[PATCH V5 04/30] csky: Exception handling and mm-fault

Guo Ren
2018-09-24T14:37:48Z

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

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
---
arch/csky/abiv1/alignment.c | 332 +++++++++++++++++++++++++++++++++
arch/csky/abiv1/inc/abi/entry.h | 160 ++++++++++++++++
arch/csky/abiv2/inc/abi/entry.h | 157 ++++++++++++++++
arch/csky/include/asm/traps.h | 40 ++++
arch/csky/include/asm/unistd.h | 4 +
arch/csky/kernel/cpu-probe.c | 79 ++++++++
arch/csky/kernel/entry.S | 397 ++++++++++++++++++++++++++++++++++++++++
arch/csky/kernel/traps.c | 168 +++++++++++++++++
arch/csky/mm/fault.c | 221 ++++++++++++++++++++++
9 files changed, 1558 insertions(+)
create mode 100644 arch/csky/abiv1/alignment.c
create mode 100644 arch/csky/abiv1/inc/abi/entry.h
create mode 100644 arch/csky/abiv2/inc/abi/entry.h
create mode 100644 arch/csky/include/asm/traps.h
create mode 100644 arch/csky/include/asm/unistd.h
create mode 100644 arch/csky/kernel/cpu-probe.c
create mode 100644 arch/csky/kernel/entry.S
create mode 100644 arch/csky/kernel/traps.c
create mode 100644 arch/csky/mm/fault.c

diff --git a/arch/csky/abiv1/alignment.c b/arch/csky/abiv1/alignment.c
new file mode 100644
index 0000000..e7dae10
--- /dev/null
+++ b/arch/csky/abiv1/alignment.c
@@ -0,0 +1,332 @@
+// 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 = 0;
+
+static inline uint32_t get_ptreg(struct pt_regs *regs, uint32_t rx)
+{
+ return *((int *)&(regs->a0) - 2 + rx);
+}
+
+static inline void put_ptreg(struct pt_regs *regs, uint32_t rx, uint32_t val)
+{
+ *((int *)&(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 volatile 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;
+
+ siginfo_t info;
+
+ 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 == 15 || rz == 0 || rz == 15)
+ 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);
+ }
+
+ info.si_signo = SIGBUS;
+ info.si_errno = 0;
+ info.si_code = BUS_ADRALN;
+ info.si_addr = (void __user *)addr;
+
+ force_sig_info(info.si_signo, &info, current);
+
+ return;
+}
+
+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 0000000..42a9b7c
--- /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 */
diff --git a/arch/csky/abiv2/inc/abi/entry.h b/arch/csky/abiv2/inc/abi/entry.h
new file mode 100644
index 0000000..b1c6dea
--- /dev/null
+++ b/arch/csky/abiv2/inc/abi/entry.h
@@ -0,0 +1,157 @@
+// 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 EPC_INCREASE 4
+#define EPC_KEEP 0
+
+#define KSPTOUSP
+#define USPTOKSP
+
+#define usp cr<14, 1>
+
+.macro INCTRAP rx
+ addi \rx, EPC_INCREASE
+.endm
+
+.macro SAVE_ALL epc_inc
+ subi sp, 152
+ stw tls, (sp, 0)
+ stw lr, (sp, 4)
+
+ mfcr lr, epc
+ movi tls, \epc_inc
+ add lr, tls
+ stw lr, (sp, 8)
+
+ mfcr lr, epsr
+ stw lr, (sp, 12)
+ mfcr lr, usp
+ 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, 40
+ stm r4-r13, (sp)
