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Diffstat (limited to 'arch/arm/kernel/unwind.c')
| -rw-r--r-- | arch/arm/kernel/unwind.c | 434 |
1 files changed, 434 insertions, 0 deletions
diff --git a/arch/arm/kernel/unwind.c b/arch/arm/kernel/unwind.c new file mode 100644 index 000000000000..1dedc2c7ff49 --- /dev/null +++ b/arch/arm/kernel/unwind.c @@ -0,0 +1,434 @@ +/* + * arch/arm/kernel/unwind.c + * + * Copyright (C) 2008 ARM Limited + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + * + * + * Stack unwinding support for ARM + * + * An ARM EABI version of gcc is required to generate the unwind + * tables. For information about the structure of the unwind tables, + * see "Exception Handling ABI for the ARM Architecture" at: + * + * http://infocenter.arm.com/help/topic/com.arm.doc.subset.swdev.abi/index.html + */ + +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/sched.h> +#include <linux/slab.h> +#include <linux/spinlock.h> +#include <linux/list.h> + +#include <asm/stacktrace.h> +#include <asm/traps.h> +#include <asm/unwind.h> + +/* Dummy functions to avoid linker complaints */ +void __aeabi_unwind_cpp_pr0(void) +{ +}; +EXPORT_SYMBOL(__aeabi_unwind_cpp_pr0); + +void __aeabi_unwind_cpp_pr1(void) +{ +}; +EXPORT_SYMBOL(__aeabi_unwind_cpp_pr1); + +void __aeabi_unwind_cpp_pr2(void) +{ +}; +EXPORT_SYMBOL(__aeabi_unwind_cpp_pr2); + +struct unwind_ctrl_block { + unsigned long vrs[16]; /* virtual register set */ + unsigned long *insn; /* pointer to the current instructions word */ + int entries; /* number of entries left to interpret */ + int byte; /* current byte number in the instructions word */ +}; + +enum regs { + FP = 11, + SP = 13, + LR = 14, + PC = 15 +}; + +extern struct unwind_idx __start_unwind_idx[]; +extern struct unwind_idx __stop_unwind_idx[]; + +static DEFINE_SPINLOCK(unwind_lock); +static LIST_HEAD(unwind_tables); + +/* Convert a prel31 symbol to an absolute address */ +#define prel31_to_addr(ptr) \ +({ \ + /* sign-extend to 32 bits */ \ + long offset = (((long)*(ptr)) << 1) >> 1; \ + (unsigned long)(ptr) + offset; \ +}) + +/* + * Binary search in the unwind index. The entries entries are + * guaranteed to be sorted in ascending order by the linker. + */ +static struct unwind_idx *search_index(unsigned long addr, + struct unwind_idx *first, + struct unwind_idx *last) +{ + pr_debug("%s(%08lx, %p, %p)\n", __func__, addr, first, last); + + if (addr < first->addr) { + pr_warning("unwind: Unknown symbol address %08lx\n", addr); + return NULL; + } else if (addr >= last->addr) + return last; + + while (first < last - 1) { + struct unwind_idx *mid = first + ((last - first + 1) >> 1); + + if (addr < mid->addr) + last = mid; + else + first = mid; + } + + return first; +} + +static struct unwind_idx *unwind_find_idx(unsigned long addr) +{ + struct unwind_idx *idx = NULL; + unsigned long flags; + + pr_debug("%s(%08lx)\n", __func__, addr); + + if (core_kernel_text(addr)) + /* main unwind table */ + idx = search_index(addr, __start_unwind_idx, + __stop_unwind_idx - 1); + else { + /* module unwind tables */ + struct unwind_table *table; + + spin_lock_irqsave(&unwind_lock, flags); + list_for_each_entry(table, &unwind_tables, list) { + if (addr >= table->begin_addr && + addr < table->end_addr) { + idx = search_index(addr, table->start, + table->stop - 1); + break; + } + } + spin_unlock_irqrestore(&unwind_lock, flags); + } + + pr_debug("%s: idx = %p\n", __func__, idx); + return idx; +} + +static unsigned long unwind_get_byte(struct unwind_ctrl_block *ctrl) +{ + unsigned