From: Douglas Anderson <dianders@chromium.org> To: Mark Rutland <mark.rutland@arm.com>, 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> Cc: linux-arm-kernel@lists.infradead.org, Masayoshi Mizuma <msys.mizuma@gmail.com>, "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>, Chen-Yu Tsai <wens@csie.org>, Lecopzer Chen <lecopzer.chen@mediatek.com>, Tomohiro Misono <misono.tomohiro@fujitsu.com>, Stephane Eranian <eranian@google.com>, kgdb-bugreport@lists.sourceforge.net, Peter Zijlstra <peterz@infradead.org>, Thomas Gleixner <tglx@linutronix.de>, Stephen Boyd <swboyd@chromium.org>, ito-yuichi@fujitsu.com, linux-perf-users@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org>, Douglas Anderson <dianders@chromium.org>, D Scott Phillips <scott@os.amperecomputing.com>, Josh Poimboeuf <jpoimboe@kernel.org>, Valentin Schneider <vschneid@redhat.com>, linux-kernel@vger.kernel.org Subject: [PATCH v12 6/7] arm64: kgdb: Implement kgdb_roundup_cpus() to enable pseudo-NMI roundup Date: Wed, 30 Aug 2023 12:11:27 -0700 [thread overview] Message-ID: <20230830121115.v12.6.I2ef26d1b3bfbed2d10a281942b0da7d9854de05e@changeid> (raw) In-Reply-To: <20230830191314.1618136-1-dianders@chromium.org> Up until now we've been using the generic (weak) implementation for kgdb_roundup_cpus() when using kgdb on arm64. Let's move to a custom one. The advantage here is that, when pseudo-NMI is enabled on a device, we'll be able to round up CPUs using pseudo-NMI. This allows us to debug CPUs that are stuck with interrupts disabled. If pseudo-NMIs are not enabled then we'll fallback to just using an IPI, which is still slightly better than the generic implementation since it avoids the potential situation described in the generic kgdb_call_nmi_hook(). Co-developed-by: Sumit Garg <sumit.garg@linaro.org> Signed-off-by: Sumit Garg <sumit.garg@linaro.org> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Reviewed-by: Stephen Boyd <swboyd@chromium.org> Signed-off-by: Douglas Anderson <dianders@chromium.org> --- I debated whether this should be in "arch/arm64/kernel/smp.c" or if I should try to find a way for it to go into "arch/arm64/kernel/kgdb.c". In the end this is so little code that it didn't seem worth it to find a way to export the IPI defines or to otherwise come up with some API between kgdb.c and smp.c. If someone has strong feelings and wants this to change, please shout and give details of your preferred solution. FWIW, it seems like ~half the other platforms put this in "smp.c" with an ifdef for KGDB and the other half put it in "kgdb.c" with an ifdef for SMP. :-P (no changes since v10) Changes in v10: - Don't allocate the cpumask on the stack; just iterate. - Moved kgdb calls to smp.c to avoid needing to export IPI info. - kgdb now has its own IPI. Changes in v9: - Remove fallback for when debug IPI isn't available. - Renamed "NMI IPI" to "debug IPI" since it might not be backed by NMI. arch/arm64/kernel/smp.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index 800c59cf9b64..1a53e57c81d0 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -32,6 +32,7 @@ #include <linux/irq_work.h> #include <linux/kernel_stat.h> #include <linux/kexec.h> +#include <linux/kgdb.h> #include <linux/kvm_host.h> #include <linux/nmi.h> @@ -79,6 +80,7 @@ enum ipi_msg_type { * with trace_ipi_* */ IPI_CPU_BACKTRACE = NR_IPI, + IPI_KGDB_ROUNDUP, MAX_IPI }; @@ -868,6 +870,22 @@ void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu) nmi_trigger_cpumask_backtrace(mask, exclude_cpu, arm64_backtrace_ipi); } +#ifdef CONFIG_KGDB +void