[PATCH v4 00/13] arm64: debug: remove hook registration, split exception entry

[Will Deacon]

Hi Ada,

On Fri, Jun 20, 2025 at 10:11:54PM +0100, Ada Couprie Diaz wrote:
> This series simplifies the debug exception entry path by removing handler
> registration mechanisms for the debug exception handlers, a holdover from
> the arm kernel, as well as the break and stepping handlers.
> This moves much of the code related to debug exceptions outside of
> `mm/fault.c` where it didn't make much sense.
> This allows us to split the debug exception entries: going from one common
> path per EL for all debug exceptions to a unique one per exception and EL.
> 
> The result is a much simpler and fully static exception entry path, which
> we tailor to the different exceptions and their constraints.

I think this looks great, thanks. I've left Reviewed-bys on everything
and a minor nit on the last patch. However, the linker is less
enthusiastic than me because it fails with this series and 'allnoconfig':

  ld.lld: error: undefined symbol: do_breakpoint
  >>> referenced by entry-common.c
  >>>               arch/arm64/kernel/entry-common.o:(el1_breakpt) in archive vmlinux.a
  >>> referenced by entry-common.c
  >>>               arch/arm64/kernel/entry-common.o:(el0_breakpt) in archive vmlinux.a

  ld.lld: error: undefined symbol: do_watchpoint
  >>> referenced by entry-common.c
  >>>               arch/arm64/kernel/entry-common.o:(el1_watchpt) in archive vmlinux.a
  >>> referenced by entry-common.c
  >>>               arch/arm64/kernel/entry-common.o:(el0_watchpt) in archive vmlinux.a
  make[2]: *** [scripts/Makefile.vmlinux:91: vmlinux] Error 1

Please can you take a look?

Will