2 * arch/arm/kernel/unwind.c
4 * Copyright (C) 2008 ARM Limited
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20 * Stack unwinding support for ARM
22 * An ARM EABI version of gcc is required to generate the unwind
23 * tables. For information about the structure of the unwind tables,
24 * see "Exception Handling ABI for the ARM Architecture" at:
26 * http://infocenter.arm.com/help/topic/com.arm.doc.subset.swdev.abi/index.html
29 #if !defined (__ARM_EABI__)
30 #warning Your compiler does not have EABI support.
31 #warning ARM unwind is known to compile only with EABI compilers.
32 #warning Change compiler or disable ARM_UNWIND option.
33 #elif (__GNUC__ == 4 && __GNUC_MINOR__ <= 2)
34 #warning Your compiler is too buggy; it is known to not compile ARM unwind support.
35 #warning Change compiler or disable ARM_UNWIND option.
38 #include <linux/kernel.h>
39 #include <linux/init.h>
40 #include <linux/module.h>
41 #include <linux/sched.h>
42 #include <linux/slab.h>
43 #include <linux/spinlock.h>
44 #include <linux/list.h>
46 #include <asm/stacktrace.h>
47 #include <asm/traps.h>
48 #include <asm/unwind.h>
50 /* Dummy functions to avoid linker complaints */
51 void __aeabi_unwind_cpp_pr0(void)
54 EXPORT_SYMBOL(__aeabi_unwind_cpp_pr0);
56 void __aeabi_unwind_cpp_pr1(void)
59 EXPORT_SYMBOL(__aeabi_unwind_cpp_pr1);
61 void __aeabi_unwind_cpp_pr2(void)
64 EXPORT_SYMBOL(__aeabi_unwind_cpp_pr2);
66 struct unwind_ctrl_block {
67 unsigned long vrs[16]; /* virtual register set */
68 unsigned long *insn; /* pointer to the current instructions word */
69 int entries; /* number of entries left to interpret */
70 int byte; /* current byte number in the instructions word */
74 #ifdef CONFIG_THUMB2_KERNEL
84 extern struct unwind_idx __start_unwind_idx[];
85 extern struct unwind_idx __stop_unwind_idx[];
87 static DEFINE_SPINLOCK(unwind_lock);
88 static LIST_HEAD(unwind_tables);
90 /* Convert a prel31 symbol to an absolute address */
91 #define prel31_to_addr(ptr) \
93 /* sign-extend to 32 bits */ \
94 long offset = (((long)*(ptr)) << 1) >> 1; \
95 (unsigned long)(ptr) + offset; \
99 * Binary search in the unwind index. The entries entries are
100 * guaranteed to be sorted in ascending order by the linker.
102 static struct unwind_idx *search_index(unsigned long addr,
103 struct unwind_idx *first,
104 struct unwind_idx *last)
106 pr_debug("%s(%08lx, %p, %p)\n", __func__, addr, first, last);
108 if (addr < first->addr) {
109 pr_warning("unwind: Unknown symbol address %08lx\n", addr);
111 } else if (addr >= last->addr)
114 while (first < last - 1) {
115 struct unwind_idx *mid = first + ((last - first + 1) >> 1);
117 if (addr < mid->addr)
126 static struct unwind_idx *unwind_find_idx(unsigned long addr)
128 struct unwind_idx *idx = NULL;
131 pr_debug("%s(%08lx)\n", __func__, addr);
133 if (core_kernel_text(addr))
134 /* main unwind table */
135 idx = search_index(addr, __start_unwind_idx,
136 __stop_unwind_idx - 1);
138 /* module unwind tables */
139 struct unwind_table *table;
141 spin_lock_irqsave(&unwind_lock, flags);
142 list_for_each_entry(table, &unwind_tables, list) {
143 if (addr >= table->begin_addr &&
144 addr < table->end_addr) {
145 idx = search_index(addr, table->start,
150 spin_unlock_irqrestore(&unwind_lock, flags);
153 pr_debug("%s: idx = %p\n", __func__, idx);
157 static unsigned long unwind_get_byte(struct unwind_ctrl_block *ctrl)
161 if (ctrl->entries <= 0) {
162 pr_warning("unwind: Corrupt unwind table\n");
166 ret = (*ctrl->insn >> (ctrl->byte * 8)) & 0xff;
168 if (ctrl->byte == 0) {
179 * Execute the current unwind instruction.
