Debugging Applications on Linux
On Linux, Intel® Pin provides application debugging capabilities utilizing GDB server protocol. This allows the user to use GDB to debug the emulated application. Intel® SDE extends this capability with disassembly and emulated registers support.
You need two windows to debug your application. In the first window you launch Intel® SDE to run the application and in the second window you run GDB.
Window number 1:
% sde -skx -debug -- myapp
The “-debug” knob sets several pin knobs. This will print out a port number you will need to connect-to from within gdb in the second window.
Window number 2:
% gdb myapp
In GDB paste the target remote string that was provided when launching Intel® SDE and you can start your debugging session.
Example:
Window number 1:
% sde -skx -debug -- avg512
Application stopped until continued from debugger.
Start GDB, then issue this command at the (gdb) prompt:
target remote :38049
Window number 2:
% gdb avg512
GNU gdb (GDB) 9.1
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License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
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There is NO WARRANTY, to the extent permitted by law.
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Type "show configuration" for configuration details.
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<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from obj-intel64/avg_avx512.intel64.noopt.exe...
(gdb) target remote :38049
Remote debugging using :38049
0x00002aaaaaaac1f0 in _start () from /lib64/ld-linux-x86-64.so.2
(gdb) break main
Breakpoint 1 at 0x401666: file avg_avx512.c, line 138.
(gdb) cont
Continuing.
Breakpoint 1, main (argc=1, argv=0x7fffffffd3b8) at avg_avx512.c:138
138 work_mode_t mode = ALL;
(gdb) list
135
136 int main(int argc, char *argv[])
137 {
138 work_mode_t mode = ALL;
139 unsigned int n = array_size;
140
141 if (argc >= 2) {
142 if (strcmp(argv[1], "scalar") == 0)
(gdb) break calc_avg_vector
Breakpoint 2 at 0x401285: file avg_avx512.c, line 87.
(gdb) c
Continuing.
Breakpoint 2, calc_avg_vector (in=0x256, n=4061683432, avg=0x2aaaf1b5d9a0, stddev=0x7fffffffd018)
at avg_avx512.c:87
87 {
(gdb) next
89 unsigned int nn = (n/8)*8;
...
(gdb) x/10i $pc
=> 0x4013b8 <calc_avg_vector+307>: vmovups -0x290(%rbp),%ymm0
0x4013c0 <calc_avg_vector+315>: vcvtps2pd %ymm0,%zmm0
0x4013c6 <calc_avg_vector+321>: vmovups %zmm0,-0x170(%rbp)
0x4013d0 <calc_avg_vector+331>: vmovups -0x170(%rbp),%zmm0
0x4013da <calc_avg_vector+341>: vmovups %zmm0,-0x130(%rbp)
0x4013e4 <calc_avg_vector+351>: vmovups -0x270(%rbp),%zmm0
0x4013ee <calc_avg_vector+361>: vmovups -0x130(%rbp),%zmm1
0x4013f8 <calc_avg_vector+371>: vaddpd %zmm1,%zmm0,%zmm0
0x4013fe <calc_avg_vector+377>: vmovupd %zmm0,-0xf0(%rbp)
0x401408 <calc_avg_vector+387>: vmovups -0xf0(%rbp),%zmm0
(gdb) p/x $zmm1.v16_int32
$2 = {0xaacce4a0, 0x2aaa, 0x1, 0x0, 0xaacce148, 0x2aaa, 0xaaab4ccc, 0x2aaa, 0x0, 0x0, 0xf216a600,
0x2aaa, 0x1, 0x2aaa, 0x0, 0x0}
...
As you can see in this example, all GDB commands are available. You can set breakpoints, see the values of variables and registers, examine the code and memory, and use the debugging next, step and continue as in any debugging session.
Note
You can use GDB print command to dump also emulated registers. This means that you can print ZMM and mask registers even on machines that do not support Intel® AVX-512 Architecture.
Intel® SDE GBD Custom Commands
Intel® SDE extends GDB commands via the monitor GDB command. You can use the monitor help command to see these extended commands.
(gdb) monitor help
general - General commands.
breakpoints - Breakpoint commands.
tracepoints - Tracepoint commands.
registers - Register names.
sde - Commands specific to Intel(R) SDE.
type "help <category>" for help on commands in that category.
