Linux Kernel Debugging Setup With Gdb and Qemu

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make defconfig ARCH=x86_64
scripts/config -e DEBUG_INFO_DWARF5 -e GDB_SCRIPTS -e FRAME_POINTER
make LLVM=1 -j8
make LLVM=1 scripts_gdb
./scripts/clang-tools/gen_compile_commands.py

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#!/bin/sh

BUILDROOT="buildroot-2023.11.1"
BUILDROOT_EXT="${BUILDROOT}/output/images/rootfs.ext4"
BUILDROOT_OVERLAY="${BUILDROOT}/output/overlay"

set -e

build_action() {
  cd $1
  echo "[*] Building $1"
  make LLVM=1 -j `nproc`
}

build_image_action() {
  cd $1
  echo "[*] Building $1 (as we might want to install modules into the image)"
  make LLVM=1 -j `nproc`
  echo "[*] Building & installing $1 modules"
  make modules_install INSTALL_MOD_PATH="../$BUILDROOT_OVERLAY"
  echo "[*] Building $BUILDROOT"
  cd ..
  cd $BUILDROOT
  make -j `nproc`
}

lsp_action() {
  cd $1
  echo "[*] Generating $1 compile_commands.json"
  ./scripts/clang-tools/gen_compile_commands.py
  echo "[*] Generating $1 cscope"
  make -j `nproc` cscope
}

run_action() {
  echo "[*] Running qemu"
  qemu-kvm -kernel $1/arch/x86_64/boot/bzImage \
	  -drive file=$BUILDROOT_EXT,format=raw \
	  -net nic -net user,hostfwd=tcp::2222-:22 \
	  -nographic \
	  -append "root=/dev/sda console=ttyS0"
}

debug_action() {
  echo "[*] Opening gdb shell"
  foot sh -c "cd $PWD/$1; gdb -ex 'target remote localhost:1234' -ex 'source \
    vmlinux-gdb.py' $PWD/$1/vmlinux" 1>/dev/null 2>/dev/null &
  echo "[*] Running qemu w/gdbserver"
  qemu-system-x86_64 -kernel $1/arch/x86_64/boot/bzImage \
	  -drive file=$BUILDROOT_EXT,format=raw \
	  -nographic \
	  -append "nokaslr mitigations=off kpti=0 root=/dev/sda console=ttyS0" \
	  -S \
	  -s
}

case $1 in
  build) build_action $2;;
  buildimage) build_image_action $2;;
  run) run_action $2;;
  lsp) lsp_action $2;;
  debug) debug_action $2;;
  *)
    echo "[!] Wrong command" ;
    exit 1 ;;
esac