Add a new library for collecting stack traces.

Supports collecting the stack trace of the current thread,
another thread in the same process, or a thread in a
different process (using ptrace).

Change-Id: Ica2594e4436edde4ceb7bcc3d78e6c31a7902cbf

14 files changed, 1673 insertions, 0 deletions

diff --git a/libcorkscrew/Android.mk b/libcorkscrew/Android.mk
new file mode 100644
index 000000000..08432ef2e
--- /dev/null
+++ b/libcorkscrew/Android.mk
@@ -0,0 +1,41 @@
+# Copyright (C) 2011 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+LOCAL_PATH:= $(call my-dir)
+
+include $(CLEAR_VARS)
+
+LOCAL_SRC_FILES := \
+	backtrace.c \
+	backtrace-helper.c \
+	demangle.c \
+	map_info.c \
+	ptrace.c \
+	symbol_table.c
+
+ifeq ($(TARGET_ARCH),arm)
+LOCAL_SRC_FILES += \
+	arch-arm/backtrace-arm.c \
+	arch-arm/ptrace-arm.c
+LOCAL_CFLAGS += -DCORKSCREW_HAVE_ARCH -DCORKSCREW_HAVE_LIBIBERTY
+LOCAL_LDFLAGS += -liberty
+endif
+
+LOCAL_SHARED_LIBRARIES += libdl libcutils
+
+LOCAL_CFLAGS += -std=gnu99 -Werror
+LOCAL_MODULE := libcorkscrew
+LOCAL_MODULE_TAGS := optional
+
+include $(BUILD_SHARED_LIBRARY)
diff --git a/libcorkscrew/MODULE_LICENSE_APACHE2 b/libcorkscrew/MODULE_LICENSE_APACHE2
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/libcorkscrew/MODULE_LICENSE_APACHE2
diff --git a/libcorkscrew/NOTICE b/libcorkscrew/NOTICE
new file mode 100644
index 000000000..becc12079
--- /dev/null
+++ b/libcorkscrew/NOTICE
@@ -0,0 +1,190 @@
+
+   Copyright (c) 2011, The Android Open Source Project
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
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+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
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+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
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+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
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+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
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+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
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+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
diff --git a/libcorkscrew/arch-arm/backtrace-arm.c b/libcorkscrew/arch-arm/backtrace-arm.c
new file mode 100644
index 000000000..f2db64294
--- /dev/null
+++ b/libcorkscrew/arch-arm/backtrace-arm.c
@@ -0,0 +1,516 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * Backtracing functions for ARM.
+ *
+ * This implementation uses the exception unwinding tables provided by
+ * the compiler to unwind call frames.  Refer to the ARM Exception Handling ABI
+ * documentation (EHABI) for more details about what's going on here.
+ *
+ * An ELF binary may contain an EXIDX section that provides an index to
+ * the exception handling table of each function, sorted by program
+ * counter address.
+ *
+ * When the executable is statically linked, the EXIDX section can be
+ * accessed by querying the values of the __exidx_start and __exidx_end
+ * symbols.  That said, this library is currently only compiled as
+ * a dynamic library, so we will not trouble ourselves with statically
+ * linked executables any further.
+ *
+ * When the Bionic dynamic linker is used, it exports a function called
+ * dl_unwind_find_exidx that obtains the EXIDX section for a given
+ * absolute program counter address.
+ *
+ * This implementation also supports unwinding other processes via ptrace().
+ * In that case, the EXIDX section is found by reading the ELF section table
+ * structures using ptrace().
+ *
+ * Because the tables are used for exception handling, it can happen that
+ * a given function will not have an exception handling table.  In particular,
+ * exceptions are assumes to only ever be thrown at call sites.  Therefore,
+ * by definition leaf functions will not have exception handling tables.
+ * This may make unwinding impossible in some cases although we can still get
+ * some idea of the call stack by examining the PC and LR registers.
+ *
+ * As we are only interested in backtrace information, we do not need
+ * to perform all of the work of unwinding such as restoring register
+ * state and running cleanup functions.  Unwinding is performed virtually on
+ * an abstract machine context consisting of just the ARM core registers.
+ * Furthermore, we do not run generic "personality functions" because
+ * we may not be in a position to execute arbitrary code, especially if
+ * we are running in a signal handler or using ptrace()!
+ */
+
+#define LOG_TAG "Corkscrew"
+//#define LOG_NDEBUG 0
+
+#include "../backtrace-arch.h"
+#include "../backtrace-helper.h"
+#include "../ptrace-arch.h"
+#include <corkscrew/ptrace.h>
+
+#include <stdlib.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <limits.h>
+#include <errno.h>
+#include <sys/ptrace.h>
+#include <sys/exec_elf.h>
+#include <cutils/log.h>
+
+/* Machine context at the time a signal was raised. */
+typedef struct ucontext {
+    uint32_t uc_flags;
+    struct ucontext* uc_link;
+    stack_t uc_stack;
+    struct sigcontext {
+        uint32_t trap_no;
+        uint32_t error_code;
+        uint32_t oldmask;
+        uint32_t gregs[16];
+        uint32_t arm_cpsr;
+        uint32_t fault_address;
+    } uc_mcontext;
+    uint32_t uc_sigmask;
+} ucontext_t;
+
+/* Unwind state. */
+typedef struct {
+    uint32_t gregs[16];
+} unwind_state_t;
+
+static const int R_SP = 13;
+static const int R_LR = 14;
+static const int R_PC = 15;
+
+/* Special EXIDX value that indicates that a frame cannot be unwound. */
+static const uint32_t EXIDX_CANTUNWIND = 1;
+
+/* The function exported by the Bionic linker to find the EXIDX
+ * table for a given program counter address. */
+extern uintptr_t dl_unwind_find_exidx(uintptr_t pc, size_t* out_exidx_size);
+
+/* Transforms a 31-bit place-relative offset to an absolute address.
+ * We assume the most significant bit is clear. */
+static uintptr_t prel_to_absolute(uintptr_t place, uint32_t prel_offset) {
+    return place + (((int32_t)(prel_offset << 1)) >> 1);
+}
+
+static uintptr_t get_exception_handler(
+        const ptrace_context_t* context, pid_t tid, uintptr_t pc) {
+    uintptr_t exidx_start;
+    size_t exidx_size;
+    if (tid < 0) {
+        exidx_start = dl_unwind_find_exidx(pc, &exidx_size);
+    } else {
+        const map_info_t* mi = find_map_info(context->map_info_list, pc);
+        if (mi && mi->data) {
+            const map_info_data_t* data = (const map_info_data_t*)mi->data;
+            exidx_start = data->exidx_start;
+            exidx_size = data->exidx_size;
+        } else {
+            exidx_start = 0;
+            exidx_size = 0;
+        }
+    }
+
+    // The PC points to the instruction following the branch.
