~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/arch/microblaze/kernel/unwind.c

Version: ~ [ linux-5.6-rc3 ] ~ [ linux-5.5.6 ] ~ [ linux-5.4.22 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.106 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.171 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.214 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.214 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.82 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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/export.h>
 17 #include <linux/kallsyms.h>
 18 #include <linux/kernel.h>
 19 #include <linux/sched.h>
 20 #include <linux/stacktrace.h>
 21 #include <linux/types.h>
 22 #include <linux/errno.h>
 23 #include <linux/io.h>
 24 #include <asm/sections.h>
 25 #include <asm/exceptions.h>
 26 #include <asm/unwind.h>
 27 #include <asm/switch_to.h>
 28 
 29 struct stack_trace;
 30 
 31 /*
 32  * On Microblaze, finding the previous stack frame is a little tricky.
 33  * At this writing (3/2010), Microblaze does not support CONFIG_FRAME_POINTERS,
 34  * and even if it did, gcc (4.1.2) does not store the frame pointer at
 35  * a consistent offset within each frame. To determine frame size, it is
 36  * necessary to search for the assembly instruction that creates or reclaims
 37  * the frame and extract the size from it.
 38  *
 39  * Microblaze stores the stack pointer in r1, and creates a frame via
 40  *
 41  *     addik r1, r1, -FRAME_SIZE
 42  *
 43  * The frame is reclaimed via
 44  *
 45  *     addik r1, r1, FRAME_SIZE
 46  *
 47  * Frame creation occurs at or near the top of a function.
 48  * Depending on the compiler, reclaim may occur at the end, or before
 49  * a mid-function return.
 50  *
 51  * A stack frame is usually not created in a leaf function.
 52  *
 53  */
 54 
 55 /**
 56  * get_frame_size - Extract the stack adjustment from an
 57  *                  "addik r1, r1, adjust" instruction
 58  * @instr : Microblaze instruction
 59  *
 60  * Return - Number of stack bytes the instruction reserves or reclaims
 61  */
 62 inline long get_frame_size(unsigned long instr)
 63 {
 64         return abs((s16)(instr & 0xFFFF));
 65 }
 66 
 67 /**
 68  * find_frame_creation - Search backward to find the instruction that creates
 69  *                       the stack frame (hopefully, for the same function the
 70  *                       initial PC is in).
 71  * @pc : Program counter at which to begin the search
 72  *
 73  * Return - PC at which stack frame creation occurs
 74  *          NULL if this cannot be found, i.e. a leaf function
 75  */
 76 static unsigned long *find_frame_creation(unsigned long *pc)
 77 {
 78         int i;
 79 
 80         /* NOTE: Distance to search is arbitrary
 81          *       250 works well for most things,
 82          *       750 picks up things like tcp_recvmsg(),
 83          *      1000 needed for fat_fill_super()
 84          */
 85         for (i = 0; i < 1000; i++, pc--) {
 86                 unsigned long instr;
 87                 s16 frame_size;
 88 
 89                 if (!kernel_text_address((unsigned long) pc))
 90                         return NULL;
 91 
 92                 instr = *pc;
 93 
 94                 /* addik r1, r1, foo ? */
 95                 if ((instr & 0xFFFF0000) != 0x30210000)
 96                         continue;       /* No */
 97 
 98                 frame_size = get_frame_size(instr);
 99                 if ((frame_size < 8) || (frame_size & 3)) {
100                         pr_debug("    Invalid frame size %d at 0x%p\n",
101                                  frame_size, pc);
102                         return NULL;
103                 }
104 
105                 pr_debug("    Found frame creation at 0x%p, size %d\n", pc,
106                          frame_size);
107                 return pc;
108         }
109 
110         return NULL;
111 }
112 
113 /**
114  * lookup_prev_stack_frame - Find the stack frame of the previous function.