+
+ addi sp, 40
+ stm r16-r30,(sp)
+#ifdef CONFIG_CPU_HAS_HILO
+ mfhi lr
+ stw lr, (sp, 60)
+ mflo lr
+ stw lr, (sp, 64)
+#endif
+ subi sp, 80
+.endm
+
+.macro RESTORE_ALL
+ psrclr ie
+ ldw tls, (sp, 0)
+ ldw lr, (sp, 4)
+ ldw a0, (sp, 8)
+ mtcr a0, epc
+ ldw a0, (sp, 12)
+ mtcr a0, epsr
+ ldw a0, (sp, 16)
+ mtcr a0, usp
+
+#ifdef CONFIG_CPU_HAS_HILO
+ ldw a0, (sp, 140)
+ mthi a0
+ ldw a0, (sp, 144)
+ mtlo a0
+#endif
+
+ ldw a0, (sp, 24)
+ ldw a1, (sp, 28)
+ ldw a2, (sp, 32)
+ ldw a3, (sp, 36)
+
+ addi sp, 40
+ ldm r4-r13, (sp)
+ addi sp, 40
+ ldm r16-r30,(sp)
+ addi sp, 72
+ rte
+.endm
+
+.macro SAVE_SWITCH_STACK
+ subi sp, 64
+ stm r4-r11,(sp)
+ stw r15, (sp, 32)
+ stw r16, (sp, 36)
+ stw r17, (sp, 40)
+ stw r26, (sp, 44)
+ stw r27, (sp, 48)
+ stw r28, (sp, 52)
+ stw r29, (sp, 56)
+ stw r30, (sp, 60)
+.endm
+
+.macro RESTORE_SWITCH_STACK
+ ldm r4-r11,(sp)
+ ldw r15, (sp, 32)
+ ldw r16, (sp, 36)
+ ldw r17, (sp, 40)
+ ldw r26, (sp, 44)
+ ldw r27, (sp, 48)
+ ldw r28, (sp, 52)
+ ldw r29, (sp, 56)
+ ldw r30, (sp, 60)
+ addi sp, 64
+.endm
+
+/* MMU registers operators. */
+.macro RD_MIR rx
+ mfcr \rx, cr<0, 15>
+.endm
+
+.macro RD_MEH rx
+ mfcr \rx, cr<4, 15>
+.endm
+
+.macro RD_MCIR rx
+ mfcr \rx, cr<8, 15>
+.endm
+
+.macro RD_PGDR rx
+ mfcr \rx, cr<29, 15>
+.endm
+
+.macro RD_PGDR_K rx
+ mfcr \rx, cr<28, 15>
+.endm
+
+.macro WR_MEH rx
+ mtcr \rx, cr<4, 15>
+.endm
+
+.macro WR_MCIR rx
+ mtcr \rx, cr<8, 15>
+.endm
+
+.macro SETUP_MMU rx
+ lrw \rx, PHYS_OFFSET | 0xe
+ mtcr \rx, cr<30, 15>
+ lrw \rx, (PHYS_OFFSET + 0x20000000) | 0xe
+ mtcr \rx, cr<31, 15>
+.endm
+
+#endif /* __ASM_CSKY_ENTRY_H */
diff --git a/arch/csky/include/asm/traps.h b/arch/csky/include/asm/traps.h
new file mode 100644
index 0000000..e52e64e
--- /dev/null
+++ b/arch/csky/include/asm/traps.h
@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#ifndef __ASM_CSKY_TRAPS_H
+#define __ASM_CSKY_TRAPS_H
+
+#define VEC_RESET 0
+#define VEC_ALIGN 1
+#define VEC_ACCESS 2
+#define VEC_ZERODIV 3
+#define VEC_ILLEGAL 4
+#define VEC_PRIV 5
+#define VEC_TRACE 6
+#define VEC_BREAKPOINT 7
+#define VEC_UNRECOVER 8
+#define VEC_SOFTRESET 9
+#define VEC_AUTOVEC 10
+#define VEC_FAUTOVEC 11
+#define VEC_HWACCEL 12
+
+#define VEC_TLBMISS 14
+#define VEC_TLBMODIFIED 15
+
+#define VEC_TRAP0 16
+#define VEC_TRAP1 17
+#define VEC_TRAP2 18
+#define VEC_TRAP3 19
+
+#define VEC_TLBINVALIDL 20
+#define VEC_TLBINVALIDS 21
+
+#define VEC_PRFL 29
+#define VEC_FPE 30
+
+extern void * vec_base[];
+#define VEC_INIT(i, func) vec_base[i] = (void *)func
+
+void csky_alignment(struct pt_regs*);
+
+#endif /* __ASM_CSKY_TRAPS_H */
diff --git a/arch/csky/include/asm/unistd.h b/arch/csky/include/asm/unistd.h
new file mode 100644
index 0000000..2356a1e
--- /dev/null
+++ b/arch/csky/include/asm/unistd.h
@@ -0,0 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#include <uapi/asm/unistd.h>