+    // We want to find the exception handler entry that corresponds to the branch itself,
+    // so we offset the PC backwards into the previous instruction.
+    // ARM instructions are 4 bytes, Thumb are 2, so we just subtract two so we either
+    // end up in the middle (ARM) or at the beginning of the instruction (Thumb).
+    if (pc >= 2) {
+        pc -= 2;
+    }
+
+    uint32_t handler = 0;
+    if (exidx_start) {
+        uint32_t low = 0;
+        uint32_t high = exidx_size;
+        while (low < high) {
+            uint32_t index = (low + high) / 2;
+            uintptr_t entry = exidx_start + index * 8;
+            uint32_t entry_prel_pc;
+            if (!try_get_word(tid, entry, &entry_prel_pc)) {
+                break;
+            }
+            uintptr_t entry_pc = prel_to_absolute(entry, entry_prel_pc);
+            if (pc < entry_pc) {
+                high = index;
+                continue;
+            }
+            if (index + 1 < exidx_size) {
+                uintptr_t next_entry = entry + 8;
+                uint32_t next_entry_prel_pc;
+                if (!try_get_word(tid, next_entry, &next_entry_prel_pc)) {
+                    break;
+                }
+                uintptr_t next_entry_pc = prel_to_absolute(next_entry, next_entry_prel_pc);
+                if (pc >= next_entry_pc) {
+                    low = index + 1;
+                    continue;
+                }
+            }
+
+            uintptr_t entry_handler_ptr = entry + 4;
+            uint32_t entry_handler;
+            if (!try_get_word(tid, entry_handler_ptr, &entry_handler)) {
+                break;
+            }
+            if (entry_handler & (1L << 31)) {
+                handler = entry_handler_ptr; // in-place handler data
+            } else if (entry_handler != EXIDX_CANTUNWIND) {
+                handler = prel_to_absolute(entry_handler_ptr, entry_handler);
+            }
+            break;
+        }
+    }
+    LOGV("get handler: pc=0x%08x, exidx_start=0x%08x, exidx_size=%d, handler=0x%08x",
+            pc, exidx_start, exidx_size, handler);
+    return handler;
+}
+
+typedef struct {
+    uintptr_t ptr;
+    uint32_t word;
+} byte_stream_t;
+
+static bool try_next_byte(pid_t tid, byte_stream_t* stream, uint8_t* out_value) {
+    uint8_t result;
+    switch (stream->ptr & 3) {
+    case 0:
+        if (!try_get_word(tid, stream->ptr, &stream->word)) {
+            *out_value = 0;
+            return false;
+        }
+        *out_value = stream->word >> 24;
+        break;
+
+    case 1:
+        *out_value = stream->word >> 16;
+        break;
+
+    case 2:
+        *out_value = stream->word >> 8;
+        break;
+
+    default:
+        *out_value = stream->word;
+        break;
+    }
+
+    LOGV("next_byte: ptr=0x%08x, value=0x%02x", stream->ptr, *out_value);
+    stream->ptr += 1;
+    return true;
+}
+
+static void set_reg(unwind_state_t* state, uint32_t reg, uint32_t value) {
+    LOGV("set_reg: reg=%d, value=0x%08x", reg, value);
+    state->gregs[reg] = value;
+}
+
+static bool try_pop_registers(pid_t tid, unwind_state_t* state, uint32_t mask) {
+    uint32_t sp = state->gregs[R_SP];
+    bool sp_updated = false;
+    for (int i = 0; i < 16; i++) {
+        if (mask & (1 << i)) {
+            uint32_t value;
+            if (!try_get_word(tid, sp, &value)) {
+                return false;
+            }
+            if (i == R_SP) {
+                sp_updated = true;
+            }
+            set_reg(state, i, value);
+            sp += 4;
+        }
+    }
+    if (!sp_updated) {
+        set_reg(state, R_SP, sp);
+    }
+    return true;
+}
+
+/* Executes a built-in personality routine as defined in the EHABI.
+ * Returns true if unwinding should continue.
+ *
+ * The data for the built-in personality routines consists of a sequence
+ * of unwinding instructions, followed by a sequence of scope descriptors,
+ * each of which has a length and offset encoded using 16-bit or 32-bit
+ * values.
+ *
+ * We only care about the unwinding instructions.  They specify the
+ * operations of an abstract machine whose purpose is to transform the
+ * virtual register state (including the stack pointer) such that
+ * the call frame is unwound and the PC register points to the call site.
+ */
+static bool execute_personality_routine(pid_t tid, unwind_state_t* state,
+        byte_stream_t* stream, int pr_index) {
+    size_t size;
+    switch (pr_index) {
+    case 0: // Personality routine #0, short frame, descriptors have 16-bit scope.
+        size = 3;
+        break;
+    case 1: // Personality routine #1, long frame, descriptors have 16-bit scope.
+    case 2: { // Personality routine #2, long frame, descriptors have 32-bit scope.
+        uint8_t size_byte;
+        if (!try_next_byte(tid, stream, &size_byte)) {
+            return false;
+        }
+        size = (uint32_t)size_byte * sizeof(uint32_t) + 2;
+        break;
+    }
+    default: // Unknown personality routine.  Stop here.
