Doesn't compile on ARM

[floyd-fuh]

gcc -std=c99 -pthread -O3 -Wall src/argon2.c src/argon2-core.c src/kat.c src/blake2/blake2b-ref.c src/argon2-ref-core.c src/argon2-test.c -Isrc  -o argon2
src/argon2-test.c: In function 'run':
src/argon2-test.c:189:9: warning: implicit declaration of function 'strdup' [-Wimplicit-function-declaration]
         in = ( uint8_t * )strdup( pwd );
         ^
src/argon2-test.c: In function 'benchmark':
src/argon2-test.c:40:5: error: impossible constraint in 'asm'
     __asm__ __volatile__ ( "rdtsc" : "=a" ( rax ), "=d" ( rdx ) : : );
     ^
src/argon2-test.c:40:5: error: impossible constraint in 'asm'
     __asm__ __volatile__ ( "rdtsc" : "=a" ( rax ), "=d" ( rdx ) : : );
     ^
src/argon2-test.c:40:5: error: impossible constraint in 'asm'
     __asm__ __volatile__ ( "rdtsc" : "=a" ( rax ), "=d" ( rdx ) : : );
     ^

System:

$ uname -a
Linux odroid-003 3.8.13.23 #1 SMP PREEMPT Tue Jun 10 14:54:36 UTC 2014 armv7l armv7l armv7l GNU/Linux

A configure script would be nice. The code doesn't honor $CC.

[veorq]

Thanks for reporting this. Indeed this code is not compatible with ARM processors. For compatibility we can disable high-precision timing in ARM, and/or use the SysTick feature in most recent ARMs (see http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.faqs/ka8713.html, https://github.com/google/benchmark/blob/master/src/cycleclock.h).

[floyd-fuh]

Just tried something like that. Seems like it could be a little pain to make sure it works with all the ARM versions/precompiler macros. My short attempt was this one ripped out of gperftools with the newest git version of argon2, where argon2-test.c was renamed to main.c. Obviously this is highly flawed (we don't even have a return value for all cases):

#elif __arm__ // TODO: V6 is the earliest arch that has a standard cyclecount, will not work for pre-V6
    uint32_t pmccntr;
    uint32_t pmuseren;
    uint32_t pmcntenset;
    // Read the user mode perf monitor counter access permissions.
    __asm__ __volatile__ ("mrc p15, 0, %0, c9, c14, 0" : "=r" (pmuseren));
    if (pmuseren & 1) {  // Allows reading perfmon counters for user mode code.
      __asm__ __volatile__ ("mrc p15, 0, %0, c9, c12, 1" : "=r" (pmcntenset));
      if (pmcntenset & 0x80000000ul) {  // Is it counting?
        __asm__ __volatile__ ("mrc p15, 0, %0, c9, c13, 0" : "=r" (pmccntr));
        // The counter is set up to count every 64th cycle
        return pmccntr << 6;
      }
    }

However the benchmarking seems to produce wrong results:

$ ./argon2-plain/argon2 b Argon2d 1 pass(es) 1 Mbytes 1 threads: 4190208.00 cpb 4190208.00 Mcycles Argon2i 1 pass(es) 1 Mbytes 1 threads: 4307550208.00 cpb 4307550208.00 Mcycles 0.0217 seconds

Argon2d 1 pass(es) 1 Mbytes 2 threads: 4194304.00 cpb 4194304.00 Mcycles Argon2i 1 pass(es) 1 Mbytes 2 threads: 4307550208.00 cpb 4307550208.00 Mcycles 0.0224 seconds

Argon2d 1 pass(es) 1 Mbytes 4 threads: 4194304.00 cpb 4194304.00 Mcycles Argon2i 1 pass(es) 1 Mbytes 4 threads: 4307550208.00 cpb 4307550208.00 Mcycles 0.0146 seconds

Argon2d 1 pass(es) 1 Mbytes 6 threads: 4194304.00 cpb 4194304.00 Mcycles Argon2i 1 pass(es) 1 Mbytes 6 threads: 4240441344.00 cpb 4240441344.00 Mcycles 0.0168 seconds

Argon2d 1 pass(es) 1 Mbytes 8 threads: 4194304.00 cpb 4194304.00 Mcycles Argon2i 1 pass(es) 1 Mbytes 8 threads: 4307550208.00 cpb 4307550208.00 Mcycles 0.0155 seconds

Argon2d 1 pass(es) 1 Mbytes 16 threads: 4194304.00 cpb 4194304.00 Mcycles Argon2i 1 pass(es) 1 Mbytes 16 threads: 4307550208.00 cpb 4307550208.00 Mcycles 0.0255 seconds

I suppose I let the maintainers figure this out, but I'm happy to help further testing on ARM.

[floyd-fuh]

Btw. it doesn't compile on 32bit either (compiled with gcc, regular "make"):

gcc -std=c99 -pthread -O3 -Wall -g src/argon2.c src/core.c src/kat.c src/blake2/blake2b-ref.c src/ref.c src/main.c -Isrc  -o argon2
src/main.c: In function 'run':
src/main.c:204:9: warning: implicit declaration of function 'strdup' [-Wimplicit-function-declaration]
         in = ( uint8_t * )strdup( pwd );
         ^
src/main.c: In function 'benchmark':
src/main.c:57:5: error: inconsistent operand constraints in an 'asm'
     __asm__ __volatile__ ( "rdtsc" : "=a" ( rax ), "=d" ( rdx ) : : );
     ^
src/main.c:57:5: error: inconsistent operand constraints in an 'asm'
     __asm__ __volatile__ ( "rdtsc" : "=a" ( rax ), "=d" ( rdx ) : : );
     ^
src/main.c:57:5: error: inconsistent operand constraints in an 'asm'
     __asm__ __volatile__ ( "rdtsc" : "=a" ( rax ), "=d" ( rdx ) : : );
     ^
make: *** [argon2] Error 1

$ uname -a
Linux user-xubuntu-32-vbox 3.13.0-39-generic #66-Ubuntu SMP Tue Oct 28 13:31:23 UTC 2014 i686 i686 i686 GNU/Linux

[veorq]

Thanks for the update! For the latest message about 32-bit, what's the CPU? (cat /proc/cpuinfo?)

[veorq]

@sneves just pushed a change that should solve the issue on 32-bit x86.

[floyd-fuh]

Confirmed, compiles on 32bit now. Leaving the bug open for ARM.

[sneves]

Things should build OK now on ARM. Exceptions are:

• make OPT=TRUE does not build on ARM, since it is x86-specific;
• make bench also does not work by the same reason it didn't before---no portable timestamp counter available.

I can use Linux's perf_event API with PERF_COUNT_HW_CPU_CYCLES to read cycles, but that will be (obviously) Linux specific.