(gdb) monitor help sde
xdis ADDRESS NBYTES - Disassemble NBYTES at ADDRESS
xdis-xml ADDRESS NBYTES - Disassemble NBYTES at ADDRESS with XML formatting
register-information - Description of supported registers
tile-get-config - Dump the AMX state configurations
tile-get-regs <as type> - Dump the TMM tiles.
type options: flat, int16, int16x2, int16x4,
int32, int8, int8x4, uint32. use "dec" for decimal base
tile-get-reg N <as type> - Dump the TMM tile N.
type options: flat, int16, int16x2, int16x4,
int32, int8, int8x4, uint32. use "dec" for decimal base
k-set-reg N VALUE - Set the mask register N to hex VALUE
zmm-set-reg N VALUE - Set the ZMM register N to hex VALUE.
k-get-regs - Dump the mask registers
k-get-reg N - Dump the mask register N
zmm-get-reg N - Dump the ZMM register N in various formats
zmm-get-regs - Dump the ZMM registers in hex
With our example:
(gdb) monitor xdis 0x4013b8 40
XDIS 00000000004013b8: AVX C5FC108570FDFFFF vmovups ymm0, ymmword ptr [rbp-0x290]
XDIS 00000000004013c0: AVX512EVEX 62F17C485AC0 vcvtps2pd zmm0, ymm0
XDIS 00000000004013c6: AVX512EVEX 62F17C48118590FEFFFF vmovups zmmword ptr [rbp-0x170], zmm0
XDIS 00000000004013d0: AVX512EVEX 62F17C48108590FEFFFF vmovups zmm0, zmmword ptr [rbp-0x170]
(gdb) monitor zmm-get-reg 1
zmm01 = {
v16_float = {-3.63963e-13, 1.5305e-41, 1.4013e-45, 0, -3.6394e-13, 1.5305e-41, -3.0429e-13,
1.5305e-41, 0, 0, -2.9839e+30, 1.5305e-41, 1.4013e-45, 1.5305e-41, 0, 0},
v8_double = {2.31779e-310, 4.94066e-324, 2.31779e-310, 2.31779e-310, 0, 2.31784e-310, 2.31764e-310, 0},
v64_int8 = {-96, -28, -52, -86, -86, 42, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 72, -31, -52, -86, -86, 42,
0, 0, -52, 76, -85, -86, -86, 42, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -90, 22, -14, -86,
42, 0, 0, 1, 0, 0, 0, -86, 42, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
v32_int16 = {-7008, -21812, 10922, 0, 1, 0, 0, 0, -7864, -21812, 10922, 0, 19660, -21845, 10922, 0, 0,
0, 0, 0, -23040, -3562, 10922, 0, 1, 0, 10922, 0, 0, 0, 0, 0},
v16_int32 = {-1429412704, 10922, 1, 0, -1429413560, 10922, -1431614260, 10922, 0, 0, -233396736, 10922,
1, 10922, 0, 0},
v8_int64 = {46912498361504, 1, 46912498360648, 46912496159948, 0, 46913694377472, 46909632806913, 0},
v64_uint8 = {160, 228, 204, 170, 170, 42, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 72, 225, 204, 170, 170, 42, 0,
0, 204, 76, 171, 170, 170, 42, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 166, 22, 242, 170, 42, 0
0, 1, 0, 0, 0, 170, 42, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
v32_uint16 = {58528, 43724, 10922, 0, 1, 0, 0, 0, 57672, 43724, 10922, 0, 19660, 43691, 10922, 0, 0, 0,
0, 0, 42496, 61974, 10922, 0, 1, 0, 10922, 0, 0, 0, 0, 0},
v16_uint32 = {2865554592, 10922, 1, 0, 2865553736, 10922, 2863353036, 10922, 0, 0, 4061570560, 10922,
1, 10922, 0, 0},
v8_uint64 = {46912498361504, 1, 46912498360648, 46912496159948, 0, 46913694377472, 46909632806913, 0}
}
Intel® SDE application debugging provides an advanced breakpoints options that use binary instrumentation to detect the triggering event. More information is available in the monitor help breakpoints command.