From: takahiro.akashi@linaro.org (AKASHI Takahiro) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v19 10/13] arm64: kdump: add VMCOREINFO's for user-space coredump tools Date: Thu, 23 Jun 2016 17:42:28 +0900 [thread overview] Message-ID: <20160623081545.GA20774@linaro.org> (raw) In-Reply-To: <20160623071412.GA16398@dhcppc9> On Thu, Jun 23, 2016 at 12:44:12PM +0530, Pratyush Anand wrote: > Hi Takahiro, > > Thanks for your reply. > > On 22/06/2016:02:59:41 PM, AKASHI Takahiro wrote: > > On Mon, Jun 20, 2016 at 11:02:22AM +0530, Pratyush Anand wrote: > > > +Atsushi > > > > > > Hi Takahiro, > > > > > > On 16/06/2016:11:48:28 PM, Geoff Levand wrote: > > > > From: AKASHI Takahiro <takahiro.akashi@linaro.org> > > > > > > > > For the current crash utility, we need to know, at least, > > > > - kimage_voffset > > > > - PHYS_OFFSET > > > > to handle the contents of core dump file (/proc/vmcore) correctly due to > > > > the introduction of KASLR (CONFIG_RANDOMIZE_BASE) in v4.6. > > > > This patch puts them as VMCOREINFO's into the file. > > > > > > > > - VA_BITS > > > > is also added for makedumpfile command. > > > > > > Thanks for adding them. They are quite helpful for makedumpfile as well. > > > > > > > More VMCOREINFO's may be added later. > > > > > > Yes, we will need to pass VMCOREINFO_SYMBOL(_text) and VMCOREINFO_SYMBOL(_end) > > > in order to work with makedumpfile. > > > > I know that adding those symbols is the easiest way, but > > theoretically, if we know the physical address of "swapper_pg_dir", > > But, we know only it's virtual address. What I meant here is that, if we know the physical address of "swapper_pg_dir", we don't have to know neither of "_text", "_end", "kimage_voffset" nor "PHYS_OFFSET". I just wanted to ask you whether you thought of this possibility. > > > instead of its virtual address, we can access all the memory pointed to > > by any kernel virtual address. > > How do you rationalize that we need to know "_text" and "_end"? > > Well, we need some mechanism so that we can decide if an address can be > translated using linear mapping of virt_to_phys(). All the entries in MMU tables are based on "physical" addresses, and so we don't care whether a given address is in linear mapping or not in walking through MMU. See what I mean? Thanks, -Takahiro AKASHI > Alternatively, probably we can do like this: > -- Translate all address between "SYMBOL(swapper_pg_dir)" and "SYMBOL(swapper_pg_dir) > + SWAPPER_DIR_SIZE" using virt_to_phys() and now we can read values from > dumpfile using that physical address. This way we can get PGD/PMD/PUD values. > -- PTE values may lie out side this range, however that address should still be > linearly translatable. We can use virt_to_phys() macro from them as well. > > In summary, we can translate address of PGD/PMD/PUD/PTE using virt_to_phys() > and rest all can be translated using page table entries. > > ~Pratyush
WARNING: multiple messages have this Message-ID (diff)
From: AKASHI Takahiro <takahiro.akashi@linaro.org> To: Pratyush Anand <panand@redhat.com> Cc: Mark Rutland <mark.rutland@arm.com>, Geoff Levand <geoff@infradead.org>, Catalin Marinas <catalin.marinas@arm.com>, Atsushi Kumagai <ats-kumagai@wm.jp.nec.com>, Will Deacon <will.deacon@arm.com>, marc.zyngier@arm.com, James Morse <james.morse@arm.com>, kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v19 10/13] arm64: kdump: add VMCOREINFO's for user-space coredump tools Date: Thu, 23 Jun 2016 17:42:28 +0900 [thread overview] Message-ID: <20160623081545.GA20774@linaro.org> (raw) In-Reply-To: <20160623071412.GA16398@dhcppc9> On Thu, Jun 23, 2016 at 12:44:12PM +0530, Pratyush Anand wrote: > Hi Takahiro, > > Thanks for your reply. > > On 22/06/2016:02:59:41 PM, AKASHI Takahiro wrote: > > On Mon, Jun 20, 2016 at 11:02:22AM +0530, Pratyush Anand wrote: > > > +Atsushi > > > > > > Hi Takahiro, > > > > > > On 16/06/2016:11:48:28 PM, Geoff Levand wrote: > > > > From: AKASHI Takahiro <takahiro.akashi@linaro.org> > > > > > > > > For the current crash utility, we need to know, at least, > > > > - kimage_voffset > > > > - PHYS_OFFSET > > > > to handle the contents of core dump file (/proc/vmcore) correctly due to > > > > the introduction of KASLR (CONFIG_RANDOMIZE_BASE) in v4.6. > > > > This patch puts them as VMCOREINFO's into the file. > > > > > > > > - VA_BITS > > > > is also added for makedumpfile command. > > > > > > Thanks for adding them. They are quite helpful for makedumpfile as well. > > > > > > > More