long ret; + + if (ctrl->entries <= 0) { + pr_warning("unwind: Corrupt unwind table\n"); + return 0; + } + + ret = (*ctrl->insn >> (ctrl->byte * 8)) & 0xff; + + if (ctrl->byte == 0) { + ctrl->insn++; + ctrl->entries--; + ctrl->byte = 3; + } else + ctrl->byte--; + + return ret; +} + +/* + * Execute the current unwind instruction. + */ +static int unwind_exec_insn(struct unwind_ctrl_block *ctrl) +{ + unsigned long insn = unwind_get_byte(ctrl); + + pr_debug("%s: insn = %08lx\n", __func__, insn); + + if ((insn & 0xc0) == 0x00) + ctrl->vrs[SP] += ((insn & 0x3f) << 2) + 4; + else if ((insn & 0xc0) == 0x40) + ctrl->vrs[SP] -= ((insn & 0x3f) << 2) + 4; + else if ((insn & 0xf0) == 0x80) { + unsigned long mask; + unsigned long *vsp = (unsigned long *)ctrl->vrs[SP]; + int load_sp, reg = 4; + + insn = (insn << 8) | unwind_get_byte(ctrl); + mask = insn & 0x0fff; + if (mask == 0) { + pr_warning("unwind: 'Refuse to unwind' instruction %04lx\n", + insn); + return -URC_FAILURE; + } + + /* pop R4-R15 according to mask */ + load_sp = mask & (1 << (13 - 4)); + while (mask) { + if (mask & 1) + ctrl->vrs[reg] = *vsp++; + mask >>= 1; + reg++; + } + if (!load_sp) + ctrl->vrs[SP] = (unsigned long)vsp; + } else if ((insn & 0xf0) == 0x90 && + (insn & 0x0d) != 0x0d) + ctrl->vrs[SP] = ctrl->vrs[insn & 0x0f]; + else if ((insn & 0xf0) == 0xa0) { + unsigned long *vsp = (unsigned long *)ctrl->vrs[SP]; + int reg; + + /* pop R4-R[4+bbb] */ + for (reg = 4; reg <= 4 + (insn & 7); reg++) + ctrl->vrs[reg] = *vsp++; + if (insn & 0x80) + ctrl->vrs[14] = *vsp++; + ctrl->vrs[SP] = (unsigned long)vsp; + } else if (insn == 0xb0) { + ctrl->vrs[PC] = ctrl->vrs[LR]; + /* no further processing */ + ctrl->entries = 0; + } else if (insn == 0xb1) { + unsigned long mask = unwind_get_byte(ctrl); + unsigned long *vsp = (unsigned long *)ctrl->vrs[SP]; + int reg = 0; + + if (mask == 0 || mask & 0xf0) { + pr_warning("unwind: Spare encoding %04lx\n", + (insn << 8) | mask); + return -URC_FAILURE; + } + + /* pop R0-R3 according to mask */ + while (mask) { + if (mask & 1) + ctrl->vrs[reg] = *vsp++; + mask >>= 1; + reg++; + } + ctrl->vrs[SP] = (unsigned long)vsp; + } else if (insn == 0xb2) { + unsigned long uleb128 = unwind_get_byte(ctrl); + + ctrl->vrs[SP] += 0x204 + (uleb128 << 2); + } else { + pr_warning("unwind: Unhandled instruction %02lx\n", insn); + return -URC_FAILURE; + } + + pr_debug("%s: fp = %08lx sp = %08lx lr = %08lx pc = %08lx\n", __func__, + ctrl->vrs[FP], ctrl->vrs[SP], ctrl->vrs[LR], ctrl->vrs[PC]); + + return URC_OK; +} + +/* + * Unwind a single frame starting with *sp for the symbol at *pc. It + * updates the *pc and *sp with the new values. + */ +int unwind_frame(struct stackframe *frame) +{ + unsigned long high, low; + struct unwind_idx *idx; + struct unwind_ctrl_block ctrl; + + /* only go to a higher address on the stack */ + low = frame->sp; + high = ALIGN(low, THREAD_SIZE) + THREAD_SIZE; + + pr_debug("%s(pc = %08lx lr = %08lx sp = %08lx)\n", __func__, + frame->pc, frame->lr, frame->sp); + + if (!kernel_text_address(frame->pc)) + return -URC_FAILURE; + + idx = unwind_find_idx(frame->pc); + if (!idx) { + pr_warning("unwind: Index not found %08lx\n", frame->pc); + return -URC_FAILURE; + } + + ctrl.vrs[FP] = frame->fp; + ctrl.vrs[SP] = frame->sp; + ctrl.vrs[LR] = frame->lr; + ctrl.vrs[PC] = 0; + + if (idx->insn == 1) + /* can't unwind */ + return -URC_FAILURE; + else if ((idx->insn & 0x80000000) == 0) + /* prel31 to the unwind table */ + ctrl.insn = (unsigned long *)prel31_to_addr(&idx->insn); + else if ((idx->insn & 