- /dev/null
+++ b/arch/sh/kernel/kgdb.c
@@ -0,0 +1,378 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * SuperH KGDB support
+ *
+ * Copyright (C) 2008 - 2012  Paul Mundt
+ *
+ * Single stepping taken from the old stub by Henry Bell and Jeremy Siegel.
+ */
+#include <linux/kgdb.h>
+#include <linux/kdebug.h>
+#include <linux/irq.h>
+#include <linux/io.h>
+#include <linux/sched.h>
+#include <linux/sched/task_stack.h>
+
+#include <asm/cacheflush.h>
+#include <asm/traps.h>
+
+/* Macros for single step instruction identification */
+#define OPCODE_BT(op)		(((op) & 0xff00) == 0x8900)
+#define OPCODE_BF(op)		(((op) & 0xff00) == 0x8b00)
+#define OPCODE_BTF_DISP(op)	(((op) & 0x80) ? (((op) | 0xffffff80) << 1) : \
+				 (((op) & 0x7f ) << 1))
+#define OPCODE_BFS(op)		(((op) & 0xff00) == 0x8f00)
+#define OPCODE_BTS(op)		(((op) & 0xff00) == 0x8d00)
+#define OPCODE_BRA(op)		(((op) & 0xf000) == 0xa000)
+#define OPCODE_BRA_DISP(op)	(((op) & 0x800) ? (((op) | 0xfffff800) << 1) : \
+				 (((op) & 0x7ff) << 1))
+#define OPCODE_BRAF(op)		(((op) & 0xf0ff) == 0x0023)
+#define OPCODE_BRAF_REG(op)	(((op) & 0x0f00) >> 8)
+#define OPCODE_BSR(op)		(((op) & 0xf000) == 0xb000)
+#define OPCODE_BSR_DISP(op)	(((op) & 0x800) ? (((op) | 0xfffff800) << 1) : \
+				 (((op) & 0x7ff) << 1))
+#define OPCODE_BSRF(op)		(((op) & 0xf0ff) == 0x0003)
+#define OPCODE_BSRF_REG(op)	(((op) >> 8) & 0xf)
+#define OPCODE_JMP(op)		(((op) & 0xf0ff) == 0x402b)
+#define OPCODE_JMP_REG(op)	(((op) >> 8) & 0xf)
+#define OPCODE_JSR(op)		(((op) & 0xf0ff) == 0x400b)
+#define OPCODE_JSR_REG(op)	(((op) >> 8) & 0xf)
+#define OPCODE_RTS(op)		((op) == 0xb)
+#define OPCODE_RTE(op)		((op) == 0x2b)
+
+#define SR_T_BIT_MASK           0x1
+#define STEP_OPCODE             0xc33d
+
+/* Calculate the new address for after a step */
+static short *get_step_address(struct pt_regs *linux_regs)
+{
+	insn_size_t op = __raw_readw(linux_regs->pc);
+	long addr;
+
+	/* BT */
+	if (OPCODE_BT(op)) {
+		if (linux_regs->sr & SR_T_BIT_MASK)
+			addr = linux_regs->pc + 4 + OPCODE_BTF_DISP(op);
+		else
+			addr = linux_regs->pc + 2;
+	}
+
+	/* BTS */
+	else if (OPCODE_BTS(op)) {
+		if (linux_regs->sr & SR_T_BIT_MASK)
+			addr = linux_regs->pc + 4 + OPCODE_BTF_DISP(op);
+		else
+			addr = linux_regs->pc + 4;	/* Not in delay slot */
+	}
+
+	/* BF */
+	else if (OPCODE_BF(op)) {
+		if (!(linux_regs->sr & SR_T_BIT_MASK))
+			addr = linux_regs->pc + 4 + OPCODE_BTF_DISP(op);
+		else
+			addr = linux_regs->pc + 2;
+	}
+
+	/* BFS */
+	else if (OPCODE_BFS(op)) {
+		if (!(linux_regs->sr & SR_T_BIT_MASK))
+			addr = linux_regs->pc + 4 + OPCODE_BTF_DISP(op);
+		else
+			addr = linux_regs->pc + 4;	/* Not in delay slot */
+	}
+
+	/* BRA */
+	else if (OPCODE_BRA(op))
+		addr = linux_regs->pc + 4 + OPCODE_BRA_DISP(op);
+
+	/* BRAF */
+	else if (OPCODE_BRAF(op))
+		addr = linux_regs->pc + 4
+		    + linux_regs->regs[OPCODE_BRAF_REG(op)];
+
+	/* BSR */
+	else if (OPCODE_BSR(op))
+		addr = linux_regs->pc + 4 + OPCODE_BSR_DISP(op);
+
+	/* BSRF */
+	else if (OPCODE_BSRF(op))
+		addr = linux_regs->pc + 4
+		    + linux_regs->regs[OPCODE_BSRF_REG(op)];
+
+	/* JMP */
+	else if (OPCODE_JMP(op))
+		addr = linux_regs->regs[OPCODE_JMP_REG(op)];
+
+	/* JSR */
+	else if (OPCODE_JSR(op))
+		addr = linux_regs->regs[OPCODE_JSR_REG(op)];
+
+	/* RTS */
+	else if (OPCODE_RTS(op))
+		addr = linux_regs->pr;
+
+	/* RTE */
+	else if (OPCODE_RTE(op))
+		addr = linux_regs->regs[15];
+
+	/* Other */
+	else
+		addr = linux_regs->pc + instruction_size(op);
+
+	flush_icache_range(addr, addr + instruction_size(op));
+	return (short *)addr;
+}
+
+/*
+ * Replace the instruction immediately after the current instruction
+ * (i.e. next in the expected flow of control) with a trap instruction,
+ * so that returning will cause only a single instruction to be executed.
