1 files changed, 318 insertions, 0 deletions
diff --git a/arch/microblaze/kernel/unwind.c b/arch/microblaze/kernel/unwind.c
new file mode 100644
index 000000000000..fefac5c33586
--- /dev/null
+++ b/arch/microblaze/kernel/unwind.c
@@ -0,0 +1,318 @@
+/*
+ * Backtrace support for Microblaze
+ *
+ * Copyright (C) 2010  Digital Design Corporation
+ *
+ * Based on arch/sh/kernel/cpu/sh5/unwind.c code which is:
+ * Copyright (C) 2004  Paul Mundt
+ * Copyright (C) 2004  Richard Curnow
+ *
+ * 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.
+ */
+/* #define DEBUG 1 */
+#include <linux/kallsyms.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/stacktrace.h>
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <asm/sections.h>
+#include <asm/exceptions.h>
+#include <asm/unwind.h>
+struct stack_trace;
+/*
+ * On Microblaze, finding the previous stack frame is a little tricky.
+ * At this writing (3/2010), Microblaze does not support CONFIG_FRAME_POINTERS,
+ * and even if it did, gcc (4.1.2) does not store the frame pointer at
+ * a consistent offset within each frame. To determine frame size, it is
+ * necessary to search for the assembly instruction that creates or reclaims
+ * the frame and extract the size from it.
+ *
+ * Microblaze stores the stack pointer in r1, and creates a frame via
+ *
+ *     addik r1, r1, -FRAME_SIZE
+ *
+ * The frame is reclaimed via
+ *
+ *     addik r1, r1, FRAME_SIZE
+ *
+ * Frame creation occurs at or near the top of a function.
+ * Depending on the compiler, reclaim may occur at the end, or before
+ * a mid-function return.
+ *
+ * A stack frame is usually not created in a leaf function.
+ *
+ */
+/**
+ * get_frame_size - Extract the stack adjustment from an
+ *                  "addik r1, r1, adjust" instruction
+ * @instr : Microblaze instruction
+ *
+ * Return - Number of stack bytes the instruction reserves or reclaims
+ */
+inline long get_frame_size(unsigned long instr)
+{
+        return abs((s16)(instr & 0xFFFF));
+}
+/**
+ * find_frame_creation - Search backward to find the instruction that creates
+ *                       the stack frame (hopefully, for the same function the
+ *                       initial PC is in).
+ * @pc : Program counter at which to begin the search
+ *
+ * Return - PC at which stack frame creation occurs
+ *          NULL if this cannot be found, i.e. a leaf function
+ */
+static unsigned long *find_frame_creation(unsigned long *pc)
+{
+        int i;
+        /* NOTE: Distance to search is arbitrary
+         *       250 works well for most things,
+         *       750 picks up things like tcp_recvmsg(),
+         *      1000 needed for fat_fill_super()
+         */
+        for (i = 0; i < 1000; i++, pc--) {
+                unsigned long instr;
+                s16 frame_size;
+                if (!kernel_text_address((unsigned long) pc))
+                        return NULL;
+                instr = *pc;
+                /* addik r1, r1, foo ? */
+                if ((instr & 0xFFFF0000) != 0x30210000)
+                        continue;       /* No */
+                frame_size = get_frame_size(instr);
+                if ((frame_size < 8) || (frame_size & 3)) {
+                        pr_debug("    Invalid frame size %d at 0x%p\n",
+                                 frame_size, pc);
+                        return NULL;
+                }
+                pr_debug("    Found frame creation at 0x%p, size %d\n", pc,
+                         frame_size);
+                return pc;
+        }
+        return NULL;
+}
+/**
+ * lookup_prev_stack_frame - Find the stack frame of the previous function.
+ * @fp          : Frame (stack) pointer for current function
+ * @pc          : Program counter within current function
+ * @leaf_return : r15 value within current function. If the current function
+ *                is a leaf, this is the caller's return address.
