Update debuggerd to use libbacktrace.

Remove all of the code in debuggerd that uses libcorkscrew directly
and replace with libbacktrace.

Also do a bit of refactoring to clean up some functions that were
passing around variables that weren't used.

Bug: 8410085

Change-Id: I27da4fbe3f12ce38a85b4432fc1119984c9c391b

8 files changed, 172 insertions, 204 deletions

diff --git a/debuggerd/Android.mk b/debuggerd/Android.mk
index 8621e9c..2fe7c7a 100644
--- a/debuggerd/Android.mk
+++ b/debuggerd/Android.mk
@@ -24,11 +24,11 @@ LOCAL_CFLAGS += -DWITH_VFP_D32
 endif # ARCH_ARM_HAVE_VFP_D32
 
 LOCAL_SHARED_LIBRARIES := \
+	libbacktrace \
+	libc \
 	libcutils \
 	liblog \
-	libc \
-	libcorkscrew \
-	libselinux
+	libselinux \
 
 include $(BUILD_EXECUTABLE)
 
diff --git a/debuggerd/arm/machine.c b/debuggerd/arm/machine.c
index 67e3028..6bcd07e 100644
--- a/debuggerd/arm/machine.c
+++ b/debuggerd/arm/machine.c
@@ -42,7 +42,7 @@
 #endif
 #endif
 
-static void dump_memory(log_t* log, pid_t tid, uintptr_t addr, int scopeFlags) {
+static void dump_memory(log_t* log, pid_t tid, uintptr_t addr, int scope_flags) {
     char code_buffer[64];       /* actual 8+1+((8+1)*4) + 1 == 45 */
     char ascii_buffer[32];      /* actual 16 + 1 == 17 */
     uintptr_t p, end;
@@ -102,7 +102,7 @@ static void dump_memory(log_t* log, pid_t tid, uintptr_t addr, int scopeFlags) {
             p += 4;
         }
         *asc_out = '\0';
-        _LOG(log, scopeFlags, "    %s %s\n", code_buffer, ascii_buffer);
+        _LOG(log, scope_flags, "    %s %s\n", code_buffer, ascii_buffer);
     }
 }
 
@@ -110,16 +110,13 @@ static void dump_memory(log_t* log, pid_t tid, uintptr_t addr, int scopeFlags) {
  * If configured to do so, dump memory around *all* registers
  * for the crashing thread.
  */
-void dump_memory_and_code(const ptrace_context_t* context __attribute((unused)),
-        log_t* log, pid_t tid, bool at_fault) {
+void dump_memory_and_code(log_t* log, pid_t tid, int scope_flags) {
     struct pt_regs regs;
     if(ptrace(PTRACE_GETREGS, tid, 0, &regs)) {
         return;
     }
 
-    int scopeFlags = at_fault ? SCOPE_AT_FAULT : 0;
-
-    if (at_fault && DUMP_MEMORY_FOR_ALL_REGISTERS) {
+    if (IS_AT_FAULT(scope_flags) && DUMP_MEMORY_FOR_ALL_REGISTERS) {
         static const char REG_NAMES[] = "r0r1r2r3r4r5r6r7r8r9slfpipsp";
 
         for (int reg = 0; reg < 14; reg++) {
@@ -134,39 +131,36 @@ void dump_memory_and_code(const ptrace_context_t* context __attribute((unused)),
                 continue;
             }
 
-            _LOG(log, scopeFlags | SCOPE_SENSITIVE, "\nmemory near %.2s:\n", &REG_NAMES[reg * 2]);
-            dump_memory(log, tid, addr, scopeFlags | SCOPE_SENSITIVE);
+            _LOG(log, scope_flags | SCOPE_SENSITIVE, "\nmemory near %.2s:\n", &REG_NAMES[reg * 2]);
+            dump_memory(log, tid, addr, scope_flags | SCOPE_SENSITIVE);
         }
     }
 
     /* explicitly allow upload of code dump logging */
-    _LOG(log, scopeFlags, "\ncode around pc:\n");
-    dump_memory(log, tid, (uintptr_t)regs.ARM_pc, scopeFlags);
+    _LOG(log, scope_flags, "\ncode around pc:\n");
+    dump_memory(log, tid, (uintptr_t)regs.ARM_pc, scope_flags);
 
     if (regs.ARM_pc != regs.ARM_lr) {
-        _LOG(log, scopeFlags, "\ncode around lr:\n");
-        dump_memory(log, tid, (uintptr_t)regs.ARM_lr, scopeFlags);
+        _LOG(log, scope_flags, "\ncode around lr:\n");
+        dump_memory(log, tid, (uintptr_t)regs.ARM_lr, scope_flags);
     }
 }
 
-void dump_registers(const ptrace_context_t* context __attribute((unused)),
-        log_t* log, pid_t tid, bool at_fault)
+void dump_registers(log_t* log, pid_t tid, int scope_flags)
 {
     struct pt_regs r;
-    int scopeFlags = at_fault ? SCOPE_AT_FAULT : 0;
-
     if(ptrace(PTRACE_GETREGS, tid, 0, &r)) {
-        _LOG(log, scopeFlags, "cannot get registers: %s\n", strerror(errno));
+        _LOG(log, scope_flags, "cannot get registers: %s\n", strerror(errno));
         return;
     }
 
-    _LOG(log, scopeFlags, "    r0 %08x  r1 %08x  r2 %08x  r3 %08x\n",
+    _LOG(log, scope_flags, "    r0 %08x  r1 %08x  r2 %08x  r3 %08x\n",
             (uint32_t)r.ARM_r0, (uint32_t)r.ARM_r1, (uint32_t)r.ARM_r2, (uint32_t)r.ARM_r3);
-    _LOG(log, scopeFlags, "    r4 %08x  r5 %08x  r6 %08x  r7 %08x\n",
+    _LOG(log, scope_flags, "    r4 %08x  r5 %08x  r6 %08x  r7 %08x\n",
             (uint32_t)r.ARM_r4, (uint32_t)r.ARM_r5, (uint32_t)r.ARM_r6, (uint32_t)r.ARM_r7);
-    _LOG(log, scopeFlags, "    r8 %08x  r9 %08x  sl %08x  fp %08x\n",
+    _LOG(log, scope_flags, "    r8 %08x  r9 %08x  sl %08x  fp %08x\n",
             (uint32_t)r.ARM_r8, (uint32_t)r.ARM_r9, (uint32_t)r.ARM_r10, (uint32_t)r.ARM_fp);
-    _LOG(log, scopeFlags, "    ip %08x  sp %08x  lr %08x  pc %08x  cpsr %08x\n",
+    _LOG(log, scope_flags, "    ip %08x  sp %08x  lr %08x  pc %08x  cpsr %08x\n",
             (uint32_t)r.ARM_ip, (uint32_t)r.ARM_sp, (uint32_t)r.ARM_lr,
             (uint32_t)r.ARM_pc, (uint32_t)r.ARM_cpsr);
 
@@ -175,14 +169,14 @@ void dump_registers(const ptrace_context_t* context __attribute((unused)),
     int i;
 
     if(ptrace(PTRACE_GETVFPREGS, tid, 0, &vfp_regs)) {
-        _LOG(log, scopeFlags, "cannot get registers: %s\n", strerror(errno));
+        _LOG(log, scope_flags, "cannot get registers: %s\n", strerror(errno));
         return;
     }
 
     for (i = 0; i < NUM_VFP_REGS; i += 2) {
-        _LOG(log, scopeFlags, "    d%-2d %016llx  d%-2d %016llx\n",
+        _LOG(log, scope_flags, "    d%-2d %016llx  d%-2d %016llx\n",
                 i, vfp_regs.fpregs[i], i+1, vfp_regs.fpregs[i+1]);
     }
-    _LOG(log, scopeFlags, "    scr %08lx\n", vfp_regs.fpscr);
+    _LOG(log, scope_flags, "    scr %08lx\n", vfp_regs.fpscr);
 #endif
 }
diff --git a/debuggerd/backtrace.c b/debuggerd/backtrace.c
index f42f24c..6f82792 100644
--- a/debuggerd/backtrace.c
+++ b/debuggerd/backtrace.c
@@ -27,13 +27,11 @@
 #include <sys/types.h>
 #include <sys/ptrace.h>
 
-#include <corkscrew/backtrace.h>
+#include <backtrace/backtrace.h>
 
-#include "tombstone.h"
+#include "backtrace.h"
 #include "utility.h"
 
-#define STACK_DEPTH 32
-
 static void dump_process_header(log_t* log, pid_t pid) {
     char path[PATH_MAX];
     char procnamebuf[1024];
@@ -62,7 +60,7 @@ static void dump_process_footer(log_t* log, pid_t pid) {
     _LOG(log, SCOPE_AT_FAULT, "\n----- end %d -----\n", pid);
 }
 
-static void dump_thread(log_t* log, pid_t tid, ptrace_context_t* context, bool attached,
+static void dump_thread(log_t* log, pid_t tid, bool attached,
         bool* detach_failed, int* total_sleep_time_usec) {
     char path[PATH_MAX];
     char threadnamebuf[1024];
@@ -91,20 +89,12 @@ static void dump_thread(log_t* log, pid_t tid, ptrace_context_t* context, bool a
 
     wait_for_stop(tid, total_sleep_time_usec);
 
-    backtrace_frame_t backtrace[STACK_DEPTH];
-    ssize_t frames = unwind_backtrace_ptrace(tid, context, backtrace, 0, STACK_DEPTH);
-    if (frames <= 0) {
-        _LOG(log, SCOPE_AT_FAULT, "Could not obtain stack trace for thread.\n");
+    backtrace_t backtrace;
+    if (!backtrace_get_data(&backtrace, tid)) {
+        _LOG(log, SCOPE_AT_FAULT, "Could not create backtrace context.\n");
     } else {
-        backtrace_symbol_t backtrace_symbols[STACK_DEPTH];
-        get_backtrace_symbols_ptrace(context, backtrace, frames, backtrace_symbols);
-        for (size_t i = 0; i < (size_t)frames; i++) {
-            char line[MAX_BACKTRACE_LINE_LENGTH];
-            format_backtrace_line(i, &backtrace[i], &backtrace_symbols[i],
-                    line, MAX_BACKTRACE_LINE_LENGTH);
-            _LOG(log, SCOPE_AT_FAULT, "  %s\n", line);
-        }
-        free_backtrace_symbols(backtrace_symbols, frames);
+        dump_backtrace_to_log(&backtrace, log, SCOPE_AT_FAULT, "  ");
+        backtrace_free_data(&backtrace);
     }
 
     if (!attached && ptrace(PTRACE_DETACH, tid, 0, 0) != 0) {
@@ -120,9 +110,8 @@ void dump_backtrace(int fd, int amfd, pid_t pid, pid_t tid, bool* detach_failed,
     log.amfd = amfd;
     log.quiet = true;
 
-    ptrace_context_t* context = load_ptrace_context(tid);
     dump_process_header(&log, pid);
-    dump_thread(&log, tid, context, true, detach_failed, total_sleep_time_usec);
+    dump_thread(&log, tid, true, detach_failed, total_sleep_time_usec);
 
     char task_path[64];
     snprintf(task_path, sizeof(task_path), "/proc/%d/task", pid);
@@ -140,11 +129,19 @@ void dump_backtrace(int fd, int amfd, pid_t pid, pid_t tid, bool* detach_failed,
                 continue;
             }
 
-            dump_thread(&log, new_tid, context, false, detach_failed, total_sleep_time_usec);
+            dump_thread(&log, new_tid, false, detach_failed, total_sleep_time_usec);
         }
         closedir(d);
     }
 
     dump_process_footer(&log, pid);
-    free_ptrace_context(context);
+}
+
+void dump_backtrace_to_log(const backtrace_t* backtrace, log_t* log,
+                           int scope_flags, const char* prefix) {
+    char buf[512];
+    for (size_t i = 0; i < backtrace->num_frames; i++) {
+        backtrace_format_frame_data(&backtrace->frames[i], i, buf, sizeof(buf));
+        _LOG(log, scope_flags, "%s%s\n", prefix, buf);
+    }
 }
diff --git a/debuggerd/backtrace.h b/debuggerd/backtrace.h
index c5c786a..9d61e6f 100644
--- a/debuggerd/backtrace.h
+++ b/debuggerd/backtrace.h
@@ -21,11 +21,17 @@
 #include <stdbool.h>
 #include <sys/types.h>
 
-#include <corkscrew/ptrace.h>
+#include <backtrace/backtrace.h>
+
+#include "utility.h"
 
 /* Dumps a backtrace using a format similar to what Dalvik uses so that the result
  * can be intermixed in a bug report. */
 void dump_backtrace(int fd, int amfd, pid_t pid, pid_t tid, bool* detach_failed,
         int* total_sleep_time_usec);
 
+/* Dumps the backtrace in the backtrace data structure to the log. */
+void dump_backtrace_to_log(const backtrace_t* backtrace, log_t* log,
+        int scope_flags, const char* prefix);
+
 #endif // _DEBUGGERD_BACKTRACE_H
diff --git a/debuggerd/machine.h b/debuggerd/machine.h
index 1619dd3..2f1e201 100644
--- a/debuggerd/machine.h
+++ b/debuggerd/machine.h
@@ -17,15 +17,11 @@
 #ifndef _DEBUGGERD_MACHINE_H
 #define _DEBUGGERD_MACHINE_H
 
-#include <stddef.h>
-#include <stdbool.h>
 #include <sys/types.h>
 
-#include <corkscrew/ptrace.h>
-
 #include "utility.h"
 
-void dump_memory_and_code(const ptrace_context_t* context, log_t* log, pid_t tid, bool at_fault);
-void dump_registers(const ptrace_context_t* context, log_t* log, pid_t tid, bool at_fault);
+void dump_memory_and_code(log_t* log, pid_t tid, int scope_flags);
+void dump_registers(log_t* log, pid_t tid, int scope_flags);
 
 #endif // _DEBUGGERD_MACHINE_H
diff --git a/debuggerd/mips/machine.c b/debuggerd/mips/machine.c
index 65fdf02..e06a50c 100644
--- a/debuggerd/mips/machine.c
+++ b/debuggerd/mips/machine.c
@@ -36,7 +36,7 @@
 
 #define R(x) ((unsigned int)(x))
 
-static void dump_memory(log_t* log, pid_t tid, uintptr_t addr, int scopeFlags) {
+static void dump_memory(log_t* log, pid_t tid, uintptr_t addr, int scope_flags) {
     char code_buffer[64];       /* actual 8+1+((8+1)*4) + 1 == 45 */
     char ascii_buffer[32];      /* actual 16 + 1 == 17 */
     uintptr_t p, end;
@@ -92,7 +92,7 @@ static void dump_memory(log_t* log, pid_t tid, uintptr_t addr, int scopeFlags) {
             p += 4;
         }
         *asc_out = '\0';
-        _LOG(log, scopeFlags, "    %s %s\n", code_buffer, ascii_buffer);
+        _LOG(log, scope_flags, "    %s %s\n", code_buffer, ascii_buffer);
     }
 }
 
@@ -100,15 +100,13 @@ static void dump_memory(log_t* log, pid_t tid, uintptr_t addr, int scopeFlags) {
  * If configured to do so, dump memory around *all* registers
  * for the crashing thread.
  */
-void dump_memory_and_code(const ptrace_context_t* context __attribute((unused)),
-        log_t* log, pid_t tid, bool at_fault) {
+void dump_memory_and_code(log_t* log, pid_t tid, int scope_flags) {
     pt_regs_mips_t r;
     if(ptrace(PTRACE_GETREGS, tid, 0, &r)) {
         return;
     }
 
-    int scopeFlags = at_fault ? SCOPE_AT_FAULT : 0;
-    if (at_fault && DUMP_MEMORY_FOR_ALL_REGISTERS) {
+    if (IS_AT_FAULT(scope_flags) && DUMP_MEMORY_FOR_ALL_REGISTERS) {
         static const char REG_NAMES[] = "$0atv0v1a0a1a2a3t0t1t2t3t4t5t6t7s0s1s2s3s4s5s6s7t8t9k0k1gpsps8ra";
 
         for (int reg = 0; reg < 32; reg++) {
@@ -130,50 +128,47 @@ void dump_memory_and_code(const ptrace_context_t* context __attribute((unused)),
                 continue;
             }
 
-            _LOG(log, scopeFlags | SCOPE_SENSITIVE, "\nmemory near %.2s:\n", &REG_NAMES[reg * 2]);
-            dump_memory(log, tid, addr, scopeFlags | SCOPE_SENSITIVE);
+            _LOG(log, scope_flags | SCOPE_SENSITIVE, "\nmemory near %.2s:\n", &REG_NAMES[reg * 2]);
+            dump_memory(log, tid, addr, scope_flags | SCOPE_SENSITIVE);
         }
     }
 
     unsigned int pc = R(r.cp0_epc);
     unsigned int ra = R(r.regs[31]);
 
-    _LOG(log, scopeFlags, "\ncode around pc:\n");
-    dump_memory(log, tid, (uintptr_t)pc, scopeFlags);
+    _LOG(log, scope_flags, "\ncode around pc:\n");
+    dump_memory(log, tid, (uintptr_t)pc, scope_flags);
 
     if (pc != ra) {
-        _LOG(log, scopeFlags, "\ncode around ra:\n");
-        dump_memory(log, tid, (uintptr_t)ra, scopeFlags);
+        _LOG(log, scope_flags, "\ncode around ra:\n");
+        dump_memory(log, tid, (uintptr_t)ra, scope_flags);
     }
 }
 
-void dump_registers(const ptrace_context_t* context __attribute((unused)),
-        log_t* log, pid_t tid, bool at_fault)
+void dump_registers(log_t* log, pid_t tid, int scope_flags)
 {
     pt_regs_mips_t r;
-    int scopeFlags = at_fault ? SCOPE_AT_FAULT : 0;
-
     if(ptrace(PTRACE_GETREGS, tid, 0, &r)) {
-        _LOG(log, scopeFlags, "cannot get registers: %s\n", strerror(errno));
+        _LOG(log, scope_flags, "cannot get registers: %s\n", strerror(errno));
         return;
     }
 
-    _LOG(log, scopeFlags, " zr %08x  at %08x  v0 %08x  v1 %08x\n",
+    _LOG(log, scope_flags, " zr %08x  at %08x  v0 %08x  v1 %08x\n",
      R(r.regs[0]), R(r.regs[1]), R(r.regs[2]), R(r.regs[3]));
-    _LOG(log, scopeFlags, " a0 %08x  a1 %08x  a2 %08x  a3 %08x\n",
+    _LOG(log, scope_flags, " a0 %08x  a1 %08x  a2 %08x  a3 %08x\n",
      R(r.regs[4]), R(r.regs[5]), R(r.regs[6]), R(r.regs[7]));
-    _LOG(log, scopeFlags, " t0 %08x  t1 %08x  t2 %08x  t3 %08x\n",
+    _LOG(log, scope_flags, " t0 %08x  t1 %08x  t2 %08x  t3 %08x\n",
      R(r.regs[8]), R(r.regs[9]), R(r.regs[10]), R(r.regs[11]));
-    _LOG(log, scopeFlags, " t4 %08x  t5 %08x  t6 %08x  t7 %08x\n",
+    _LOG(log, scope_flags, " t4 %08x  t5 %08x  t6 %08x  t7 %08x\n",
      R(r.regs[12]), R(r.regs[13]), R(r.regs[14]), R(r.regs[15]));
-    _LOG(log, scopeFlags, " s0 %08x  s1 %08x  s2 %08x  s3 %08x\n",
+    _LOG(log, scope_flags, " s0 %08x  s1 %08x  s2 %08x  s3 %08x\n",
      R(r.regs[16]), R(r.regs[17]), R(r.regs[18]), R(r.regs[19]));
-    _LOG(log, scopeFlags, " s4 %08x  s5 %08x  s6 %08x  s7 %08x\n",
+    _LOG(log, scope_flags, " s4 %08x  s5 %08x  s6 %08x  s7 %08x\n",
      R(r.regs[20]), R(r.regs[21]), R(r.regs[22]), R(r.regs[23]));
-    _LOG(log, scopeFlags, " t8 %08x  t9 %08x  k0 %08x  k1 %08x\n",
+    _LOG(log, scope_flags, " t8 %08x  t9 %08x  k0 %08x  k1 %08x\n",
      R(r.regs[24]), R(r.regs[25]), R(r.regs[26]), R(r.regs[27]));
-    _LOG(log, scopeFlags, " gp %08x  sp %08x  s8 %08x  ra %08x\n",
+    _LOG(log, scope_flags, " gp %08x  sp %08x  s8 %08x  ra %08x\n",
      R(r.regs[28]), R(r.regs[29]), R(r.regs[30]), R(r.regs[31]));
-    _LOG(log, scopeFlags, " hi %08x  lo %08x bva %08x epc %08x\n",
+    _LOG(log, scope_flags, " hi %08x  lo %08x bva %08x epc %08x\n",
      R(r.hi), R(r.lo), R(r.cp0_badvaddr), R(r.cp0_epc));
 }
diff --git a/debuggerd/tombstone.c b/debuggerd/tombstone.c
index 77f6ef1..1a6066e 100644
--- a/debuggerd/tombstone.c
+++ b/debuggerd/tombstone.c
@@ -32,8 +32,7 @@
 #include <cutils/logger.h>
 #include <cutils/properties.h>
 