115  * @fp          : Frame (stack) pointer for current function
116  * @pc          : Program counter within current function
117  * @leaf_return : r15 value within current function. If the current function
118  *                is a leaf, this is the caller's return address.
119  * @pprev_fp    : On exit, set to frame (stack) pointer for previous function
120  * @pprev_pc    : On exit, set to current function caller's return address
121  *
122  * Return - 0 on success, -EINVAL if the previous frame cannot be found
123  */
124 static int lookup_prev_stack_frame(unsigned long fp, unsigned long pc,
125                                    unsigned long leaf_return,
126                                    unsigned long *pprev_fp,
127                                    unsigned long *pprev_pc)
128 {
129         unsigned long *prologue = NULL;
130 
131         /* _switch_to is a special leaf function */
132         if (pc != (unsigned long) &_switch_to)
133                 prologue = find_frame_creation((unsigned long *)pc);
134 
135         if (prologue) {
136                 long frame_size = get_frame_size(*prologue);
137 
138                 *pprev_fp = fp + frame_size;
139                 *pprev_pc = *(unsigned long *)fp;
140         } else {
141                 if (!leaf_return)
142                         return -EINVAL;
143                 *pprev_pc = leaf_return;
144                 *pprev_fp = fp;
145         }
146 
147         /* NOTE: don't check kernel_text_address here, to allow display
148          *       of userland return address
149          */
150         return (!*pprev_pc || (*pprev_pc & 3)) ? -EINVAL : 0;
151 }
152 
153 static void microblaze_unwind_inner(struct task_struct *task,
154                                     unsigned long pc, unsigned long fp,
155                                     unsigned long leaf_return,
156                                     struct stack_trace *trace);
157 
158 /**
159  * unwind_trap - Unwind through a system trap, that stored previous state
160  *               on the stack.
161  */
162 #ifdef CONFIG_MMU
163 static inline void unwind_trap(struct task_struct *task, unsigned long pc,
164                                 unsigned long fp, struct stack_trace *trace)
165 {
166         /* To be implemented */
167 }
168 #else
169 static inline void unwind_trap(struct task_struct *task, unsigned long pc,
170                                 unsigned long fp, struct stack_trace *trace)
171 {
172         const struct pt_regs *regs = (const struct pt_regs *) fp;
173         microblaze_unwind_inner(task, regs->pc, regs->r1, regs->r15, trace);
174 }
175 #endif
176 
177 /**
178  * microblaze_unwind_inner - Unwind the stack from the specified point
179  * @task  : Task whose stack we are to unwind (may be NULL)
180  * @pc    : Program counter from which we start unwinding
181  * @fp    : Frame (stack) pointer from which we start unwinding
182  * @leaf_return : Value of r15 at pc. If the function is a leaf, this is
183  *                                the caller's return address.
184  * @trace : Where to store stack backtrace (PC values).