+ * @pprev_fp    : On exit, set to frame (stack) pointer for previous function
+ * @pprev_pc    : On exit, set to current function caller's return address
+ *
+ * Return - 0 on success, -EINVAL if the previous frame cannot be found
+ */
+static int lookup_prev_stack_frame(unsigned long fp, unsigned long pc,
+                                   unsigned long leaf_return,
+                                   unsigned long *pprev_fp,
+                                   unsigned long *pprev_pc)
+{
+        unsigned long *prologue = NULL;
+        /* _switch_to is a special leaf function */
+        if (pc != (unsigned long) &_switch_to)
+                prologue = find_frame_creation((unsigned long *)pc);
+        if (prologue) {
+                long frame_size = get_frame_size(*prologue);
+                *pprev_fp = fp + frame_size;
+                *pprev_pc = *(unsigned long *)fp;
+        } else {
+                if (!leaf_return)
+                        return -EINVAL;
+                *pprev_pc = leaf_return;
+                *pprev_fp = fp;
+        }
+        /* NOTE: don't check kernel_text_address here, to allow display
+         *       of userland return address
+         */
+        return (!*pprev_pc || (*pprev_pc & 3)) ? -EINVAL : 0;
+}
+static void microblaze_unwind_inner(struct task_struct *task,
+                                    unsigned long pc, unsigned long fp,
+                                    unsigned long leaf_return,
+                                    struct stack_trace *trace);
+/**
+ * unwind_trap - Unwind through a system trap, that stored previous state
+ *               on the stack.
+ */
+#ifdef CONFIG_MMU
+static inline void unwind_trap(struct task_struct *task, unsigned long pc,
+                                unsigned long fp, struct stack_trace *trace)
+{
+        /* To be implemented */
+}
+#else
+static inline void unwind_trap(struct task_struct *task, unsigned long pc,
+                                unsigned long fp, struct stack_trace *trace)
+{
+        const struct pt_regs *regs = (const struct pt_regs *) fp;
+        microblaze_unwind_inner(task, regs->pc, regs->r1, regs->r15, trace);
+}
+#endif
+/**
+ * microblaze_unwind_inner - Unwind the stack from the specified point
+ * @task  : Task whose stack we are to unwind (may be NULL)
+ * @pc    : Program counter from which we start unwinding
+ * @fp    : Frame (stack) pointer from which we start unwinding
+ * @leaf_return : Value of r15 at pc. If the function is a leaf, this is
+ *                                the caller's return address.
+ * @trace : Where to store stack backtrace (PC values).
+ *          NULL == print backtrace to kernel log
+ */
+void microblaze_unwind_inner(struct task_struct *task,
+                             unsigned long pc, unsigned long fp,
+                             unsigned long leaf_return,
+                             struct stack_trace *trace)
+{
+        int ofs = 0;
+        pr_debug("    Unwinding with PC=%p, FP=%p\n", (void *)pc, (void *)fp);
+        if (!pc || !fp || (pc & 3) || (fp & 3)) {
+                pr_debug("    Invalid state for unwind, aborting\n");
+                return;
+        }
+        for (; pc != 0;) {
+                unsigned long next_fp, next_pc = 0;
+                unsigned long return_to = pc +  2 * sizeof(unsigned long);
+                const struct trap_handler_info *handler =
+                        &microblaze_trap_handlers;
+                /* Is previous function the HW exception handler? */
+                if ((return_to >= (unsigned long)&_hw_exception_handler)
+                    &&(return_to < (unsigned long)&ex_handler_unhandled)) {
+                        /*
+                         * HW exception handler doesn't save all registers,
+                         * so we open-code a special case of unwind_trap()
+                         */
+#ifndef CONFIG_MMU
+                        const struct pt_regs *regs =
+                                (const struct pt_regs *) fp;
+#endif
+                        pr_info("HW EXCEPTION\n");
+#ifndef CONFIG_MMU
+                        microblaze_unwind_inner(task, regs->r17 - 4,
+                                                fp + EX_HANDLER_STACK_SIZ,
+                                                regs->r15, trace);
+#endif
+                        return;
+                }
+                /* Is previous function a trap handler? */