+        return false;
+    }
+
+    bool pc_was_set = false;
+    while (size--) {
+        uint8_t op;
+        if (!try_next_byte(tid, stream, &op)) {
+            return false;
+        }
+        if ((op & 0xc0) == 0x00) {
+            // "vsp = vsp + (xxxxxx << 2) + 4"
+            set_reg(state, R_SP, state->gregs[R_SP] + ((op & 0x3f) << 2) + 4);
+        } else if ((op & 0xc0) == 0x40) {
+            // "vsp = vsp - (xxxxxx << 2) - 4"
+            set_reg(state, R_SP, state->gregs[R_SP] - ((op & 0x3f) << 2) - 4);
+        } else if ((op & 0xf0) == 0x80) {
+            uint8_t op2;
+            if (!(size--) || !try_next_byte(tid, stream, &op2)) {
+                return false;
+            }
+            uint32_t mask = (((uint32_t)op & 0x0f) << 12) | ((uint32_t)op2 << 4);
+            if (mask) {
+                // "Pop up to 12 integer registers under masks {r15-r12}, {r11-r4}"
+                if (!try_pop_registers(tid, state, mask)) {
+                    return false;
+                }
+                if (mask & (1 << R_PC)) {
+                    pc_was_set = true;
+                }
+            } else {
+                // "Refuse to unwind"
+                return false;
+            }
+        } else if ((op & 0xf0) == 0x90) {
+            if (op != 0x9d && op != 0x9f) {
+                // "Set vsp = r[nnnn]"
+                set_reg(state, R_SP, state->gregs[op & 0x0f]);
+            } else {
+                // "Reserved as prefix for ARM register to register moves"
+                // "Reserved as prefix for Intel Wireless MMX register to register moves"
+                return false;
+            }
+        } else if ((op & 0xf8) == 0xa0) {
+            // "Pop r4-r[4+nnn]"
+            uint32_t mask = (0x0ff0 >> (7 - (op & 0x07))) & 0x0ff0;
+            if (!try_pop_registers(tid, state, mask)) {
+                return false;
+            }
+        } else if ((op & 0xf8) == 0xa8) {
+            // "Pop r4-r[4+nnn], r14"
+            uint32_t mask = ((0x0ff0 >> (7 - (op & 0x07))) & 0x0ff0) | 0x4000;
+            if (!try_pop_registers(tid, state, mask)) {
+                return false;
+            }
+        } else if (op == 0xb0) {
+            // "Finish"
+            break;
+        } else if (op == 0xb1) {
+            uint8_t op2;
+            if (!(size--) || !try_next_byte(tid, stream, &op2)) {
+                return false;
+            }
+            if (op2 != 0x00 && (op2 & 0xf0) == 0x00) {
+                // "Pop integer registers under mask {r3, r2, r1, r0}"
+                if (!try_pop_registers(tid, state, op2)) {
+                    return false;
+                }
+            } else {
+                // "Spare"
+                return false;
+            }
+        } else if (op == 0xb2) {
+            // "vsp = vsp + 0x204 + (uleb128 << 2)"
+            uint32_t value = 0;
+            uint32_t shift = 0;
+            uint8_t op2;
+            do {
+                if (!(size--) || !try_next_byte(tid, stream, &op2)) {
+                    return false;
+                }
+                value |= (op2 & 0x7f) << shift;
+                shift += 7;
+            } while (op2 & 0x80);
+            set_reg(state, R_SP, state->gregs[R_SP] + (value << 2) + 0x204);
+        } else if (op == 0xb3) {
+            // "Pop VFP double-precision registers D[ssss]-D[ssss+cccc] saved (as if) by FSTMFDX"
+            uint8_t op2;
+            if (!(size--) || !try_next_byte(tid, stream, &op2)) {
+                return false;
+            }
+            set_reg(state, R_SP, state->gregs[R_SP] + (uint32_t)(op2 & 0x0f) * 8 + 12);
+        } else if ((op & 0xf8) == 0xb8) {
+            // "Pop VFP double-precision registers D[8]-D[8+nnn] saved (as if) by FSTMFDX"
+            set_reg(state, R_SP, state->gregs[R_SP] + (uint32_t)(op & 0x07) * 8 + 12);
+        } else if ((op & 0xf8) == 0xc0) {
+            // "Intel Wireless MMX pop wR[10]-wR[10+nnn]"
+            set_reg(state, R_SP, state->gregs[R_SP] + (uint32_t)(op & 0x07) * 8 + 8);
+        } else if (op == 0xc6) {
+            // "Intel Wireless MMX pop wR[ssss]-wR[ssss+cccc]"
+            uint8_t op2;
+            if (!(size--) || !try_next_byte(tid, stream, &op2)) {
+                return false;
+            }
+            set_reg(state, R_SP, state->gregs[R_SP] + (uint32_t)(op2 & 0x0f) * 8 + 8);
+        } else if (op == 0xc7) {
+            uint8_t op2;
+            if (!(size--) || !try_next_byte(tid, stream, &op2)) {
+                return false;
+            }
+            if (op2 != 0x00 && (op2 & 0xf0) == 0x00) {
+                // "Intel Wireless MMX pop wCGR registers under mask {wCGR3,2,1,0}"
+                set_reg(state, R_SP, state->gregs[R_SP] + __builtin_popcount(op2) * 4);
+            } else {
+                // "Spare"
+                return false;
+            }
+        } else if (op == 0xc8) {
+            // "Pop VFP double precision registers D[16+ssss]-D[16+ssss+cccc]
+            // saved (as if) by FSTMFD"
+            uint8_t op2;
+            if (!(size--) || !try_next_byte(tid, stream, &op2)) {
+                return false;
+            }
+            set_reg(state, R_SP, state->gregs[R_SP] + (uint32_t)(op2 & 0x0f) * 8 + 8);
+        } else if (op == 0xc9) {
+            // "Pop VFP double precision registers D[ssss]-D[ssss+cccc] saved (as if) by FSTMFDD"
+            uint8_t op2;
+            if (!(size--) || !try_next_byte(tid, stream, &op2)) {
+                return false;
+            }
+            set_reg(state, R_SP, state->gregs[R_SP] + (uint32_t)(op2 & 0x0f) * 8 + 8);
+        } else if ((op == 0xf8) == 0xd0) {
+            // "Pop VFP double-precision registers D[8]-D[8+nnn] saved (as if) by FSTMFDD"
+            set_reg(state, R_SP, state->gregs[R_SP] + (uint32_t)(op & 0x07) * 8 + 8);
+        } else {
+            // "Spare"
+            return false;
+        }
+    }
+    if (!pc_was_set) {
+        set_reg(state, R_PC, state->gregs[R_LR]);
+    }
+    return true;
+}
+
+static ssize_t unwind_backtrace_common(pid_t tid, const ptrace_context_t* context,
+        unwind_state_t* state, backtrace_frame_t* backtrace,
+        size_t ignore_depth, size_t max_depth) {
+    size_t ignored_frames = 0;
+    size_t returned_frames = 0;
+
+    uintptr_t handler = get_exception_handler(context, tid, state->gregs[R_PC]);
+    if (!handler) {
+        // If there is no handler for the PC, the program may have branched to
+        // an invalid address.  Check whether we have a handler for the LR
+        // where we came from and use that instead.
+        backtrace_frame_t* frame = add_backtrace_entry(state->gregs[R_PC], backtrace,
+                ignore_depth, max_depth, &ignored_frames, &returned_frames);
+        if (frame) {
+            frame->stack_top = state->gregs[R_SP];
+        }
+
+        handler = get_exception_handler(context, tid, state->gregs[R_LR]);
+        if (!handler) {
+            // We don't have a handler here either.  Unwinding will not be possible.
+            // Return the PC and LR (if it looks sane) and call it good.
