Re: [PATCH 0/4] arm64: kgdb/kdb: Fix single-step debugging issues
Hi, On Wed, Jul 8, 2020 at 3:06 PM Will Deacon wrote: > > Doug, > > On Mon, Jul 06, 2020 at 02:37:05PM -0700, Doug Anderson wrote: > > On Tue, Jun 30, 2020 at 12:22 AM Will Deacon wrote: > > > On Mon, Jun 29, 2020 at 02:20:11PM -0700, Doug Anderson wrote: > > > > On Sat, May 16, 2020 at 1:20 AM liwei (GF) wrote: > > > > > On 2020/5/14 8:34, Doug Anderson wrote: > > > > > > On Sat, May 9, 2020 at 6:49 AM Wei Li 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 > > > > Actually, I'm pretty sure that patch #1 of Wei Li's patch series would > > still be needed. Would you object to landing it now just to get one > > patch outta the way? > > > > https://lkml.kernel.org/r/20200509214159.19680-2-liwei...@huawei.com > > I've grabbed patch 1, cheers. Thanks! > > > 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. > > > > Thanks for the pointer! Unfortunately this is yet another area that > > I'm keenly interested in it working but pretty much clueless about how > > this whole area of the system works. :-| > > I'm also keen to fix it up but, although I roughly know how it works, I > always fail to find the time to spend on it. :-| Yeah, I know how it is. I love working on kgdb but I always have a hard time putting it ahead of other tasks and there are always other tasks. Knowing that other people use it helps me, at least, and some of my recent work on kgdb was because a whole pile of other people were all discussing how to get kgdb working. ;-) > > My first question, though, is why would we want interrupts enabled > > while we're single stepping? If you're trying to get the processor to > > just step one instruction forward you don't really want a bunch of > > IRQs going off in the middle of it, do you? While in kgdb and > > debugging the kernel I would assume that a single step would run the > > very least amount of code that it could (other than debugger code). > > In general every time I exit kgdb (and re-start running the kernel > > normally) I sorta assume that there's a chance that something in the > > system will hit a timeout (maybe it's talking to external hardware > > that will gi
Re: [PATCH 0/4] arm64: kgdb/kdb: Fix single-step debugging issues
Doug, On Mon, Jul 06, 2020 at 02:37:05PM -0700, Doug Anderson wrote: > On Tue, Jun 30, 2020 at 12:22 AM Will Deacon wrote: > > On Mon, Jun 29, 2020 at 02:20:11PM -0700, Doug Anderson wrote: > > > On Sat, May 16, 2020 at 1:20 AM liwei (GF) wrote: > > > > On 2020/5/14 8:34, Doug Anderson wrote: > > > > > On Sat, May 9, 2020 at 6:49 AM Wei Li 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 > > Actually, I'm pretty sure that patch #1 of Wei Li's patch series would > still be needed. Would you object to landing it now just to get one > patch outta the way? > > https://lkml.kernel.org/r/20200509214159.19680-2-liwei...@huawei.com I've grabbed patch 1, cheers. > > 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. > > Thanks for the pointer! Unfortunately this is yet another area that > I'm keenly interested in it working but pretty much clueless about how > this whole area of the system works. :-| I'm also keen to fix it up but, although I roughly know how it works, I always fail to find the time to spend on it. :-| > My first question, though, is why would we want interrupts enabled > while we're single stepping? If you're trying to get the processor to > just step one instruction forward you don't really want a bunch of > IRQs going off in the middle of it, do you? While in kgdb and > debugging the kernel I would assume that a single step would run the > very least amount of code that it could (other than debugger code). > In general every time I exit kgdb (and re-start running the kernel > normally) I sorta assume that there's a chance that something in the > system will hit a timeout (maybe it's talking to external hardware > that will give up or something). If I'm stepping through code I just > want that little bit of code I'm running to move forward and the rest > of the kernel to stand still. If I want the rest of the kernel to > proceed I guess I'd set a breakpoint and then say "continue". I understand where you're coming from, but I also think it's a reasonably narrow viewpoint. If you disable IRQs during a step, you can change the behaviour of the instruction being stepped. For example, an MRS of DAIF will now see the I bit set instead of clear, and so something like irqs_disabled() could go wrong while being stepped. But I think the main re
Re: [PATCH 0/4] arm64: kgdb/kdb: Fix single-step debugging issues
