From: Mark Rutland <mark.rutland@arm.com> To: Douglas Anderson <dianders@chromium.org> Cc: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, Sumit Garg <sumit.garg@linaro.org>, Daniel Thompson <daniel.thompson@linaro.org>, Marc Zyngier <maz@kernel.org>, linux-perf-users@vger.kernel.org, ito-yuichi@fujitsu.com, Chen-Yu Tsai <wens@csie.org>, Ard Biesheuvel <ardb@kernel.org>, Stephen Boyd <swboyd@chromium.org>, Peter Zijlstra <peterz@infradead.org>, Thomas Gleixner <tglx@linutronix.de>, linux-arm-kernel@lists.infradead.org, kgdb-bugreport@lists.sourceforge.net, Masayoshi Mizuma <msys.mizuma@gmail.com>, "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>, Lecopzer Chen <lecopzer.chen@mediatek.com>, Ben Dooks <ben-linux@fluff.org>, Ingo Molnar <mingo@kernel.org>, Josh Poimboeuf <jpoimboe@kernel.org>, Valentin Schneider <vschneid@redhat.com>, linux-kernel@vger.kernel.org Subject: Re: [PATCH v9 4/7] arm64: smp: Assign and setup the debug IPI Date: Mon, 7 Aug 2023 11:17:45 +0100 [thread overview] Message-ID: <ZNDEyT3mHCl0UQIV@FVFF77S0Q05N.cambridge.arm.com> (raw) In-Reply-To: <20230601143109.v9.4.I6d7f7d5fa0aa293c8c3374194947254b93114d37@changeid> On Thu, Jun 01, 2023 at 02:31:48PM -0700, Douglas Anderson wrote: > From: Sumit Garg <sumit.garg@linaro.org> > > All current arm64 interrupt controllers have at least 8 > IPIs. Currently we are only using 7 of them on arm64. Let's use the > 8th one as a debug IPI. This uses the new "debug IPI" infrastructure > which will try to allocate this IPI as an NMI/pseudo NMI if possible. > > Signed-off-by: Sumit Garg <sumit.garg@linaro.org> > Signed-off-by: Douglas Anderson <dianders@chromium.org> I think with my suggestion on the prior patch, we don't need the additional logic here. > --- > I could imagine that people object to using up the last free IPI on > interrupt controllers with only 8 IPIs. However, it shouldn't be a big > deal. If we later need an extra IPI, it shouldn't be too hard to > combine some of the existing ones. Presumably we could just get rid of > the "crash stop" IPI and have the normal "stop" IPI do the crash if > "waiting_for_crash_ipi" is non-zero TBH, I'd love to unify the logic for IPI_CPU_STOP and IPI_CPU_CRASH_STOP as they have a bunch of pointless divergence. We could also remove IPI_WAKEUP and replace that with something else (e.g. IPI_CALL_FUNC with an empty function) in order to free up an IPI. I'd *also* prefer to have separate IPI_CPU_BACKTRACE and IPI_CPU_DEBUG as the backtrace logic is used for a bunch of things other than KGDB (e.g. RCU stalls, panic), and that would clearly separate the logic for the two cases. Thanks, Mark. > > Changes in v9: > - Add a warning if we don't have enough IPIs for the NMI IPI > - Renamed "NMI IPI" to "debug IPI" since it might not be backed by NMI. > - Update commit description > > Changes in v8: > - debug_ipi_setup() and debug_ipi_teardown() no longer take cpu param > > arch/arm64/kernel/smp.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c > index edd63894d61e..db019b49d3bd 100644 > --- a/arch/arm64/kernel/smp.c > +++ b/arch/arm64/kernel/smp.c > @@ -53,6 +53,8 @@ > > #include <trace/events/ipi.h> > > +#include "ipi_debug.h" > + > DEFINE_PER_CPU_READ_MOSTLY(int, cpu_number); > EXPORT_PER_CPU_SYMBOL(cpu_number); > > @@ -935,6 +937,8 @@ static void ipi_setup(int cpu) > > for (i = 0; i < nr_ipi; i++) > enable_percpu_irq(ipi_irq_base + i, 0); > + > + debug_ipi_setup(); > } > > #ifdef CONFIG_HOTPLUG_CPU > @@ -947,6 +951,8 @@ static void ipi_teardown(int cpu) > > for (i = 0; i < nr_ipi; i++) > disable_percpu_irq(ipi_irq_base + i); > + > + debug_ipi_teardown(); > } > #endif > > @@ -968,6 +974,11 @@ void __init set_smp_ipi_range(int ipi_base, int n) > irq_set_status_flags(ipi_base + i, IRQ_HIDDEN); > } > > + if (n > nr_ipi) > + set_smp_debug_ipi(ipi_base + nr_ipi); > + else > + WARN(1, "Not enough IPIs for NMI IPI\n"); > + > ipi_irq_base = ipi_base; > > /* Setup the boot CPU immediately */ > -- > 2.41.0.rc2.161.g9c6817b8e7-goog >