+            if (state->gregs[R_LR] && state->gregs[R_LR] != state->gregs[R_PC]) {
+                // Don't return the SP for this second frame because we don't
+                // know how big the first one is so we don't know where this
+                // one starts.
+                frame = add_backtrace_entry(state->gregs[R_LR], backtrace,
+                        ignore_depth, max_depth, &ignored_frames, &returned_frames);
+            }
+            return returned_frames;
+        }
+
+        // Ok, continue from the LR.
+        set_reg(state, R_PC, state->gregs[R_LR]);
+    }
+
+    while (handler && returned_frames < max_depth) {
+        backtrace_frame_t* frame = add_backtrace_entry(state->gregs[R_PC], backtrace,
+                ignore_depth, max_depth, &ignored_frames, &returned_frames);
+        if (frame) {
+            frame->stack_top = state->gregs[R_SP];
+        }
+
+        byte_stream_t stream;
+        stream.ptr = handler;
+        uint8_t pr;
+        if (!try_next_byte(tid, &stream, &pr)) {
+            break;
+        }
+        if ((pr & 0xf0) != 0x80) {
+            // The first word is a place-relative pointer to a generic personality
+            // routine function.  We don't support invoking such functions, so stop here.
+            break;
+        }
+
+        // The first byte indicates the personality routine to execute.
+        // Following bytes provide instructions to the personality routine.
+        if (!execute_personality_routine(tid, state, &stream, pr & 0x0f)) {
+            break;
+        }
+        if (frame && state->gregs[R_SP] > frame->stack_top) {
+            frame->stack_size = state->gregs[R_SP] - frame->stack_top;
+        }
+
+        handler = get_exception_handler(context, tid, state->gregs[R_PC]);
+    }
+    return returned_frames;
+}
+
+ssize_t unwind_backtrace_signal_arch(siginfo_t* siginfo, void* sigcontext,
+        backtrace_frame_t* backtrace, size_t ignore_depth, size_t max_depth) {
+    const ucontext_t* uc = (const ucontext_t*)sigcontext;
+
+    unwind_state_t state;
+    for (int i = 0; i < 16; i++) {
+        state.gregs[i] = uc->uc_mcontext.gregs[i];
+    }
+
+    return unwind_backtrace_common(-1, NULL, &state, backtrace, ignore_depth, max_depth);
+}
+
+ssize_t unwind_backtrace_ptrace_arch(pid_t tid, const ptrace_context_t* context,
+        backtrace_frame_t* backtrace, size_t ignore_depth, size_t max_depth) {
+    struct pt_regs regs;
+    if (ptrace(PTRACE_GETREGS, tid, 0, &regs)) {
+        return -1;
+    }
+
+    unwind_state_t state;
+    for (int i = 0; i < 16; i++) {
+        state.gregs[i] = regs.uregs[i];
+    }
+
+    return unwind_backtrace_common(tid, context, &state, backtrace, ignore_depth, max_depth);
+}
diff --git a/libcorkscrew/arch-arm/ptrace-arm.c b/libcorkscrew/arch-arm/ptrace-arm.c
new file mode 100644
index 000000000..fd155056f
--- /dev/null
+++ b/libcorkscrew/arch-arm/ptrace-arm.c
@@ -0,0 +1,65 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "Corkscrew"
+//#define LOG_NDEBUG 0
+
+#include "../ptrace-arch.h"
+
+#include <sys/exec_elf.h>
+#include <cutils/log.h>
+
+#ifndef PT_ARM_EXIDX
+#define PT_ARM_EXIDX 0x70000001
+#endif
+
+static void load_exidx_header(pid_t pid, map_info_t* mi,
+        uintptr_t* out_exidx_start, size_t* out_exidx_size) {
+    uint32_t elf_phoff;
+    uint32_t elf_phnum;
+    if (try_get_word(pid, mi->start + offsetof(Elf32_Ehdr, e_phoff), &elf_phoff)
+            && try_get_word(pid, mi->start + offsetof(Elf32_Ehdr, e_phnum), &elf_phnum)) {
+        for (uint32_t i = 0; i < elf_phnum; i++) {
+            uintptr_t elf_phdr = mi->start + elf_phoff + i * sizeof(Elf32_Phdr);
+            uint32_t elf_phdr_type;
+            if (!try_get_word(pid, elf_phdr + offsetof(Elf32_Phdr, p_type), &elf_phdr_type)) {
+                break;
+            }
+            if (elf_phdr_type == PT_ARM_EXIDX) {
+                uint32_t elf_phdr_offset;
+                uint32_t elf_phdr_filesz;
+                if (!try_get_word(pid, elf_phdr + offsetof(Elf32_Phdr, p_offset),
+                        &elf_phdr_offset)
+                        || !try_get_word(pid, elf_phdr + offsetof(Elf32_Phdr, p_filesz),
+                                &elf_phdr_filesz)) {
+                    break;
+                }
+                *out_exidx_start = mi->start + elf_phdr_offset;
+                *out_exidx_size = elf_phdr_filesz;
+                return;
+            }
+        }
+    }
+    *out_exidx_start = 0;
+    *out_exidx_size = 0;
+}
+
+void load_ptrace_map_info_data_arch(pid_t pid, map_info_t* mi, map_info_data_t* data) {
+    load_exidx_header(pid, mi, &data->exidx_start, &data->exidx_size);
+}
+
+void free_ptrace_map_info_data_arch(map_info_t* mi, map_info_data_t* data) {
+}
diff --git a/libcorkscrew/backtrace-arch.h b/libcorkscrew/backtrace-arch.h
new file mode 100644
index 000000000..80bca2bbb
--- /dev/null
+++ b/libcorkscrew/backtrace-arch.h
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* Architecture dependent functions. */
+
+#ifndef _CORKSCREW_BACKTRACE_ARCH_H
+#define _CORKSCREW_BACKTRACE_ARCH_H
+
+#include "ptrace-arch.h"
+#include <corkscrew/backtrace.h>
+
+#include <signal.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+ssize_t unwind_backtrace_signal_arch(siginfo_t* siginfo, void* sigcontext,
+        backtrace_frame_t* backtrace, size_t ignore_depth, size_t max_depth);
+
+ssize_t unwind_backtrace_ptrace_arch(pid_t tid, const ptrace_context_t* context,
+        backtrace_frame_t* backtrace, size_t ignore_depth, size_t max_depth);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // _CORKSCREW_BACKTRACE_ARCH_H
diff --git a/libcorkscrew/backtrace-helper.c b/libcorkscrew/backtrace-helper.c
new file mode 100644
index 000000000..bf9d3f3dd
--- /dev/null
+++ b/libcorkscrew/backtrace-helper.c
@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "Corkscrew"
+//#define LOG_NDEBUG 0
+
+#include "backtrace-helper.h"
+
+#include <cutils/log.h>
+
+backtrace_frame_t* add_backtrace_entry(uintptr_t pc, backtrace_frame_t* backtrace,
+        size_t ignore_depth, size_t max_depth,
+        size_t* ignored_frames, size_t* returned_frames) {
+    if (*ignored_frames < ignore_depth) {
+        *ignored_frames += 1;
+        return NULL;
+    }
+    if (*returned_frames >= max_depth) {
+        return NULL;
+    }
+    backtrace_frame_t* frame = &backtrace[*returned_frames];
+    frame->absolute_pc = pc;
+    frame->stack_top = 0;
+    frame->stack_size = 0;
+    *returned_frames += 1;
+    return frame;
+}
diff --git a/libcorkscrew/backtrace-helper.h b/libcorkscrew/backtrace-helper.h
new file mode 100644
index 000000000..4d8a87403
--- /dev/null
+++ b/libcorkscrew/backtrace-helper.h
@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* Backtrace helper functions. */
+
+#ifndef _CORKSCREW_BACKTRACE_HELPER_H
+#define _CORKSCREW_BACKTRACE_HELPER_H
+
+#include <corkscrew/backtrace.h>
+#include <sys/types.h>
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * Add a program counter to a backtrace if it will fit.
