GDB Common Commands

"Print Call stack"

(GDB) bt #0 epoll_wait () at bionic/libc/arch-arm/syscalls/epoll_wait. S:10 #1 0x401275ea in Android::looper::p ollinner ([email protected]=0x747fd3f0, timeoutmillis=<optimized out [email protected]=85688516] at system/core/libutils/looper.cpp:223 #2 0x40127814 in Android::Looper:: Pollonce (this=0x747fd3f0, timeoutmillis=85688516, [email protected]=0x0, [email protected]=0x0, [email  protected]=0x0) at system/core/libutils/looper.cpp:191 #3 0x401d13dc in pollonce (timeoutmillis=<optimized o Ut&gt, this=<optimized out>) at system/core/include/utils/looper.h:176 #4 Android::nativemessagequeue:: Pollonce (this=0x747fef58, env=0x4151dfa8, timeoutmillis=<optimized out>) at frameworks/base/core/jni/android_ os_messagequeue.cpp:97 #5 0x4153d310 in Dvmplatforminvoke () @ dalvik/vm/arch/arm/calleabi.s:258 #6 0x4156d8de in DvmCa Lljnimethod (Args=0x6d5a5e18, presult=0x4151f568, Method=0x6d60e2d8, self=0x4151f558) at dalvik/vm/Jni.cpp:1159 #7 0x41546724 in Dalvik_mterp () at dalvik/vm/mterp/out/interpasm-armv7-a-neon.s:16240 

"Switch to the nth layer of the call stack"

(GDB) F-one #11 0x41587ff6 in dalvik_java_lang_reflect_method_invokenative (args=<optimized out>, pResult= 0x4151f568) at dalvik/vm/native/java_lang_reflect_method.cpp:101101                    Noaccesscheck);

"Show assembly Code"

 (GDB) disassemble Dump of assembler code for function dalvik_java_lang_reflect_method_invokenative (U4 const*, jvalue*):    0x41587f7c <+0>: Stmdb sp!, {r0, r1, R2, R4, R5, R6, R7, R8, R9, R10, R11, LR} 0x41587f80 <+4>:     ADD.W R4, R0, #12 0x41587f84 <+8>: ldmia.w R4, {r4, R8, R9} 0x41587f88 <+12>: mov R5, R0     0x41587f8a <+14&gt: mov r11, R1 0x41587f8c <+16>: Ldr R6, [R0, #4] 0x41587f8e <+18>: Ldr R7, [R0, #8] 0x41587f90 <+20>: LDR.W R10, [R0, #28] 0x41587f94 <+24>: Ldr R1, [R5 , #24] 0x41587f96 <+26>: mov r0, r4 0x41587f98 <+28>: BL 0x4158e828 <dvmslottomethod (Clas sobject*, int) > 0x41587f9c <+32>: Ldr R3, [R0, #4] ... (GDB) Disassemble 0x401b406c Dump of assembler code for function _jnienv::callstaticvoidmethod (_jclass*, _jmethodid*, ... ): 0x401b4058 <+0>: Push {R2, r3} 0x401b405a <+2>: Push {r0, r1, R4, LR} 0x401b405c <+4>: Add R3, SP, #16 0x401b405e <+6>: Ldr R4, [R0 , #0] 0x401b4060 <+8>: LDR.W R2, [R3], #4 0x401b4064 <+12>: LDR.W R4, [R4, #568];     0x238 0x401b4068 <+16>: str R3, [SP, #4] 0x401b406a <+18>: BLX R4 0x401b406c <+20>: LDMIA.W sp!, {R2, R3, R4, LR} 0x401b4070 <+24>: Add sp, #8 0x401b4072 <+26>: bx LR En D of Assembler dump.

"View Current Register Value"

(GDB) Info reg r0             0x0    0 R1             0x4151dfa8    1095884712 R2             0x10    0             R3 0x0 R4 0x4175c138    1098236216 R5             0x6d68eeb8    1835593400 R6             0x0    0 R7             0x42dc4350    1121731408 R8             0x42dc4278    1121731192 r9             0x416f12a8    1097798312 r10            0x0    0 R11            0x4151f568    1095890280 R12            0xbe88e2d8    3196642008 sp             0xbe88e6c0    0xbe88e6c0 LR             0X41587FF7    1096318967 pc             0x41587ff6    0x41587ff6 <dalvik_java_lang_reflect_method_invokenative ( U4 const*, jvalue*) +122> cpsr           0x200f0030    537854000

"Show all threads for the current process"

 (GDB) info thread ID Target ID Frame 1992 LWP epoll_wait () at Bionic/libc/arch-arm/syscalls /epoll_wait. S:10 LWP 2076 epoll_wait () at bionic/libc/arch-arm/syscalls/epoll_wait. S:10 LWP 1815 __futex_syscall3 () at Bionic/libc/arch-arm/bionic/futex_arm. s:39 LWP 1814 recvmsg () at bionic/libc/arch-arm/syscalls/recvmsg. S:9 One LWP 1808 __futex_syscall3 () at Bionic/libc/arch-arm/bionic/futex_arm. s:39 LWP 1817 __futex_syscall3 () at Bionic/libc/arch-arm/bionic/futex_arm. s:39 9 LWP 1813 __rt_sigtimedwait () at bionic/libc/arch-arm/syscalls/__rt_sigtimedwait. S:10 8 LWP 1819 __futex_syscall3 () at Bionic/libc/arch-arm/bionic/futex_arm. s:39 7 LWP 2062 __futex_syscall3 () at Bionic/libc/arch-arm/bionic/futex_arm. s:39 6 LWP 1818 __futex_syscall3 () at Bionic/libc/arch-arm/bionic/futex_arm. s:39 5 LWP 1826 __ioctl () at BioniC/libc/arch-arm/syscalls/__ioctl. S:9 4 LWP 2320 __ioctl () at Bionic/libc/arch-arm/syscalls/__ioctl. S:9 3 LWP 2210 epoll_wait () at bionic/libc/arch-arm/syscalls/epoll_wait. S:10 2 LWP 1824 __ioctl () at Bionic/libc/arch-arm/syscalls/__ioctl. S:9 * 1 LWP 1804 epoll_wait () at bionic/libc/arch-arm/syscalls/epoll_wait. S:10