+ * Note that this model is slightly broken for instructions with delay
+ * slots (e.g. B[TF]S, BSR, BRA etc), where both the branch and the
+ * instruction in the delay slot will be executed.
+ */
+
+static unsigned long stepped_address;
+static insn_size_t stepped_opcode;
+
+static void do_single_step(struct pt_regs *linux_regs)
+{
+	/* Determine where the target instruction will send us to */
+	unsigned short *addr = get_step_address(linux_regs);
+
+	stepped_address = (int)addr;
+
+	/* Replace it */
+	stepped_opcode = __raw_readw((long)addr);
+	*addr = STEP_OPCODE;
+
+	/* Flush and return */
+	flush_icache_range((long)addr, (long)addr +
+			   instruction_size(stepped_opcode));
+}
+
+/* Undo a single step */
+static void undo_single_step(struct pt_regs *linux_regs)
+{
+	/* If we have stepped, put back the old instruction */
+	/* Use stepped_address in case we stopped elsewhere */
+	if (stepped_opcode != 0) {
+		__raw_writew(stepped_opcode, stepped_address);
+		flush_icache_range(stepped_address, stepped_address + 2);
+	}
+
+	stepped_opcode = 0;
+}
+
+struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = {
+	{ "r0",		GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[0]) },
+	{ "r1",		GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[1]) },
+	{ "r2",		GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[2]) },
+	{ "r3",		GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[3]) },
+	{ "r4",		GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[4]) },
+	{ "r5",		GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[5]) },
+	{ "r6",		GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[6]) },
+	{ "r7",		GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[7]) },
+	{ "r8",		GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[8]) },
+	{ "r9",		GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[9]) },
+	{ "r10",	GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[10]) },
+	{ "r11",	GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[11]) },
+	{ "r12",	GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[12]) },
+	{ "r13",	GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[13]) },
+	{ "r14",	GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[14]) },
+	{ "r15",	GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[15]) },
+	{ "pc",		GDB_SIZEOF_REG, offsetof(struct pt_regs, pc) },
+	{ "pr",		GDB_SIZEOF_REG, offsetof(struct pt_regs, pr) },
+	{ "sr",		GDB_SIZEOF_REG, offsetof(struct pt_regs, sr) },
+	{ "gbr",	GDB_SIZEOF_REG, offsetof(struct pt_regs, gbr) },
+	{ "mach",	GDB_SIZEOF_REG, offsetof(struct pt_regs, mach) },
+	{ "macl",	GDB_SIZEOF_REG, offsetof(struct pt_regs, macl) },
+	{ "vbr",	GDB_SIZEOF_REG, -1 },
+};
+
+int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
+{
+	if (regno < 0 || regno >= DBG_MAX_REG_NUM)
+		return -EINVAL;
+
+	if (dbg_reg_def[regno].offset != -1)
+		memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
+		       dbg_reg_def[regno].size);
+
+	return 0;
+}
+
+char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
+{
+	if (regno >= DBG_MAX_REG_NUM || regno < 0)
+		return NULL;
+
+	if (dbg_reg_def[regno].size != -1)
+		memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
+		       dbg_reg_def[regno].size);
+
+	switch (regno) {
+	case GDB_VBR:
+		__asm__ __volatile__ ("stc vbr, %0" : "=r" (mem));
+		break;
+	}
+
+	return dbg_reg_def[regno].name;
+}
+
+void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
+{
+	struct pt_regs *thread_regs = task_pt_regs(p);
+	int reg;
+
+	/* Initialize to zero */
+	for (reg = 0; reg < DBG_MAX_REG_NUM; reg++)
+		gdb_regs[reg] = 0;
+
+	/*
+	 * Copy out GP regs 8 to 14.
