Better seccomp/kuser_helper diagnostics from debuggerd.

Also switch to Android.bp for crasher.

Bug: http://b/34629282 (seccomp)
Bug: http://b/34705831 (seccomp)
Bug: http://b/34884086 (kuser_helpers)
Test: manual
Change-Id: I8ee79c635518faeba751742919af69a505b5e3e1
diff --git a/debuggerd/crasher/Android.bp b/debuggerd/crasher/Android.bp
new file mode 100644
index 0000000..4727894
--- /dev/null
+++ b/debuggerd/crasher/Android.bp
@@ -0,0 +1,81 @@
+cc_defaults {
+    name: "crasher-defaults",
+
+    cppflags: [
+        "-std=gnu++14",
+        "-W",
+        "-Wall",
+        "-Wextra",
+        "-Wunused",
+        "-Werror",
+        "-O0",
+        "-fstack-protector-all",
+        "-Wno-free-nonheap-object",
+        "-Wno-date-time",
+    ],
+    srcs: ["crasher.cpp"],
+    arch: {
+        arm: {
+            srcs: ["arm/crashglue.S"],
+
+            armv7_a_neon: {
+                asflags: ["-DHAS_VFP_D32"],
+            },
+        },
+        arm64: {
+            srcs: ["arm64/crashglue.S"],
+        },
+        mips: {
+            srcs: ["mips/crashglue.S"],
+        },
+        mips64: {
+            srcs: ["mips64/crashglue.S"],
+        },
+        x86: {
+            srcs: ["x86/crashglue.S"],
+        },
+        x86_64: {
+            srcs: ["x86_64/crashglue.S"],
+        },
+    },
+    compile_multilib: "both",
+}
+
+cc_binary {
+    name: "crasher",
+
+    defaults: ["crasher-defaults"],
+    shared_libs: [
+        "libbase",
+        "liblog",
+    ],
+    multilib: {
+        lib32: {
+            stem: "crasher",
+        },
+        lib64: {
+            stem: "crasher64",
+        },
+    },
+}
+
+cc_binary {
+    name: "static_crasher",
+
+    defaults: ["crasher-defaults"],
+    cppflags: ["-DSTATIC_CRASHER"],
+    static_executable: true,
+    static_libs: [
+        "libdebuggerd_handler",
+        "libbase",
+        "liblog",
+    ],
+    multilib: {
+        lib32: {
+            stem: "static_crasher",
+        },
+        lib64: {
+            stem: "static_crasher64",
+        },
+    },
+}
diff --git a/debuggerd/crasher/Android.mk b/debuggerd/crasher/Android.mk
deleted file mode 100644
index b8b786b..0000000
--- a/debuggerd/crasher/Android.mk
+++ /dev/null
@@ -1,66 +0,0 @@
-LOCAL_PATH := $(call my-dir)
-
-crasher_cppflags := \
-    -std=gnu++14 \
-    -W \
-    -Wall \
-    -Wextra \
-    -Wunused \
-    -Werror \
-    -O0 \
-    -fstack-protector-all \
-    -Wno-free-nonheap-object \
-    -Wno-date-time
-
-include $(CLEAR_VARS)
-LOCAL_SRC_FILES := crasher.cpp
-LOCAL_SRC_FILES_arm    := arm/crashglue.S
-LOCAL_SRC_FILES_arm64  := arm64/crashglue.S
-LOCAL_SRC_FILES_mips   := mips/crashglue.S
-LOCAL_SRC_FILES_mips64 := mips64/crashglue.S
-LOCAL_SRC_FILES_x86    := x86/crashglue.S
-LOCAL_SRC_FILES_x86_64 := x86_64/crashglue.S
-LOCAL_MODULE_PATH := $(TARGET_OUT_OPTIONAL_EXECUTABLES)
-LOCAL_MODULE_TAGS := optional
-LOCAL_CPPFLAGS := $(crasher_cppflags)
-LOCAL_SHARED_LIBRARIES := libbase liblog
-
-# The arm emulator has VFP but not VFPv3-D32.
-ifeq ($(ARCH_ARM_HAVE_VFP_D32),true)
-LOCAL_ASFLAGS_arm += -DHAS_VFP_D32
-endif
-
-LOCAL_MODULE := crasher
-LOCAL_MODULE_STEM_32 := crasher
-LOCAL_MODULE_STEM_64 := crasher64
-LOCAL_MULTILIB := both
-
-include $(BUILD_EXECUTABLE)
-
-include $(CLEAR_VARS)
-LOCAL_SRC_FILES := crasher.cpp
-LOCAL_SRC_FILES_arm    := arm/crashglue.S
-LOCAL_SRC_FILES_arm64  := arm64/crashglue.S
-LOCAL_SRC_FILES_mips   := mips/crashglue.S
-LOCAL_SRC_FILES_mips64 := mips64/crashglue.S
-LOCAL_SRC_FILES_x86    := x86/crashglue.S
-LOCAL_SRC_FILES_x86_64 := x86_64/crashglue.S
-LOCAL_MODULE_PATH := $(TARGET_OUT_OPTIONAL_EXECUTABLES)
-LOCAL_MODULE_TAGS := optional
-LOCAL_CPPFLAGS := $(crasher_cppflags) -DSTATIC_CRASHER
-LOCAL_FORCE_STATIC_EXECUTABLE := true
-LOCAL_SHARED_LIBRARIES := libbase liblog
-
-# The arm emulator has VFP but not VFPv3-D32.
-ifeq ($(ARCH_ARM_HAVE_VFP_D32),true)
-LOCAL_ASFLAGS_arm += -DHAS_VFP_D32
-endif
-
-LOCAL_MODULE := static_crasher
-LOCAL_MODULE_STEM_32 := static_crasher
-LOCAL_MODULE_STEM_64 := static_crasher64
-LOCAL_MULTILIB := both
-
-LOCAL_STATIC_LIBRARIES := libdebuggerd_handler libbase liblog
-
-include $(BUILD_EXECUTABLE)
diff --git a/debuggerd/crasher/crasher.cpp b/debuggerd/crasher/crasher.cpp
index 288f116..64a38dd 100644
--- a/debuggerd/crasher/crasher.cpp
+++ b/debuggerd/crasher/crasher.cpp
@@ -36,6 +36,19 @@
 #include "debuggerd/handler.h"
 #endif
 