+                for (; handler->start_addr; ++handler) {
+                        if ((return_to >= handler->start_addr)
+                            && (return_to <= handler->end_addr)) {
+                                if (!trace)
+                                        pr_info("%s\n", handler->trap_name);
+                                unwind_trap(task, pc, fp, trace);
+                                return;
+                        }
+                }
+                pc -= ofs;
+                if (trace) {
+#ifdef CONFIG_STACKTRACE
+                        if (trace->skip > 0)
+                                trace->skip--;
+                        else
+                                trace->entries[trace->nr_entries++] = pc;
+                        if (trace->nr_entries >= trace->max_entries)
+                                break;
+#endif
+                } else {
+                        /* Have we reached userland? */
+                        if (unlikely(pc == task_pt_regs(task)->pc)) {
+                                pr_info("[<%p>] PID %lu [%s]\n",
+                                        (void *) pc,
+                                        (unsigned long) task->pid,
+                                        task->comm);
+                                break;
+                        } else
+                                print_ip_sym(pc);
+                }
+                /* Stop when we reach anything not part of the kernel */
+                if (!kernel_text_address(pc))
+                        break;
+                if (lookup_prev_stack_frame(fp, pc, leaf_return, &next_fp,
+                                            &next_pc) == 0) {
+                        ofs = sizeof(unsigned long);
+                        pc = next_pc & ~3;
+                        fp = next_fp;
+                        leaf_return = 0;
+                } else {
+                        pr_debug("    Failed to find previous stack frame\n");
+                        break;
+                }
+                pr_debug("    Next PC=%p, next FP=%p\n",
+                         (void *)next_pc, (void *)next_fp);
+        }
+}
+/**
+ * microblaze_unwind - Stack unwinder for Microblaze (external entry point)
+ * @task  : Task whose stack we are to unwind (NULL == current)
+ * @trace : Where to store stack backtrace (PC values).
+ *          NULL == print backtrace to kernel log
+ */
+void microblaze_unwind(struct task_struct *task, struct stack_trace *trace)
+{
+        if (task) {
+                if (task == current) {
+                        const struct pt_regs *regs = task_pt_regs(task);
+                        microblaze_unwind_inner(task, regs->pc, regs->r1,
+                                                regs->r15, trace);
+                } else {
+                        struct thread_info *thread_info =
+                                (struct thread_info *)(task->stack);
+                        const struct cpu_context *cpu_context =
+                                &thread_info->cpu_context;
+                        microblaze_unwind_inner(task,
+                                                (unsigned long) &_switch_to,
+                                                cpu_context->r1,
+                                                cpu_context->r15, trace);
+                }
+        } else {
+                unsigned long pc, fp;
+                __asm__ __volatile__ ("or %0, r1, r0" : "=r" (fp));
+                __asm__ __volatile__ (
+                        "brlid %0, 0f;"
+                        "nop;"
+                        "0:"
+                        : "=r" (pc)
+                );
+                /* Since we are not a leaf function, use leaf_return = 0 */
+                microblaze_unwind_inner(current, pc, fp, 0, trace);
+        }
+}

diff --git a/arch/microblaze/kernel/unwind.c b/arch/microblaze/kernel/unwind.c new file mode 100644 index 000000000000..fefac5c33586 --- /dev/null +++ b/arch/microblaze/kernel/unwind.c
@@ -0,0 +1,318 @@
	1	/*
	2	* Backtrace support for Microblaze
	3	*
	4	* Copyright (C) 2010 Digital Design Corporation
	5	*
	6	* Based on arch/sh/kernel/cpu/sh5/unwind.c code which is:
	7	* Copyright (C) 2004 Paul Mundt
	8	* Copyright (C) 2004 Richard Curnow
	9	*
	10	* This file is subject to the terms and conditions of the GNU General Public
	11	* License. See the file "COPYING" in the main directory of this archive
	12	* for more details.
