From: Anshuman Khandual <anshuman.khandual@arm.com> To: Pavel Tatashin <pasha.tatashin@soleen.com>, tyhicks@linux.microsoft.com, jmorris@namei.org, catalin.marinas@arm.com, will@kernel.org, akpm@linux-foundation.org, rppt@kernel.org, logang@deltatee.com, ardb@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, mhocko@suse.com, linux-mm@kvack.org Subject: Re: [PATCH v3 1/1] arm64: mm: correct the inside linear map range during hotplug check Date: Wed, 24 Feb 2021 12:42:31 +0530 [thread overview] Message-ID: <605fb3ad-7208-6d27-f055-cb642be8804b@arm.com> (raw) In-Reply-To: <20210216150351.129018-2-pasha.tatashin@soleen.com> On 2/16/21 8:33 PM, Pavel Tatashin wrote: > Memory hotplug may fail on systems with CONFIG_RANDOMIZE_BASE because the > linear map range is not checked correctly. > > The start physical address that linear map covers can be actually at the > end of the range because of randomization. Check that and if so reduce it > to 0. > > This can be verified on QEMU with setting kaslr-seed to ~0ul: > > memstart_offset_seed = 0xffff > START: __pa(_PAGE_OFFSET(vabits_actual)) = ffff9000c0000000 > END: __pa(PAGE_END - 1) = 1000bfffffff This would have tripped the check in mhp_get_pluggable_range() with errors something like here, which is expected. Hotplug memory [0x680000000-0x688000000] exceeds maximum addressable range [0x0-0x0] Hotplug memory [0x6c0000000-0x6c8000000] exceeds maximum addressable range [0x0-0x0] Hotplug memory [0x700000000-0x708000000] exceeds maximum addressable range [0x0-0x0] Hotplug memory [0x780000000-0x788000000] exceeds maximum addressable range [0x0-0x0] Hotplug memory [0x7c0000000-0x7c8000000] exceeds maximum addressable range [0x0-0x0] > > Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com> > Fixes: 58284a901b42 ("arm64/mm: Validate hotplug range before creating linear mapping") > Tested-by: Tyler Hicks <tyhicks@linux.microsoft.com> > --- > arch/arm64/mm/mmu.c | 21 +++++++++++++++++++-- > 1 file changed, 19 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index ef7698c4e2f0..0d9c115e427f 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -1447,6 +1447,22 @@ static void __remove_pgd_mapping(pgd_t *pgdir, unsigned long start, u64 size) > struct range arch_get_mappable_range(void) > { > struct range mhp_range; > + u64 start_linear_pa = __pa(_PAGE_OFFSET(vabits_actual)); > + u64 end_linear_pa = __pa(PAGE_END - 1); > + > + if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { > + /* > + * Check for a wrap, it is possible because of randomized linear > + * mapping the start physical address is actually bigger than > + * the end physical address. In this case set start to zero > + * because [0, end_linear_pa] range must still be able to cover > + * all addressable physical addresses. > + */ > + if (start_linear_pa > end_linear_pa) > + start_linear_pa = 0; > + } > + > + WARN_ON(start_linear_pa > end_linear_pa); > > /* > * Linear mapping region is the range [PAGE_OFFSET..(PAGE_END - 1)] > @@ -1454,8 +1470,9 @@ struct range arch_get_mappable_range(void) > * range which can be mapped inside this linear mapping range, must > * also be derived from its end points. > */ > - mhp_range.start = __pa(_PAGE_OFFSET(vabits_actual)); > - mhp_range.end = __pa(PAGE_END - 1); > + mhp_range.start = start_linear_pa; > + mhp_range.end = end_linear_pa; > + > return mhp_range; > } LGTM. Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
WARNING: multiple messages have this Message-ID (diff)
From: Anshuman Khandual <anshuman.khandual@arm.com> To: Pavel Tatashin <pasha.tatashin@soleen.com>, tyhicks@linux.microsoft.com, jmorris@namei.org, catalin.marinas@arm.com, will@kernel.org, akpm@linux-foundation.org, rppt@kernel.org, logang@deltatee.com, ardb@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, mhocko@suse.com, linux-mm@kvack.org Subject: Re: [PATCH v3 1/1] arm64: mm: correct the inside linear map range during hotplug check Date: Wed, 24 Feb 2021 12:42:31 +0530 [thread overview] Message-ID: <605fb3ad-7208-6d27-f055-cb642be8804b@arm.com> (raw) In-Reply-To: <20210216150351.129018-2-pasha.tatashin@soleen.com> On 2/16/21 8:33 PM, Pavel Tatashin wrote: > Memory hotplug may fail on systems with CONFIG_RANDOMIZE_BASE because the > linear