Messages in this thread | | | Date | Tue, 30 Jun 2020 08:22:22 +0100 | From | Will Deacon <> | Subject | Re: [PATCH 0/4] arm64: kgdb/kdb: Fix single-step debugging issues |
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On Mon, Jun 29, 2020 at 02:20:11PM -0700, Doug Anderson wrote: > On Sat, May 16, 2020 at 1:20 AM liwei (GF) <liwei391@huawei.com> wrote: > > On 2020/5/14 8:34, Doug Anderson wrote: > > > On Sat, May 9, 2020 at 6:49 AM Wei Li <liwei391@huawei.com> wrote: > > >> > > >> This patch set is to fix several issues of single-step debugging > > >> in kgdb/kdb on arm64. > > >> > > >> It seems that these issues have been shelved a very long time, > > >> but i still hope to solve them, as the single-step debugging > > >> is an useful feature. > > >> > > >> Note: > > >> Based on patch "arm64: cacheflush: Fix KGDB trap detection", > > >> https://www.spinics.net/lists/arm-kernel/msg803741.html > > >> > > >> Wei Li (4): > > >> arm64: kgdb: Fix single-step exception handling oops > > >> arm64: Extract kprobes_save_local_irqflag() and > > >> kprobes_restore_local_irqflag() > > >> arm64: kgdb: Fix single-stepping into the irq handler wrongly > > >> arm64: kgdb: Set PSTATE.SS to 1 to reenable single-step > > >> > > >> arch/arm64/include/asm/debug-monitors.h | 6 ++++++ > > >> arch/arm64/kernel/debug-monitors.c | 28 ++++++++++++++++++++++++- > > >> arch/arm64/kernel/kgdb.c | 16 +++++++++++--- > > >> arch/arm64/kernel/probes/kprobes.c | 28 ++----------------------- > > >> 4 files changed, 48 insertions(+), 30 deletions(-) > > > > > > Just an overall note that I'm very happy that you posted this patch > > > series! It's always been a thorn in my side that stepping and > > > breakpoints were so broken on arm64 and I'm really excited that you're > > > fixing them. Now I'll have to get in the habit of using kgdb for more > > > than just debugging crashes and maybe I can use it more for exploring > > > how functions work more. :-) > > > > I'll also note that with your patch series I'm even seeing the "call" > > > feature of gdb working now. That has always been terribly broken for > > > me. > > > > > Thanks for reviewing and testing this series. > > Enjoy exploring the kernel with kgdb/kdb! :-) > > I'm curious to know if you plan another spin. The feedback you > received was fairly minor so it hopefully shouldn't be too hard. I'd > very much like to get your patches landed and I'd be happy to try to > address the feedback and spin them myself if you're no longer > available for it.
I'd welcome some feedback on the proposal I sent out at the end of last week:
https://lore.kernel.org/r/20200626095551.GA9312@willie-the-truck
which looks to solve some (all?) of these issues slightly differently, because it turns out we need to perform some low-level surgery for preempt-rt *anyway*...
I'm particularly keen to hear any thoughts concerning the reschedule on return to EL1 after handling an interrupt that hit during a step.
Will
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