	13	*/
	14
	15	/* #define DEBUG 1 */
	16	#include <linux/kallsyms.h>
	17	#include <linux/kernel.h>
	18	#include <linux/sched.h>
	19	#include <linux/stacktrace.h>
	20	#include <linux/types.h>
	21	#include <linux/errno.h>
	22	#include <linux/module.h>
	23	#include <linux/io.h>
	24	#include <asm/sections.h>
	25	#include <asm/exceptions.h>
	26	#include <asm/unwind.h>
	27
	28	struct stack_trace;
	29
	30	/*
	31	* On Microblaze, finding the previous stack frame is a little tricky.
	32	* At this writing (3/2010), Microblaze does not support CONFIG_FRAME_POINTERS,
	33	* and even if it did, gcc (4.1.2) does not store the frame pointer at
	34	* a consistent offset within each frame. To determine frame size, it is
	35	* necessary to search for the assembly instruction that creates or reclaims
	36	* the frame and extract the size from it.
	37	*
	38	* Microblaze stores the stack pointer in r1, and creates a frame via
	39	*
	40	* addik r1, r1, -FRAME_SIZE
	41	*
	42	* The frame is reclaimed via
	43	*
	44	* addik r1, r1, FRAME_SIZE
	45	*
	46	* Frame creation occurs at or near the top of a function.
	47	* Depending on the compiler, reclaim may occur at the end, or before
	48	* a mid-function return.
	49	*
	50	* A stack frame is usually not created in a leaf function.
	51	*
	52	*/
	53
	54	/**
	55	* get_frame_size - Extract the stack adjustment from an
	56	* "addik r1, r1, adjust" instruction
	57	* @instr : Microblaze instruction
	58	*
	59	* Return - Number of stack bytes the instruction reserves or reclaims
	60	*/
	61	inline long get_frame_size(unsigned long instr)
	62	{
	63	return abs((s16)(instr & 0xFFFF));
	64	}
	65
	66	/**
	67	* find_frame_creation - Search backward to find the instruction that creates
	68	* the stack frame (hopefully, for the same function the
	69	* initial PC is in).
	70	* @pc : Program counter at which to begin the search
	71	*
	72	* Return - PC at which stack frame creation occurs
	73	* NULL if this cannot be found, i.e. a leaf function
	74	*/
	75	static unsigned long find_frame_creation(unsigned long pc)
	76	{
	77	int i;
	78
	79	/* NOTE: Distance to search is arbitrary
	80	* 250 works well for most things,
	81	* 750 picks up things like tcp_recvmsg(),
	82	* 1000 needed for fat_fill_super()
	83	*/
	84	for (i = 0; i < 1000; i++, pc--) {
	85	unsigned long instr;
	86	s16 frame_size;
	87
	88	if (!kernel_text_address((unsigned long) pc))
	89	return NULL;
	90
	91	instr = *pc;
	92
	93	/* addik r1, r1, foo ? */
	94	if ((instr & 0xFFFF0000) != 0x30210000)
	95	continue; /* No */
	96
	97	frame_size = get_frame_size(instr);
	98	if ((frame_size < 8) \|\| (frame_size & 3)) {
	99	pr_debug(" Invalid frame size %d at 0x%p\n",
	100	frame_size, pc);
	101	return NULL;
	102	}
	103
	104	pr_debug(" Found frame creation at 0x%p, size %d\n", pc,
	105	frame_size);
	106	return pc;
	107	}
	108
	109	return NULL;
	110	}
	111
	112	/**
	113	* lookup_prev_stack_frame - Find the stack frame of the previous function.