181 static int unwind_exec_insn(struct unwind_ctrl_block *ctrl)
183 unsigned long insn = unwind_get_byte(ctrl);
185 pr_debug("%s: insn = %08lx\n", __func__, insn);
187 if ((insn & 0xc0) == 0x00)
188 ctrl->vrs[SP] += ((insn & 0x3f) << 2) + 4;
189 else if ((insn & 0xc0) == 0x40)
190 ctrl->vrs[SP] -= ((insn & 0x3f) << 2) + 4;
191 else if ((insn & 0xf0) == 0x80) {
193 unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
194 int load_sp, reg = 4;
196 insn = (insn << 8) | unwind_get_byte(ctrl);
197 mask = insn & 0x0fff;
199 pr_warning("unwind: 'Refuse to unwind' instruction %04lx\n",
204 /* pop R4-R15 according to mask */
205 load_sp = mask & (1 << (13 - 4));
208 ctrl->vrs[reg] = *vsp++;
213 ctrl->vrs[SP] = (unsigned long)vsp;
214 } else if ((insn & 0xf0) == 0x90 &&
215 (insn & 0x0d) != 0x0d)
216 ctrl->vrs[SP] = ctrl->vrs[insn & 0x0f];
217 else if ((insn & 0xf0) == 0xa0) {
218 unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
221 /* pop R4-R[4+bbb] */
222 for (reg = 4; reg <= 4 + (insn & 7); reg++)
223 ctrl->vrs[reg] = *vsp++;
225 ctrl->vrs[14] = *vsp++;
226 ctrl->vrs[SP] = (unsigned long)vsp;
227 } else if (insn == 0xb0) {
228 if (ctrl->vrs[PC] == 0)
229 ctrl->vrs[PC] = ctrl->vrs[LR];
230 /* no further processing */
232 } else if (insn == 0xb1) {
233 unsigned long mask = unwind_get_byte(ctrl);
234 unsigned long *vsp = (unsigned long *)ctrl->vrs[SP];
237 if (mask == 0 || mask & 0xf0) {
238 pr_warning("unwind: Spare encoding %04lx\n",
243 /* pop R0-R3 according to mask */
246 ctrl->vrs[reg] = *vsp++;
250 ctrl->vrs[SP] = (unsigned long)vsp;
251 } else if (insn == 0xb2) {
252 unsigned long uleb128 = unwind_get_byte(ctrl);
254 ctrl->vrs[SP] += 0x204 + (uleb128 << 2);
256 pr_warning("unwind: Unhandled instruction %02lx\n", insn);
260 pr_debug("%s: fp = %08lx sp = %08lx lr = %08lx pc = %08lx\n", __func__,
261 ctrl->vrs[FP], ctrl->vrs[SP], ctrl->vrs[LR], ctrl->vrs[PC]);
267 * Unwind a single frame starting with *sp for the symbol at *pc. It
268 * updates the *pc and *sp with the new values.