+ * Returns the newly added frame, or NULL if none.
+ */
+backtrace_frame_t* add_backtrace_entry(uintptr_t pc,
+        backtrace_frame_t* backtrace,
+        size_t ignore_depth, size_t max_depth,
+        size_t* ignored_frames, size_t* returned_frames);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // _CORKSCREW_BACKTRACE_HELPER_H
diff --git a/libcorkscrew/backtrace.c b/libcorkscrew/backtrace.c
new file mode 100644
index 000000000..b03c43fb3
--- /dev/null
+++ b/libcorkscrew/backtrace.c
@@ -0,0 +1,205 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "Corkscrew"
+//#define LOG_NDEBUG 0
+
+#include "backtrace-arch.h"
+#include "backtrace-helper.h"
+#include "ptrace-arch.h"
+#include <corkscrew/map_info.h>
+#include <corkscrew/symbol_table.h>
+#include <corkscrew/ptrace.h>
+#include <corkscrew/demangle.h>
+
+#include <unistd.h>
+#include <signal.h>
+#include <pthread.h>
+#include <unwind.h>
+#include <sys/exec_elf.h>
+#include <cutils/log.h>
+
+#if HAVE_DLADDR
+#include <dlfcn.h>
+#endif
+
+typedef struct {
+    backtrace_frame_t* backtrace;
+    size_t ignore_depth;
+    size_t max_depth;
+    size_t ignored_frames;
+    size_t returned_frames;
+} backtrace_state_t;
+
+static _Unwind_Reason_Code unwind_backtrace_callback(struct _Unwind_Context* context, void* arg) {
+    backtrace_state_t* state = (backtrace_state_t*)arg;
+    uintptr_t pc = _Unwind_GetIP(context);
+    if (pc) {
+        // TODO: Get information about the stack layout from the _Unwind_Context.
+        //       This will require a new architecture-specific function to query
+        //       the appropriate registers.  Current callers of unwind_backtrace
+        //       don't need this information, so we won't bother collecting it just yet.
+        add_backtrace_entry(pc, state->backtrace,
+                state->ignore_depth, state->max_depth,
+                &state->ignored_frames, &state->returned_frames);
+    }
+    return state->returned_frames < state->max_depth ? _URC_NO_REASON : _URC_END_OF_STACK;
+}
+
+ssize_t unwind_backtrace(backtrace_frame_t* backtrace, size_t ignore_depth, size_t max_depth) {
+    backtrace_state_t state;
+    state.backtrace = backtrace;
+    state.ignore_depth = ignore_depth;
+    state.max_depth = max_depth;
+    state.ignored_frames = 0;
+    state.returned_frames = 0;
+
+    _Unwind_Reason_Code rc =_Unwind_Backtrace(unwind_backtrace_callback, &state);
+    if (state.returned_frames) {
+        return state.returned_frames;
+    }
+    return rc == _URC_END_OF_STACK ? 0 : -1;
+}
+
+#ifdef CORKSCREW_HAVE_ARCH
+static pthread_mutex_t g_unwind_signal_mutex = PTHREAD_MUTEX_INITIALIZER;
+static volatile struct {
+    backtrace_frame_t* backtrace;
+    size_t ignore_depth;
+    size_t max_depth;
+    size_t returned_frames;
+    bool done;
+} g_unwind_signal_state;
+
+static void unwind_backtrace_thread_signal_handler(int n, siginfo_t* siginfo, void* sigcontext) {
+    backtrace_frame_t* backtrace = g_unwind_signal_state.backtrace;
+    if (backtrace) {
+        g_unwind_signal_state.backtrace = NULL;
+        g_unwind_signal_state.returned_frames = unwind_backtrace_signal_arch(
+                siginfo, sigcontext, backtrace,
+                g_unwind_signal_state.ignore_depth,
+                g_unwind_signal_state.max_depth);
+        g_unwind_signal_state.done = true;
+    }
+}
+#endif
+
+ssize_t unwind_backtrace_thread(pid_t tid, backtrace_frame_t* backtrace,
+        size_t ignore_depth, size_t max_depth) {
+#ifdef CORKSCREW_HAVE_ARCH
+    struct sigaction act;
+    struct sigaction oact;
+    memset(&act, 0, sizeof(act));
+    act.sa_sigaction = unwind_backtrace_thread_signal_handler;
+    act.sa_flags = SA_RESTART | SA_SIGINFO;
+    sigemptyset(&act.sa_mask);
+
+    pthread_mutex_lock(&g_unwind_signal_mutex);
+
+    g_unwind_signal_state.backtrace = backtrace;
+    g_unwind_signal_state.ignore_depth = ignore_depth;
+    g_unwind_signal_state.max_depth = max_depth;
+    g_unwind_signal_state.returned_frames = 0;
+    g_unwind_signal_state.done = false;
+
+    ssize_t frames = -1;
+    if (!sigaction(SIGURG, &act, &oact)) {
+        if (!kill(tid, SIGURG)) {
+            while (!g_unwind_signal_state.done) {
+                usleep(1000);
+            }
+            frames = g_unwind_signal_state.returned_frames;
+        }
+        sigaction(SIGURG, &oact, NULL);
+    }
+
+    g_unwind_signal_state.backtrace = NULL;
+
+    pthread_mutex_unlock(&g_unwind_signal_mutex);
+    return frames;
+#else
+    return -1;
+#endif
+}
+
+ssize_t unwind_backtrace_ptrace(pid_t tid, const ptrace_context_t* context,
+        backtrace_frame_t* backtrace, size_t ignore_depth, size_t max_depth) {
+#ifdef CORKSCREW_HAVE_ARCH
+    return unwind_backtrace_ptrace_arch(tid, context, backtrace, ignore_depth, max_depth);
+#else
+    return -1;
+#endif
+}
+
+static void init_backtrace_symbol(backtrace_symbol_t* symbol, uintptr_t pc) {
+    symbol->relative_pc = pc;
+    symbol->map_info = NULL;
+    symbol->name = NULL;
+    symbol->demangled_name = NULL;
+}
+
+void get_backtrace_symbols(const backtrace_frame_t* backtrace, size_t frames,
+        backtrace_symbol_t* backtrace_symbols) {
+    const map_info_t* milist = my_map_info_list();
+    for (size_t i = 0; i < frames; i++) {
+        const backtrace_frame_t* frame = &backtrace[i];