WARNING: multiple messages have this Message-ID (diff)
From: Mark Rutland <mark.rutland@arm.com> To: Douglas Anderson <dianders@chromium.org> Cc: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, Sumit Garg <sumit.garg@linaro.org>, Daniel Thompson <daniel.thompson@linaro.org>, Marc Zyngier <maz@kernel.org>, linux-perf-users@vger.kernel.org, ito-yuichi@fujitsu.com, Chen-Yu Tsai <wens@csie.org>, Ard Biesheuvel <ardb@kernel.org>, Stephen Boyd <swboyd@chromium.org>, Peter Zijlstra <peterz@infradead.org>, Thomas Gleixner <tglx@linutronix.de>, linux-arm-kernel@lists.infradead.org, kgdb-bugreport@lists.sourceforge.net, Masayoshi Mizuma <msys.mizuma@gmail.com>, "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>, Lecopzer Chen <lecopzer.chen@mediatek.com>, Ben Dooks <ben-linux@fluff.org>, Ingo Molnar <mingo@kernel.org>, Josh Poimboeuf <jpoimboe@kernel.org>, Valentin Schneider <vschneid@redhat.com>, linux-kernel@vger.kernel.org Subject: Re: [PATCH v9 4/7] arm64: smp: Assign and setup the debug IPI Date: Mon, 7 Aug 2023 11:17:45 +0100 [thread overview] Message-ID: <ZNDEyT3mHCl0UQIV@FVFF77S0Q05N.cambridge.arm.com> (raw) In-Reply-To: <20230601143109.v9.4.I6d7f7d5fa0aa293c8c3374194947254b93114d37@changeid> On Thu, Jun 01, 2023 at 02:31:48PM -0700, Douglas Anderson wrote: > From: Sumit Garg <sumit.garg@linaro.org> > > All current arm64 interrupt controllers have at least 8 > IPIs. Currently we are only using 7 of them on arm64. Let's use the > 8th one as a debug IPI. This uses the new "debug IPI" infrastructure > which will try to allocate this IPI as an NMI/pseudo NMI if possible. > > Signed-off-by: Sumit Garg <sumit.garg@linaro.org> > Signed-off-by: Douglas Anderson <dianders@chromium.org> I think with my suggestion on the prior patch, we don't need the additional logic here. > --- > I could imagine that people object to using up the last free IPI on > interrupt controllers with only 8 IPIs. However, it shouldn't be a big > deal. If we later need an extra IPI, it shouldn't be too hard to > combine some of the existing ones. Presumably we could just get rid of > the "crash stop" IPI and have the normal "stop" IPI do the crash if > "waiting_for_crash_ipi" is non-zero TBH, I'd love to unify the logic for IPI_CPU_STOP and IPI_CPU_CRASH_STOP as they have a bunch of pointless divergence. We could also remove IPI_WAKEUP and replace that with something else (e.g. IPI_CALL_FUNC with an empty function) in order to free up an IPI. I'd *also* prefer to have separate IPI_CPU_BACKTRACE and IPI_CPU_DEBUG as the backtrace logic is used for a bunch of things other than KGDB (e.g. RCU stalls, panic), and that would clearly separate the logic for the two cases. Thanks, Mark. > > Changes in v9: > - Add a warning if we don't have enough IPIs for the NMI IPI > - Renamed "NMI IPI" to "debug IPI" since it might not be backed by NMI. > - Update commit description > > Changes in v8: > - debug_ipi_setup() and debug_ipi_teardown() no longer take cpu param > > arch/arm64/kernel/smp.