forked from rpms/kernel
93 lines
4.0 KiB
Diff
93 lines
4.0 KiB
Diff
From patchwork Wed Mar 30 07:46:23 2016
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Content-Type: text/plain; charset="utf-8"
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MIME-Version: 1.0
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Content-Transfer-Encoding: 7bit
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Subject: efi/arm64: don't apply MEMBLOCK_NOMAP to UEFI memory map mapping
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From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
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X-Patchwork-Id: 8693271
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Message-Id: <1459323983-9120-1-git-send-email-ard.biesheuvel@linaro.org>
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To: linux-efi@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
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matt@codeblueprint.co.uk
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Cc: mark.rutland@arm.com, mlangsdo@redhat.com,
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Ard Biesheuvel <ard.biesheuvel@linaro.org>, leif.lindholm@linaro.org,
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jeremy.linton@arm.com, msalter@redhat.com
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Date: Wed, 30 Mar 2016 09:46:23 +0200
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Hi Matt,
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Could we queue this as a fix for v4.6 with a cc:stable for v4.5, please?
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(assuming no objections from any of the cc'ees)
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Thanks,
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Ard.
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----------8<--------------
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Commit 4dffbfc48d65 ("arm64/efi: mark UEFI reserved regions as
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MEMBLOCK_NOMAP") updated the mapping logic of both the RuntimeServices
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regions as well as the kernel's copy of the UEFI memory map to set the
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MEMBLOCK_NOMAP flag, which causes these regions to be omitted from the
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kernel direct mapping, and from being covered by a struct page.
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For the RuntimeServices regions, this is an obvious win, since the contents
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of these regions have significance to the firmware executable code itself,
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and are mapped in the EFI page tables using attributes that are described in
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the UEFI memory map, and which may differ from the attributes we use for
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mapping system RAM. It also prevents the contents from being modified
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inadvertently, since the EFI page tables are only live during runtime
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service invocations.
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None of these concerns apply to the allocation that covers the UEFI memory
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map, since it is entirely owned by the kernel. Setting the MEMBLOCK_NOMAP on
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the region did allow us to use ioremap_cache() to map it both on arm64 and
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on ARM, since the latter does not allow ioremap_cache() to be used on
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regions that are covered by a struct page.
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The ioremap_cache() on ARM restriction will be lifted in the v4.7 timeframe,
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but in the mean time, it has been reported that commit 4dffbfc48d65 causes
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a regression on 64k granule kernels. This is due to the fact that, given
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the 64 KB page size, the region that we end up removing from the kernel
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direct mapping is rounded up to 64 KB, and this 64 KB page frame may be
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shared with the initrd when booting via GRUB (which does not align its
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EFI_LOADER_DATA allocations to 64 KB like the stub does). This will crash
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the kernel as soon as it tries to access the initrd.
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Since the issue is specific to arm64, revert back to memblock_reserve()'ing
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the UEFI memory map when running on arm64. This is a temporary fix for v4.5
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and v4.6, and will be superseded in the v4.7 timeframe when we will be able
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to move back to memblock_reserve() unconditionally.
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Fixes: 4dffbfc48d65 ("arm64/efi: mark UEFI reserved regions as MEMBLOCK_NOMAP")
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Reported-by: Mark Salter <msalter@redhat.com>
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Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
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---
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drivers/firmware/efi/arm-init.c | 18 +++++++++++++++---
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1 file changed, 15 insertions(+), 3 deletions(-)
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diff --git a/drivers/firmware/efi/arm-init.c b/drivers/firmware/efi/arm-init.c
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index aa1f743152a2..8714f8c271ba 100644
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--- a/drivers/firmware/efi/arm-init.c
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+++ b/drivers/firmware/efi/arm-init.c
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@@ -203,7 +203,19 @@ void __init efi_init(void)
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reserve_regions();
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early_memunmap(memmap.map, params.mmap_size);
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- memblock_mark_nomap(params.mmap & PAGE_MASK,
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- PAGE_ALIGN(params.mmap_size +
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- (params.mmap & ~PAGE_MASK)));
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+
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+ if (IS_ENABLED(CONFIG_ARM)) {
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+ /*
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+ * ARM currently does not allow ioremap_cache() to be called on
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+ * memory regions that are covered by struct page. So remove the
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+ * UEFI memory map from the linear mapping.
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+ */
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+ memblock_mark_nomap(params.mmap & PAGE_MASK,
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+ PAGE_ALIGN(params.mmap_size +
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+ (params.mmap & ~PAGE_MASK)));
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+ } else {
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+ memblock_reserve(params.mmap & PAGE_MASK,
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+ PAGE_ALIGN(params.mmap_size +
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+ (params.mmap & ~PAGE_MASK)));
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+ }
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}
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