I'm using ftrace to get trace for sys_read call in kernel. With function or graph tracers, setting set_ftrace_filter to sys_write fails
# echo sys_read > tracing/set_ftrace_filter
-sh: echo: write error: Invalid argument
Here are my ftrace kconfigs
# zcat /proc/config.gz | grep -i ftrace
CONFIG_HAVE_DYNAMIC_FTRACE=y
CONFIG_HAVE_FTRACE_MCOUNT_RECORD=y
CONFIG_FTRACE=y
CONFIG_FTRACE_SYSCALLS=y
CONFIG_DYNAMIC_FTRACE=y
CONFIG_FTRACE_MCOUNT_RECORD=y
# CONFIG_FTRACE_STARTUP_TEST is not set
I do not have sys_read or sys_write in available_filter_functions as well. I'm using 3.14 kernel on an arm platform. Please help.
If you haven't figured already
# egrep -i "^sys_read$|^sys_write$" tracing/available_filter_functions
SyS_read
SyS_write