perf stat event raw encoding

Hi,

I would like to use a hardware counter that would allow me to measure the number of instructions in a program that make and acces in the main memory(RAM) using the perf tool. For example perf stat -e /rffc7 ./test_program allows to measure the number of floating intructions of a program who as the name test_program on intel architecture. I am currently on a ThunderX2 system with a debian and I would like to know which raw encoding to use with the perf tool event in order to measure the number of intructions causing access in main memory within a program.