VMCOREINFO's may be added later. > > > > > > Yes, we will need to pass VMCOREINFO_SYMBOL(_text) and VMCOREINFO_SYMBOL(_end) > > > in order to work with makedumpfile. > > > > I know that adding those symbols is the easiest way, but > > theoretically, if we know the physical address of "swapper_pg_dir", > > But, we know only it's virtual address. What I meant here is that, if we know the physical address of "swapper_pg_dir", we don't have to know neither of "_text", "_end", "kimage_voffset" nor "PHYS_OFFSET". I just wanted to ask you whether you thought of this possibility. > > > instead of its virtual address, we can access all the memory pointed to > > by any kernel virtual address. > > How do you rationalize that we need to know "_text" and "_end"? > > Well, we need some mechanism so that we can decide if an address can be > translated using linear mapping of virt_to_phys(). All the entries in MMU tables are based on "physical" addresses, and so we don't care whether a given address is in linear mapping or not in walking through MMU. See what I mean? Thanks, -Takahiro AKASHI > Alternatively, probably we can do like this: > -- Translate all address between "SYMBOL(swapper_pg_dir)" and "SYMBOL(swapper_pg_dir) > + SWAPPER_DIR_SIZE" using virt_to_phys() and now we can read values from > dumpfile using that physical address. This way we can get PGD/PMD/PUD values. > -- PTE values may lie out side this range, however that address should still be > linearly translatable. We can use virt_to_phys() macro from them as well. > > In summary, we can translate address of PGD/PMD/PUD/PTE using virt_to_phys() > and rest all can be translated using page table entries. > > ~Pratyush _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec
next prev parent reply other threads:[~2016-06-23 8:42 UTC|newest] Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-06-16 23:48 [PATCH v19 00/13] arm64 kexec kernel patches Geoff Levand 2016-06-16 23:48 ` Geoff Levand 2016-06-16 23:48 ` [PATCH v19 05/13] arm64/kexec: Add pr_debug output Geoff Levand 2016-06-16 23:48 ` Geoff Levand 2016-06-20 16:06 ` James Morse 2016-06-20 16:06 ` James Morse 2016-06-20 16:50 ` Geoff Levand 2016-06-20 16:50 ` Geoff Levand 2016-06-16 23:48 ` [PATCH v19 02/13] arm64: Add back cpu reset routines Geoff Levand 2016-06-16 23:48 ` Geoff Levand 2016-06-16 23:48 ` [PATCH v19 04/13] arm64/kexec: Enable kexec in the arm64 defconfig Geoff Levand 2016-06-16 23:48 ` Geoff Levand 2016-06-16 23:48 ` [PATCH v19 01/13] arm64: Add cpus_are_stuck_in_kernel Geoff Levand 2016-06-16 23:48 ` Geoff Levand 2016-06-16 23:48 ` [PATCH v19 03/13] arm64/kexec: Add core kexec support Geoff Levand 2016-06-16 23:48 ` Geoff Levand 2016-06-20 15:36 ` James Morse 2016-06-20 15:36 ` James Morse 2016-06-20 16:49 ` Geoff Levand 2016-06-20 16:49 ` Geoff Levand 2016-06-16 23:48 ` [PATCH v19 11/13] arm64: kdump: enable kdump in the arm64 defconfig Geoff Levand 2016-06-16 23:48 ` Geoff Levand 2016-06-16 23:48 ` [PATCH v19 13/13] Documentation: dt: usable-memory and elfcorehdr nodes for arm64 kexec Geoff Levand 2016-06-16 23:48 ` Geoff Levand 2016-06-16 23:48 ` [PATCH v19 12/13] arm64: kdump: update a kernel doc Geoff Levand 2016-06-16 23:48 ` Geoff Levand 2016-06-16 23:48 ` [PATCH v19 10/13] arm64: kdump: add VMCOREINFO's for user-space coredump tools Geoff Levand 2016-06-16 23:48 ` Geoff Levand 2016-06-20 5:32 ` Pratyush Anand 2016-06-20 5:32 ` Pratyush Anand 2016-06-22 5:59 ` AKASHI Takahiro 2016-06-22 5:59 ` AKASHI Takahiro 2016-06-23 7:14 ` Pratyush Anand 2016-06-23 7:14 ` Pratyush Anand 2016-06-23 8:42 ` AKASHI Takahiro [this message] 2016-06-23 8:42 ` AKASHI Takahiro 2016-06-23 15:46 ` Pratyush Anand 2016-06-23 15:46 ` Pratyush Anand 2016-06-30 0:44 ` AKASHI Takahiro 2016-06-30 0:44 ` AKASHI Takahiro 2016-06-16 23:48 ` [PATCH v19 07/13] arm64: limit memory regions based on DT property, usable-memory Geoff Levand 2016-06-16 23:48 ` Geoff Levand 2016-06-16 23:48 ` [PATCH v19 08/13] arm64: kdump: implement machine_crash_shutdown() Geoff Levand 2016-06-16 23:48 ` Geoff Levand 2016-06-16 23:48 ` [PATCH v19 06/13] arm64: kdump: reserve memory for crash dump kernel Geoff Levand 2016-06-16 23:48 ` Geoff Levand 2016-06-20 16:07 ` James Morse 2016-06-20 16:07 ` James Morse 2016-06-21 1:23 ` AKASHI Takahiro 2016-06-21 1:23 ` AKASHI Takahiro 2016-06-16 23:48 ` [PATCH v19 09/13] arm64: kdump: add kdump support Geoff Levand 2016-06-16 23:48 ` Geoff Levand
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