On Mon, Feb 16, 2015 at 3:22 PM, Andrew Haley <aph@xxxxxxxxxx> wrote: > [off-topic for gcc; redirect to gcc-help] > > On 15/02/15 22:00, Niklaus wrote: > >> I'm trying to do a live update of a function without killing or >> stopping the program. This is a single threaded application which runs >> something similar to the below code. Maximum time is spent in the >> while(1) loop. >> >> What i want to do is compile with gcc-4.8 with -pg and -mfentry and >> then call function g() and then do the int y=x*3 and everything else. >> I have thought of an idea about registering a sigHandler and then >> setjmp/longjmp to g.. Please note i'm trying to fix some bugs here >> without stopping the process. >> >> I want to do something akin to Kgraft/Kpatch or Erlang's dynamic >> updation system. >> >> Can you please help me by throwing some light on this . > > OK, I'll bite. You want to be able to break out of a function while > it is running and return to some other function. There's no portable > way to do that is general. However, there are things which are easy, > such as calling the loop body via a function pointer. > Thanks. I'm only looking at the gcc compiler on linux platform with binutils x86 and x86_64. Can you help with an example of mfentry ?
