In 2010, I tried to use callgrind to profile a project on Arm, after having used it to great effect on x86, and discovered that because of the variety of ways to return (and call!) functions on Arm, callgrind was unable to reliably identify function call and return sites. It created cycles in the call graph and even failed to record a function's self measurements correctly (because it could not tell when you left that function).
The problem boiled down to the valgrind frontend code that splits things up into basic blocks being incapable of having an instruction be both a conditional jump and a function call / return at the same time. That never happens on x86, but of course this is possible (and totally normal) on 32-bit Arm. Sadly, I ran out of time to try to re-architect this code and had to move on to other projects.
The problem boiled down to the valgrind frontend code that splits things up into basic blocks being incapable of having an instruction be both a conditional jump and a function call / return at the same time. That never happens on x86, but of course this is possible (and totally normal) on 32-bit Arm. Sadly, I ran out of time to try to re-architect this code and had to move on to other projects.
Over 12 years later, it looks like it never did get fixed: https://bugs.kde.org/show_bug.cgi?id=252091