James,
On Fri, Jan 19, 2018 at 11:39:58AM +0000, James Morse wrote:
> Hi Akashi,
>
> On 11/01/18 11:38, AKASHI Takahiro wrote:
> > On Wed, Jan 10, 2018 at 11:26:55AM +0000, James Morse wrote:
> >> On 10/01/18 10:09, AKASHI Takahiro wrote:
> >>> This is a fix against the issue that crash dump kernel may hang up
> >>> during booting, which can happen on any ACPI-based system with "ACPI
> >>> Reclaim Memory."
>
> >>> (diagnosis)
> >>> * This fault is a data abort, alignment fault (ESR=0x96000021)
> >>> during reading out ACPI table.
> >>> * Initial ACPI tables are normally stored in system ram and marked as
> >>> "ACPI Reclaim memory" by the firmware.
> >>> * After the commit f56ab9a5b73c ("efi/arm: Don't mark ACPI reclaim
> >>> memory as MEMBLOCK_NOMAP"), those regions' attribute were changed
> >>> removing NOMAP bit and they are instead "memblock-reserved".
> >>> * When crash dump kernel boots up, it tries to accesses ACPI tables by
> >>> ioremap'ing them (through acpi_os_ioremap()).
> >>> * Since those regions are not included in device tree's
> >>> "usable-memory-range" and so not recognized as part of crash dump
> >>> kernel's system ram, ioremap() will create a non-cacheable mapping here.
> >>
> >> Ugh, because acpi_os_ioremap() looks at the efi memory map through the prism of
> >> what we pulled into memblock, which is different during kdump.
> >>
> >> Is an alternative to teach acpi_os_ioremap() to ask
> >> efi_mem_attributes() directly for the attributes to use?
> >> (e.g. arch_apei_get_mem_attribute())
> >
> > I didn't think of this approach.
> > Do you mean a change like the patch below?
>
> Yes. Aha, you can pretty much re-use the helper directly.
>
> It was just a suggestion, removing the extra abstraction that is causing the bug
> could be cleaner ...
>
> > (I'm still debugging this code since the kernel fails to boot.)
>
> ... but might be too fragile.
>
> There are points during boot when the EFI memory map isn't mapped.
Right, this was a problem for my patch.
Attached is the revised and workable one.
Efi_memmap_init_late() may alternatively be called in acpi_early_init() or
even in acpi_os_ioremap(), but either way it looks a bit odd.
Thanks,
-Takahiro AKASHI
> I think that
> helper will return 'device memory' for everything when this happens.
>
>
> Thanks,
>
> James
===8<===
>From c88f4c8106ba7a918c835b1cdf538b1d21019863 Mon Sep 17 00:00:00 2001
From: AKASHI Takahiro <takahiro.akashi@xxxxxxxxxx>
Date: Mon, 29 Jan 2018 15:07:43 +0900
Subject: [PATCH] arm64: kdump: make acpi_os_ioremap() more generic
---
arch/arm64/include/asm/acpi.h | 23 ++++++++++++++++-------
arch/arm64/kernel/acpi.c | 7 ++-----
init/main.c | 4 ++++
3 files changed, 22 insertions(+), 12 deletions(-)
diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
index 32f465a80e4e..d53c95f4e1a9 100644
--- a/arch/arm64/include/asm/acpi.h
+++ b/arch/arm64/include/asm/acpi.h
@@ -12,10 +12,12 @@
#ifndef _ASM_ACPI_H
#define _ASM_ACPI_H
+#include <linux/efi.h>
#include <linux/memblock.h>
#include <linux/psci.h>
#include <asm/cputype.h>
+#include <asm/io.h>
#include <asm/smp_plat.h>
#include <asm/tlbflush.h>
@@ -29,18 +31,22 @@
/* Basic configuration for ACPI */
#ifdef CONFIG_ACPI
+pgprot_t __acpi_get_mem_attribute(phys_addr_t addr);
+
/* ACPI table mapping after acpi_permanent_mmap is set */
static inline void __iomem *acpi_os_ioremap(acpi_physical_address phys,
acpi_size size)
{
+ /* For normal memory we already have a cacheable mapping. */
+ if (memblock_is_map_memory(phys))
+ return (void __iomem *)__phys_to_virt(phys);
+
/*
- * EFI's reserve_regions() call adds memory with the WB attribute
- * to memblock via early_init_dt_add_memory_arch().
+ * We should still honor the memory's attribute here because
+ * crash dump kernel possibly excludes some ACPI (reclaim)
+ * regions from memblock list.
*/
- if (!memblock_is_memory(phys))
- return ioremap(phys, size);
-
- return ioremap_cache(phys, size);
+ return __ioremap(phys, size, __acpi_get_mem_attribute(phys));
}
#define acpi_os_ioremap acpi_os_ioremap
@@ -125,7 +131,10 @@ static inline const char *acpi_get_enable_method(int cpu)
* for compatibility.
*/
#define acpi_disable_cmcff 1
-pgprot_t arch_apei_get_mem_attribute(phys_addr_t addr);
+static inline pgprot_t arch_apei_get_mem_attribute(phys_addr_t addr)
+{
+ return __acpi_get_mem_attribute(addr);
+}
#endif /* CONFIG_ACPI_APEI */
#ifdef CONFIG_ACPI_NUMA
diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
index b3162715ed78..f94bdf7be439 100644
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c
@@ -31,10 +31,9 @@
#include <asm/cpu_ops.h>
#include <asm/smp_plat.h>
-#ifdef CONFIG_ACPI_APEI
+/* CONFIG_ACPI_APEI */
# include <linux/efi.h>
# include <asm/pgtable.h>
-#endif
int acpi_noirq = 1; /* skip ACPI IRQ initialization */
int acpi_disabled = 1;
@@ -239,8 +238,7 @@ void __init acpi_boot_table_init(void)
}
}
-#ifdef CONFIG_ACPI_APEI
-pgprot_t arch_apei_get_mem_attribute(phys_addr_t addr)
+pgprot_t __acpi_get_mem_attribute(phys_addr_t addr)
{
/*
* According to "Table 8 Map: EFI memory types to AArch64 memory
@@ -261,4 +259,3 @@ pgprot_t arch_apei_get_mem_attribute(phys_addr_t addr)
return __pgprot(PROT_NORMAL_NC);
return __pgprot(PROT_DEVICE_nGnRnE);
}
-#endif
diff --git a/init/main.c b/init/main.c
index a8100b954839..a479ece2bae9 100644
--- a/init/main.c
+++ b/init/main.c
@@ -674,6 +674,10 @@ asmlinkage __visible void __init start_kernel(void)
debug_objects_mem_init();
setup_per_cpu_pageset();
numa_policy_init();
+#if defined(CONFIG_ARM64) && defined(CONFIG_EFI)
+ efi_memmap_init_late(efi.memmap.phys_map,
+ efi.memmap.nr_map * efi.memmap.desc_size);
+#endif
acpi_early_init();
if (late_time_init)
late_time_init();
--
2.15.1
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