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c > index edd63894d61e..db019b49d3bd 100644 > --- a/arch/arm64/kernel/smp.c > +++ b/arch/arm64/kernel/smp.c > @@ -53,6 +53,8 @@ > > #include <trace/events/ipi.h> > > +#include "ipi_debug.h" > + > DEFINE_PER_CPU_READ_MOSTLY(int, cpu_number); > EXPORT_PER_CPU_SYMBOL(cpu_number); > > @@ -935,6 +937,8 @@ static void ipi_setup(int cpu) > > for (i = 0; i < nr_ipi; i++) > enable_percpu_irq(ipi_irq_base + i, 0); > + > + debug_ipi_setup(); > } > > #ifdef CONFIG_HOTPLUG_CPU > @@ -947,6 +951,8 @@ static void ipi_teardown(int cpu) > > for (i = 0; i < nr_ipi; i++) > disable_percpu_irq(ipi_irq_base + i); > + > + debug_ipi_teardown(); > } > #endif > > @@ -968,6 +974,11 @@ void __init set_smp_ipi_range(int ipi_base, int n) > irq_set_status_flags(ipi_base + i, IRQ_HIDDEN); > } > > + if (n > nr_ipi) > + set_smp_debug_ipi(ipi_base + nr_ipi); > + else > + WARN(1, "Not enough IPIs for NMI IPI\n"); > + > ipi_irq_base = ipi_base; > > /* Setup the boot CPU immediately */ > -- > 2.41.0.rc2.161.g9c6817b8e7-goog > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2023-08-07 10:17 UTC|newest] Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-06-01 21:31 [PATCH v9 0/7] arm64: Add debug IPI for backtraces / kgdb; try to use NMI for it Douglas Anderson 2023-06-01 21:31 ` Douglas Anderson 2023-06-01 21:31 ` [PATCH v9 1/7] irqchip/gic-v3: Enable support for SGIs to act as NMIs Douglas Anderson 2023-06-01 21:31 ` Douglas Anderson 2023-08-07 9:50 ` Mark Rutland 2023-08-07 9:50 ` Mark Rutland 2023-08-07 11:22 ` Sumit Garg 2023-08-07 11:22 ` Sumit Garg 2023-08-07 13:25 ` Mark Rutland 2023-08-07 13:25 ` Mark Rutland 2023-06-01 21:31 ` [PATCH v9 2/7] arm64: idle: Tag the arm64 idle functions as __cpuidle Douglas Anderson 2023-06-01 21:31 ` Douglas Anderson 2023-08-07 9:52 ` Mark Rutland 2023-08-07 9:52 ` Mark Rutland 2023-06-01 21:31 ` [PATCH v9 3/7] arm64: Add framework for a debug IPI Douglas Anderson 2023-06-01 21:31 ` Douglas Anderson 2023-08-07 10:12 ` Mark Rutland 2023-08-07 10:12 ` Mark Rutland 2023-08-21 22:16 ` Doug Anderson 2023-08-21 22:16 ` Doug Anderson 2023-08-22 6:42 ` Mark Rutland 2023-08-22 6:42 ` Mark Rutland 2023-06-01 21:31 ` [PATCH v9 4/7] arm64: smp: Assign and setup the " Douglas Anderson 2023-06-01 21:31 ` Douglas Anderson 2023-08-07 10:17 ` Mark Rutland [this message] 2023-08-07 10:17 ` Mark Rutland 2023-06-01 21:31 ` [PATCH v9 5/7] arm64: ipi_debug: Add support for backtrace using " Douglas Anderson 2023-06-01 21:31 ` Douglas Anderson 2023-08-07 10:23 ` Mark Rutland 2023-08-07 10:23 ` Mark Rutland 2023-08-22 0:06 ` Doug Anderson 2023-08-22 0:06 ` Doug Anderson 2023-08-22 6:35 ` Mark Rutland 2023-08-22 6:35 ` Mark Rutland 2023-06-01 21:31 ` [PATCH v9 6/7] kgdb: Provide a stub kgdb_nmicallback() if !CONFIG_KGDB Douglas Anderson 2023-06-01 21:31 ` Douglas Anderson 2023-06-15 18:14 ` Doug Anderson 2023-06-15 18:14 ` Doug Anderson 2023-06-26 14:30 ` Daniel Thompson 2023-06-26 14:30 ` Daniel Thompson 2023-08-07 10:27 ` Mark Rutland 2023-08-07 10:27 ` Mark Rutland 2023-08-07 10:29 ` Mark Rutland 2023-08-07 10:29 ` Mark Rutland 2023-06-01 21:31 ` [PATCH v9 7/7] arm64: kgdb: Roundup cpus using the debug IPI Douglas Anderson 2023-06-01 21:31 ` Douglas Anderson 2023-08-07 10:28 ` Mark Rutland 2023-08-07 10:28 ` Mark Rutland 2023-08-07 10:47 ` Marc Zyngier 2023-08-07 10:47 ` Marc Zyngier 2023-08-07 10:54 ` Mark Rutland 2023-08-07 10:54 ` Mark Rutland 2023-08-07 11:08 ` Marc Zyngier 2023-08-07 11:08 ` Marc Zyngier 2023-08-07 11:13 ` Mark Rutland 2023-08-07 11:13 ` Mark Rutland 2023-08-07 15:24 ` Daniel Thompson 2023-08-07 15:24 ` Daniel Thompson 2023-08-07 16:04 ` Mark Rutland 2023-08-07 16:04 ` Mark Rutland 2023-08-08 11:17 ` Daniel Thompson 2023-08-08 11:17 ` Daniel Thompson 2023-06-02 5:19 ` [PATCH v9 0/7] arm64: Add debug IPI for backtraces / kgdb; try to use NMI for it Sumit Garg 2023-06-02 5:19 ` Sumit Garg 2023-07-24 15:55 ` Doug Anderson 2023-08-07 10:41 ` Mark Rutland 2023-08-07 10:41 ` Mark Rutland 2023-08-07 12:46 ` Sumit Garg 2023-08-07 12:46 ` Sumit Garg 2023-08-07 14:43 ` Mark Rutland 2023-08-07 14:43 ` Mark Rutland
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