csky: Exception handling and mm-fault

This patch adds exception handling code, cpuinfo and mm-fault code.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>

2 files changed, 486 insertions, 0 deletions

diff --git a/arch/csky/abiv1/alignment.c b/arch/csky/abiv1/alignment.c
new file mode 100644
index 000000000000..60205e98fb87
--- /dev/null
+++ b/arch/csky/abiv1/alignment.c
@@ -0,0 +1,326 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#include <linux/kernel.h>
+#include <linux/uaccess.h>
+#include <linux/ptrace.h>
+
+static int align_enable = 1;
+static int align_count;
+
+static inline uint32_t get_ptreg(struct pt_regs *regs, uint32_t rx)
+{
+	return rx == 15 ? regs->lr : *((uint32_t *)&(regs->a0) - 2 + rx);
+}
+
+static inline void put_ptreg(struct pt_regs *regs, uint32_t rx, uint32_t val)
+{
+	if (rx == 15)
+		regs->lr = val;
+	else
+		*((uint32_t *)&(regs->a0) - 2 + rx) = val;
+}
+
+/*
+ * Get byte-value from addr and set it to *valp.
+ *
+ * Success: return 0
+ * Failure: return 1
+ */
+static int ldb_asm(uint32_t addr, uint32_t *valp)
+{
+	uint32_t val;
+	int err;
+
+	if (!access_ok(VERIFY_READ, (void *)addr, 1))
+		return 1;
+
+	asm volatile (
+		"movi	%0, 0\n"
+		"1:\n"
+		"ldb	%1, (%2)\n"
+		"br	3f\n"
+		"2:\n"
+		"movi	%0, 1\n"
+		"br	3f\n"
+		".section __ex_table,\"a\"\n"
+		".align 2\n"
+		".long	1b, 2b\n"
+		".previous\n"
+		"3:\n"
+		: "=&r"(err), "=r"(val)
+		: "r" (addr)
+	);
+
+	*valp = val;
+
+	return err;
+}
+
+/*
+ * Put byte-value to addr.
+ *
+ * Success: return 0
+ * Failure: return 1
+ */
+static int stb_asm(uint32_t addr, uint32_t val)
+{
+	int err;
+
+	if (!access_ok(VERIFY_WRITE, (void *)addr, 1))
+		return 1;
+
+	asm volatile (
+		"movi	%0, 0\n"
+		"1:\n"
+		"stb	%1, (%2)\n"
+		"br	3f\n"
+		"2:\n"
+		"movi	%0, 1\n"
+		"br	3f\n"
+		".section __ex_table,\"a\"\n"
+		".align 2\n"
+		".long	1b, 2b\n"
+		".previous\n"
+		"3:\n"
+		: "=&r"(err)
+		: "r"(val), "r" (addr)
+	);
+
+	return err;
+}
+
+/*
+ * Get half-word from [rx + imm]
+ *
+ * Success: return 0
+ * Failure: return 1
+ */
+static int ldh_c(struct pt_regs *regs, uint32_t rz, uint32_t addr)
+{
+	uint32_t byte0, byte1;
+
+	if (ldb_asm(addr, &byte0))
+		return 1;
+	addr += 1;
+	if (ldb_asm(addr, &byte1))
+		return 1;
+
+	byte0 |= byte1 << 8;
+	put_ptreg(regs, rz, byte0);
+
+	return 0;
+}
+
+/*
+ * Store half-word to [rx + imm]
+ *
+ * Success: return 0
+ * Failure: return 1
+ */
+static int sth_c(struct pt_regs *regs, uint32_t rz, uint32_t addr)
+{
+	uint32_t byte0, byte1;
+
+	byte0 = byte1 = get_ptreg(regs, rz);
+
+	byte0 &= 0xff;
+
+	if (stb_asm(addr, byte0))
+		return 1;
+
+	addr += 1;
+	byte1 = (byte1 >> 8) & 0xff;
+	if (stb_asm(addr, byte1))
+		return 1;
+
+	return 0;
+}
+
+/*
+ * Get word from [rx + imm]
+ *
+ * Success: return 0
+ * Failure: return 1
+ */
+static int ldw_c(struct pt_regs *regs, uint32_t rz, uint32_t addr)
+{
+	uint32_t byte0, byte1, byte2, byte3;
+
+	if (ldb_asm(addr, &byte0))