"Switch Threads"

(GDB) T 9 [Switching to Thread 9 (LWP 1813)] #0  __rt_sigtimedwait () at Bionic/libc/arch-arm/syscalls/__rt_sigtimedwai T.s:10        mov     r7, IP (gdb) bt #0  __rt_sigtimedwait () at bionic/libc/arch-arm/syscalls/__rt_sigtimedwait. S:10 #1  0x400b039c in sigwait (set=<optimized out>, sig=0x7194ad48) at bionic/libc/bionic/sigwait.cpp:43 #2 C6/>0x415716ca in Signalcatcherthreadstart (arg=<optimized out>) at dalvik/vm/signalcatcher.cpp:287 #3  0x41574176 in Internalthreadstart (ARG=0X747FD9D8) at dalvik/vm/thread.cpp:1746 ...

"View Memory Value"

(gdb) x/32wx 0x7194ad48 0x7194ad48:    0x00000004    0x6fbf3830 0x415dabd8 0x41573619    0x7194ad58:    0x41700880    0x42dc0768    0x00000005    0x00000001 0x7194ad68:    0x00000001    0x00000000    0x6fbf3830    0x747fd9d8 0x7194ad78:    0x415dabd8    0xbe88e598    0x747fd9d8    0x41574129 0x7194ad88:    0x7184d000    0x415db07c    0x400e92ec    0x41574177 0x7194ad98:    0x747fd9d8    0x00010002    0x747fd9f8    0x41700880 0x7194ada8:    0x7194add0    0x747f85a8    0x41574129    0x400aa1d4 0x7194adb8:    0x747fd9d8    0x747f85a8    0x7194add0    0x00000001  (gdb) x/20c 0XBE88EB48 0xbe88eb48: + '    /' + '    s '    98 ' B ' "I ' n ' []    : ' + '    /'    118 ' V ' 0xbe88eb50:    101 ' e '    n ' ['    d '    111 ' o ' '    R '/'    98 ' B '    0xbe88eb58: ' n ' + '    : ' + '    /'    s '

"Show Symbols"

(GDB) p * (method*) 0x6d682328 $ = {Clazz = 0x41755dc0, AccessFlags = 9, Methodindex = 0, registerssize = 6, outssize = 3,  Inssize = 1, name = 0x6f8c1862 <address 0x6f8c1862 out of bounds>, prototype = {Dexfile = 0x6d5aac48,  protoidx = 3750}, shorty = 0x6f88be67 <address 0x6f88be67 out of bounds>, Insns = 0x6f745d98, Jniarginfo = 0, Nativefunc = 0x0 , Fastjni = False, Noref = False, Shouldtrace = False,  

"Several configurations"

Set print pretty on: the structure looks pretty
Set Print Union: Sets whether the Union data is explicitly inside when the structure is displayed.
Set Print Vtbl: When this option is turned on, GDB will display the virtual function table in a more structured format. It is turned off by default.
For example:

(GDB)  Set print pretty on (GDB) p * (method*) 0x6d682328 $ = {   Clazz = 0x41755dc0,    accessflags = 9,    methodindex = 0,< C4/>registerssize = 6,    outssize = 3,    inssize = 1,    name = 0x6f8c1862 <address 0x6f8c1862 out of bounds>,< C8/>prototype = {     Dexfile = 0x6d5aac48,      protoidx = 3750   },    shorty = 0x6f88be67 <address 0x6f88be67 Out of Bounds>,    Insns = 0x6f745d98,    jniarginfo = 0,    nativefunc = 0x0,    Fastjni = False,    Noref = False,    Shouldtrace = False,    Registermap = 0x71a557d8,    inprofile = false}

"namespace display error problem in C + +"

(GDB)  P * (art::scopedobjectaccess *) 0xbe81e618a syntax error in expression, near ') 0xbe81e618 '.

Solution: Use single quotation marks to expand the type name, such as:

(GDB) p * (' art::scopedobjectaccess ' *) 0xbe81e618$19 = {  <art::ScopedObjectAccessUnchecked> = {    <art: :scopedobjectaccessalreadyrunnable> = {      self_ = 0xb4f07800,      env_ = 0xb4f512b0,      vm_ = 0xb4f5c280    },< C6/>members of art::scopedobjectaccessunchecked:    tsc_ = {      self_ = 0xb4f07800,      Thread_state_ = Art:: Krunnable,      old_thread_state_ = art::knative,       Expected_has_no_thread_ = False    }  }, <no data Fields>}

"How to get the offset of a class member in a class"

"How to get the size of a class"

(GDB) p ((' art::scopedobjectaccess ' *) 0) +1$33 = (art::scopedobjectaccess *) 0x1c

"Set Code search Path"

(GDB) directory ~/disk/android/source directories searched:/home/disk/android: $cdir: $CWD
(gdb) list67      }68      //uncompress an encoded reference from its bit representation.70      mirrortype* Uncompress () const shared_locks_required (locks::mutator_lock_) {        uintptr_t as_bits = kpoisonreferences? Reference_: reference_;72        return reinterpret_cast<mirrortype*> (as_bits);      }74      Friend Class object;76    

GDB Common Commands