+        backtrace_symbol_t* symbol = &backtrace_symbols[i];
+        init_backtrace_symbol(symbol, frame->absolute_pc);
+
+        const map_info_t* mi = find_map_info(milist, frame->absolute_pc);
+        if (mi) {
+            symbol->relative_pc = frame->absolute_pc - mi->start;
+            symbol->map_info = mi;
+#if HAVE_DLADDR
+            Dl_info info;
+            if (dladdr((const void*)frame->absolute_pc, &info) && info.dli_sname) {
+                symbol->name = info.dli_sname;
+                symbol->demangled_name = demangle_symbol_name(symbol->name);
+            }
+#endif
+        }
+    }
+}
+
+void get_backtrace_symbols_ptrace(const ptrace_context_t* context,
+        const backtrace_frame_t* backtrace, size_t frames,
+        backtrace_symbol_t* backtrace_symbols) {
+    for (size_t i = 0; i < frames; i++) {
+        const backtrace_frame_t* frame = &backtrace[i];
+        backtrace_symbol_t* symbol = &backtrace_symbols[i];
+        init_backtrace_symbol(symbol, frame->absolute_pc);
+
+        const map_info_t* mi;
+        const symbol_t* s;
+        find_symbol_ptrace(context, frame->absolute_pc, &mi, &s);
+        if (mi) {
+            symbol->relative_pc = frame->absolute_pc - mi->start;
+            symbol->map_info = mi;
+        }
+        if (s) {
+            symbol->name = s->name;
+            symbol->demangled_name = demangle_symbol_name(symbol->name);
+        }
+    }
+}
+
+void free_backtrace_symbols(backtrace_symbol_t* backtrace_symbols, size_t frames) {
+    for (size_t i = 0; i < frames; i++) {
+        backtrace_symbol_t* symbol = &backtrace_symbols[i];
+        free(symbol->demangled_name);
+        init_backtrace_symbol(symbol, 0);
+    }
+}
diff --git a/libcorkscrew/demangle.c b/libcorkscrew/demangle.c
new file mode 100644
index 000000000..ecb2c98c9
--- /dev/null
+++ b/libcorkscrew/demangle.c
@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "Corkscrew"
+//#define LOG_NDEBUG 0
+
+#include <corkscrew/demangle.h>
+
+#include <cutils/log.h>
+
+#ifdef CORKSCREW_HAVE_LIBIBERTY
+// Defined in libiberty.a
+extern char *cplus_demangle(const char *mangled, int options);
+#endif
+
+char* demangle_symbol_name(const char* name) {
+#ifdef CORKSCREW_HAVE_LIBIBERTY
+    return name ? cplus_demangle(name, 0) : NULL;
+#else
+    return NULL;
+#endif
+}
diff --git a/libcorkscrew/map_info.c b/libcorkscrew/map_info.c
new file mode 100644
index 000000000..60ed9b43d
--- /dev/null
+++ b/libcorkscrew/map_info.c
@@ -0,0 +1,112 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "Corkscrew"
+//#define LOG_NDEBUG 0
+
+#include <corkscrew/map_info.h>
+
+#include <ctype.h>
+#include <stdio.h>
+#include <string.h>
+#include <limits.h>
+#include <pthread.h>
+#include <unistd.h>
+#include <cutils/log.h>
+
+// 6f000000-6f01e000 rwxp 00000000 00:0c 16389419   /system/lib/libcomposer.so\n
+// 012345678901234567890123456789012345678901234567890123456789
+// 0         1         2         3         4         5
+static map_info_t* parse_maps_line(const char* line)
+{
+    unsigned long int start;
+    unsigned long int end;
+    char permissions[5];
+    int name_pos;
+    if (sscanf(line, "%lx-%lx %4s %*x %*x:%*x %*d%n", &start, &end,
+            permissions, &name_pos) != 3) {
+        return NULL;
+    }
+
+    while (isspace(line[name_pos])) {
+        name_pos += 1;
+    }
+    const char* name = line + name_pos;
+    size_t name_len = strlen(name);
+    if (name_len && name[name_len - 1] == '\n') {
+        name_len -= 1;
+    }
+
+    map_info_t* mi = calloc(1, sizeof(map_info_t) + name_len + 1);
+    if (mi) {
+        mi->start = start;
+        mi->end = end;
+        mi->is_executable = strlen(permissions) == 4 && permissions[2] == 'x';
+        mi->data = NULL;
+        memcpy(mi->name, name, name_len);
+        mi->name[name_len] = '\0';
+    }
+    return mi;
+}
+
+map_info_t* load_map_info_list(pid_t tid) {
+    char path[PATH_MAX];
+    char line[1024];
+    FILE* fp;
+    map_info_t* milist = NULL;
+
+    snprintf(path, PATH_MAX, "/proc/%d/maps", tid);
+    fp = fopen(path, "r");
+    if (fp) {
+        while(fgets(line, sizeof(line), fp)) {
+            map_info_t* mi = parse_maps_line(line);
+            if (mi) {
+                mi->next = milist;
+                milist = mi;
+            }
+        }
+        fclose(fp);
+    }
+    return milist;
+}
+
+void free_map_info_list(map_info_t* milist) {
+    while (milist) {
+        map_info_t* next = milist->next;
+        free(milist);
+        milist = next;
+    }
+}
+
+const map_info_t* find_map_info(const map_info_t* milist, uintptr_t addr) {
+    const map_info_t* mi = milist;
+    while (mi && !(addr >= mi->start && addr < mi->end)) {
+        mi = mi->next;
+    }
+    return mi;
+}
+
+static pthread_once_t g_my_milist_once = PTHREAD_ONCE_INIT;
+static map_info_t* g_my_milist = NULL;
+
+static void init_my_milist_once() {
+    g_my_milist = load_map_info_list(getpid());
+}
+
+const map_info_t* my_map_info_list() {
+    pthread_once(&g_my_milist_once, init_my_milist_once);
+    return g_my_milist;
+}
diff --git a/libcorkscrew/ptrace-arch.h b/libcorkscrew/ptrace-arch.h
new file mode 100644
index 000000000..c02df52bc
--- /dev/null
+++ b/libcorkscrew/ptrace-arch.h
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* Architecture dependent functions. */