map range is not checked correctly. > > The start physical address that linear map covers can be actually at the > end of the range because of randomization. Check that and if so reduce it > to 0. > > This can be verified on QEMU with setting kaslr-seed to ~0ul: > > memstart_offset_seed = 0xffff > START: __pa(_PAGE_OFFSET(vabits_actual)) = ffff9000c0000000 > END: __pa(PAGE_END - 1) = 1000bfffffff This would have tripped the check in mhp_get_pluggable_range() with errors something like here, which is expected. Hotplug memory [0x680000000-0x688000000] exceeds maximum addressable range [0x0-0x0] Hotplug memory [0x6c0000000-0x6c8000000] exceeds maximum addressable range [0x0-0x0] Hotplug memory [0x700000000-0x708000000] exceeds maximum addressable range [0x0-0x0] Hotplug memory [0x780000000-0x788000000] exceeds maximum addressable range [0x0-0x0] Hotplug memory [0x7c0000000-0x7c8000000] exceeds maximum addressable range [0x0-0x0] > > Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com> > Fixes: 58284a901b42 ("arm64/mm: Validate hotplug range before creating linear mapping") > Tested-by: Tyler Hicks <tyhicks@linux.microsoft.com> > --- > arch/arm64/mm/mmu.c | 21 +++++++++++++++++++-- > 1 file changed, 19 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index ef7698c4e2f0..0d9c115e427f 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -1447,6 +1447,22 @@ static void __remove_pgd_mapping(pgd_t *pgdir, unsigned long start, u64 size) > struct range arch_get_mappable_range(void) > { > struct range mhp_range; > + u64 start_linear_pa = __pa(_PAGE_OFFSET(vabits_actual)); > + u64 end_linear_pa = __pa(PAGE_END - 1); > + > + if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { > + /* > + * Check for a wrap, it is possible because of randomized linear > + * mapping the start physical address is actually bigger than > + * the end physical address. In this case set start to zero > + * because [0, end_linear_pa] range must still be able to cover > + * all addressable physical addresses. > + */ > + if (start_linear_pa > end_linear_pa) > + start_linear_pa = 0; > + } > + > + WARN_ON(start_linear_pa > end_linear_pa); > > /* > * Linear mapping region is the range [PAGE_OFFSET..(PAGE_END - 1)] > @@ -1454,8 +1470,9 @@ struct range arch_get_mappable_range(void) > * range which can be mapped inside this linear mapping range, must > * also be derived from its end points. > */ > - mhp_range.start = __pa(_PAGE_OFFSET(vabits_actual)); > - mhp_range.end = __pa(PAGE_END - 1); > + mhp_range.start = start_linear_pa; > + mhp_range.end = end_linear_pa; > + > return mhp_range; > } LGTM. Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com> _______________________________________________ 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:[~2021-02-24 7:13 UTC|newest] Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-02-16 15:03 [PATCH v3 0/1] correct the inside linear map range during hotplug check Pavel Tatashin 2021-02-16 15:03 ` Pavel Tatashin 2021-02-16 15:03 ` [PATCH v3 1/1] arm64: mm: " Pavel Tatashin 2021-02-16 15:03 ` Pavel Tatashin 2021-02-19 19:18 ` Will Deacon 2021-02-19 19:18 ` Will Deacon 2021-02-19 19:44 ` Pavel Tatashin 2021-02-19 19:44 ` Pavel Tatashin 2021-02-19 19:44 ` Pavel Tatashin 2021-02-22 12:25 ` Will Deacon 2021-02-22 12:25 ` Will Deacon 2021-02-22 14:17 ` Pavel Tatashin 2021-02-22 14:17 ` Pavel Tatashin 2021-02-22 14:17 ` Pavel Tatashin 2021-03-19 15:43 ` Pavel Tatashin 2021-03-19 15:43 ` Pavel Tatashin 2021-03-19 15:43 ` Pavel Tatashin 2021-02-24 7:12 ` Anshuman Khandual [this message] 2021-02-24 7:12 ` Anshuman Khandual 2021-03-22 13:19 ` [PATCH v3 0/1] " Will Deacon 2021-03-22 13:19 ` Will Deacon
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=605fb3ad-7208-6d27-f055-cb642be8804b@arm.com \ --to=anshuman.khandual@arm.com \ --cc=akpm@linux-foundation.org \ --cc=ardb@kernel.org \ --cc=catalin.marinas@arm.com \ --cc=jmorris@namei.org \ --cc=linux-arm-kernel@lists.infradead.org \ --cc=linux-kernel@vger.kernel.org \ --cc=linux-mm@kvack.org \ --cc=logang@deltatee.com \ --cc=mhocko@suse.com \ --cc=pasha.tatashin@soleen.com \ --cc=rppt@kernel.org \ --cc=tyhicks@linux.microsoft.com \ --cc=will@kernel.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.