270 int unwind_frame(struct stackframe *frame)
272 unsigned long high, low;
273 struct unwind_idx *idx;
274 struct unwind_ctrl_block ctrl;
276 /* only go to a higher address on the stack */
278 high = ALIGN(low, THREAD_SIZE) + THREAD_SIZE;
280 pr_debug("%s(pc = %08lx lr = %08lx sp = %08lx)\n", __func__,
281 frame->pc, frame->lr, frame->sp);
283 if (!kernel_text_address(frame->pc))
286 idx = unwind_find_idx(frame->pc);
288 pr_warning("unwind: Index not found %08lx\n", frame->pc);
292 ctrl.vrs[FP] = frame->fp;
293 ctrl.vrs[SP] = frame->sp;
294 ctrl.vrs[LR] = frame->lr;
300 else if ((idx->insn & 0x80000000) == 0)
301 /* prel31 to the unwind table */
302 ctrl.insn = (unsigned long *)prel31_to_addr(&idx->insn);
303 else if ((idx->insn & 0xff000000) == 0x80000000)
304 /* only personality routine 0 supported in the index */
305 ctrl.insn = &idx->insn;
307 pr_warning("unwind: Unsupported personality routine %08lx in the index at %p\n",
312 /* check the personality routine */
313 if ((*ctrl.insn & 0xff000000) == 0x80000000) {
316 } else if ((*ctrl.insn & 0xff000000) == 0x81000000) {
318 ctrl.entries = 1 + ((*ctrl.insn & 0x00ff0000) >> 16);
320 pr_warning("unwind: Unsupported personality routine %08lx at %p\n",
321 *ctrl.insn, ctrl.insn);
325 while (ctrl.entries > 0) {
326 int urc = unwind_exec_insn(&ctrl);
329 if (ctrl.vrs[SP] < low || ctrl.vrs[SP] >= high)
333 if (ctrl.vrs[PC] == 0)
334 ctrl.vrs[PC] = ctrl.vrs[LR];
336 /* check for infinite loop */
337 if (frame->pc == ctrl.vrs[PC])
340 frame->fp = ctrl.vrs[FP];
341 frame->sp = ctrl.vrs[SP];
342 frame->lr = ctrl.vrs[LR];
343 frame->pc = ctrl.vrs[PC];
348 void unwind_backtrace(struct pt_regs *regs, struct task_struct *tsk)
350 struct stackframe frame;
351 register unsigned long current_sp asm ("sp");
353 pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
359 frame.fp = regs->ARM_fp;
360 frame.sp = regs->ARM_sp;
361 frame.lr = regs->ARM_lr;
362 frame.pc = regs->ARM_pc;
363 } else if (tsk == current) {
364 frame.fp = (unsigned long)__builtin_frame_address(0);
365 frame.sp = current_sp;
366 frame.lr = (unsigned long)__builtin_return_address(0);
367 frame.pc = (unsigned long)unwind_backtrace;
369 /* task blocked in __switch_to */
370 frame.fp = thread_saved_fp(tsk);
371 frame.sp = thread_saved_sp(tsk);
373 * The function calling __switch_to cannot be a leaf function
374 * so LR is recovered from the stack.
377 frame.pc = thread_saved_pc(tsk);
382 unsigned long where = frame.pc;
384 urc = unwind_frame(&frame);
387 dump_backtrace_entry(where, frame.pc, frame.sp - 4);
391 struct unwind_table *unwind_table_add(unsigned long start, unsigned long size,
392 unsigned long text_addr,
393 unsigned long text_size)
396 struct unwind_idx *idx;
397 struct unwind_table *tab = kmalloc(sizeof(*tab), GFP_KERNEL);
399 pr_debug("%s(%08lx, %08lx, %08lx, %08lx)\n", __func__, start, size,
400 text_addr, text_size);
405 tab->start = (struct unwind_idx *)start;
406 tab->stop = (struct unwind_idx *)(start + size);
407 tab->begin_addr = text_addr;
408 tab->end_addr = text_addr + text_size;
410 /* Convert the symbol addresses to absolute values */
411 for (idx = tab->start; idx < tab->stop; idx++)
412 idx->addr = prel31_to_addr(&idx->addr);
414 spin_lock_irqsave(&unwind_lock, flags);
415 list_add_tail(&tab->list, &unwind_tables);
416 spin_unlock_irqrestore(&unwind_lock, flags);
421 void unwind_table_del(struct unwind_table *tab)
428 spin_lock_irqsave(&unwind_lock, flags);
429 list_del(&tab->list);
430 spin_unlock_irqrestore(&unwind_lock, flags);
435 int __init unwind_init(void)
437 struct unwind_idx *idx;
439 /* Convert the symbol addresses to absolute values */
440 for (idx = __start_unwind_idx; idx < __stop_unwind_idx; idx++)
441 idx->addr = prel31_to_addr(&idx->addr);
443 pr_debug("unwind: ARM stack unwinding initialised\n");