+
+#ifndef _CORKSCREW_PTRACE_ARCH_H
+#define _CORKSCREW_PTRACE_ARCH_H
+
+#include <corkscrew/ptrace.h>
+#include <corkscrew/map_info.h>
+#include <corkscrew/symbol_table.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Custom extra data we stuff into map_info_t structures as part
+ * of our ptrace_context_t. */
+typedef struct {
+#ifdef __arm__
+    uintptr_t exidx_start;
+    size_t exidx_size;
+#endif
+    symbol_table_t* symbol_table;
+} map_info_data_t;
+
+void load_ptrace_map_info_data_arch(pid_t pid, map_info_t* mi, map_info_data_t* data);
+void free_ptrace_map_info_data_arch(map_info_t* mi, map_info_data_t* data);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // _CORKSCREW_PTRACE_ARCH_H
diff --git a/libcorkscrew/ptrace.c b/libcorkscrew/ptrace.c
new file mode 100644
index 000000000..6ed77c45b
--- /dev/null
+++ b/libcorkscrew/ptrace.c
@@ -0,0 +1,134 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "Corkscrew"
+//#define LOG_NDEBUG 0
+
+#include "ptrace-arch.h"
+#include <corkscrew/ptrace.h>
+
+#include <errno.h>
+#include <sys/ptrace.h>
+#include <cutils/log.h>
+
+static const uint32_t ELF_MAGIC = 0x464C457f; // "ELF\0177"
+
+#ifndef PAGE_SIZE
+#define PAGE_SIZE 4096
+#endif
+
+#ifndef PAGE_MASK
+#define PAGE_MASK (~(PAGE_SIZE - 1))
+#endif
+
+bool try_get_word(pid_t tid, uintptr_t ptr, uint32_t* out_value) {
+    if (ptr & 3) {
+        LOGV("try_get_word: invalid pointer 0x%08x", ptr);
+        *out_value = 0;
+        return false;
+    }
+    if (tid < 0) {
+#if 0 /*unreliable, unclear whether this is safe from a signal handler context*/
+        // Determine whether the pointer is likely to be valid before dereferencing it.
+        unsigned char vec[1];
+        while (mincore((void*)(ptr & PAGE_MASK), sizeof(uint32_t), vec)) {
+            if (errno != EAGAIN && errno != EINTR) {
+                LOGV("try_get_word: invalid pointer 0x%08x, mincore() errno=%d", ptr, errno);
+                *out_value = 0;
+                return false;
+            }
+        }
+#endif
+        *out_value = *(uint32_t*)ptr;
+        return true;
+    } else {
+        // ptrace() returns -1 and sets errno when the operation fails.
+        // To disambiguate -1 from a valid result, we clear errno beforehand.
+        errno = 0;
+        *out_value = ptrace(PTRACE_PEEKTEXT, tid, (void*)ptr, NULL);
+        if (*out_value == 0xffffffffL && errno) {
+            LOGV("try_get_word: invalid pointer 0x%08x, ptrace() errno=%d", ptr, errno);
+            *out_value = 0;
+            return false;
+        }
+        return true;
+    }
+}
+
+static void load_ptrace_map_info_data(pid_t pid, map_info_t* mi) {
+    if (mi->is_executable) {
+        uint32_t elf_magic;
+        if (try_get_word(pid, mi->start, &elf_magic) && elf_magic == ELF_MAGIC) {
+            map_info_data_t* data = (map_info_data_t*)calloc(1, sizeof(map_info_data_t));
+            if (data) {
+                mi->data = data;
+                if (mi->name[0]) {
+                    data->symbol_table = load_symbol_table(mi->name);
+                }
+#ifdef CORKSCREW_HAVE_ARCH
+                load_ptrace_map_info_data_arch(pid, mi, data);
+#endif
+            }
+        }
+    }
+}
+
+ptrace_context_t* load_ptrace_context(pid_t pid) {
+    ptrace_context_t* context =
+            (ptrace_context_t*)calloc(1, sizeof(ptrace_context_t));
+    if (context) {
+        context->map_info_list = load_map_info_list(pid);
+        for (map_info_t* mi = context->map_info_list; mi; mi = mi->next) {
+            load_ptrace_map_info_data(pid, mi);
+        }
+    }
+    return context;
+}
+
+static void free_ptrace_map_info_data(map_info_t* mi) {
+    map_info_data_t* data = (map_info_data_t*)mi->data;
+    if (data) {
+        if (data->symbol_table) {
+            free_symbol_table(data->symbol_table);
+        }
+#ifdef CORKSCREW_HAVE_ARCH
+        free_ptrace_map_info_data_arch(mi, data);
+#endif
+        free(data);
+        mi->data = NULL;
+    }
+}
+
+void free_ptrace_context(ptrace_context_t* context) {
+    for (map_info_t* mi = context->map_info_list; mi; mi = mi->next) {
+        free_ptrace_map_info_data(mi);
+    }
+    free_map_info_list(context->map_info_list);
+}
+
+void find_symbol_ptrace(const ptrace_context_t* context,
+        uintptr_t addr, const map_info_t** out_map_info, const symbol_t** out_symbol) {
+    const map_info_t* mi = find_map_info(context->map_info_list, addr);
+    const symbol_t* symbol = NULL;
+    if (mi) {
+        const map_info_data_t* data = (const map_info_data_t*)mi->data;
+        if (data && data->symbol_table) {
+            symbol = find_symbol(data->symbol_table, addr - mi->start);
+        }
+    }
+    *out_map_info = mi;
+    *out_symbol = symbol;
+}
diff --git a/libcorkscrew/symbol_table.c b/libcorkscrew/symbol_table.c
new file mode 100644
index 000000000..8257c7737
--- /dev/null
+++ b/libcorkscrew/symbol_table.c
@@ -0,0 +1,204 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "Corkscrew"
+//#define LOG_NDEBUG 0
+
+#include <corkscrew/symbol_table.h>
+
+#include <stdlib.h>
+#include <fcntl.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include <sys/exec_elf.h>
+#include <cutils/log.h>
+
+// Compare function for qsort
+static int qcompar(const void *a, const void *b) {
