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Subject[PATCH 07/58] microblaze_v5: exception handling
Date
From: Michal Simek <monstr@monstr.eu>

Acked-by: Stephen Neuendorffer <stephen.neuendorffer@xilinx.com>
Signed-off-by: Michal Simek <monstr@monstr.eu>
---
arch/microblaze/kernel/exceptions.c | 77 +++++
arch/microblaze/kernel/hw_exception_handler.S | 391 +++++++++++++++++++++++++
include/asm-microblaze/exceptions.h | 61 ++++
3 files changed, 529 insertions(+), 0 deletions(-)
create mode 100644 arch/microblaze/kernel/exceptions.c
create mode 100644 arch/microblaze/kernel/hw_exception_handler.S
create mode 100644 include/asm-microblaze/exceptions.h

diff --git a/arch/microblaze/kernel/exceptions.c b/arch/microblaze/kernel/exceptions.c
new file mode 100644
index 0000000..734038e
--- /dev/null
+++ b/arch/microblaze/kernel/exceptions.c
@@ -0,0 +1,77 @@
+/*
+ * HW exception handling
+ *
+ * Copyright (C) 2007 Xilinx, Inc.
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License. See the file COPYING in the main directory of this
+ * archive for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <asm/exceptions.h>
+#include <asm/entry.h> /* For KM CPU var */
+
+/* Initialize_exception_handlers() - called from setup.c/trap_init() */
+void initialize_exception_handlers(void)
+{
+}
+
+#define MICROBLAZE_ILL_OPCODE_EXCEPTION 0x02
+#define MICROBLAZE_IOPB_BUS_EXCEPTION 0x03
+#define MICROBLAZE_DOPB_BUS_EXCEPTION 0x04
+#define MICROBLAZE_DIV_ZERO_EXCEPTION 0x05
+#define MICROBLAZE_FPU_EXCEPTION 0x06
+
+static void handle_unexpected_exception(unsigned int esr,
+ unsigned int kernel_mode, unsigned int addr)
+{
+ printk(KERN_WARNING "Unexpected exception %02x in %s mode, PC=%08x\n",
+ esr, kernel_mode ? "kernel" : "user", addr);
+}
+
+static void handle_exception(const char *message, int signal,
+ unsigned int kernel_mode, unsigned int addr)
+{
+ if (kernel_mode)
+ panic("%s in the kernel mode, PC=%08x\n", message, addr);
+ else
+ force_sig(signal, current);
+}
+
+asmlinkage void other_exception_handler(unsigned int esr, unsigned int addr)
+{
+ unsigned int kernel_mode = per_cpu(KM, 0);
+
+ switch (esr) {
+
+ case MICROBLAZE_ILL_OPCODE_EXCEPTION:
+ handle_exception("Illegal instruction", SIGILL,
+ kernel_mode, addr);
+ break;
+
+ case MICROBLAZE_IOPB_BUS_EXCEPTION:
+ handle_exception("Instruction bus error", SIGBUS,
+ kernel_mode, addr);
+ break;
+
+ case MICROBLAZE_DOPB_BUS_EXCEPTION:
+ handle_exception("Data bus error", SIGBUS, kernel_mode, addr);
+ break;
+
+ case MICROBLAZE_DIV_ZERO_EXCEPTION:
+ handle_exception("Divide by zero", SIGILL, kernel_mode, addr);
+ break;
+
+ case MICROBLAZE_FPU_EXCEPTION:
+ handle_exception("FPU error", SIGFPE, kernel_mode, addr);
+ break;
+
+ default:
+ handle_unexpected_exception(esr, kernel_mode, addr);
+ }
+
+ return;
+}
diff --git a/arch/microblaze/kernel/hw_exception_handler.S b/arch/microblaze/kernel/hw_exception_handler.S
new file mode 100644
index 0000000..c96edcf
--- /dev/null
+++ b/arch/microblaze/kernel/hw_exception_handler.S
@@ -0,0 +1,391 @@
+/*
+ * Unaligned exception handling for Microblaze
+ *
+ * cleanup code (C) 2007 Michal Simek <monstr@monstr.eu>
+ * uClinux customisation (C) 2005 John Williams
+ *
+ * Original code
+ * Copyright (C) 2004 Xilinx, Inc. All rights reserved.
+ *
+ * Xilinx, Inc.
