From: geoff@infradead.org (Geoff Levand) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v18 04/13] arm64/kexec: Add pr_debug output Date: Thu, 16 Jun 2016 15:58:49 -0700 [thread overview] Message-ID: <1466117929.21058.55.camel@infradead.org> (raw) In-Reply-To: <57618CEB.6040807@arm.com> On Wed, 2016-06-15 at 18:14 +0100, James Morse wrote: > On 09/06/16 21:08, Geoff Levand wrote: > > To aid in debugging kexec problems or when adding new functionality to kexec add > > a new routine kexec_image_info() and several inline pr_debug statements. > > diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c > > +/** > > + * kexec_is_dtb - Helper routine to check the device tree header signature. > > + */ > > +static bool kexec_is_dtb(const void *dtb) > > +{ > > +> > > > __be32 magic; > > + > > +> > > > if (get_user(magic, (__be32 *)dtb)) > > +> > > > > > return false; > > + > > You pass this function 'kimage->segment[i].buf', this looks like the user space > memory that contained the dtb when kexec-tools first ran to load the image. > > This will work when you call it from machine_kexec_prepare(), but by the time we > get to machine_kexec() that process is long gone, and this pointer should be > considered junk. > > I don't think its possible to find this information from machine_kexec(), as the > DTB will be split up into page size chunks and scattered through memory. That's correct. I don't think it that important to print the dtb segment, so I'll just remove this kexec_is_dtb() routine. > > + > > void machine_kexec_cleanup(struct kimage *kimage) > > { > > > > > > /* Empty routine needed to avoid build errors. */ > > @@ -65,6 +107,8 @@ int machine_kexec_prepare(struct kimage *kimage) > > > > > > > > } > > > > > > } > > > > +> > > > kexec_image_info(kimage); > > + > > You want to put this at the start of machine_kexec_prepare(), otherwise we may > return from: > > #ifdef CONFIG_HOTPLUG_CPU > > > > /* any_cpu as we don't mind being preempted */ > > > > int any_cpu = raw_smp_processor_id(); > > > > > > if (cpu_ops[any_cpu]->cpu_die) > > > > > > return 0; > > #endif /* CONFIG_HOTPLUG_CPU */ > > This maybe-return-an-error block needs to be the last thing in the function. OK. > I'm not sure if the debug output is actually useful this early: kexec-tools > prints out exactly the same information shortly after this function returns. I thought it good to do it here, kexec-tools is not the only user of kexec see https://github.com/antonblanchard/kexec-lite. Thanks for checking. -Geoff
WARNING: multiple messages have this Message-ID (diff)
From: Geoff Levand <geoff@infradead.org> To: James Morse <james.morse@arm.com> Cc: Mark Rutland <mark.rutland@arm.com>, marc.zyngier@arm.com, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, AKASHI Takahiro <takahiro.akashi@linaro.org>, kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v18 04/13] arm64/kexec: Add pr_debug output Date: Thu, 16 Jun 2016 15:58:49 -0700 [thread overview] Message-ID: <1466117929.21058.55.camel@infradead.org> (raw) In-Reply-To: <57618CEB.6040807@arm.com> On Wed, 2016-06-15 at 18:14 +0100, James Morse wrote: > On 09/06/16 21:08, Geoff Levand wrote: > > To aid in debugging kexec problems or when adding new functionality to kexec add > > a new routine kexec_image_info() and several inline pr_debug statements. > > diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c > > +/** > > + * kexec_is_dtb - Helper routine to check the device tree header signature. > > + */ > > +static bool kexec_is_dtb(const void *dtb) > > +{ > > +> > > > __be32 magic; > > + > > +> > > > if (get_user(magic, (__be32 *)dtb)) > > +> > > > > > return false; > > + > > You pass this function 'kimage->segment[i].buf', this looks like the user space > memory that contained the dtb when kexec-tools first ran to load the image. > > This will work when you call it from machine_kexec_prepare(), but