On Sun, 10 May 2020 05:41:55 +0800, Wei Li 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. > > [...] Applied to arm64 (for-next/fixes), thanks! [1/1] arm64: kgdb: Fix single-step exception handling oops https://git.kernel.org/arm64/c/8523c006264d Cheers, -- Will https://fixes.arm64.dev https://next.arm64.dev https://will.arm64.dev
Re: [PATCH 0/4] arm64: kgdb/kdb: Fix single-step debugging issues
Hi Doug, On 2020/6/30 5:20, Doug Anderson wrote: > Wei, > > On Sat, May 16, 2020 at 1:20 AM liwei (GF) wrote: >> >> Hi Douglas, >> >> On 2020/5/14 8:34, Doug Anderson wrote: >>> Hi, >>> >>> On Sat, May 9, 2020 at 6:49 AM Wei Li 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. > Sorry for the long delay. I was busy on a project and missed some mail. I did receive some feedback about typo or coding style before, so i was expecting more comment about the logic or people just don't care about these. After all, this issue has lived a very long time. It's a good news to hear that Will has plan to solve these issues, i will follow that to do my bit. Before that, i can send the next version in this week. Thanks, Wei
Re: [PATCH 0/4] arm64: kgdb/kdb: Fix single-step debugging issues
Hi, On Tue, Jun 30, 2020 at 12:22 AM Will Deacon wrote: > > On Mon, Jun 29, 2020 at 02:20:11PM -0700, Doug Anderson wrote: > > On Sat, May 16, 2020 at 1:20 AM liwei (GF) wrote: > > > On 2020/5/14 8:34, Doug Anderson wrote: > > > > On Sat, May 9, 2020 at 6:49 AM Wei Li 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 Actually, I'm pretty sure that patch #1 of Wei Li's patch series would still be needed. Would you object to landing it now just to get one patch outta the way? https://lkml.kernel.org/r/20200509214159.19680-2-liwei...@huawei.com > 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. Thanks for the pointer! Unfortunately this is yet another area that I'm keenly interested in it working but pretty much clueless about how this whole area of the system works. :-| My first question, though, is why would we want interrupts enabled while we're single stepping? If you're trying to get the processor to just step one instruction forward you don't really want a bunch of IRQs going off in the middle of it, do you? While in kgdb and debugging the kernel I would assume that a single step would run the very least amount of code that it could (other than debugger code). In general every time I exit kgdb (and re-start running the kernel normally) I sorta assume that there's a chance that something in the system will hit a timeout (maybe it's talking to external hardware that will give up or something). If I'm stepping through code I just want that little bit of code I'm running to move forward and the rest of the kernel to stand still. If I want the rest of the kernel to proceed I guess I'd set a breakpoint and then say "continue". It seemed like with Wei Li's patch that we were closing holes and being more consistent about keeping interrupts disabled when stepping and I liked that. Maybe if we made it so that taking interrupts didn't break everything then it would be _OK_ to let them fire, but if I had a choice I'd rather they didn't. ...of course, I'm looking at all this from the point of view of kgdb. I don't know nearly enough about how other parts of the kernel use single step to comment much on what would be best for them. Did what I said make sense at all, or was it gibberish? ...or not gibberish but not what you were looking for? -Doug
Re: [PATCH 0/4] arm64: kgdb/kdb: Fix single-step debugging issues
On Mon, Jun 29, 2020 at 02:20:11PM -0700, Doug Anderson wrote: > On Sat, May 16, 2020 at 1:20 AM liwei (GF) wrote: > > On 2020/5/14 8:34, Doug Anderson wrote: > > > On Sat, May 9, 2020 at 6:49 AM Wei Li 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
Re: [PATCH 0/4] arm64: kgdb/kdb: Fix single-step debugging issues
Wei, On Sat, May 16, 2020 at 1:20 AM liwei (GF) wrote: > > Hi Douglas, > > On 2020/5/14 8:34, Doug Anderson wrote: > > Hi, > > > > On Sat, May 9, 2020 at 6:49 AM Wei Li 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. Thanks! -Doug
Re: [PATCH 0/4] arm64: kgdb/kdb: Fix single-step debugging issues
Hi Douglas, On 2020/5/14 8:34, Doug Anderson wrote: > Hi, > > On Sat, May 9, 2020 at 6:49 AM Wei Li 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! :-) Thanks, Wei
Re: [PATCH 0/4] arm64: kgdb/kdb: Fix single-step debugging issues
Hi, On Sat, May 9, 2020 at 6:49 AM Wei Li 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. -Doug
[PATCH 0/4] arm64: kgdb/kdb: Fix single-step debugging issues
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(-) -- 2.17.1
