Re: [Valgrind-users] Valgrind on arm system startup message

[John R. <jr...@bi...>]

>> To make progress in the meantime, replace those 32 bits by the two instructions
>>      mov r0,#0
>>      mov r1,#0
>> which clear general registers r0 and r1.  This is a guess that zeroes
>> mean "this CPU has no such hardware assist".  The libcrypto software
>> will choose slower but equivalent code, instead of using
>> any special hardware assist.

> How do I "replace" those 32 bits with instructions before the library is loaded at run-time ?

If you have the source for libcrypto.so.1.1, which is in software package openssl-1.1.0h
(or openssl-libs-1.1.0h depending on your Linux distro) then in file crypto/armv4cpuid.pl
change to:
=====
_armv7_tick:
#ifdef  __APPLE__
         mrrc    p15,0,r0,r1,c14         @ CNTPCT
#else
      @  mrrc    p15,1,r0,r1,c14         @ CNTVCT  <<< COMMENTED OUT
	mov r0,#0    @ replacement for valgrind-3.13
	mov r1,#0    @ replacement for valgrind-3.13
#endif
         bx      lr
=====
Build from the modified source, and install the modified shared library.

If you don't have source, then use a hex (binary) editor such as hexedit.
Assemble a one-instruction program "mov r0,#0", then over-write the bytes
for "mrrc p15,1,r0,r1,cr14" with the bytes for "mov r0,#0".  If the code
is 32-bit ARM mode, then that's all there is to do.  If the code is 16-bit
Thumb mode, then over-write the second 16-bit word with "mov r1,#0".
Your initial report said "(thumb)", but perhaps that is inaccurate.