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