+	 *
+	 * switch_to() relies on SR.RB toggling, so regs 0->7 are banked
+	 * and need privileged instructions to get to. The r15 value we
+	 * fetch from the thread info directly.
+	 */
+	for (reg = GDB_R8; reg < GDB_R15; reg++)
+		gdb_regs[reg] = thread_regs->regs[reg];
+
+	gdb_regs[GDB_R15] = p->thread.sp;
+	gdb_regs[GDB_PC] = p->thread.pc;
+
+	/*
+	 * Additional registers we have context for
+	 */
+	gdb_regs[GDB_PR] = thread_regs->pr;
+	gdb_regs[GDB_GBR] = thread_regs->gbr;
+}
+
+int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
+			       char *remcomInBuffer, char *remcomOutBuffer,
+			       struct pt_regs *linux_regs)
+{
+	unsigned long addr;
+	char *ptr;
+
+	/* Undo any stepping we may have done */
+	undo_single_step(linux_regs);
+
+	switch (remcomInBuffer[0]) {
+	case 'c':
+	case 's':
+		/* try to read optional parameter, pc unchanged if no parm */
+		ptr = &remcomInBuffer[1];
+		if (kgdb_hex2long(&ptr, &addr))
+			linux_regs->pc = addr;
+		fallthrough;
+	case 'D':
+	case 'k':
+		atomic_set(&kgdb_cpu_doing_single_step, -1);
+
+		if (remcomInBuffer[0] == 's') {
+			do_single_step(linux_regs);
+			kgdb_single_step = 1;
+
+			atomic_set(&kgdb_cpu_doing_single_step,
+				   raw_smp_processor_id());
+		}
+
+		return 0;
+	}
+
+	/* this means that we do not want to exit from the handler: */
+	return -1;
+}
+
+unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs)
+{
+	if (exception == 60)
+		return instruction_pointer(regs) - 2;
+	return instruction_pointer(regs);
+}
+
+void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
+{
+	regs->pc = ip;
+}
+
+/*
+ * The primary entry points for the kgdb debug trap table entries.
+ */
+BUILD_TRAP_HANDLER(singlestep)
+{
+	unsigned long flags;
+	TRAP_HANDLER_DECL;
+
+	local_irq_save(flags);
+	regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
+	kgdb_handle_exception(0, SIGTRAP, 0, regs);
+	local_irq_restore(flags);
+}
+
+static int __kgdb_notify(struct die_args *args, unsigned long cmd)
+{
+	int ret;
+
+	switch (cmd) {
+	case DIE_BREAKPOINT:
+		/*
+		 * This means a user thread is single stepping
+		 * a system call which should be ignored
+		 */
+		if (test_thread_flag(TIF_SINGLESTEP))
+			return NOTIFY_DONE;
+
+		ret = kgdb_handle_exception(args->trapnr & 0xff, args->signr,
+					    args->err, args->regs);
+		if (ret)
+			return NOTIFY_DONE;
+
+		break;
+	}
+
+	return NOTIFY_STOP;
+}
+
+static int
+kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
+{
+	unsigned long flags;
+	int ret;
+
+	local_irq_save(flags);
+	ret = __kgdb_notify(ptr, cmd);
+	local_irq_restore(flags);
+
+	return ret;
+}
+
+static struct notifier_block kgdb_notifier = {
+	.notifier_call	= kgdb_notify,
+
+	/*
+	 * Lowest-prio notifier priority, we want to be notified last:
+	 */
+	.priority	= -INT_MAX,
+};
+
+int kgdb_arch_init(void)
+{
+	return register_die_notifier(&kgdb_notifier);
+}
+
+void kgdb_arch_exit(void)
+{
+	unregister_die_notifier(&kgdb_notifier);
+}
+
+const struct kgdb_arch arch_kgdb_ops = {
+	/* Breakpoint instruction: trapa #0x3c */
+#ifdef CONFIG_CPU_LITTLE_ENDIAN
+	.gdb_bpt_instr		= { 0x3c, 0xc3 },
+#else
+	.gdb_bpt_instr		= { 0xc3, 0x3c },
+#endif
+};