+		return 1;
+
+	addr += 1;
+	if (ldb_asm(addr, &byte1))
+		return 1;
+
+	addr += 1;
+	if (ldb_asm(addr, &byte2))
+		return 1;
+
+	addr += 1;
+	if (ldb_asm(addr, &byte3))
+		return 1;
+
+	byte0 |= byte1 << 8;
+	byte0 |= byte2 << 16;
+	byte0 |= byte3 << 24;
+
+	put_ptreg(regs, rz, byte0);
+
+	return 0;
+}
+
+/*
+ * Store word to [rx + imm]
+ *
+ * Success: return 0
+ * Failure: return 1
+ */
+static int stw_c(struct pt_regs *regs, uint32_t rz, uint32_t addr)
+{
+	uint32_t byte0, byte1, byte2, byte3;
+
+	byte0 = byte1 = byte2 = byte3 = get_ptreg(regs, rz);
+
+	byte0 &= 0xff;
+
+	if (stb_asm(addr, byte0))
+		return 1;
+
+	addr += 1;
+	byte1 = (byte1 >> 8) & 0xff;
+	if (stb_asm(addr, byte1))
+		return 1;
+
+	addr += 1;
+	byte2 = (byte2 >> 16) & 0xff;
+	if (stb_asm(addr, byte2))
+		return 1;
+
+	addr += 1;
+	byte3 = (byte3 >> 24) & 0xff;
+	if (stb_asm(addr, byte3))
+		return 1;
+
+	align_count++;
+
+	return 0;
+}
+
+extern int fixup_exception(struct pt_regs *regs);
+
+#define OP_LDH 0xc000
+#define OP_STH 0xd000
+#define OP_LDW 0x8000
+#define OP_STW 0x9000
+
+void csky_alignment(struct pt_regs *regs)
+{
+	int ret;
+	uint16_t tmp;
+	uint32_t opcode = 0;
+	uint32_t rx     = 0;
+	uint32_t rz     = 0;
+	uint32_t imm    = 0;
+	uint32_t addr   = 0;
+
+	if (!user_mode(regs))
+		goto bad_area;
+
+	ret = get_user(tmp, (uint16_t *)instruction_pointer(regs));
+	if (ret) {
+		pr_err("%s get_user failed.\n", __func__);
+		goto bad_area;
+	}
+
+	opcode = (uint32_t)tmp;
+
+	rx  = opcode & 0xf;
+	imm = (opcode >> 4) & 0xf;
+	rz  = (opcode >> 8) & 0xf;
+	opcode &= 0xf000;
+
+	if (rx == 0 || rx == 1 || rz == 0 || rz == 1)
+		goto bad_area;
+
+	switch (opcode) {
+	case OP_LDH:
+		addr = get_ptreg(regs, rx) + (imm << 1);
+		ret = ldh_c(regs, rz, addr);
+		break;
+	case OP_LDW:
+		addr = get_ptreg(regs, rx) + (imm << 2);
+		ret = ldw_c(regs, rz, addr);
+		break;
+	case OP_STH:
+		addr = get_ptreg(regs, rx) + (imm << 1);
+		ret = sth_c(regs, rz, addr);
+		break;
+	case OP_STW:
+		addr = get_ptreg(regs, rx) + (imm << 2);
+		ret = stw_c(regs, rz, addr);
+		break;
+	}
+
+	if (ret)
+		goto bad_area;
+
+	regs->pc += 2;
+
+	return;
+
+bad_area:
+	if (!user_mode(regs)) {
+		if (fixup_exception(regs))
+			return;
+
+		bust_spinlocks(1);
+		pr_alert("%s opcode: %x, rz: %d, rx: %d, imm: %d, addr: %x.\n",
+				__func__, opcode, rz, rx, imm, addr);
+		show_regs(regs);
+		bust_spinlocks(0);
+		do_exit(SIGKILL);
+	}
+
+	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)addr, current);
+}
+
+static struct ctl_table alignment_tbl[4] = {
+	{
+		.procname = "enable",
+		.data = &align_enable,
+		.maxlen = sizeof(align_enable),
+		.mode = 0666,
+		.proc_handler = &proc_dointvec
+	},
+	{
+		.procname = "count",
+		.data = &align_count,
+		.maxlen = sizeof(align_count),
+		.mode = 0666,
+		.proc_handler = &proc_dointvec
+	},
+	{}
+};
+
+static struct ctl_table sysctl_table[2] = {
+	{
+	 .procname = "csky_alignment",
+	 .mode = 0555,