diff --git a/arch/csky/kernel/cpu-probe.c b/arch/csky/kernel/cpu-probe.c
new file mode 100644
index 0000000..5f15ca3
--- /dev/null
+++ b/arch/csky/kernel/cpu-probe.c
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#include <linux/of.h>
+#include <linux/init.h>
+#include <linux/seq_file.h>
+#include <linux/memblock.h>
+
+#include <abi/reg_ops.h>
+
+static void percpu_print(void *arg)
+{
+ struct seq_file *m = (struct seq_file *)arg;
+ unsigned int cur, next, i;
+
+ seq_printf(m, "processor : %d\n", smp_processor_id());
+ seq_printf(m, "C-SKY CPU model : %s\n", CSKYCPU_DEF_NAME);
+
+ /* read processor id, max is 100 */
+ cur = mfcr("cr13");
+ for (i = 0; i < 100; i++) {
+ seq_printf(m, "product info[%d] : 0x%08x\n", i, cur);
+
+ next = mfcr("cr13");
+
+ /* some CPU only has one id reg */
+ if (cur == next)
+ break;
+
+ cur = next;
+
+ /* cpid index is 31-28, reset */
+ if (!(next >> 28)) {
+ while ((mfcr("cr13") >> 28) != i);
+ break;
+ }
+ }
+
+ /* CPU feature regs, setup by bootloader or gdbinit */
+ seq_printf(m, "hint (CPU funcs): 0x%08x\n", mfcr_hint());
+ seq_printf(m, "ccr (L1C & MMU): 0x%08x\n", mfcr("cr18"));
+ seq_printf(m, "ccr2 (L2C) : 0x%08x\n", mfcr_ccr2());
+ seq_printf(m, "\n");
+}
+
+static int c_show(struct seq_file *m, void *v)
+{
+ int cpu;
+
+ for_each_online_cpu(cpu)
+ smp_call_function_single(cpu, percpu_print, m, true);
+
+#ifdef CSKY_ARCH_VERSION
+ seq_printf(m, "arch-version : %s\n", CSKY_ARCH_VERSION);
+ seq_printf(m, "\n");
+#endif
+
+ return 0;
+}
+
+static void *c_start(struct seq_file *m, loff_t *pos)
+{
+ return *pos < 1 ? (void *)1 : NULL;
+}
+
+static void *c_next(struct seq_file *m, void *v, loff_t *pos)
+{
+ ++*pos;
+ return NULL;
+}
+
+static void c_stop(struct seq_file *m, void *v) {}
+
+const struct seq_operations cpuinfo_op = {
+ .start = c_start,
+ .next = c_next,
+ .stop = c_stop,
+ .show = c_show,
+};
diff --git a/arch/csky/kernel/entry.S b/arch/csky/kernel/entry.S
new file mode 100644
index 0000000..eee5389
--- /dev/null
+++ b/arch/csky/kernel/entry.S
@@ -0,0 +1,397 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#include <linux/linkage.h>
+#include <abi/entry.h>
+#include <abi/pgtable-bits.h>
+#include <asm/errno.h>
+#include <asm/setup.h>
+#include <asm/unistd.h>
+#include <asm/asm-offsets.h>
+#include <linux/threads.h>
+#include <asm/setup.h>
+#include <asm/page.h>
+#include <asm/thread_info.h>
+
+#define PTE_INDX_MSK 0xffc
+#define PTE_INDX_SHIFT 10
+#define _PGDIR_SHIFT 22
+
+.macro tlbop_begin name, val0, val1, val2
+ENTRY(csky_\name)
+ mtcr a3, ss2
+ mtcr r6, ss3
+ mtcr a2, ss4
+
+ RD_PGDR r6
+ RD_MEH a3
+#ifdef CONFIG_CPU_HAS_TLBI
+ tlbi.vaas a3
+ sync.is
+
+ btsti a3, 31
+ bf 1f
+ RD_PGDR_K r6
+1:
+#else
+ bgeni a2, 31
+ WR_MCIR a2
+ bgeni a2, 25
+ WR_MCIR a2
+#endif
+ bclri r6, 0
+ lrw a2, PHYS_OFFSET
+ subu r6, a2
+ bseti r6, 31
+
+ mov a2, a3
+ lsri a2, _PGDIR_SHIFT
