linux: where's the "real" segmentation fault handler?
linux, linux-kernel, segmentation-fault
Solution
Everything flows from the architectures trap table. This is usually called entry.S (split on x86 between entry_32 and entry_64.S) and has assembler linkage that does a number of things (depending on config) before heading into the C code of the kernel proper.
So an invalid memory access should enter through either page_fault or general_protection and will probably end up doing force_sig_info before finally being queued back to user space in send_signal (kernel/signal.c).
Problem
If I read/write/jump to an ummapped address ie. ``` .text .global _start _start: movl $1,%edx jmp *%edx ``` this causes a segmentation fault. I wonder, what's the actual part of the system (kernel) that intercepts reads/writes to unmapped addresses (how ?) and throws the "user mode" signal ?