185  *          NULL == print backtrace to kernel log
186  */
187 static void microblaze_unwind_inner(struct task_struct *task,
188                              unsigned long pc, unsigned long fp,
189                              unsigned long leaf_return,
190                              struct stack_trace *trace)
191 {
192         int ofs = 0;
193 
194         pr_debug("    Unwinding with PC=%p, FP=%p\n", (void *)pc, (void *)fp);
195         if (!pc || !fp || (pc & 3) || (fp & 3)) {
196                 pr_debug("    Invalid state for unwind, aborting\n");
197                 return;
198         }
199         for (; pc != 0;) {
200                 unsigned long next_fp, next_pc = 0;
201                 unsigned long return_to = pc +  2 * sizeof(unsigned long);
202                 const struct trap_handler_info *handler =
203                         &microblaze_trap_handlers;
204 
205                 /* Is previous function the HW exception handler? */
206                 if ((return_to >= (unsigned long)&_hw_exception_handler)
207                     &&(return_to < (unsigned long)&ex_handler_unhandled)) {
208                         /*
209                          * HW exception handler doesn't save all registers,
210                          * so we open-code a special case of unwind_trap()
211                          */
212 #ifndef CONFIG_MMU
213                         const struct pt_regs *regs =
214                                 (const struct pt_regs *) fp;
215 #endif
216                         pr_info("HW EXCEPTION\n");
217 #ifndef CONFIG_MMU
218                         microblaze_unwind_inner(task, regs->r17 - 4,
219                                                 fp + EX_HANDLER_STACK_SIZ,
220                                                 regs->r15, trace);
221 #endif
222                         return;
223                 }
224 
225                 /* Is previous function a trap handler? */
226                 for (; handler->start_addr; ++handler) {
227                         if ((return_to >= handler->start_addr)
228                             && (return_to <= handler->end_addr)) {
229                                 if (!trace)
230                                         pr_info("%s\n", handler->trap_name);
231                                 unwind_trap(task, pc, fp, trace);
232                                 return;
233                         }
234                 }
235                 pc -= ofs;
236 
237                 if (trace) {
238 #ifdef CONFIG_STACKTRACE
239                         if (trace->skip > 0)
240                                 trace->skip--;
241                         else
242                                 trace->entries[trace->nr_entries++] = pc;
243 
244                         if (trace->nr_entries >= trace->max_entries)
245                                 break;
246 #endif
247                 } else {
248                         /* Have we reached userland? */
249                         if (unlikely(pc == task_pt_regs(task)->pc)) {
250                                 pr_info("[<%p>] PID %lu [%s]\n",
251                                         (void *) pc,
252                                         (unsigned long) task->pid,
253                                         task->comm);
254                                 break;
255                         } else
256                                 print_ip_sym(pc);
257                 }
258 
259                 /* Stop when we reach anything not part of the kernel */
260                 if (!kernel_text_address(pc))
261                         break;
262 
263                 if (lookup_prev_stack_frame(fp, pc, leaf_return, &next_fp,
264                                             &next_pc) == 0) {
265                         ofs = sizeof(unsigned long);
266                         pc = next_pc & ~3;
267                         fp = next_fp;
268                         leaf_return = 0;
269                 } else {
270                         pr_debug("    Failed to find previous stack frame\n");
271                         break;
272                 }
273 
274                 pr_debug("    Next PC=%p, next FP=%p\n",
275                          (void *)next_pc, (void *)next_fp);
276         }
277 }
278 
279 /**
280  * microblaze_unwind - Stack unwinder for Microblaze (external entry point)
281  * @task  : Task whose stack we are to unwind (NULL == current)
282  * @trace : Where to store stack backtrace (PC values).
283  *          NULL == print backtrace to kernel log
284  */
285 void microblaze_unwind(struct task_struct *task, struct stack_trace *trace)
286 {
287         if (task) {
288                 if (task == current) {
289                         const struct pt_regs *regs = task_pt_regs(task);
290                         microblaze_unwind_inner(task, regs->pc, regs->r1,
291                                                 regs->r15, trace);
292                 } else {
293                         struct thread_info *thread_info =
294                                 (struct thread_info *)(task->stack);
295                         const struct cpu_context *cpu_context =
296                                 &thread_info->cpu_context;
297 
298                         microblaze_unwind_inner(task,
299                                                 (unsigned long) &_switch_to,
300                                                 cpu_context->r1,
301                                                 cpu_context->r15, trace);
302                 }
303         } else {
304                 unsigned long pc, fp;
305 
306                 __asm__ __volatile__ ("or %0, r1, r0" : "=r" (fp));
307 
308                 __asm__ __volatile__ (
309                         "brlid %0, 0f;"
310                         "nop;"
311                         "0:"
312                         : "=r" (pc)
313                 );
314 
315                 /* Since we are not a leaf function, use leaf_return = 0 */
316                 microblaze_unwind_inner(current, pc, fp, 0, trace);
317         }
318 }
319 
320 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp