Support libcorkscrew on x86 hosts in binaries using glibc.

Change-Id: I1f2b7f21cc7f8227dbe7d294fed88cb691a24d09

libcorkscrew/Android.mk

@@ -14,9 +14,7 @@
 
 LOCAL_PATH:= $(call my-dir)
 
-include $(CLEAR_VARS)
-
-LOCAL_SRC_FILES := \
+generic_src_files := \
 	backtrace.c \
 	backtrace-helper.c \
 	demangle.c \
@@ -24,16 +22,24 @@ LOCAL_SRC_FILES := \
 	ptrace.c \
 	symbol_table.c
 
-ifeq ($(TARGET_ARCH),arm)
-LOCAL_SRC_FILES += \
+arm_src_files := \
 	arch-arm/backtrace-arm.c \
 	arch-arm/ptrace-arm.c
+
+x86_src_files := \
+	arch-x86/backtrace-x86.c \
+	arch-x86/ptrace-x86.c
+
+include $(CLEAR_VARS)
+
+LOCAL_SRC_FILES := $(generic_src_files)
+
+ifeq ($(TARGET_ARCH),arm)
+LOCAL_SRC_FILES += $(arm_src_files)
 LOCAL_CFLAGS += -DCORKSCREW_HAVE_ARCH
 endif
 ifeq ($(TARGET_ARCH),x86)
-LOCAL_SRC_FILES += \
-	arch-x86/backtrace-x86.c \
-	arch-x86/ptrace-x86.c
+LOCAL_SRC_FILES += $(x86_src_files)
 LOCAL_CFLAGS += -DCORKSCREW_HAVE_ARCH
 endif
 
@@ -44,3 +50,38 @@ LOCAL_MODULE := libcorkscrew
 LOCAL_MODULE_TAGS := optional
 
 include $(BUILD_SHARED_LIBRARY)
+
+# Build test.
+include $(CLEAR_VARS)
+LOCAL_SRC_FILES := test.c
+LOCAL_CFLAGS += -std=gnu99 -Werror -fno-inline-small-functions
+LOCAL_SHARED_LIBRARIES := libcorkscrew
+LOCAL_MODULE := libcorkscrew_test
+LOCAL_MODULE_TAGS := optional
+include $(BUILD_EXECUTABLE)
+
+
+ifeq ($(HOST_OS)-$(HOST_ARCH),linux-x86)
+
+# Build libcorkscrew.
+include $(CLEAR_VARS)
+LOCAL_SRC_FILES += $(generic_src_files) $(x86_src_files)
+LOCAL_CFLAGS += -DCORKSCREW_HAVE_ARCH
+LOCAL_SHARED_LIBRARIES += libgccdemangle
+LOCAL_STATIC_LIBRARIES += libcutils
+LOCAL_LDLIBS += -ldl -lrt
+LOCAL_CFLAGS += -std=gnu99 -Werror
+LOCAL_MODULE := libcorkscrew
+LOCAL_MODULE_TAGS := optional
+include $(BUILD_HOST_SHARED_LIBRARY)
+
+# Build test.
+include $(CLEAR_VARS)
+LOCAL_SRC_FILES := test.c
+LOCAL_CFLAGS += -std=gnu99 -Werror -fno-inline-small-functions
+LOCAL_SHARED_LIBRARIES := libcorkscrew
+LOCAL_MODULE := libcorkscrew_test
+LOCAL_MODULE_TAGS := optional
+include $(BUILD_HOST_EXECUTABLE)
+
+endif # linux-x86

libcorkscrew/arch-x86/backtrace-x86.c

@@ -31,40 +31,10 @@
 #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 gs;
-        uint32_t fs;
-        uint32_t es;
-        uint32_t ds;
-        uint32_t edi;
-        uint32_t esi;
-        uint32_t ebp;
-        uint32_t esp;
-        uint32_t ebx;
-        uint32_t edx;
-        uint32_t ecx;
-        uint32_t eax;
-        uint32_t trapno;
-        uint32_t err;
-        uint32_t eip;
-        uint32_t cs;
-        uint32_t efl;
-        uint32_t uesp;
-        uint32_t ss;
-        void* fpregs;
-        uint32_t oldmask;
-        uint32_t cr2;
-    } uc_mcontext;
-    uint32_t uc_sigmask;
-} ucontext_t;
+#define __USE_GNU // For REG_EBP, REG_ESP, and REG_EIP.
+#include <ucontext.h>
 