	114	* @fp : Frame (stack) pointer for current function
	115	* @pc : Program counter within current function
	116	* @leaf_return : r15 value within current function. If the current function
	117	* is a leaf, this is the caller's return address.
	118	* @pprev_fp : On exit, set to frame (stack) pointer for previous function
	119	* @pprev_pc : On exit, set to current function caller's return address
	120	*
	121	* Return - 0 on success, -EINVAL if the previous frame cannot be found
	122	*/
	123	static int lookup_prev_stack_frame(unsigned long fp, unsigned long pc,
	124	unsigned long leaf_return,
	125	unsigned long *pprev_fp,
	126	unsigned long *pprev_pc)
	127	{
	128	unsigned long *prologue = NULL;
	129
	130	/* _switch_to is a special leaf function */
	131	if (pc != (unsigned long) &_switch_to)
	132	prologue = find_frame_creation((unsigned long *)pc);
	133
	134	if (prologue) {
	135	long frame_size = get_frame_size(*prologue);
	136
	137	*pprev_fp = fp + frame_size;
	138	pprev_pc = (unsigned long *)fp;
	139	} else {
	140	if (!leaf_return)
	141	return -EINVAL;
	142	*pprev_pc = leaf_return;
	143	*pprev_fp = fp;
	144	}
	145
	146	/* NOTE: don't check kernel_text_address here, to allow display
	147	* of userland return address
	148	*/
	149	return (!pprev_pc \|\| (pprev_pc & 3)) ? -EINVAL : 0;
	150	}
	151
	152	static void microblaze_unwind_inner(struct task_struct *task,
	153	unsigned long pc, unsigned long fp,
	154	unsigned long leaf_return,
	155	struct stack_trace *trace);
	156
	157	/**
	158	* unwind_trap - Unwind through a system trap, that stored previous state
	159	* on the stack.
	160	*/
	161	#ifdef CONFIG_MMU
	162	static inline void unwind_trap(struct task_struct *task, unsigned long pc,
	163	unsigned long fp, struct stack_trace *trace)
	164	{
	165	/* To be implemented */
	166	}
	167	#else
	168	static inline void unwind_trap(struct task_struct *task, unsigned long pc,
	169	unsigned long fp, struct stack_trace *trace)
	170	{
	171	const struct pt_regs regs = (const struct pt_regs ) fp;
	172	microblaze_unwind_inner(task, regs->pc, regs->r1, regs->r15, trace);
	173	}
	174	#endif
	175
	176	/**
	177	* microblaze_unwind_inner - Unwind the stack from the specified point
	178	* @task : Task whose stack we are to unwind (may be NULL)
	179	* @pc : Program counter from which we start unwinding
	180	* @fp : Frame (stack) pointer from which we start unwinding
	181	* @leaf_return : Value of r15 at pc. If the function is a leaf, this is
	182	* the caller's return address.
	183	* @trace : Where to store stack backtrace (PC values).