+	 .child = alignment_tbl},
+	{}
+};
+
+static struct ctl_path sysctl_path[2] = {
+	{.procname = "csky"},
+	{}
+};
+
+static int __init csky_alignment_init(void)
+{
+	register_sysctl_paths(sysctl_path, sysctl_table);
+	return 0;
+}
+
+arch_initcall(csky_alignment_init);
diff --git a/arch/csky/abiv1/inc/abi/entry.h b/arch/csky/abiv1/inc/abi/entry.h
new file mode 100644
index 000000000000..3f3faab3d747
--- /dev/null
+++ b/arch/csky/abiv1/inc/abi/entry.h
@@ -0,0 +1,160 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#ifndef __ASM_CSKY_ENTRY_H
+#define __ASM_CSKY_ENTRY_H
+
+#include <asm/setup.h>
+#include <abi/regdef.h>
+
+#define LSAVE_PC	8
+#define LSAVE_PSR	12
+#define LSAVE_A0	24
+#define LSAVE_A1	28
+#define LSAVE_A2	32
+#define LSAVE_A3	36
+#define LSAVE_A4	40
+#define LSAVE_A5	44
+
+#define EPC_INCREASE	2
+#define EPC_KEEP	0
+
+.macro USPTOKSP
+	mtcr	sp, ss1
+	mfcr	sp, ss0
+.endm
+
+.macro KSPTOUSP
+	mtcr	sp, ss0
+	mfcr	sp, ss1
+.endm
+
+.macro INCTRAP	rx
+	addi	\rx, EPC_INCREASE
+.endm
+
+.macro	SAVE_ALL epc_inc
+	mtcr    r13, ss2
+	mfcr    r13, epsr
+	btsti   r13, 31
+	bt      1f
+	USPTOKSP
+1:
+	subi    sp, 32
+	subi    sp, 32
+	subi    sp, 16
+	stw     r13, (sp, 12)
+
+	stw     lr, (sp, 4)
+
+	mfcr	lr, epc
+	movi	r13, \epc_inc
+	add	lr, r13
+	stw     lr, (sp, 8)
+
+	mfcr	lr, ss1
+	stw     lr, (sp, 16)
+
+	stw     a0, (sp, 20)
+	stw     a0, (sp, 24)
+	stw     a1, (sp, 28)
+	stw     a2, (sp, 32)
+	stw     a3, (sp, 36)
+
+	addi	sp, 32
+	addi	sp, 8
+	mfcr    r13, ss2
+	stw	r6, (sp)
+	stw	r7, (sp, 4)
+	stw	r8, (sp, 8)
+	stw	r9, (sp, 12)
+	stw	r10, (sp, 16)
+	stw	r11, (sp, 20)
+	stw	r12, (sp, 24)
+	stw	r13, (sp, 28)
+	stw	r14, (sp, 32)
+	stw	r1, (sp, 36)
+	subi	sp, 32
+	subi	sp, 8
+.endm
+
+.macro	RESTORE_ALL
+	psrclr  ie
+	ldw	lr, (sp, 4)
+	ldw     a0, (sp, 8)
+	mtcr    a0, epc
+	ldw     a0, (sp, 12)
+	mtcr    a0, epsr
+	btsti   a0, 31
+	ldw     a0, (sp, 16)
+	mtcr	a0, ss1
+
+	ldw     a0, (sp, 24)
+	ldw     a1, (sp, 28)
+	ldw     a2, (sp, 32)
+	ldw     a3, (sp, 36)
+
+	addi	sp, 32
+	addi	sp, 8
+	ldw	r6, (sp)
+	ldw	r7, (sp, 4)
+	ldw	r8, (sp, 8)
+	ldw	r9, (sp, 12)
+	ldw	r10, (sp, 16)
+	ldw	r11, (sp, 20)
+	ldw	r12, (sp, 24)
+	ldw	r13, (sp, 28)
+	ldw	r14, (sp, 32)
+	ldw	r1, (sp, 36)
+	addi	sp, 32
+	addi	sp, 8
+
+	bt      1f
+	KSPTOUSP
+1:
+	rte
+.endm
+
+.macro SAVE_SWITCH_STACK
+	subi    sp, 32
+	stm     r8-r15, (sp)
+.endm
+
+.macro RESTORE_SWITCH_STACK
+	ldm     r8-r15, (sp)
+	addi    sp, 32
+.endm
+
+/* MMU registers operators. */
+.macro RD_MIR	rx
+	cprcr   \rx, cpcr0
+.endm
+
+.macro RD_MEH	rx
+	cprcr   \rx, cpcr4
+.endm
+
+.macro RD_MCIR	rx
+	cprcr   \rx, cpcr8
+.endm
+
+.macro RD_PGDR  rx
+	cprcr   \rx, cpcr29
+.endm
+
+.macro WR_MEH	rx
+	cpwcr   \rx, cpcr4
+.endm
+
+.macro WR_MCIR	rx
+	cpwcr   \rx, cpcr8
+.endm
+
+.macro SETUP_MMU rx
+	lrw	\rx, PHYS_OFFSET | 0xe
+	cpwcr	\rx, cpcr30
+	lrw	\rx, (PHYS_OFFSET + 0x20000000) | 0xe
+	cpwcr	\rx, cpcr31
+.endm
+
+#endif /* __ASM_CSKY_ENTRY_H */