+#if defined(__arm__)
+// See https://www.kernel.org/doc/Documentation/arm/kernel_user_helpers.txt for details.
+#define __kuser_helper_version (*(int32_t*) 0xffff0ffc)
+typedef void * (__kuser_get_tls_t)(void);
+#define __kuser_get_tls (*(__kuser_get_tls_t*) 0xffff0fe0)
+typedef int (__kuser_cmpxchg_t)(int oldval, int newval, volatile int *ptr);
+#define __kuser_cmpxchg (*(__kuser_cmpxchg_t*) 0xffff0fc0)
+typedef void (__kuser_dmb_t)(void);
+#define __kuser_dmb (*(__kuser_dmb_t*) 0xffff0fa0)
+typedef int (__kuser_cmpxchg64_t)(const int64_t*, const int64_t*, volatile int64_t*);
+#define __kuser_cmpxchg64 (*(__kuser_cmpxchg64_t*) 0xffff0f60)
+#endif
+
 #define noinline __attribute__((__noinline__))
 
 // Avoid name mangling so that stacks are more readable.
@@ -142,22 +155,36 @@
     fprintf(stderr, "where KIND is:\n");
     fprintf(stderr, "  smash-stack           overwrite a -fstack-protector guard\n");
     fprintf(stderr, "  stack-overflow        recurse until the stack overflows\n");
+    fprintf(stderr, "  nostack               crash with a NULL stack pointer\n");
+    fprintf(stderr, "\n");
     fprintf(stderr, "  heap-corruption       cause a libc abort by corrupting the heap\n");
     fprintf(stderr, "  heap-usage            cause a libc abort by abusing a heap function\n");
-    fprintf(stderr, "  nostack               crash with a NULL stack pointer\n");
+    fprintf(stderr, "\n");
     fprintf(stderr, "  abort                 call abort()\n");
     fprintf(stderr, "  assert                call assert() without a function\n");
     fprintf(stderr, "  assert2               call assert() with a function\n");
     fprintf(stderr, "  exit                  call exit(1)\n");
+    fprintf(stderr, "\n");
     fprintf(stderr, "  fortify               fail a _FORTIFY_SOURCE check\n");
+    fprintf(stderr, "  seccomp               fail a seccomp check\n");
+#if defined(__arm__)
+    fprintf(stderr, "  kuser_helper_version  call kuser_helper_version\n");
+    fprintf(stderr, "  kuser_get_tls         call kuser_get_tls\n");
+    fprintf(stderr, "  kuser_cmpxchg         call kuser_cmpxchg\n");
+    fprintf(stderr, "  kuser_memory_barrier  call kuser_memory_barrier\n");
+    fprintf(stderr, "  kuser_cmpxchg64       call kuser_cmpxchg64\n");
+#endif
+    fprintf(stderr, "\n");
     fprintf(stderr, "  LOG_ALWAYS_FATAL      call liblog LOG_ALWAYS_FATAL\n");
     fprintf(stderr, "  LOG_ALWAYS_FATAL_IF   call liblog LOG_ALWAYS_FATAL_IF\n");
     fprintf(stderr, "  LOG-FATAL             call libbase LOG(FATAL)\n");
+    fprintf(stderr, "\n");
     fprintf(stderr, "  SIGFPE                cause a SIGFPE\n");
     fprintf(stderr, "  SIGSEGV               cause a SIGSEGV at address 0x0 (synonym: crash)\n");
     fprintf(stderr, "  SIGSEGV-non-null      cause a SIGSEGV at a non-zero address\n");
     fprintf(stderr, "  SIGSEGV-unmapped      mmap/munmap a region of memory and then attempt to access it\n");
     fprintf(stderr, "  SIGTRAP               cause a SIGTRAP\n");
+    fprintf(stderr, "\n");
     fprintf(stderr, "  fprintf-NULL          pass a null pointer to fprintf\n");
     fprintf(stderr, "  readdir-NULL          pass a null pointer to readdir\n");
     fprintf(stderr, "  strlen-NULL           pass a null pointer to strlen\n");
@@ -235,6 +262,20 @@
                                                  MAP_SHARED | MAP_ANONYMOUS, -1, 0));
         munmap(map, sizeof(int));
         map[0] = '8';
+    } else if (!strcasecmp(arg, "seccomp")) {
+        syscall(99999);
+#if defined(__arm__)
+    } else if (!strcasecmp(arg, "kuser_helper_version")) {
+        return __kuser_helper_version;
+    } else if (!strcasecmp(arg, "kuser_get_tls")) {
+        return !__kuser_get_tls();
+    } else if (!strcasecmp(arg, "kuser_cmpxchg")) {
+        return __kuser_cmpxchg(0, 0, 0);
+    } else if (!strcasecmp(arg, "kuser_memory_barrier")) {
+        __kuser_dmb();
+    } else if (!strcasecmp(arg, "kuser_cmpxchg64")) {
+        return __kuser_cmpxchg64(0, 0, 0);
+#endif
     } else {
         return usage();
     }