+    const symbol_t* asym = (const symbol_t*)a;
+    const symbol_t* bsym = (const symbol_t*)b;
+    if (asym->start > bsym->start) return 1;
+    if (asym->start < bsym->start) return -1;
+    return 0;
+}
+
+// Compare function for bsearch
+static int bcompar(const void *key, const void *element) {
+    uintptr_t addr = *(const uintptr_t*)key;
+    const symbol_t* symbol = (const symbol_t*)element;
+    if (addr < symbol->start) return -1;
+    if (addr >= symbol->end) return 1;
+    return 0;
+}
+
+symbol_table_t* load_symbol_table(const char *filename) {
+    symbol_table_t* table = NULL;
+
+    int fd = open(filename, O_RDONLY);
+    if (fd < 0) {
+        goto out;
+    }
+
+    struct stat sb;
+    if (fstat(fd, &sb)) {
+        goto out_close;
+    }
+
+    size_t length = sb.st_size;
+    char* base = mmap(NULL, length, PROT_READ, MAP_PRIVATE, fd, 0);
+    if (base == MAP_FAILED) {
+        goto out_close;
+    }
+
+    // Parse the file header
+    Elf32_Ehdr *hdr = (Elf32_Ehdr*)base;
+    if (!IS_ELF(*hdr)) {
+        goto out_close;
+    }
+    Elf32_Shdr *shdr = (Elf32_Shdr*)(base + hdr->e_shoff);
+
+    // Search for the dynamic symbols section
+    int sym_idx = -1;
+    int dynsym_idx = -1;
+    for (Elf32_Half i = 0; i < hdr->e_shnum; i++) {
+        if (shdr[i].sh_type == SHT_SYMTAB) {
+            sym_idx = i;
+        }
+        if (shdr[i].sh_type == SHT_DYNSYM) {
+            dynsym_idx = i;
+        }
+    }
+    if (dynsym_idx == -1 && sym_idx == -1) {
+        goto out_unmap;
+    }
+
+    table = malloc(sizeof(symbol_table_t));
+    if(!table) {
+        goto out_unmap;
+    }
+    table->num_symbols = 0;
+
+    Elf32_Sym *dynsyms = NULL;
+    int dynnumsyms = 0;
+    char *dynstr = NULL;
+    if (dynsym_idx != -1) {
+        dynsyms = (Elf32_Sym*)(base + shdr[dynsym_idx].sh_offset);
+        dynnumsyms = shdr[dynsym_idx].sh_size / shdr[dynsym_idx].sh_entsize;
+        int dynstr_idx = shdr[dynsym_idx].sh_link;
+        dynstr = base + shdr[dynstr_idx].sh_offset;
+    }
+
+    Elf32_Sym *syms = NULL;
+    int numsyms = 0;
+    char *str = NULL;
+    if (sym_idx != -1) {
+        syms = (Elf32_Sym*)(base + shdr[sym_idx].sh_offset);
+        numsyms = shdr[sym_idx].sh_size / shdr[sym_idx].sh_entsize;
+        int str_idx = shdr[sym_idx].sh_link;
+        str = base + shdr[str_idx].sh_offset;
+    }
+
+    int dynsymbol_count = 0;
+    if (dynsym_idx != -1) {
+        // Iterate through the dynamic symbol table, and count how many symbols
+        // are actually defined
+        for (int i = 0; i < dynnumsyms; i++) {
+            if (dynsyms[i].st_shndx != SHN_UNDEF) {
+                dynsymbol_count++;
+            }
+        }
+    }
+
+    size_t symbol_count = 0;
+    if (sym_idx != -1) {
+        // Iterate through the symbol table, and count how many symbols
+        // are actually defined
+        for (int i = 0; i < numsyms; i++) {
+            if (syms[i].st_shndx != SHN_UNDEF
+                    && str[syms[i].st_name]
+                    && syms[i].st_value
+                    && syms[i].st_size) {
+                symbol_count++;
+            }
+        }
+    }
+
+    // Now, create an entry in our symbol table structure for each symbol...
+    table->num_symbols += symbol_count + dynsymbol_count;
+    table->symbols = malloc(table->num_symbols * sizeof(symbol_t));
+    if (!table->symbols) {
+        free(table);
+        table = NULL;
+        goto out_unmap;
+    }
+
+    size_t symbol_index = 0;
+    if (dynsym_idx != -1) {
+        // ...and populate them
+        for (int i = 0; i < dynnumsyms; i++) {
+            if (dynsyms[i].st_shndx != SHN_UNDEF) {
+                table->symbols[symbol_index].name = strdup(dynstr + dynsyms[i].st_name);
+                table->symbols[symbol_index].start = dynsyms[i].st_value;
+                table->symbols[symbol_index].end = dynsyms[i].st_value + dynsyms[i].st_size;
+                symbol_index += 1;
+            }
+        }
+    }
+
+    if (sym_idx != -1) {
+        // ...and populate them
+        for (int i = 0; i < numsyms; i++) {
+            if (syms[i].st_shndx != SHN_UNDEF
+                    && str[syms[i].st_name]
+                    && syms[i].st_value
+                    && syms[i].st_size) {
+                table->symbols[symbol_index].name = strdup(str + syms[i].st_name);
+                table->symbols[symbol_index].start = syms[i].st_value;
+                table->symbols[symbol_index].end = syms[i].st_value + syms[i].st_size;
+                symbol_index += 1;
+            }
+        }
+    }
+
+    // Sort the symbol table entries, so they can be bsearched later
+    qsort(table->symbols, table->num_symbols, sizeof(symbol_t), qcompar);
+
+out_unmap:
+    munmap(base, length);
+
+out_close:
+    close(fd);
+
+out:
+    return table;
+}
+
+void free_symbol_table(symbol_table_t* table) {
+    if (table) {
+        for (size_t i = 0; i < table->num_symbols; i++) {
+            free(table->symbols[i].name);
+        }
+        free(table->symbols);
+        free(table);
+    }
+}
+
+const symbol_t* find_symbol(const symbol_table_t* table, uintptr_t addr) {
+    if (!table) return NULL;
+    return (const symbol_t*)bsearch(&addr, table->symbols, table->num_symbols,
+            sizeof(symbol_t), bcompar);
+}