From: Jonathan (Zhixiong) Zhang Date: Fri, 4 Sep 2015 13:11:42 +0000 (+0100) Subject: acpi/apei: Use appropriate pgprot_t to map GHES memory X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=8ece249a811e93d3f60e3f1ebdc86c7e7a95bdbf;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git acpi/apei: Use appropriate pgprot_t to map GHES memory If the ACPI APEI firmware handles hardware error first (called "firmware first handling"), the firmware updates the GHES memory region with hardware error record (called "generic hardware error record"). Essentially the firmware writes hardware error records in the GHES memory region, triggers an NMI/interrupt, then the GHES driver goes off and grabs the error record from the GHES region. The kernel currently maps the GHES memory region as cacheable (PAGE_KERNEL) for all architectures. However, on some arm64 platforms, there is a mismatch between how the kernel maps the GHES region (PAGE_KERNEL) and how the firmware maps it (EFI_MEMORY_UC, ie. uncacheable), leading to the possibility of the kernel GHES driver reading stale data from the cache when it receives the interrupt. With stale data being read, the kernel is unaware there is new hardware error to be handled when there actually is; this may lead to further damage in various scenarios, such as error propagation caused data corruption. If uncorrected error (such as double bit ECC error) happened in memory operation and if the kernel is unaware of such an event happening, errorneous data may be propagated to the disk. Instead GHES memory region should be mapped with page protection type according to what is returned from arch_apei_get_mem_attribute(). Signed-off-by: Jonathan (Zhixiong) Zhang Signed-off-by: Matt Fleming [ Small stylistic tweaks. ] Reviewed-by: Matt Fleming Acked-by: Borislav Petkov Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1441372302-23242-3-git-send-email-matt@codeblueprint.co.uk Signed-off-by: Ingo Molnar --- diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c index 2bfd53cbfe80..e661695cf123 100644 --- a/drivers/acpi/apei/ghes.c +++ b/drivers/acpi/apei/ghes.c @@ -161,11 +161,15 @@ static void __iomem *ghes_ioremap_pfn_nmi(u64 pfn) static void __iomem *ghes_ioremap_pfn_irq(u64 pfn) { - unsigned long vaddr; + unsigned long vaddr, paddr; + pgprot_t prot; vaddr = (unsigned long)GHES_IOREMAP_IRQ_PAGE(ghes_ioremap_area->addr); - ioremap_page_range(vaddr, vaddr + PAGE_SIZE, - pfn << PAGE_SHIFT, PAGE_KERNEL); + + paddr = pfn << PAGE_SHIFT; + prot = arch_apei_get_mem_attribute(paddr); + + ioremap_page_range(vaddr, vaddr + PAGE_SIZE, paddr, prot); return (void __iomem *)vaddr; }