-#include <corkscrew/demangle.h>
-#include <corkscrew/backtrace.h>
+#include <backtrace/backtrace.h>
 
 #include <sys/socket.h>
 #include <linux/un.h>
@@ -42,9 +41,8 @@
 
 #include "machine.h"
 #include "tombstone.h"
-#include "utility.h"
+#include "backtrace.h"
 
-#define STACK_DEPTH 32
 #define STACK_WORDS 16
 
 #define MAX_TOMBSTONES  10
@@ -193,7 +191,7 @@ static void dump_fault_addr(log_t* log, pid_t tid, int sig)
     }
 }
 
-static void dump_thread_info(log_t* log, pid_t pid, pid_t tid, bool at_fault) {
+static void dump_thread_info(log_t* log, pid_t pid, pid_t tid, int scope_flags) {
     char path[64];
     char threadnamebuf[1024];
     char* threadname = NULL;
@@ -211,7 +209,7 @@ static void dump_thread_info(log_t* log, pid_t pid, pid_t tid, bool at_fault) {
         }
     }
 
-    if (at_fault) {
+    if (IS_AT_FAULT(scope_flags)) {
         char procnamebuf[1024];
         char* procname = NULL;
 
@@ -230,64 +228,46 @@ static void dump_thread_info(log_t* log, pid_t pid, pid_t tid, bool at_fault) {
     }
 }
 
-static void dump_backtrace(const ptrace_context_t* context __attribute((unused)),
-        log_t* log, pid_t tid __attribute((unused)), bool at_fault,
-        const backtrace_frame_t* backtrace, size_t frames) {
-    int scopeFlags = at_fault ? SCOPE_AT_FAULT : 0;
-    _LOG(log, scopeFlags, "\nbacktrace:\n");
-
-    backtrace_symbol_t backtrace_symbols[STACK_DEPTH];
-    get_backtrace_symbols_ptrace(context, backtrace, frames, backtrace_symbols);
-    for (size_t i = 0; i < frames; i++) {
-        char line[MAX_BACKTRACE_LINE_LENGTH];
-        format_backtrace_line(i, &backtrace[i], &backtrace_symbols[i],
-                line, MAX_BACKTRACE_LINE_LENGTH);
-        _LOG(log, scopeFlags, "    %s\n", line);
-    }
-    free_backtrace_symbols(backtrace_symbols, frames);
-}
-
-static void dump_stack_segment(const ptrace_context_t* context, log_t* log, pid_t tid,
-        int scopeFlags, uintptr_t* sp, size_t words, int label) {
+static void dump_stack_segment(const backtrace_t* backtrace, log_t* log,
+        int scope_flags, uintptr_t *sp, size_t words, int label) {
     for (size_t i = 0; i < words; i++) {
         uint32_t stack_content;
-        if (!try_get_word_ptrace(tid, *sp, &stack_content)) {
+        if (!backtrace_read_word(backtrace, *sp, &stack_content)) {
             break;
         }
 
-        const map_info_t* mi;
-        const symbol_t* symbol;
-        find_symbol_ptrace(context, stack_content, &mi, &symbol);
-
-        if (symbol) {
-            char* demangled_name = demangle_symbol_name(symbol->name);
-            const char* symbol_name = demangled_name ? demangled_name : symbol->name;
-            uint32_t offset = stack_content - (mi->start + symbol->start);
+        const char* map_name = backtrace_get_map_info(backtrace, stack_content, NULL);
+        if (!map_name) {
+            map_name = "";
+        }
+        uintptr_t offset = 0;
+        char* proc_name = backtrace_get_proc_name(backtrace, stack_content, &offset);
+        if (proc_name) {
             if (!i && label >= 0) {
                 if (offset) {
-                    _LOG(log, scopeFlags, "    #%02d  %08x  %08x  %s (%s+%u)\n",
-                            label, *sp, stack_content, mi ? mi->name : "", symbol_name, offset);
+                    _LOG(log, scope_flags, "    #%02d  %08x  %08x  %s (%s+%u)\n",
+                            label, *sp, stack_content, map_name, proc_name, offset);
                 } else {
-                    _LOG(log, scopeFlags, "    #%02d  %08x  %08x  %s (%s)\n",
-                            label, *sp, stack_content, mi ? mi->name : "", symbol_name);
+                    _LOG(log, scope_flags, "    #%02d  %08x  %08x  %s (%s)\n",
+                            label, *sp, stack_content, map_name, proc_name);
                 }
             } else {
                 if (offset) {
-                    _LOG(log, scopeFlags, "         %08x  %08x  %s (%s+%u)\n",
-                            *sp, stack_content, mi ? mi->name : "", symbol_name, offset);
+                    _LOG(log, scope_flags, "         %08x  %08x  %s (%s+%u)\n",
+                            *sp, stack_content, map_name, proc_name, offset);
                 } else {
-                    _LOG(log, scopeFlags, "         %08x  %08x  %s (%s)\n",
-                            *sp, stack_content, mi ? mi->name : "", symbol_name);
+                    _LOG(log, scope_flags, "         %08x  %08x  %s (%s)\n",
+                            *sp, stack_content, map_name, proc_name);
                 }
             }
-            free(demangled_name);
+            free(proc_name);
         } else {
             if (!i && label >= 0) {
-                _LOG(log, scopeFlags, "    #%02d  %08x  %08x  %s\n",
-                        label, *sp, stack_content, mi ? mi->name : "");
+                _LOG(log, scope_flags, "    #%02d  %08x  %08x  %s\n",
+                        label, *sp, stack_content, map_name);
             } else {
-                _LOG(log, scopeFlags, "         %08x  %08x  %s\n",
-                        *sp, stack_content, mi ? mi->name : "");
+                _LOG(log, scope_flags, "         %08x  %08x  %s\n",
+                        *sp, stack_content, map_name);
             }
         }
 