+ * XILINX IS PROVIDING THIS DESIGN, CODE, OR INFORMATION "AS IS" AS A
+ * COURTESY TO YOU. BY PROVIDING THIS DESIGN, CODE, OR INFORMATION AS
+ * ONE POSSIBLE IMPLEMENTATION OF THIS FEATURE, APPLICATION OR
+ * STANDARD, XILINX IS MAKING NO REPRESENTATION THAT THIS IMPLEMENTATION
+ * IS FREE FROM ANY CLAIMS OF INFRINGEMENT, AND YOU ARE RESPONSIBLE
+ * FOR OBTAINING ANY RIGHTS YOU MAY REQUIRE FOR YOUR IMPLEMENTATION.
+ * XILINX EXPRESSLY DISCLAIMS ANY WARRANTY WHATSOEVER WITH RESPECT TO
+ * THE ADEQUACY OF THE IMPLEMENTATION, INCLUDING BUT NOT LIMITED TO
+ * ANY WARRANTIES OR REPRESENTATIONS THAT THIS IMPLEMENTATION IS FREE
+ * FROM CLAIMS OF INFRINGEMENT, IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * $Id: hw_exception_handler.S,v 1.1.2.1 2007/03/16 16:09:57 imanuilov Exp $
+ *
+ */
+
+/*
+ * Microblaze HW Exception Handler
+ * - Non self-modifying exception handler for the following exception conditions
+ * - Unalignment
+ * - Instruction bus error
+ * - Data bus error
+ * - Illegal instruction opcode
+ * - Divide-by-zero
+ *
+ * Note we disable interrupts during exception handling, otherwise we will
+ * possibly get multiple re-entrancy if interrupt handles themselves cause
+ * exceptions. JW
+ */
+
+#include <asm/exceptions.h>
+#include <asm/unistd.h>
+
+/* Helpful Macros */
+#define EX_HANDLER_STACK_SIZ (4*19)
+#define RMSR_OFFSET 0
+#define REG_OFFSET(regnum) (4*regnum)
+#define NUM_TO_REG(num) r ## num
+
+#define R3_TO_STACK(regnum) swi r3, r1, REG_OFFSET(regnum)
+#define R3_FROM_STACK(regnum) lwi r3, r1, REG_OFFSET(regnum)
+
+#define PUSH_REG(regnum) swi NUM_TO_REG(regnum), r1, REG_OFFSET(regnum)
+#define POP_REG(regnum) lwi NUM_TO_REG(regnum), r1, REG_OFFSET(regnum)
+
+/* Uses r5 */
+#define PUSH_MSR \
+ mfs r5, rmsr; \
+ swi r5, r1, RMSR_OFFSET;
+
+#define PUSH_MSR_AND_ENABLE_EXC \
+ mfs r5, rmsr; \
+ swi r5, r1, RMSR_OFFSET; \
+ ori r5, r5, 0x100; /* Turn ON the EE bit */ \
+ andi r5, r5, ~2; /* Disable interrupts */ \
+ mts rmsr, r5;
+
+/* Uses r5 */
+#define POP_MSR \
+ lwi r5, r1, RMSR_OFFSET; \
+ mts rmsr, r5;
+
+#define LWREG_NOP \
+ bri ex_handler_unhandled; \
+ nop;
+
+#define SWREG_NOP \
+ bri ex_handler_unhandled; \
+ nop;
+
+/* r3 is the source */
+#define R3_TO_LWREG_V(regnum) \
+ R3_TO_STACK(regnum); \
+ bri ex_handler_done;
+
+/* r3 is the source */
+#define R3_TO_LWREG(regnum) \
+ or NUM_TO_REG (regnum), r0, r3; \
+ bri ex_handler_done;
+
+/* r3 is the target */
+#define SWREG_TO_R3_V(regnum) \
+ R3_FROM_STACK (regnum); \
+ bri ex_sw_tail;
+
+/* r3 is the target */
+#define SWREG_TO_R3(regnum) \
+ or r3, r0, NUM_TO_REG (regnum); \
+ bri ex_sw_tail;
+
+.extern other_exception_handler /* Defined in exception.c */
+
+/*
+ * hw_exception_handler - Handler for unaligned exceptions
+ * Exception handler notes:
+ * - Does not handle exceptions other than unaligned exceptions
+ * - Does not handle exceptions during load into r17, r1, r0.