0xff000000) == 0x80000000) + /* only personality routine 0 supported in the index */ + ctrl.insn = &idx->insn; + else { + pr_warning("unwind: Unsupported personality routine %08lx in the index at %p\n", + idx->insn, idx); + return -URC_FAILURE; + } + + /* check the personality routine */ + if ((*ctrl.insn & 0xff000000) == 0x80000000) { + ctrl.byte = 2; + ctrl.entries = 1; + } else if ((*ctrl.insn & 0xff000000) == 0x81000000) { + ctrl.byte = 1; + ctrl.entries = 1 + ((*ctrl.insn & 0x00ff0000) >> 16); + } else { + pr_warning("unwind: Unsupported personality routine %08lx at %p\n", + *ctrl.insn, ctrl.insn); + return -URC_FAILURE; + } + + while (ctrl.entries > 0) { + int urc; + + if (ctrl.vrs[SP] < low || ctrl.vrs[SP] >= high) + return -URC_FAILURE; + urc = unwind_exec_insn(&ctrl); + if (urc < 0) + return urc; + } + + if (ctrl.vrs[PC] == 0) + ctrl.vrs[PC] = ctrl.vrs[LR]; + + frame->fp = ctrl.vrs[FP]; + frame->sp = ctrl.vrs[SP]; + frame->lr = ctrl.vrs[LR]; + frame->pc = ctrl.vrs[PC]; + + return URC_OK; +} + +void unwind_backtrace(struct pt_regs *regs, struct task_struct *tsk) +{ + struct stackframe frame; + unsigned long high, low; + register unsigned long current_sp asm ("sp"); + + pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk); + + if (!tsk) + tsk = current; + + if (regs) { + frame.fp = regs->ARM_fp; + frame.sp = regs->ARM_sp; + frame.lr = regs->ARM_lr; + frame.pc = regs->ARM_pc; + } else if (tsk == current) { + frame.fp = (unsigned long)__builtin_frame_address(0); + frame.sp = current_sp; + frame.lr = (unsigned long)__builtin_return_address(0); + frame.pc = (unsigned long)unwind_backtrace; + } else { + /* task blocked in __switch_to */ + frame.fp = thread_saved_fp(tsk); + frame.sp = thread_saved_sp(tsk); + /* + * The function calling __switch_to cannot be a leaf function + * so LR is recovered from the stack. + */ + frame.lr = 0; + frame.pc = thread_saved_pc(tsk); + } + + low = frame.sp & ~(THREAD_SIZE - 1); + high = low + THREAD_SIZE; + + while (1) { + int urc; + unsigned long where = frame.pc; + + urc = unwind_frame(&frame); + if (urc < 0) + break; + dump_backtrace_entry(where, frame.pc, frame.sp - 4); + } +} + +struct unwind_table *unwind_table_add(unsigned long start, unsigned long size, + unsigned long text_addr, + unsigned long text_size) +{ + unsigned long flags; + struct unwind_idx *idx; + struct unwind_table *tab = kmalloc(sizeof(*tab), GFP_KERNEL); + + pr_debug("%s(%08lx, %08lx, %08lx, %08lx)\n", __func__, start, size, + text_addr, text_size); + + if (!tab) + return tab; + + tab->start = (struct unwind_idx *)start; + tab->stop = (struct unwind_idx *)(start + size); + tab->begin_addr = text_addr; + tab->end_addr = text_addr + text_size; + + /* Convert the symbol addresses to absolute values */ + for (idx = tab->start; idx < tab->stop; idx++) + idx->addr = prel31_to_addr(&idx->addr); + + spin_lock_irqsave(&unwind_lock, flags); + list_add_tail(&tab->list, &unwind_tables); + spin_unlock_irqrestore(&unwind_lock, flags); + + return tab; +} + +void unwind_table_del(struct unwind_table *tab) +{ + unsigned long flags; + + if (!tab) + return; + + spin_lock_irqsave(&unwind_lock, flags); + list_del(&tab->list); + spin_unlock_irqrestore(&unwind_lock, flags); + + kfree(tab); +} + +int __init unwind_init(void) +{ + struct unwind_idx *idx; + + /* Convert the symbol addresses to absolute values */ + for (idx = __start_unwind_idx; idx < __stop_unwind_idx; idx++) + idx->addr = prel31_to_addr(&idx->addr); + + pr_debug("unwind: ARM stack unwinding initialised\n"); + + return 0; +} |