@@ -295,45 +275,42 @@ static void dump_stack_segment(const ptrace_context_t* context, log_t* log, pid_
     }
 }
 
-static void dump_stack(const ptrace_context_t* context, log_t* log, pid_t tid, bool at_fault,
-        const backtrace_frame_t* backtrace, size_t frames) {
-    bool have_first = false;
-    size_t first, last;
-    for (size_t i = 0; i < frames; i++) {
-        if (backtrace[i].stack_top) {
-            if (!have_first) {
-                have_first = true;
-                first = i;
+static void dump_stack(const backtrace_t* backtrace, log_t* log, int scope_flags) {
+    size_t first = 0, last;
+    for (size_t i = 0; i < backtrace->num_frames; i++) {
+        if (backtrace->frames[i].sp) {
+            if (!first) {
+                first = i+1;
             }
             last = i;
         }
     }
-    if (!have_first) {
+    if (!first) {
         return;
     }
+    first--;
 
-    int scopeFlags = SCOPE_SENSITIVE | (at_fault ? SCOPE_AT_FAULT : 0);
-    _LOG(log, scopeFlags, "\nstack:\n");
+    scope_flags |= SCOPE_SENSITIVE;
 
     // Dump a few words before the first frame.
-    uintptr_t sp = backtrace[first].stack_top - STACK_WORDS * sizeof(uint32_t);
-    dump_stack_segment(context, log, tid, scopeFlags, &sp, STACK_WORDS, -1);
+    uintptr_t sp = backtrace->frames[first].sp - STACK_WORDS * sizeof(uint32_t);
+    dump_stack_segment(backtrace, log, scope_flags, &sp, STACK_WORDS, -1);
 
     // Dump a few words from all successive frames.
     // Only log the first 3 frames, put the rest in the tombstone.
     for (size_t i = first; i <= last; i++) {
-        const backtrace_frame_t* frame = &backtrace[i];
-        if (sp != frame->stack_top) {
-            _LOG(log, scopeFlags, "         ........  ........\n");
-            sp = frame->stack_top;
+        const backtrace_frame_data_t* frame = &backtrace->frames[i];
+        if (sp != frame->sp) {
+            _LOG(log, scope_flags, "         ........  ........\n");
+            sp = frame->sp;
         }
         if (i - first == 3) {
-            scopeFlags &= (~SCOPE_AT_FAULT);
+            scope_flags &= (~SCOPE_AT_FAULT);
         }
         if (i == last) {
-            dump_stack_segment(context, log, tid, scopeFlags, &sp, STACK_WORDS, i);
-            if (sp < frame->stack_top + frame->stack_size) {
-                _LOG(log, scopeFlags, "         ........  ........\n");
+            dump_stack_segment(backtrace, log, scope_flags, &sp, STACK_WORDS, i);
+            if (sp < frame->sp + frame->stack_size) {
+                _LOG(log, scope_flags, "         ........  ........\n");
             }
         } else {
             size_t words = frame->stack_size / sizeof(uint32_t);
@@ -342,39 +319,40 @@ static void dump_stack(const ptrace_context_t* context, log_t* log, pid_t tid, b
             } else if (words > STACK_WORDS) {
                 words = STACK_WORDS;
             }
-            dump_stack_segment(context, log, tid, scopeFlags, &sp, words, i);
+            dump_stack_segment(backtrace, log, scope_flags, &sp, words, i);
         }
     }
 }
 
-static void dump_backtrace_and_stack(const ptrace_context_t* context, log_t* log, pid_t tid,
-        bool at_fault) {
-    backtrace_frame_t backtrace[STACK_DEPTH];
-    ssize_t frames = unwind_backtrace_ptrace(tid, context, backtrace, 0, STACK_DEPTH);
-    if (frames > 0) {
-        dump_backtrace(context, log, tid, at_fault, backtrace, frames);
-        dump_stack(context, log, tid, at_fault, backtrace, frames);
+static void dump_backtrace_and_stack(const backtrace_t* backtrace, log_t* log,
+        int scope_flags) {
+    if (backtrace->num_frames) {
+        _LOG(log, scope_flags, "\nbacktrace:\n");
+        dump_backtrace_to_log(backtrace, log, scope_flags, "    ");
+
+        _LOG(log, scope_flags, "\nstack:\n");
+        dump_stack(backtrace, log, scope_flags);
     }
 }
 
