kgdb has traditionally adopted a no safety rails approach to breakpoint placement. If the debugger is commanded to place a breakpoint at an address then it will do so even if that breakpoint results in kgdb becoming inoperable.
A stop-the-world debugger with memory peek/poke intrinsically provides its operator with the means to hose their system in all manner of exciting ways (not least because stopping-the-world is already a DoS attack ;-) ). Nevertheless the current no safety rail approach is difficult to defend, especially given kprobes can provide us with plenty of machinery to mark the parts of the kernel where breakpointing is discouraged. This patchset introduces some safety rails by using the existing kprobes infrastructure and ensures this will be enabled by default on architectures that implement kprobes. At present it does not cover absolutely all locations where breakpoints can cause trouble but it will block off several avenues, including the architecture specific parts that are handled by arch_within_kprobe_blacklist(). Daniel Thompson (3): kgdb: Honour the kprobe blocklist when setting breakpoints kgdb: Use the kprobe blocklist to limit single stepping kgdb: Add NOKPROBE labels on the trap handler functions include/linux/kgdb.h | 19 +++++++++++++++++++ kernel/debug/debug_core.c | 25 +++++++++++++++++++++++++ kernel/debug/gdbstub.c | 10 +++++++++- kernel/debug/kdb/kdb_bp.c | 17 +++++++++++------ kernel/debug/kdb/kdb_main.c | 10 ++++++++-- lib/Kconfig.kgdb | 14 ++++++++++++++ 6 files changed, 86 insertions(+), 9 deletions(-) -- 2.25.4 _______________________________________________ Kgdb-bugreport mailing list Kgdb-bugreport@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kgdb-bugreport