+ * - Does not handle exceptions during store from r17 (cannot be done)
+ * and r1 (slows down common case)
+ *
+ * Relevant register structures
+ *
+ * EAR - |----|----|----|----|----|----|----|----|
+ * - < ## 32 bit faulting address ## >
+ *
+ * ESR - |----|----|----|----|----| - | - |-----|-----|
+ * - W S REG EXC
+ *
+ *
+ * STACK FRAME STRUCTURE
+ * ---------------------
+ *
+ * +-------------+ + 0
+ * | MSR |
+ * +-------------+ + 4
+ * | r1 |
+ * | . |
+ * | . |
+ * | . |
+ * | . |
+ * | r18 |
+ * +-------------+ + 76
+ * | . |
+ * | . |
+ */
+
+.global _hw_exception_handler
+.section .text
+.align 4
+.ent _hw_exception_handler
+_hw_exception_handler:
+ addik r1, r1, -(EX_HANDLER_STACK_SIZ); /* Create stack frame */
+ PUSH_REG(3);
+ PUSH_REG(4);
+ PUSH_REG(5);
+ PUSH_REG(6);
+ mfs r3, resr;
+
+ andi r5, r3, 0x1000;
+ beqi r5, not_in_delay_slot;
+ mfs r17, rbtr;
+not_in_delay_slot:
+
+ PUSH_REG(17);
+ /* Exceptions enabled here. This will allow nested exceptions */
+ PUSH_MSR_AND_ENABLE_EXC;
+
+ andi r5, r3, 0x1F; /* Extract ESR[EXC] */
+
+ xori r6, r5, 1; /* 00001 = Unaligned Exception */
+ /* Jump to unalignment exception handler */
+ beqi r6, handle_unaligned_ex;
+
+handle_other_ex: /* Handle Other exceptions here */
+ /* Save other volatiles before we make procedure calls below */
+ PUSH_REG(7);
+ PUSH_REG(8);
+ PUSH_REG(9);
+ PUSH_REG(10);
+ PUSH_REG(11);
+ PUSH_REG(12);
+ PUSH_REG(14);
+ PUSH_REG(15);
+ PUSH_REG(18);
+
+ andi r5, r3, 0x1F; /* Load ESR[EC] */
+ addk r6, r17, r0; /* Load exception address */
+ bralid r15, other_exception_handler; /* Branch to the handler */
+ nop;
+
+ /*
+ * Trigger execution of the signal handler by enabling
+ * interrupts and calling an invalid syscall.
+ */
+ mfs r5, rmsr;
+ ori r5, r5, 2;
+ mts rmsr, r5;
+ addi r12, r0, NR_syscalls;
+ brki r14, 0x08;
+ mfs r5, rmsr;
+ andi r5, r5, ~2;
+ mts rmsr, r5;
+
+ POP_REG(7); /* Restore other volatiles */
+ POP_REG(8);
+ POP_REG(9);
+ POP_REG(10);
+ POP_REG(11);
+ POP_REG(12);
+ POP_REG(14);
+ POP_REG(15);
+ POP_REG(18);
+
+ bri ex_handler_done; /* Complete exception handling */
+handle_unaligned_ex:
+ andi r6, r3, 0x3E0; /* Mask and extract the register operand */
+ srl r6, r6; /* r6 >> 5 */
+ srl r6, r6;
+ srl r6, r6;
+ srl r6, r6;
+ srl r6, r6;
+ /* Store the register operand in a temporary location */
+ sbi r6, r0, ex_reg_op;
+ mfs r4, rear;
+ andi r6, r3, 0x400; /* Extract ESR[S] */
+ bnei r6, ex_sw;
+ex_lw:
+ andi r6, r3, 0x800; /* Extract ESR[W] */
+ beqi r6, ex_lhw;
+ lbui r5, r4, 0; /* Exception address in r4 */
+ /* Load a word, byte-by-byte from destination address
+ and save it in tmp space */
+ sbi r5, r0, ex_tmp_data_loc_0;
+ lbui r5, r4, 1;
+ sbi r5, r0, ex_tmp_data_loc_1;
+ lbui r5, r4, 2;
+ sbi r5, r0, ex_tmp_data_loc_2;
+ lbui r5, r4, 3;
+ sbi r5, r0, ex_tmp_data_loc_3;
+ /* Get the destination register value into r3 */
+ lwi r3, r0, ex_tmp_data_loc_0;
+ bri ex_lw_tail;
+ex_lhw:
+ lbui r5, r4, 0; /* Exception address in r4 */
+ /* Load a half-word, byte-by-byte from destination
+ address and save it in tmp space */
+ sbi r5, r0, ex_tmp_data_loc_0;
+ lbui r5, r4, 1;
+ sbi r5, r0, ex_tmp_data_loc_1;
+ /* Get the destination register value into r3 */
+ lhui r3, r0, ex_tmp_data_loc_0;
+ex_lw_tail:
+ /* Get the destination register number into r5 */
+ lbui r5, r0, ex_reg_op;
+ /* Form load_word jump table offset (lw_table + (8 * regnum)) */
+ la r6, r0, lw_table;
+ addk r5, r5, r5;
+ addk r5, r5, r5;
+ addk r5, r5, r5;
+ addk r5, r5, r6;
+ bra r5;
+ex_lw_end: /* Exception handling of load word, ends */
+ex_sw:
+ /* Get the destination register number into r5 */
+ lbui r5, r0, ex_reg_op;
+ /* Form store_word jump table offset (sw_table + (8 * regnum)) */
+ la r6, r0, sw_table;
+ add r5, r5, r5;
+ add r5, r5, r5;
+ add r5, r5, r5;
+ add r5, r5, r6;
+ bra r5;
+ex_sw_tail:
+ mfs r6, resr;
+ andi r6, r6, 0x800; /* Extract ESR[W] */
+ beqi r6, ex_shw;
+ swi r3, r0, ex_tmp_data_loc_0;
+ /* Store the word, byte-by-byte into destination address */
+ lbui r3, r0, ex_tmp_data_loc_0;
+ sbi r3, r4, 0;
+ lbui r3, r0, ex_tmp_data_loc_1;
+ sbi r3, r4, 1;
+ lbui r3, r0, ex_tmp_data_loc_2;
+ sbi r3, r4, 2;
+ lbui r3, r0, ex_tmp_data_loc_3;
+ sbi r3, r4, 3;
+ bri ex_handler_done;
+ex_shw:
+ /* Store the lower half-word, byte-by-byte into destination address */
+ swi r3, r0, ex_tmp_data_loc_0;
+ lbui r3, r0, ex_tmp_data_loc_2;
+ sbi r3, r4, 0;
+ lbui r3, r0, ex_tmp_data_loc_3;
+ sbi r3, r4, 1;
+ex_sw_end: /* Exception handling of store word, ends. */
+
+ex_handler_done:
+ POP_MSR;
+ POP_REG(3);
+ POP_REG(4);
+ POP_REG(5);
+ POP_REG(6);
+ POP_REG(17);
+ rted r17, 0
+ addik r1, r1, (EX_HANDLER_STACK_SIZ); /* Restore stack frame */
+ex_handler_unhandled:
+ bri 0 /* UNHANDLED. TRAP HERE */
+.end _hw_exception_handler
+
+/*
+* hw_exception_handler Jump Table
+* - Contains code snippets for each register that caused the unaligned exception
+* - Hence exception handler is NOT self-modifying
+* - Separate table for load exceptions and store exceptions.
+* - Each table is of size: (8 * 32) = 256 bytes
+*/
+
+.section .text
+.align 4
+lw_table:
+lw_r0: R3_TO_LWREG (0);
+lw_r1: LWREG_NOP;
+lw_r2: R3_TO_LWREG (2);
+lw_r3: R3_TO_LWREG_V (3);
+lw_r4: R3_TO_LWREG_V (4);
+lw_r5: R3_TO_LWREG_V (5);
+lw_r6: R3_TO_LWREG_V (6);
+lw_r7: R3_TO_LWREG (7);
+lw_r8: R3_TO_LWREG (8);
+lw_r9: R3_TO_LWREG (9);
+lw_r10: R3_TO_LWREG (10);
+lw_r11: R3_TO_LWREG (11);
+lw_r12: R3_TO_LWREG (12);
+lw_r13: R3_TO_LWREG (13);
+lw_r14: R3_TO_LWREG (14);
+lw_r15: R3_TO_LWREG (15);
+lw_r16: R3_TO_LWREG (16);
+lw_r17: LWREG_NOP;
+lw_r18: R3_TO_LWREG (18);
+lw_r19: R3_TO_LWREG (19);
+lw_r20: R3_TO_LWREG (20);
+lw_r21: R3_TO_LWREG (21);
+lw_r22: R3_TO_LWREG (22);
+lw_r23: R3_TO_LWREG (23);
+lw_r24: R3_TO_LWREG (24);
+lw_r25: R3_TO_LWREG (25);
+lw_r26: R3_TO_LWREG (26);
+lw_r27: R3_TO_LWREG (27);
+lw_r28: R3_TO_LWREG (28);
+lw_r29: R3_TO_LWREG (29);