+ lsli a2, 2
+ addu r6, a2
+ ldw r6, (r6)
+
+ lrw a2, PHYS_OFFSET
+ subu r6, a2
+ bseti r6, 31
+
+ lsri a3, PTE_INDX_SHIFT
+ lrw a2, PTE_INDX_MSK
+ and a3, a2
+ addu r6, a3
+ ldw a3, (r6)
+
+ movi a2, (_PAGE_PRESENT | \val0)
+ and a3, a2
+ cmpne a3, a2
+ bt \name
+
+ /* First read/write the page, just update the flags */
+ ldw a3, (r6)
+ bgeni a2, PAGE_VALID_BIT
+ bseti a2, PAGE_ACCESSED_BIT
+ bseti a2, \val1
+ bseti a2, \val2
+ or a3, a2
+ stw a3, (r6)
+
+ /* Some cpu tlb-hardrefill bypass the cache */
+#ifdef CONFIG_CPU_NEED_TLBSYNC
+ movi a2, 0x22
+ bseti a2, 6
+ mtcr r6, cr22
+ mtcr a2, cr17
+ sync
+#endif
+
+ mfcr a3, ss2
+ mfcr r6, ss3
+ mfcr a2, ss4
+ rte
+\name:
+ mfcr a3, ss2
+ mfcr r6, ss3
+ mfcr a2, ss4
+ SAVE_ALL EPC_KEEP
+.endm
+.macro tlbop_end is_write
+ RD_MEH a2
+ psrset ee, ie
+ mov a0, sp
+ movi a1, \is_write
+ jbsr do_page_fault
+ movi r11_sig, 0 /* r11 = 0, Not a syscall. */
+ jmpi ret_from_exception
+.endm
+
+.text
+
+tlbop_begin tlbinvalidl, _PAGE_READ, PAGE_VALID_BIT, PAGE_ACCESSED_BIT
+tlbop_end 0
+
+tlbop_begin tlbinvalids, _PAGE_WRITE, PAGE_DIRTY_BIT, PAGE_MODIFIED_BIT
+tlbop_end 1
+
+tlbop_begin tlbmodified, _PAGE_WRITE, PAGE_DIRTY_BIT, PAGE_MODIFIED_BIT
+#ifndef CONFIG_CPU_HAS_LDSTEX
+jbsr csky_cmpxchg_fixup
+#endif
+tlbop_end 1
+
+ENTRY(csky_systemcall)
+ SAVE_ALL EPC_INCREASE
+
+ psrset ee, ie
+
+ /* Stack frame for syscall, origin call set_esp0 */
+ mov r12, sp
+
+ bmaski r11, 13
+ andn r12, r11
+ bgeni r11, 9
+ addi r11, 32
+ addu r12, r11
+ st sp, (r12, 0)
+
+ lrw r11, __NR_syscalls
+ cmphs syscallid, r11 /* Check nr of syscall */
+ bt ret_from_exception
+
+ lrw r13, sys_call_table
+ ixw r13, syscallid /* Index into syscall table */
+ ldw r11, (r13) /* Get syscall function */
+ cmpnei r11, 0 /* Check for not null */
+ bf ret_from_exception
+
+ mov r9, sp /* Get task pointer */
+ bmaski r10, THREAD_SHIFT
+ andn r9, r10 /* Get thread_info */
+ ldw r8, (r9, TINFO_FLAGS) /* Get thread_info.flags value */
+ btsti r8, TIF_SYSCALL_TRACE /* Check if TIF_SYSCALL_TRACE set */
+ bt 1f
+#if defined(__CSKYABIV2__)
+ subi sp, 8
+ stw r5, (sp, 0x4)
+ stw r4, (sp, 0x0)
+ jsr r11 /* Do system call */
+ addi sp, 8
+#else
+ jsr r11
+#endif
+ stw a0, (sp, LSAVE_A0) /* Save return value */
+ jmpi ret_from_exception
+
+1:
+ movi a0, 0 /* enter system call */
+ mov a1, sp /* right now, sp --> pt_regs */
+ jbsr syscall_trace
+ /* Prepare args before do system call */
+ ldw a0, (sp, LSAVE_A0)
+ ldw a1, (sp, LSAVE_A1)
+ ldw a2, (sp, LSAVE_A2)
+ ldw a3, (sp, LSAVE_A3)
+#if defined(__CSKYABIV2__)
+ subi sp, 8
+ stw r5, (sp, 0x4)
+ stw r4, (sp, 0x0)
+#else
+ ldw r6, (sp, LSAVE_A4)
+ ldw r7, (sp, LSAVE_A5)
+#endif
+ jsr r11 /* Do system call */
+#if defined(__CSKYABIV2__)
+ addi sp, 8
+#endif
+ stw a0, (sp, LSAVE_A0) /* Save return value */
+
+ movi a0, 1 /* leave system call */
+ mov a1, sp /* right now, sp --> pt_regs */