by the time we > get to machine_kexec() that process is long gone, and this pointer should be > considered junk. > > I don't think its possible to find this information from machine_kexec(), as the > DTB will be split up into page size chunks and scattered through memory. That's correct. I don't think it that important to print the dtb segment, so I'll just remove this kexec_is_dtb() routine. > > + > > void machine_kexec_cleanup(struct kimage *kimage) > > { > > > > > > /* Empty routine needed to avoid build errors. */ > > @@ -65,6 +107,8 @@ int machine_kexec_prepare(struct kimage *kimage) > > > > > > > > } > > > > > > } > > > > +> > > > kexec_image_info(kimage); > > + > > You want to put this at the start of machine_kexec_prepare(), otherwise we may > return from: > > #ifdef CONFIG_HOTPLUG_CPU > > > > /* any_cpu as we don't mind being preempted */ > > > > int any_cpu = raw_smp_processor_id(); > > > > > > if (cpu_ops[any_cpu]->cpu_die) > > > > > > return 0; > > #endif /* CONFIG_HOTPLUG_CPU */ > > This maybe-return-an-error block needs to be the last thing in the function. OK. > I'm not sure if the debug output is actually useful this early: kexec-tools > prints out exactly the same information shortly after this function returns. I thought it good to do it here, kexec-tools is not the only user of kexec see https://github.com/antonblanchard/kexec-lite. Thanks for checking. -Geoff _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec
next prev parent reply other threads:[~2016-06-16 22:58 UTC|newest] Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-06-09 20:08 [PATCH v18 00/13] arm64 kexec kernel patches Geoff Levand 2016-06-09 20:08 ` Geoff Levand 2016-06-09 20:08 ` [PATCH v18 06/13] arm64: kdump: reserve memory for crash dump kernel Geoff Levand 2016-06-09 20:08 ` Geoff Levand 2016-06-09 20:08 ` [PATCH v18 03/13] arm64/kexec: Add core kexec support Geoff Levand 2016-06-09 20:08 ` Geoff Levand 2016-06-15 8:14 ` AKASHI Takahiro 2016-06-15 8:14 ` AKASHI Takahiro 2016-06-15 17:10 ` James Morse 2016-06-15 17:10 ` James Morse 2016-06-16 22:41 ` Geoff Levand 2016-06-16 22:41 ` Geoff Levand 2016-06-09 20:08 ` [PATCH v18 02/13] arm64: Add cpus_are_stuck_in_kernel Geoff Levand 2016-06-09 20:08 ` Geoff Levand 2016-06-09 20:08 ` [PATCH v18 05/13] arm64/kexec: Enable kexec in the arm64 defconfig Geoff Levand 2016-06-09 20:08 ` Geoff Levand 2016-06-09 20:08 ` [PATCH v18 07/13] arm64: limit memory regions based on DT property, usable-memory Geoff Levand 2016-06-09 20:08 ` Geoff Levand 2016-06-09 20:08 ` [PATCH v18 04/13] arm64/kexec: Add pr_debug output Geoff Levand 2016-06-09 20:08 ` Geoff Levand 2016-06-15 17:14 ` James Morse 2016-06-15 17:14 ` James Morse 2016-06-16 22:58 ` Geoff Levand [this message] 2016-06-16 22:58 ` Geoff Levand 2016-06-09 20:08 ` [PATCH v18 08/13] arm64: kdump: implement machine_crash_shutdown() Geoff Levand 2016-06-09 20:08 ` Geoff Levand 2016-06-14 7:13 ` AKASHI Takahiro 2016-06-14 7:13 ` AKASHI Takahiro 2016-06-14 21:56 ` Geoff Levand 2016-06-14 21:56 ` Geoff Levand 2016-06-09 20:08 ` [PATCH v18 01/13] arm64: Add back cpu reset routines Geoff Levand 2016-06-09 20:08 ` Geoff Levand 2016-06-09 20:08 ` [PATCH v18 09/13] arm64: kdump: add kdump support Geoff Levand 2016-06-09 20:08 ` Geoff Levand 2016-06-09 20:08 ` [PATCH v18 12/13] arm64: kdump: update a kernel doc Geoff Levand 2016-06-09 20:08 ` Geoff Levand 2016-06-09 20:08 ` [PATCH v18 10/13] arm64: kdump: add VMCOREINFO for user-space coredump tools Geoff Levand 2016-06-09 20:08 ` Geoff Levand 2016-06-09 20:08 ` [PATCH v18 13/13] Documentation: dt: usable-memory and elfcorehdr nodes for arm64 kexec Geoff Levand 2016-06-09 20:08 ` Geoff Levand 2016-06-09 20:08 ` [PATCH v18 11/13] arm64: kdump: enable kdump in the arm64 defconfig Geoff Levand 2016-06-09 20:08 ` Geoff Levand
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