Debugging Linux Kernel using ftrace Part17 - Finding out how user space code gets into kernel

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We can find out what is the first kernel function called when the user space code gets into the kernel using 'max_graph_depth' file. This file can only be used with the function tracer.

max_graph_depth file contains the maximum depth it will trace into a function. Default value is 0, which means unlimited.

If you 'echo 1 > max_graph_depth', it will only the trace the first function and ignore the other functions.


You can see, 'do_syscall_64()' is the function through which the user space code gets into the kernel space.

If we want to find out the next function after 'do_syscall_64()', 'echo 2 > max_graph_depth'


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