+ jbsr syscall_trace
+
+syscall_exit_work:
+ ld syscallid, (sp, LSAVE_PSR)
+ btsti syscallid, 31
+ bt 2f
+
+ jmpi resume_userspace
+
+2: RESTORE_ALL
+
+ENTRY(ret_from_kernel_thread)
+ jbsr schedule_tail
+ mov a0, r8
+ jsr r9
+ jbsr ret_from_exception
+
+ENTRY(ret_from_fork)
+ jbsr schedule_tail
+ mov r9, sp /* Get task pointer */
+ bmaski r10, THREAD_SHIFT
+ andn r9, r10 /* Get thread_info */
+ ldw r8, (r9, TINFO_FLAGS) /* Get thread_info.flags value */
+ movi r11_sig, 1 /* is a syscall */
+ btsti r8, TIF_SYSCALL_TRACE /* Check if TIF_SYSCALL_TRACE set */
+ bf 3f
+ movi a0, 1 /* leave system call */
+ mov a1, sp /* right now, sp --> pt_regs */
+ jbsr syscall_trace
+3:
+ jbsr ret_from_exception
+
+ret_from_exception:
+ ld syscallid, (sp, LSAVE_PSR)
+ btsti syscallid, 31
+ bt 1f
+ /*
+ * Load address of current->thread_info, Then get address of task_struct
+ * Get task_needreshed in task_struct
+ */
+ mov r9, sp /* Get current stack pointer */
+ bmaski r10, THREAD_SHIFT
+ andn r9, r10 /* Get task_struct */
+
+resume_userspace:
+ ldw r8, (r9, TINFO_FLAGS)
+ andi r8, (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED)
+ cmpnei r8, 0
+ bt exit_work
+1: RESTORE_ALL
+
+exit_work:
+ mov a0, sp /* Stack address is arg[0] */
+ jbsr set_esp0 /* Call C level */
+ btsti r8, TIF_NEED_RESCHED
+ bt work_resched
+ cmpnei r8, 0 /* If thread_info->flag is empty, RESTORE_ALL. */
+ bf 1b
+ mov a1, sp
+ mov a0, r8
+ mov a2, r11_sig /* syscall? */
+ btsti r8, TIF_SIGPENDING /* delivering a signal? */
+ clrt r11_sig /* prevent further restarts(set r11 = 0) */
+ jbsr do_notify_resume /* do signals */
+ br resume_userspace
+
+work_resched:
+ lrw syscallid, ret_from_exception
+ mov r15, syscallid /* Return address in link */
+ jmpi schedule
+
+ENTRY(sys_rt_sigreturn)
+ movi r11_sig, 0
+ jmpi do_rt_sigreturn
+
+/*
+ * Common trap handler. Standard traps come through here first
+ */
+
+ENTRY(csky_trap)
+ SAVE_ALL EPC_KEEP
+ psrset ee
+ movi r11_sig, 0 /* r11 = 0, Not a syscall. */
+ mov a0, sp /* Push Stack pointer arg */
+ jbsr trap_c /* Call C-level trap handler */
+ jmpi ret_from_exception
+
+/*
+ * Prototype from libc:
+ * register unsigned int __result asm("a0");
+ * asm( "trap 3" :"=r"(__result)::);
+ */
+ENTRY(csky_get_tls)
+ USPTOKSP
+
+ /* increase epc for continue */
+ mfcr a0, epc
+ INCTRAP a0
+ mtcr a0, epc
+
+ /* get current task thread_info with kernel 8K stack */
+ bmaski a0, THREAD_SHIFT
+ not a0
+ subi sp, 1
+ and a0, sp
+ addi sp, 1
+
+ /* get tls */
+ ldw a0, (a0, TINFO_TP_VALUE)
+
+ KSPTOUSP
+ rte
+
+ENTRY(csky_irq)
+ SAVE_ALL EPC_KEEP
+ psrset ee // enable exception
+ movi r11_sig, 0 /* r11 = 0, Not a syscall. */
+
+#ifdef CONFIG_PREEMPT
+ mov r9, sp /* Get current stack pointer */
+ bmaski r10, THREAD_SHIFT
+ andn r9, r10 /* Get thread_info */
+
+ /*
+ * Get task_struct->stack.preempt_count for current,
+ * and increase 1.