+lw_r30: R3_TO_LWREG (30);
+lw_r31: R3_TO_LWREG (31);
+
+sw_table:
+sw_r0: SWREG_TO_R3 (0);
+sw_r1: SWREG_NOP;
+sw_r2: SWREG_TO_R3 (2);
+sw_r3: SWREG_TO_R3_V (3);
+sw_r4: SWREG_TO_R3_V (4);
+sw_r5: SWREG_TO_R3_V (5);
+sw_r6: SWREG_TO_R3_V (6);
+sw_r7: SWREG_TO_R3 (7);
+sw_r8: SWREG_TO_R3 (8);
+sw_r9: SWREG_TO_R3 (9);
+sw_r10: SWREG_TO_R3 (10);
+sw_r11: SWREG_TO_R3 (11);
+sw_r12: SWREG_TO_R3 (12);
+sw_r13: SWREG_TO_R3 (13);
+sw_r14: SWREG_TO_R3 (14);
+sw_r15: SWREG_TO_R3 (15);
+sw_r16: SWREG_TO_R3 (16);
+sw_r17: SWREG_NOP;
+sw_r18: SWREG_TO_R3 (18);
+sw_r19: SWREG_TO_R3 (19);
+sw_r20: SWREG_TO_R3 (20);
+sw_r21: SWREG_TO_R3 (21);
+sw_r22: SWREG_TO_R3 (22);
+sw_r23: SWREG_TO_R3 (23);
+sw_r24: SWREG_TO_R3 (24);
+sw_r25: SWREG_TO_R3 (25);
+sw_r26: SWREG_TO_R3 (26);
+sw_r27: SWREG_TO_R3 (27);
+sw_r28: SWREG_TO_R3 (28);
+sw_r29: SWREG_TO_R3 (29);
+sw_r30: SWREG_TO_R3 (30);
+sw_r31: SWREG_TO_R3 (31);
+
+/* Temporary data structures used in the handler */
+.section .data
+.align 4
+ex_tmp_data_loc_0:
+ .byte 0
+ex_tmp_data_loc_1:
+ .byte 0
+ex_tmp_data_loc_2:
+ .byte 0
+ex_tmp_data_loc_3:
+ .byte 0
+ex_reg_op:
+ .byte 0
+
diff --git a/include/asm-microblaze/exceptions.h b/include/asm-microblaze/exceptions.h
new file mode 100644
index 0000000..33f19bc
--- /dev/null
+++ b/include/asm-microblaze/exceptions.h
@@ -0,0 +1,61 @@
+/*
+ * Preliminary support for HW exception handing for Microblaze
+ *
+ * Copyright (C) 2005 John Williams <jwilliams@itee.uq.edu.au>
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License. See the file COPYING in the main directory of this
+ * archive for more details.
+ */
+
+#ifndef _ASM_MICROBLAZE_EXCEPTIONS_H
+#define _ASM_MICROBLAZE_EXCEPTIONS_H
+
+#ifndef __ASSEMBLY__
+
+void initialize_exception_handlers(void);
+asmlinkage void other_exception_handler(unsigned int esr, unsigned int addr);
+
+/* Macros to enable and disable HW exceptions in the MSR */
+/* Define MSR enable bit for HW exceptions */
+#define HWEX_MSR_BIT (1 << 8)
+
+#if CONFIG_XILINX_MICROBLAZE0_USE_MSR_INSTR
+#define __enable_hw_exceptions() \
+ __asm__ __volatile__ (" msrset r0, %0; \
+ nop; " \
+ : \
+ : "i" (HWEX_MSR_BIT) \
+ : "memory")
+
+#define __disable_hw_exceptions() \
+ __asm__ __volatile__ (" msrclr r0, %0; \
+ nop; " \
+ : \
+ : "i" (HWEX_MSR_BIT) \
+ : "memory")
+#else /* !CONFIG_XILINX_MICROBLAZE0_USE_MSR_INSTR */
+#define __enable_hw_exceptions() \
+ __asm__ __volatile__ (" \
+ mfs r12, rmsr; \
+ ori r12, r12, %0; \
+ mts rmsr, r12; \
+ nop; " \
+ : \
+ : "i" (HWEX_MSR_BIT) \
+ : "memory", "r12")
+
+#define __disable_hw_exceptions() \
+ __asm__ __volatile__ (" \
+ mfs r12, rmsr; \
+ andi r12, r12, ~%0; \
+ mts rmsr, r12; \
+ nop; " \
+ : \
+ : "i" (HWEX_MSR_BIT) \
+ : "memory", "r12")
+#endif /* CONFIG_XILINX_MICROBLAZE0_USE_MSR_INSTR */
+
+#endif /*__ASSEMBLY__ */
+
+#endif /* _ASM_MICROBLAZE_EXCEPTIONS_H */
--
1.5.4.GIT


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