 /* Unwind state. */
 typedef struct {
@@ -114,9 +84,9 @@ ssize_t unwind_backtrace_signal_arch(siginfo_t* siginfo, void* sigcontext,
     const ucontext_t* uc = (const ucontext_t*)sigcontext;
 
     unwind_state_t state;
-    state.ebp = uc->uc_mcontext.ebp;
-    state.eip = uc->uc_mcontext.eip;
-    state.esp = uc->uc_mcontext.esp;
+    state.ebp = uc->uc_mcontext.gregs[REG_EBP];
+    state.esp = uc->uc_mcontext.gregs[REG_ESP];
+    state.eip = uc->uc_mcontext.gregs[REG_EIP];
 
     memory_t memory;
     init_memory(&memory, map_info_list);

libcorkscrew/backtrace.c

@@ -27,16 +27,41 @@
 
 #include <unistd.h>
 #include <signal.h>
+#include <stdlib.h>
+#include <string.h>
 #include <pthread.h>
 #include <unwind.h>
-#include <sys/exec_elf.h>
 #include <cutils/log.h>
 #include <cutils/atomic.h>
+#include <elf.h>
 
 #if HAVE_DLADDR
+#define __USE_GNU // For dladdr(3) in glibc.
 #include <dlfcn.h>
 #endif
 
+#if defined(__BIONIC__)
+
+// Bionic implements and exports gettid but only implements tgkill.
+extern int tgkill(int tgid, int tid, int sig);
+
+#else
+
+// glibc doesn't implement or export either gettid or tgkill.
+
+#include <unistd.h>
+#include <sys/syscall.h>
+
+static pid_t gettid() {
+  return syscall(__NR_gettid);
+}
+
+static int tgkill(int tgid, int tid, int sig) {
+  return syscall(__NR_tgkill, tgid, tid, sig);
+}
+
+#endif
+
 typedef struct {
     backtrace_frame_t* backtrace;
     size_t ignore_depth;
@@ -115,8 +140,6 @@ static void unwind_backtrace_thread_signal_handler(int n, siginfo_t* siginfo, vo
 }
 #endif
 
-extern int tgkill(int tgid, int tid, int sig);
-
 ssize_t unwind_backtrace_thread(pid_t tid, backtrace_frame_t* backtrace,
         size_t ignore_depth, size_t max_depth) {
     if (tid == gettid()) {

libcorkscrew/symbol_table.c

@@ -19,14 +19,22 @@
 
 #include <corkscrew/symbol_table.h>
 
+#include <stdbool.h>
 #include <stdlib.h>
+#include <elf.h>
 #include <fcntl.h>
 #include <string.h>
 #include <sys/stat.h>
 #include <sys/mman.h>
-#include <sys/exec_elf.h>
 #include <cutils/log.h>
 
+static bool is_elf(Elf32_Ehdr* e) {
+    return (e->e_ident[EI_MAG0] == ELFMAG0 &&
+            e->e_ident[EI_MAG1] == ELFMAG1 &&
+            e->e_ident[EI_MAG2] == ELFMAG2 &&
+            e->e_ident[EI_MAG3] == ELFMAG3);
+}
+
 // Compare function for qsort
 static int qcompar(const void *a, const void *b) {
     const symbol_t* asym = (const symbol_t*)a;
@@ -67,7 +75,7 @@ symbol_table_t* load_symbol_table(const char *filename) {
 
     // Parse the file header
     Elf32_Ehdr *hdr = (Elf32_Ehdr*)base;
-    if (!IS_ELF(*hdr)) {
+    if (!is_elf(hdr)) {
         goto out_close;
     }
     Elf32_Shdr *shdr = (Elf32_Shdr*)(base + hdr->e_shoff);

libcorkscrew/test.c

@@ -0,0 +1,42 @@
+#include <corkscrew/backtrace.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+void do_backtrace() {
+  const size_t MAX_DEPTH = 32;
+  backtrace_frame_t* frames = (backtrace_frame_t*) malloc(sizeof(backtrace_frame_t) * MAX_DEPTH);
+  ssize_t frame_count = unwind_backtrace(frames, 0, MAX_DEPTH);
+  fprintf(stderr, "frame_count=%d\n", (int) frame_count);
+
+  backtrace_symbol_t* backtrace_symbols = (backtrace_symbol_t*) malloc(sizeof(backtrace_symbol_t) * frame_count);
+  get_backtrace_symbols(frames, frame_count, backtrace_symbols);
+
+  for (size_t i = 0; i < (size_t) frame_count; ++i) {
+    char line[MAX_BACKTRACE_LINE_LENGTH];
+    format_backtrace_line(i, &frames[i], &backtrace_symbols[i],
+                          line, MAX_BACKTRACE_LINE_LENGTH);
+    fprintf(stderr, "  %s\n", line);
+  }
+
+  free_backtrace_symbols(backtrace_symbols, frame_count);
+  free(backtrace_symbols);
+  free(frames);
+}
+
+__attribute__ ((noinline)) void g() {
+  fprintf(stderr, "g()\n");
+  do_backtrace();
+}
+
+__attribute__ ((noinline)) int f(int i) {
+  fprintf(stderr, "f(%i)\n", i);
+  if (i == 0) {
+    g();
+    return 0;
+  }
+  return f(i - 1);
+}
+
+int main() {
+  return f(5);
+}