+ */
+ ldw r8, (r9, TINFO_PREEMPT)
+ addi r8, 1
+ stw r8, (r9, TINFO_PREEMPT)
+#endif
+
+ mov a0, sp
+ jbsr csky_do_IRQ
+
+#ifdef CONFIG_PREEMPT
+ subi r8, 1
+ stw r8, (r9, TINFO_PREEMPT)
+ cmpnei r8, 0
+ bt 2f
+ ldw r8, (r9, TINFO_FLAGS)
+ btsti r8, TIF_NEED_RESCHED
+ bf 2f
+1:
+ jbsr preempt_schedule_irq /* irq en/disable is done inside */
+ ldw r7, (r9, TINFO_FLAGS) /* get new tasks TI_FLAGS */
+ btsti r7, TIF_NEED_RESCHED
+ bt 1b /* go again */
+#endif
+2:
+ jmpi ret_from_exception
+
+/*
+ * a0 = prev task_struct *
+ * a1 = next task_struct *
+ * a0 = return next
+ */
+ENTRY(__switch_to)
+ lrw a3, TASK_THREAD /* struct_thread offset in task_struct */
+ addu a3, a0 /* a3 point to thread in prev task_struct */
+
+ mfcr a2, psr /* Save PSR value */
+ stw a2, (a3, THREAD_SR) /* Save PSR in task struct */
+ bclri a2, 6 /* Disable interrupts */
+ mtcr a2, psr
+
+ SAVE_SWITCH_STACK
+
+ stw sp, (a3, THREAD_KSP) /* Save ksp in task struct */
+
+#ifdef CONFIG_CPU_HAS_HILO
+ lrw r10, THREAD_DSPHI
+ add r10, a3
+ mfhi r6
+ mflo r7
+ stw r6, (r10, 0) /* THREAD_DSPHI */
+ stw r7, (r10, 4) /* THREAD_DSPLO */
+ mfcr r6, cr14
+ stw r6, (r10, 8) /* THREAD_DSPCSR */
+#endif
+
+ /* Set up next process to run */
+ lrw a3, TASK_THREAD /* struct_thread offset in task_struct */
+ addu a3, a1 /* a3 point to thread in next task_struct */
+
+ ldw sp, (a3, THREAD_KSP) /* Set next ksp */
+
+#ifdef CONFIG_CPU_HAS_HILO
+ lrw r10, THREAD_DSPHI
+ add r10, a3
+ ldw r6, (r10, 8) /* THREAD_DSPCSR */
+ mtcr r6, cr14
+ ldw r6, (r10, 0) /* THREAD_DSPHI */
+ ldw r7, (r10, 4) /* THREAD_DSPLO */
+ mthi r6
+ mtlo r7
+#endif
+
+ ldw a2, (a3, THREAD_SR) /* Set next PSR */
+ mtcr a2, psr
+
+#if defined(__CSKYABIV2__)
+ addi r7, a1, TASK_THREAD_INFO
+ ldw tls, (r7, TINFO_TP_VALUE)
+#endif
+
+ RESTORE_SWITCH_STACK
+
+ rts
+ENDPROC(__switch_to)
diff --git a/arch/csky/kernel/traps.c b/arch/csky/kernel/traps.c
new file mode 100644
index 0000000..5606d11
--- /dev/null
+++ b/arch/csky/kernel/traps.c
@@ -0,0 +1,168 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#include <linux/sched.h>
+#include <linux/signal.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/user.h>
+#include <linux/string.h>
+#include <linux/linkage.h>
+#include <linux/init.h>
+#include <linux/ptrace.h>
+#include <linux/kallsyms.h>
+#include <linux/rtc.h>
+#include <linux/uaccess.h>
+
+#include <asm/setup.h>
+#include <asm/traps.h>
+#include <asm/pgalloc.h>
+#include <asm/siginfo.h>
+
+#include <asm/mmu_context.h>
+
+#ifdef CONFIG_CPU_HAS_FPU
+#include <abi/fpu.h>
+#endif
+
+/* Defined in entry.S */
+asmlinkage void csky_trap(void);
+
+asmlinkage void csky_systemcall(void);
+asmlinkage void csky_cmpxchg(void);
+asmlinkage void csky_get_tls(void);
+asmlinkage void csky_irq(void);
+
+asmlinkage void csky_tlbinvalidl(void);
+asmlinkage void csky_tlbinvalids(void);
+asmlinkage void csky_tlbmodified(void);
+
+/* Defined in head.S */
+asmlinkage void _start_smp_secondary(void);
+
+void __init pre_trap_init(void)
+{
+ int i;
+
+ mtcr("vbr", vec_base);
+
+ for(i=1;i<128;i++) VEC_INIT(i, csky_trap);
+}
+
+void __init trap_init (void)
+{
+ VEC_INIT(VEC_AUTOVEC, csky_irq);
+
+ /* setup trap0 trap2 trap3 */
+ VEC_INIT(VEC_TRAP0, csky_systemcall);
+ VEC_INIT(VEC_TRAP2, csky_cmpxchg);
+ VEC_INIT(VEC_TRAP3, csky_get_tls);
+
+ /* setup MMU TLB exception */
+ VEC_INIT(VEC_TLBINVALIDL, csky_tlbinvalidl);
+ VEC_INIT(VEC_TLBINVALIDS, csky_tlbinvalids);
+ VEC_INIT(VEC_TLBMODIFIED, csky_tlbmodified);
+
+#ifdef CONFIG_CPU_HAS_FPU
+ init_fpu();
+#endif
+
+#ifdef CONFIG_SMP
+ mtcr("cr<28, 0>", virt_to_phys(vec_base));
+
+ VEC_INIT(VEC_RESET, (void *)virt_to_phys(_start_smp_secondary));