-static void dump_map(log_t* log, map_info_t* m, const char* what, int scopeFlags) {
+static void dump_map(log_t* log, const backtrace_map_info_t* m, const char* what, int scope_flags) {
     if (m != NULL) {
-        _LOG(log, scopeFlags, "    %08x-%08x %c%c%c %s\n", m->start, m->end,
+        _LOG(log, scope_flags, "    %08x-%08x %c%c%c %s\n", m->start, m->end,
              m->is_readable ? 'r' : '-',
              m->is_writable ? 'w' : '-',
              m->is_executable ? 'x' : '-',
              m->name);
     } else {
-        _LOG(log, scopeFlags, "    (no %s)\n", what);
+        _LOG(log, scope_flags, "    (no %s)\n", what);
     }
 }
 
-static void dump_nearby_maps(const ptrace_context_t* context, log_t* log, pid_t tid, bool at_fault) {
-    int scopeFlags = SCOPE_SENSITIVE | (at_fault ? SCOPE_AT_FAULT : 0);
+static void dump_nearby_maps(const backtrace_map_info_t* map_info_list, log_t* log, pid_t tid, int scope_flags) {
+    scope_flags |= SCOPE_SENSITIVE;
     siginfo_t si;
     memset(&si, 0, sizeof(si));
     if (ptrace(PTRACE_GETSIGINFO, tid, 0, &si)) {
-        _LOG(log, scopeFlags, "cannot get siginfo for %d: %s\n",
+        _LOG(log, scope_flags, "cannot get siginfo for %d: %s\n",
                 tid, strerror(errno));
         return;
     }
@@ -388,15 +366,15 @@ static void dump_nearby_maps(const ptrace_context_t* context, log_t* log, pid_t
         return;
     }
 
-    _LOG(log, scopeFlags, "\nmemory map around fault addr %08x:\n", (int)si.si_addr);
+    _LOG(log, scope_flags, "\nmemory map around fault addr %08x:\n", (int)si.si_addr);
 
     /*
      * Search for a match, or for a hole where the match would be.  The list
      * is backward from the file content, so it starts at high addresses.
      */
-    map_info_t* map = context->map_info_list;
-    map_info_t *next = NULL;
-    map_info_t *prev = NULL;
+    const backtrace_map_info_t* map = map_info_list;
+    const backtrace_map_info_t* next = NULL;
+    const backtrace_map_info_t* prev = NULL;
     while (map != NULL) {
         if (addr >= map->start && addr < map->end) {
             next = map->next;
@@ -416,31 +394,31 @@ static void dump_nearby_maps(const ptrace_context_t* context, log_t* log, pid_t
      * Show "next" then "match" then "prev" so that the addresses appear in
      * ascending order (like /proc/pid/maps).
      */
-    dump_map(log, next, "map below", scopeFlags);
-    dump_map(log, map, "map for address", scopeFlags);
-    dump_map(log, prev, "map above", scopeFlags);
+    dump_map(log, next, "map below", scope_flags);
+    dump_map(log, map, "map for address", scope_flags);
+    dump_map(log, prev, "map above", scope_flags);
 }
 
-static void dump_thread(const ptrace_context_t* context, log_t* log, pid_t tid, bool at_fault,
+static void dump_thread(const backtrace_t* backtrace, log_t* log, int scope_flags,
         int* total_sleep_time_usec) {
-    wait_for_stop(tid, total_sleep_time_usec);
+    wait_for_stop(backtrace->tid, total_sleep_time_usec);
 
-    dump_registers(context, log, tid, at_fault);
-    dump_backtrace_and_stack(context, log, tid, at_fault);
-    if (at_fault) {
-        dump_memory_and_code(context, log, tid, at_fault);
-        dump_nearby_maps(context, log, tid, at_fault);
+    dump_registers(log, backtrace->tid, scope_flags);
+    dump_backtrace_and_stack(backtrace, log, scope_flags);
+    if (IS_AT_FAULT(scope_flags)) {
+        dump_memory_and_code(log, backtrace->tid, scope_flags);
+        dump_nearby_maps(backtrace->map_info_list, log, backtrace->tid, scope_flags);
     }
 }
 
 /* Return true if some thread is not detached cleanly */
-static bool dump_sibling_thread_report(const ptrace_context_t* context,
+static bool dump_sibling_thread_report(
         log_t* log, pid_t pid, pid_t tid, int* total_sleep_time_usec) {
     char task_path[64];
     snprintf(task_path, sizeof(task_path), "/proc/%d/task", pid);
 
     DIR* d = opendir(task_path);
-    /* Bail early if cannot open the task directory */
+    /* Bail early if the task directory cannot be opened */
     if (d == NULL) {
         XLOG("Cannot open /proc/%d/task\n", pid);
         return false;
@@ -467,8 +445,12 @@ static bool dump_sibling_thread_report(const ptrace_context_t* context,
         }
 