kgdb_roundup_cpus(void) +{ + int this_cpu = raw_smp_processor_id(); + int cpu; + + for_each_online_cpu(cpu) { + /* No need to roundup ourselves */ + if (cpu == this_cpu) + continue; + + __ipi_send_single(ipi_desc[IPI_KGDB_ROUNDUP], cpu); + } +} +#endif + /* * Main handler for inter-processor interrupts */ @@ -919,6 +937,10 @@ static void do_handle_IPI(int ipinr) nmi_cpu_backtrace(get_irq_regs()); break; + case IPI_KGDB_ROUNDUP: + kgdb_nmicallback(cpu, get_irq_regs()); + break; + default: pr_crit("CPU%u: Unknown IPI message 0x%x\n", cpu, ipinr); break; @@ -949,6 +971,7 @@ static bool ipi_should_be_nmi(enum ipi_msg_type ipi) case IPI_CPU_STOP: case IPI_CPU_CRASH_STOP: case IPI_CPU_BACKTRACE: + case IPI_KGDB_ROUNDUP: return true; default: return false; -- 2.42.0.283.g2d96d420d3-goog _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
WARNING: multiple messages have this Message-ID (diff)
From: Douglas Anderson <dianders@chromium.org> To: Mark Rutland <mark.rutland@arm.com>, 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> Cc: linux-arm-kernel@lists.infradead.org, Masayoshi Mizuma <msys.mizuma@gmail.com>, "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>, Chen-Yu Tsai <wens@csie.org>, Lecopzer Chen <lecopzer.chen@mediatek.com>, Tomohiro Misono <misono.tomohiro@fujitsu.com>, Stephane Eranian <eranian@google.com>, kgdb-bugreport@lists.sourceforge.net, Peter Zijlstra <peterz@infradead.org>, Thomas Gleixner <tglx@linutronix.de>, Stephen Boyd <swboyd@chromium.org>, ito-yuichi@fujitsu.com, linux-perf-users@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org>, Douglas Anderson <dianders@chromium.org>, D Scott Phillips <scott@os.amperecomputing.com>, Josh Poimboeuf <jpoimboe@kernel.org>, Valentin Schneider <vschneid@redhat.com>, linux-kernel@vger.kernel.org Subject: [PATCH v12 6/7] arm64: kgdb: Implement kgdb_roundup_cpus() to enable pseudo-NMI roundup Date: Wed, 30 Aug 2023 12:11:27 -0700 [thread overview] Message-ID: <20230830121115.v12.6.I2ef26d1b3bfbed2d10a281942b0da7d9854de05e@changeid> (raw) In-Reply-To: <20230830191314.1618136-1-dianders@chromium.org> Up until now we've been using the generic (weak) implementation for kgdb_roundup_cpus() when using kgdb on arm64. Let's move to a custom one. The advantage here is that, when pseudo-NMI is enabled on a device, we'll be able to round up CPUs using pseudo-NMI. This allows us to debug CPUs that are stuck with interrupts disabled. If pseudo-NMIs are not enabled then we'll fallback to just using an IPI, which is still slightly better than the generic implementation since it avoids the potential situation described in the generic kgdb_call_nmi_hook(). Co-developed-by: Sumit Garg <sumit.garg@linaro.org> Signed-off-by: Sumit Garg <sumit.garg@linaro.org> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Reviewed-by: Stephen Boyd <swboyd@chromium.org> Signed-off-by: Douglas Anderson <dianders@chromium.org> --- I debated whether this should be in "arch/arm64/kernel/smp.c" or if I should try to find a way for it to go into "arch/arm64/kernel/kgdb.c". In the end this is so little code that it didn't seem worth it to find a way to export the IPI defines or to otherwise come up with some API between kgdb.c and smp.c. If someone has strong feelings and wants this to change, please shout and give details of your preferred solution. FWIW, it seems like ~half the other platforms put this in "smp.c" with an ifdef for KGDB and the other half put it in "kgdb.c" with an ifdef for SMP. :-P (no changes since v10) Changes in v10: - Don't allocate the cpumask on the stack; just iterate. - Moved kgdb calls to smp.c to avoid needing to export IPI info. - kgdb now has its own IPI. Changes in v9: - Remove fallback for when debug IPI isn't available. - Renamed "NMI IPI" to "debug IPI" since it might not be backed by NMI. arch/arm64/kernel/smp.