+#endif
+}
+
+void die_if_kernel (char *str, struct pt_regs *regs, int nr)
+{
+ if (user_mode(regs)) return;
+
+ console_verbose();
+ pr_err("%s: %08x\n",str,nr);
+ show_regs(regs);
+ add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
+ do_exit(SIGSEGV);
+}
+
+void buserr(struct pt_regs *regs)
+{
+ siginfo_t info;
+#ifdef CONFIG_CPU_CK810
+ static unsigned long prev_pc;
+
+ if ((regs->pc == prev_pc) && prev_pc != 0) {
+ prev_pc = 0;
+ } else {
+ prev_pc = regs->pc;
+ return;
+ }
+#endif
+
+ die_if_kernel("Kernel mode BUS error", regs, 0);
+
+ pr_err("User mode Bus Error\n");
+ show_regs(regs);
+
+ current->thread.esp0 = (unsigned long) regs;
+ info.si_signo = SIGSEGV;
+ info.si_errno = 0;
+ force_sig_info(SIGSEGV, &info, current);
+}
+
+asmlinkage void trap_c(struct pt_regs *regs)
+{
+ int sig;
+ unsigned long vector;
+ siginfo_t info;
+
+ vector = (mfcr("psr") >> 16) & 0xff;
+
+ switch (vector) {
+ case VEC_ZERODIV:
+ sig = SIGFPE;
+ break;
+ /* ptrace */
+ case VEC_TRACE:
+ info.si_code = TRAP_TRACE;
+ sig = SIGTRAP;
+ break;
+ case VEC_ILLEGAL:
+#ifndef CONFIG_CPU_NO_USER_BKPT
+ if (*(uint16_t *)instruction_pointer(regs) != 0x1464)
+#endif
+ {
+ sig = SIGILL;
+ break;
+ }
+ /* gdbserver breakpoint */
+ case VEC_TRAP1:
+ /* jtagserver breakpoint */
+ case VEC_BREAKPOINT:
+ info.si_code = TRAP_BRKPT;
+ sig = SIGTRAP;
+ break;
+ case VEC_ACCESS:
+ return buserr(regs);
+#ifdef CONFIG_CPU_NEED_SOFTALIGN
+ case VEC_ALIGN:
+ return csky_alignment(regs);
+#endif
+#ifdef CONFIG_CPU_HAS_FPU
+ case VEC_FPE:
+ return fpu_fpe(regs);
+ case VEC_PRIV:
+ if(fpu_libc_helper(regs)) return;
+#endif
+ default:
+ sig = SIGSEGV;
+ break;
+ }
+ send_sig(sig, current, 0);
+}
+
+asmlinkage void set_esp0 (unsigned long ssp)
+{
+ current->thread.esp0 = ssp;
+}
diff --git a/arch/csky/mm/fault.c b/arch/csky/mm/fault.c
new file mode 100644
index 0000000..a2e6e0a
--- /dev/null
+++ b/arch/csky/mm/fault.c
@@ -0,0 +1,221 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#include <linux/signal.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <linux/mman.h>
+#include <linux/mm.h>
+#include <linux/smp.h>
+#include <linux/version.h>
+#include <linux/vt_kern.h>
+#include <linux/kernel.h>
+#include <linux/extable.h>
+#include <linux/uaccess.h>
+
+#include <asm/hardirq.h>
+#include <asm/mmu_context.h>
+#include <asm/traps.h>
+#include <asm/page.h>
+
+int fixup_exception(struct pt_regs *regs)
+{
+ const struct exception_table_entry *fixup;
+
+ fixup = search_exception_tables(instruction_pointer(regs));
+ if (fixup) {
+ regs->pc = fixup->nextinsn;
+
+ return 1;
+ }
+
+ return 0;
+}
+
+/*
+ * This routine handles page faults. It determines the address,
+ * and the problem, and then passes it off to one of the appropriate
+ * routines.
+ */
+asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
+ unsigned long mmu_meh)
+{
+ struct vm_area_struct * vma = NULL;
+ struct task_struct *tsk = current;
+ struct mm_struct *mm = tsk->mm;
+ siginfo_t info;
+ int fault;
+ unsigned long address = mmu_meh & PAGE_MASK;
+
+ info.si_code = SEGV_MAPERR;
+
+#ifndef CONFIG_CPU_HAS_TLBI
+ /*
+ * We fault-in kernel-space virtual memory on-demand. The
+ * 'reference' page table is init_mm.pgd.
+ *
+ * NOTE! We MUST NOT take any locks for this case. We may
+ * be in an interrupt or a critical region, and should
+ * only copy the information from the master page table,
+ * nothing more.
+ */
+ if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END))
+ {
+ /*
+ * Synchronize this task's top level page-table
+ * with the 'reference' page table.
+ *
+ * Do _not_ use "tsk" here. We might be inside
+ * an interrupt in the middle of a task switch..