	184	* NULL == print backtrace to kernel log
	185	*/
	186	void microblaze_unwind_inner(struct task_struct *task,
	187	unsigned long pc, unsigned long fp,
	188	unsigned long leaf_return,
	189	struct stack_trace *trace)
	190	{
	191	int ofs = 0;
	192
	193	pr_debug(" Unwinding with PC=%p, FP=%p\n", (void )pc, (void )fp);
	194	if (!pc \|\| !fp \|\| (pc & 3) \|\| (fp & 3)) {
	195	pr_debug(" Invalid state for unwind, aborting\n");
	196	return;
	197	}
	198	for (; pc != 0;) {
	199	unsigned long next_fp, next_pc = 0;
	200	unsigned long return_to = pc + 2 * sizeof(unsigned long);
	201	const struct trap_handler_info *handler =
	202	&microblaze_trap_handlers;
	203
	204	/* Is previous function the HW exception handler? */
	205	if ((return_to >= (unsigned long)&_hw_exception_handler)
	206	&&(return_to < (unsigned long)&ex_handler_unhandled)) {
	207	/*
	208	* HW exception handler doesn't save all registers,
	209	* so we open-code a special case of unwind_trap()
	210	*/
	211	#ifndef CONFIG_MMU
	212	const struct pt_regs *regs =
	213	(const struct pt_regs *) fp;
	214	#endif
	215	pr_info("HW EXCEPTION\n");
	216	#ifndef CONFIG_MMU
	217	microblaze_unwind_inner(task, regs->r17 - 4,
	218	fp + EX_HANDLER_STACK_SIZ,
	219	regs->r15, trace);
	220	#endif
	221	return;
	222	}
	223
	224	/* Is previous function a trap handler? */
	225	for (; handler->start_addr; ++handler) {
	226	if ((return_to >= handler->start_addr)
	227	&& (return_to <= handler->end_addr)) {
	228	if (!trace)
	229	pr_info("%s\n", handler->trap_name);
	230	unwind_trap(task, pc, fp, trace);
	231	return;
	232	}
	233	}
	234	pc -= ofs;
	235
	236	if (trace) {
	237	#ifdef CONFIG_STACKTRACE
	238	if (trace->skip > 0)
	239	trace->skip--;
	240	else
	241	trace->entries[trace->nr_entries++] = pc;
	242
	243	if (trace->nr_entries >= trace->max_entries)
	244	break;
	245	#endif
	246	} else {
	247	/* Have we reached userland? */
	248	if (unlikely(pc == task_pt_regs(task)->pc)) {
	249	pr_info("[<%p>] PID %lu [%s]\n",
	250	(void *) pc,
	251	(unsigned long) task->pid,
	252	task->comm);
	253	break;
	254	} else
	255	print_ip_sym(pc);
	256	}
	257
	258	/* Stop when we reach anything not part of the kernel */
	259	if (!kernel_text_address(pc))
	260	break;
	261
	262	if (lookup_prev_stack_frame(fp, pc, leaf_return, &next_fp,
	263	&next_pc) == 0) {
	264	ofs = sizeof(unsigned long);
	265	pc = next_pc & ~3;
	266	fp = next_fp;
	267	leaf_return = 0;
	268	} else {
	269	pr_debug(" Failed to find previous stack frame\n");
	270	break;
	271	}
	272
	273	pr_debug(" Next PC=%p, next FP=%p\n",
	274	(void )next_pc, (void )next_fp);
	275	}
	276	}
	277
	278	/**
	279	* microblaze_unwind - Stack unwinder for Microblaze (external entry point)
	280	* @task : Task whose stack we are to unwind (NULL == current)
	281	* @trace : Where to store stack backtrace (PC values).
	282	* NULL == print backtrace to kernel log
	283	*/
	284	void microblaze_unwind(struct task_struct task, struct stack_trace trace)
	285	{
	286	if (task) {
	287	if (task == current) {
	288	const struct pt_regs *regs = task_pt_regs(task);
	289	microblaze_unwind_inner(task, regs->pc, regs->r1,
	290	regs->r15, trace);
	291	} else {
	292	struct thread_info *thread_info =
	293	(struct thread_info *)(task->stack);
	294	const struct cpu_context *cpu_context =
	295	&thread_info->cpu_context;
	296
	297	microblaze_unwind_inner(task,
	298	(unsigned long) &_switch_to,
	299	cpu_context->r1,
	300	cpu_context->r15, trace);
	301	}
	302	} else {
	303	unsigned long pc, fp;
	304
	305	__asm__ __volatile__ ("or %0, r1, r0" : "=r" (fp));
	306
	307	__asm__ __volatile__ (
	308	"brlid %0, 0f;"
	309	"nop;"
	310	"0:"
	311	: "=r" (pc)
	312	);
	313
	314	/* Since we are not a leaf function, use leaf_return = 0 */
	315	microblaze_unwind_inner(current, pc, fp, 0, trace);
	316	}
	317	}
	318