         _LOG(log, 0, "--- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---\n");
-        dump_thread_info(log, pid, new_tid, false);
-        dump_thread(context, log, new_tid, false, total_sleep_time_usec);
+        dump_thread_info(log, pid, new_tid, 0);
+        backtrace_t new_backtrace;
+        if (backtrace_get_data(&new_backtrace, new_tid)) {
+            dump_thread(&new_backtrace, log, 0, total_sleep_time_usec);
+        }
+        backtrace_free_data(&new_backtrace);
 
         if (ptrace(PTRACE_DETACH, new_tid, 0, 0) != 0) {
             LOG("ptrace detach from %d failed: %s\n", new_tid, strerror(errno));
@@ -624,7 +606,7 @@ static void dump_logs(log_t* log, pid_t pid, bool tailOnly)
     dump_log_file(log, pid, "/dev/log/main", tailOnly);
 }
 
-static void dump_abort_message(log_t* log, pid_t tid, uintptr_t address) {
+static void dump_abort_message(const backtrace_t* backtrace, log_t* log, uintptr_t address) {
   if (address == 0) {
     return;
   }
@@ -636,9 +618,10 @@ static void dump_abort_message(log_t* log, pid_t tid, uintptr_t address) {
   char* p = &msg[0];
   while (p < &msg[sizeof(msg)]) {
     uint32_t data;
-    if (!try_get_word_ptrace(tid, address, &data)) {
+    if (!backtrace_read_word(backtrace, address, &data)) {
       break;
     }
+    data = 0;
     address += sizeof(uint32_t);
 
     if ((*p++ = (data >>  0) & 0xff) == 0) {
@@ -686,14 +669,17 @@ static bool dump_crash(log_t* log, pid_t pid, pid_t tid, int signal, uintptr_t a
             "*** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***\n");
     dump_build_info(log);
     dump_revision_info(log);
-    dump_thread_info(log, pid, tid, true);
+    dump_thread_info(log, pid, tid, SCOPE_AT_FAULT);
     if (signal) {
         dump_fault_addr(log, tid, signal);
     }
-    dump_abort_message(log, tid, abort_msg_address);
 
-    ptrace_context_t* context = load_ptrace_context(tid);
-    dump_thread(context, log, tid, true, total_sleep_time_usec);
+    backtrace_t backtrace;
+    if (backtrace_get_data(&backtrace, tid)) {
+        dump_abort_message(&backtrace, log, abort_msg_address);
+        dump_thread(&backtrace, log, SCOPE_AT_FAULT, total_sleep_time_usec);
+        backtrace_free_data(&backtrace);
+    }
 
     if (want_logs) {
         dump_logs(log, pid, true);
@@ -701,11 +687,9 @@ static bool dump_crash(log_t* log, pid_t pid, pid_t tid, int signal, uintptr_t a
 
     bool detach_failed = false;
     if (dump_sibling_threads) {
-        detach_failed = dump_sibling_thread_report(context, log, pid, tid, total_sleep_time_usec);
+        detach_failed = dump_sibling_thread_report(log, pid, tid, total_sleep_time_usec);
     }
 
-    free_ptrace_context(context);
-
     if (want_logs) {
         dump_logs(log, pid, false);
     }
diff --git a/debuggerd/x86/machine.c b/debuggerd/x86/machine.c
index af79092..e00208d 100644
--- a/debuggerd/x86/machine.c
+++ b/debuggerd/x86/machine.c
@@ -31,28 +31,24 @@
 #include "../utility.h"
 #include "../machine.h"
 
-void dump_memory_and_code(const ptrace_context_t* context __attribute((unused)),
-        log_t* log, pid_t tid, bool at_fault) {
+void dump_memory_and_code(log_t* log, pid_t tid, int scope_flags) {
 }
 
-void dump_registers(const ptrace_context_t* context __attribute((unused)),
-        log_t* log, pid_t tid, bool at_fault) {
+void dump_registers(log_t* log, pid_t tid, int scope_flags) {
     struct pt_regs_x86 r;
-    int scopeFlags = (at_fault ? SCOPE_AT_FAULT : 0);
-
     if(ptrace(PTRACE_GETREGS, tid, 0, &r)) {
-        _LOG(log, scopeFlags, "cannot get registers: %s\n", strerror(errno));
+        _LOG(log, scope_flags, "cannot get registers: %s\n", strerror(errno));
         return;
     }
     //if there is no stack, no print just like arm
     if(!r.ebp)
         return;
-    _LOG(log, scopeFlags, "    eax %08x  ebx %08x  ecx %08x  edx %08x\n",
+    _LOG(log, scope_flags, "    eax %08x  ebx %08x  ecx %08x  edx %08x\n",
          r.eax, r.ebx, r.ecx, r.edx);
-    _LOG(log, scopeFlags, "    esi %08x  edi %08x\n",
+    _LOG(log, scope_flags, "    esi %08x  edi %08x\n",
          r.esi, r.edi);
-    _LOG(log, scopeFlags, "    xcs %08x  xds %08x  xes %08x  xfs %08x  xss %08x\n",
+    _LOG(log, scope_flags, "    xcs %08x  xds %08x  xes %08x  xfs %08x  xss %08x\n",
          r.xcs, r.xds, r.xes, r.xfs, r.xss);
-    _LOG(log, scopeFlags, "    eip %08x  ebp %08x  esp %08x  flags %08x\n",
+    _LOG(log, scope_flags, "    eip %08x  ebp %08x  esp %08x  flags %08x\n",
          r.eip, r.ebp, r.esp, r.eflags);
 }