+ */
+ int offset = __pgd_offset(address);
+ pgd_t *pgd, *pgd_k;
+ pud_t *pud, *pud_k;
+ pmd_t *pmd, *pmd_k;
+ pte_t *pte_k;
+
+ unsigned long pgd_base;
+ pgd_base = tlb_get_pgd();
+ pgd = (pgd_t *)pgd_base + offset;
+ pgd_k = init_mm.pgd + offset;
+
+ if (!pgd_present(*pgd_k))
+ goto no_context;
+ set_pgd(pgd, *pgd_k);
+
+ pud = (pud_t *)pgd;
+ pud_k = (pud_t *)pgd_k;
+ if (!pud_present(*pud_k))
+ goto no_context;
+
+ pmd = pmd_offset(pud, address);
+ pmd_k = pmd_offset(pud_k, address);
+ if (!pmd_present(*pmd_k))
+ goto no_context;
+ set_pmd(pmd, *pmd_k);
+
+ pte_k = pte_offset_kernel(pmd_k, address);
+ if (!pte_present(*pte_k))
+ goto no_context;
+ return;
+ }
+#endif
+ /*
+ * If we're in an interrupt or have no user
+ * context, we must not take the fault..
+ */
+ if (in_atomic() || !mm)
+ goto bad_area_nosemaphore;
+
+ down_read(&mm->mmap_sem);
+ vma = find_vma(mm, address);
+ if (!vma)
+ goto bad_area;
+ if (vma->vm_start <= address)
+ goto good_area;
+ if (!(vma->vm_flags & VM_GROWSDOWN))
+ goto bad_area;
+ if (expand_stack(vma, address))
+ goto bad_area;
+ /*
+ * Ok, we have a good vm_area for this memory access, so
+ * we can handle it..
+ */
+good_area:
+ info.si_code = SEGV_ACCERR;
+
+ if (write) {
+ if (!(vma->vm_flags & VM_WRITE))
+ goto bad_area;
+ } else {
+ if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
+ goto bad_area;
+ }
+
+ /*
+ * If for any reason at all we couldn't handle the fault,
+ * make sure we exit gracefully rather than endlessly redo
+ * the fault.
+ */
+ fault = handle_mm_fault(vma, address, write ? FAULT_FLAG_WRITE : 0);
+ if (unlikely(fault & VM_FAULT_ERROR)) {
+ if (fault & VM_FAULT_OOM)
+ goto out_of_memory;
+ else if (fault & VM_FAULT_SIGBUS)
+ goto do_sigbus;
+ else if (fault & VM_FAULT_SIGSEGV)
+ goto bad_area;
+ BUG();
+ }
+ if (fault & VM_FAULT_MAJOR)
+ tsk->maj_flt++;
+ else
+ tsk->min_flt++;
+
+ up_read(&mm->mmap_sem);
+ return;
+
+ /*
+ * Something tried to access memory that isn't in our memory map..
+ * Fix it, but check if it's kernel or user first..
+ */
+bad_area:
+ up_read(&mm->mmap_sem);
+
+bad_area_nosemaphore:
+ /* User mode accesses just cause a SIGSEGV */
+ if (user_mode(regs)) {
+ tsk->thread.address = address;
+ tsk->thread.error_code = write;
+ info.si_signo = SIGSEGV;
+ info.si_errno = 0;
+ /* info.si_code has been set above */
+ info.si_addr = (void __user *) address;
+ force_sig_info(SIGSEGV, &info, tsk);
+ return;
+ }
+
+no_context:
+ /* Are we prepared to handle this kernel fault? */
+ if (fixup_exception(regs)) return;
+
+ /*
+ * Oops. The kernel tried to access some bad page. We'll have to
+ * terminate things with extreme prejudice.
+ */
+ bust_spinlocks(1);
+ pr_alert("Unable to handle kernel paging request at virtual "
+ "address %08lx, epc == %08lx\n",
+ address, regs->pc);
+ die_if_kernel("Oops", regs, write);
+
+out_of_memory:
+ /*
+ * We ran out of memory, call the OOM killer, and return the userspace
+ * (which will retry the fault, or kill us if we got oom-killed).
+ */
+ pagefault_out_of_memory();
+ return;
+
+do_sigbus:
+ up_read(&mm->mmap_sem);
+
+ /* Kernel mode? Handle exceptions or die */
+ if (!user_mode(regs))
+ goto no_context;
+
+ tsk->thread.address = address;
+ info.si_signo = SIGBUS;
+ info.si_errno = 0;
+ info.si_code = BUS_ADRERR;
+ info.si_addr = (void __user *) address;
+ force_sig_info(SIGBUS, &info, tsk);
+
+ return;
+}
--
2.7.4