On Fri, Mar 07, 2025 at 05:27:41PM -0800, Song Liu wrote: > With proper exception boundary detection, it is possible to implment > arch_stack_walk_reliable without sframe. > > Note that, arch_stack_walk_reliable does not guarantee getting reliable > stack in all scenarios. Instead, it can reliably detect when the stack > trace is not reliable, which is enough to provide reliable livepatching. > > This version has been inspired by Weinan Liu's patch [1]. > > [1] https://lore.kernel.org/live-patching/20250127213310.2496133-7-wnliu@xxxxxxxxxx/ > Signed-off-by: Song Liu <song@xxxxxxxxxx> This looks incomplete. The reliable unwinder needs to be extra paranoid. There are several already-checked-for errors in the unwinder that don't actually set the unreliable bit. There are likely other failure modes it should also be checking for. For example I don't see where it confirms that the unwind completed to the end of the stack (which is typically at a certain offset). See for example all the error conditions in the x86 version of arch_stack_walk_reliable() and in arch/x86/kernel/unwind_frame.c. -- Josh