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index 800c59cf9b64..1a53e57c81d0 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -32,6 +32,7 @@ #include <linux/irq_work.h> #include <linux/kernel_stat.h> #include <linux/kexec.h> +#include <linux/kgdb.h> #include <linux/kvm_host.h> #include <linux/nmi.h> @@ -79,6 +80,7 @@ enum ipi_msg_type { * with trace_ipi_* */ IPI_CPU_BACKTRACE = NR_IPI, + IPI_KGDB_ROUNDUP, MAX_IPI }; @@ -868,6 +870,22 @@ void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu) nmi_trigger_cpumask_backtrace(mask, exclude_cpu, arm64_backtrace_ipi); } +#ifdef CONFIG_KGDB +void kgdb_roundup_cpus(void) +{ + int this_cpu = raw_smp_processor_id(); + int cpu; + + for_each_online_cpu(cpu) { + /* No need to roundup ourselves */ + if (cpu == this_cpu) + continue; + + __ipi_send_single(ipi_desc[IPI_KGDB_ROUNDUP], cpu); + } +} +#endif + /* * Main handler for inter-processor interrupts */ @@ -919,6 +937,10 @@ static void do_handle_IPI(int ipinr) nmi_cpu_backtrace(get_irq_regs()); break; + case IPI_KGDB_ROUNDUP: + kgdb_nmicallback(cpu, get_irq_regs()); + break; + default: pr_crit("CPU%u: Unknown IPI message 0x%x\n", cpu, ipinr); break; @@ -949,6 +971,7 @@ static bool ipi_should_be_nmi(enum ipi_msg_type ipi) case IPI_CPU_STOP: case IPI_CPU_CRASH_STOP: case IPI_CPU_BACKTRACE: + case IPI_KGDB_ROUNDUP: return true; default: return false; -- 2.42.0.283.g2d96d420d3-goog
next prev parent reply other threads:[~2023-08-30 19:14 UTC|newest] Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-08-30 19:11 [PATCH v12 0/7] arm64: Add IPI for backtraces / kgdb; try to use NMI for some IPIs Douglas Anderson 2023-08-30 19:11 ` Douglas Anderson 2023-08-30 19:11 ` [PATCH v12 1/7] irqchip/gic-v3: Enable support for SGIs to act as NMIs Douglas Anderson 2023-08-30 19:11 ` Douglas Anderson 2023-08-31 8:53 ` Mark Rutland 2023-08-31 8:53 ` Mark Rutland 2023-08-31 15:31 ` Doug Anderson 2023-08-31 15:31 ` Doug Anderson 2023-08-31 15:45 ` Mark Rutland 2023-08-31 15:45 ` Mark Rutland 2023-08-30 19:11 ` [PATCH v12 2/7] arm64: idle: Tag the arm64 idle functions as __cpuidle Douglas Anderson 2023-08-30 19:11 ` Douglas Anderson 2023-08-30 19:11 ` [PATCH v12 3/7] arm64: smp: Remove dedicated wakeup IPI Douglas Anderson 2023-08-30 19:11 ` Douglas Anderson 2023-08-30 19:11 ` [PATCH v12 4/7] arm64: smp: Add arch support for backtrace using pseudo-NMI Douglas Anderson 2023-08-30 19:11 ` Douglas Anderson 2023-08-30 19:11 ` [PATCH v12 5/7] arm64: smp: IPI_CPU_STOP and IPI_CPU_CRASH_STOP should try for NMI Douglas Anderson 2023-08-30 19:11 ` Douglas Anderson 2023-08-31 10:12 ` Mark Rutland 2023-08-31 10:12 ` Mark Rutland 2023-08-30 19:11 ` Douglas Anderson [this message] 2023-08-30 19:11 ` [PATCH v12 6/7] arm64: kgdb: Implement kgdb_roundup_cpus() to enable pseudo-NMI roundup Douglas Anderson 2023-08-31 10:14 ` Mark Rutland 2023-08-31 10:14 ` Mark Rutland 2023-08-30 19:11 ` [PATCH v12 7/7] arm64: smp: Mark IPI globals as __ro_after_init Douglas Anderson 2023-08-30 19:11 ` Douglas Anderson 2023-08-31 10:15 ` Mark Rutland 2023-08-31 10:15 ` Mark Rutland 2023-08-31 7:08 ` [PATCH v12 0/7] arm64: Add IPI for backtraces / kgdb; try to use NMI for some IPIs Chen-Yu Tsai 2023-08-31 7:08 ` Chen-Yu Tsai
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