James,
On Wed, Jan 10, 2018 at 11:26:55AM +0000, James Morse wrote:
> Hi Akashi,
>
> 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."
> >
> > <kicking off kdump after panic>
> > Bye!
> > (snip...)
> > ACPI: Core revision 20170728
> > pud=000000002e7d0003, *pmd=000000002e7c0003, *pte=00e8000039710707
> > Internal error: Oops: 96000021 [#1] SMP
> > Modules linked in:
> > CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.14.0-rc6 #1
> > task: ffff000008d05180 task.stack: ffff000008cc0000
> > PC is at acpi_ns_lookup+0x25c/0x3c0
> > LR is at acpi_ds_load1_begin_op+0xa4/0x294
> > (snip...)
> > Process swapper/0 (pid: 0, stack limit = 0xffff000008cc0000)
> > Call trace:
> > (snip...)
> > [<ffff0000084a6764>] acpi_ns_lookup+0x25c/0x3c0
> > [<ffff00000849b4f8>] acpi_ds_load1_begin_op+0xa4/0x294
> > [<ffff0000084ad4ac>] acpi_ps_build_named_op+0xc4/0x198
> > [<ffff0000084ad6cc>] acpi_ps_create_op+0x14c/0x270
> > [<ffff0000084acfa8>] acpi_ps_parse_loop+0x188/0x5c8
> > [<ffff0000084ae048>] acpi_ps_parse_aml+0xb0/0x2b8
> > [<ffff0000084a8e10>] acpi_ns_one_complete_parse+0x144/0x184
> > [<ffff0000084a8e98>] acpi_ns_parse_table+0x48/0x68
> > [<ffff0000084a82cc>] acpi_ns_load_table+0x4c/0xdc
> > [<ffff0000084b32f8>] acpi_tb_load_namespace+0xe4/0x264
> > [<ffff000008baf9b4>] acpi_load_tables+0x48/0xc0
> > [<ffff000008badc20>] acpi_early_init+0x9c/0xd0
> > [<ffff000008b70d50>] start_kernel+0x3b4/0x43c
> > Code: b9008fb9 2a000318 36380054 32190318 (b94002c0)
> > ---[ end trace c46ed37f9651c58e ]---
> > Kernel panic - not syncing: Fatal exception
> > Rebooting in 10 seconds..
> >
> > (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?
(I'm still debugging this code since the kernel fails to boot.)
Thanks,
-Takahiro AKASHI
>
> > * ACPI accessor/helper functions are compiled in without unaligned access
> > support (ACPI_MISALIGNMENT_NOT_SUPPORTED), eventually ending up a fatal
> > panic when accessing ACPI tables.
> >
> > With this patch, all the reserved memory regions, as well as NOMAP-
> > attributed ones which are presumably ACPI runtime code and data, are set
> > to be retained in system ram even if they are outside of usable memory
> > range specified by device tree blob. Accordingly, ACPI tables are mapped
> > as cacheable and can be safely accessed without causing unaligned access
> > faults.
>
>
> Thanks,
>
> James
===8<===
diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
index 32f465a80e4e..6953aaaf2bfa 100644
--- a/arch/arm64/include/asm/acpi.h
+++ b/arch/arm64/include/asm/acpi.h
@@ -16,6 +16,7 @@
#include <linux/psci.h>
#include <asm/cputype.h>
+#include <asm/io.h>
#include <asm/smp_plat.h>
#include <asm/tlbflush.h>
@@ -29,18 +30,13 @@
/* 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)
{
- /*
- * EFI's reserve_regions() call adds memory with the WB attribute
- * to memblock via early_init_dt_add_memory_arch().
- */
- 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 +121,10 @@ 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..43e9d8371f88 100644
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c
@@ -239,8 +239,7 @@ 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 +260,3 @@ pgprot_t arch_apei_get_mem_attribute(phys_addr_t addr)
return __pgprot(PROT_NORMAL_NC);
return __pgprot(PROT_DEVICE_nGnRnE);
}
-#endif
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