6 files changed, 540 insertions, 0 deletions

diff --git a/arch/arm/boot/compressed/vmlinux.lds.in b/arch/arm/boot/compressed/vmlinux.lds.in
index 153a07e7222b..a5924b9b88bd 100644
--- a/arch/arm/boot/compressed/vmlinux.lds.in
+++ b/arch/arm/boot/compressed/vmlinux.lds.in
@@ -11,6 +11,11 @@ OUTPUT_ARCH(arm)
 ENTRY(_start)
 SECTIONS
 {
+  /DISCARD/ : {
+    *(.ARM.exidx*)
+    *(.ARM.extab*)
+  }
+
   . = TEXT_START;
   _text = .;
 
diff --git a/arch/arm/include/asm/unwind.h b/arch/arm/include/asm/unwind.h
new file mode 100644
index 000000000000..a5edf421005c
--- /dev/null
+++ b/arch/arm/include/asm/unwind.h
@@ -0,0 +1,69 @@
+/*
+ * arch/arm/include/asm/unwind.h
+ *
+ * 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
+ */
+
+#ifndef __ASM_UNWIND_H
+#define __ASM_UNWIND_H
+
+#ifndef __ASSEMBLY__
+
+/* Unwind reason code according the the ARM EABI documents */
+enum unwind_reason_code {
+        URC_OK = 0,                     /* operation completed successfully */
+        URC_CONTINUE_UNWIND = 8,
+        URC_FAILURE = 9                 /* unspecified failure of some kind */
+};
+
+struct unwind_idx {
+        unsigned long addr;
+        unsigned long insn;
+};
+
+struct unwind_table {
+        struct list_head list;
+        struct unwind_idx *start;
+        struct unwind_idx *stop;
+        unsigned long begin_addr;
+        unsigned long end_addr;
+};
+
+extern struct unwind_table *unwind_table_add(unsigned long start,
+                                             unsigned long size,
+                                             unsigned long text_addr,
+                                             unsigned long text_size);
+extern void unwind_table_del(struct unwind_table *tab);
+extern void unwind_backtrace(struct pt_regs *regs, struct task_struct *tsk);
+
+#ifdef CONFIG_ARM_UNWIND
+extern int __init unwind_init(void);
+#else
+static inline int __init unwind_init(void)
+{
+        return 0;
+}
+#endif
+
+#endif  /* !__ASSEMBLY__ */
+
+#ifdef CONFIG_ARM_UNWIND
+#define UNWIND(code...)         code
+#else
+#define UNWIND(code...)
+#endif
+
+#endif  /* __ASM_UNWIND_H */
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 645ec7436681..8d21427bb679 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -40,6 +40,7 @@
 #include <asm/mach/irq.h>
 #include <asm/mach/time.h>
 #include <asm/traps.h>
+#include <asm/unwind.h>
 
 #include "compat.h"
 #include "atags.h"
@@ -684,6 +685,8 @@ void __init setup_arch(char **cmdline_p)
         struct machine_desc *mdesc;
         char *from = default_command_line;
 
+        unwind_init();
+
         setup_processor();
         mdesc = setup_machine(machine_arch_type);
         machine_name = mdesc->name;
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index f68ca0fb0ed7..57eb0f6f6005 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -27,6 +27,7 @@
 #include <asm/system.h>
 #include <asm/unistd.h>
 #include <asm/traps.h>
+#include <asm/unwind.h>
 
 #include "ptrace.h"
 #include "signal.h"
@@ -61,6 +62,7 @@ void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long
                 dump_mem("Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
 }
 
+#ifndef CONFIG_ARM_UNWIND
 /*
  * Stack pointers should always be within the kernels view of
  * physical memory.  If it is not there, then we can't dump
@@ -74,6 +76,7 @@ static int verify_stack(unsigned long sp)
 
         return 0;
 }
+#endif
 
 /*
  * Dump out the contents of some memory nicely...
@@ -150,6 +153,12 @@ static void dump_instr(struct pt_regs *regs)
         set_fs(fs);
 }
 
+#ifdef CONFIG_ARM_UNWIND
+static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
+{
+        unwind_backtrace(regs, tsk);
+}
+#else
 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
 {
         unsigned int fp, mode;
@@ -184,6 +193,7 @@ static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
         if (ok)
                 c_backtrace(fp, mode);
 }
+#endif
 
 void dump_stack(void)
 {
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;
+}
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index 00216071eaf7..5f664599c945 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -80,6 +80,8 @@ SECTIONS
                 EXIT_TEXT
                 EXIT_DATA
                 *(.exitcall.exit)
+                *(.ARM.exidx.exit.text)
+                *(.ARM.extab.exit.text)
 #ifndef CONFIG_MMU
                 *(.fixup)
                 *(__ex_table)
@@ -110,6 +112,23 @@ SECTIONS
 
         _etext = .;                     /* End of text and rodata section */
 
+#ifdef CONFIG_ARM_UNWIND
+        /*
+         * Stack unwinding tables
+         */
+        . = ALIGN(8);
+        .ARM.unwind_idx : {
+                __start_unwind_idx = .;
+                *(.ARM.exidx*)
+                __stop_unwind_idx = .;
+        }
+        .ARM.unwind_tab : {
+                __start_unwind_tab = .;
+                *(.ARM.extab*)
+                __stop_unwind_tab = .;
+        }
+#endif
+
 #ifdef CONFIG_XIP_KERNEL
         __data_loc = ALIGN(4);          /* location in binary */
         . = PAGE_OFFSET + TEXT_OFFSET;