[PATCH] arm64: acpi,efi: fix alignment fault in accessing ACPI tables at kdump
AKASHI Takahiro
takahiro.akashi at linaro.org
Thu Feb 1 20:35:21 PST 2018
On Thu, Feb 01, 2018 at 05:34:26PM +0000, Ard Biesheuvel wrote:
> On 1 February 2018 at 09:04, AKASHI Takahiro <takahiro.akashi at linaro.org> 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."
> >
> > (kernel messages after panic kicked off kdump)
> > (snip...)
> > 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 are differently handled
> > as they are "memblock-reserved", without NOMAP bit.
> > * So they are now excluded from device tree's "usable-memory-range"
> > which kexec-tools determines based on a current view of /proc/iomem.
>
> So this patch does fix the fallout of how this issue affects ACPI boot
> in particular, but is it correct in the first place for the kexec
> tools to disregard memory that has been memblock_reserved()?
My previous patch[1] is just for this. It would work not only for
the case here but also for any "reserved" memory regions.
The only noticeable drawback that I see in this approach is that
the meaning of "usable-memory-range" is now a bit obscure.
Alternatively we may want to modify /proc/iomem, adding a specific
resource entry for "ACPI Reclaim regions," and in turn kexec-tool so as
to put them into "usable-memory-range", but it is rather a stopgap
measure in my opinion. I don't like kexec relying heavily on userspace
tool as exporting the reserved regions in /proc/iomem is also useless
for most users.
(In this sense, I would go for kexec_file :)
> For
> instance, the UEFI memory map is memblock_reserve()d as well, along
> with other parts of memory that have been populated by the firmware.
>
> > * When crash dump kernel boots up, it tries to accesses ACPI tables by
> > mapping them with ioremap(), not ioremap_cache(), in acpi_os_ioremap()
> > since they are no longer part of mapped system ram.
> > * Given that ACPI accessor/helper functions are compiled in without
> > unaligned access support (ACPI_MISALIGNMENT_NOT_SUPPORTED),
> > any unaligned access to ACPI tables can cause a fatal panic.
> >
> > With this patch, acpi_os_ioremap() always honors a memory attribute
> > provided by the firmware (efi). Hence retaining cacheability in said cases
> > allows the kernel safe access to ACPI tables.
> >
> > Please note that arm_enable_runtime_services(), which is renamed to
> > efi_enter_virtual_mode() due to the similarity to x86's, is now called
> > earlier before acpi_early_init() since efi_mem_attributes() relies on
> > efi.memmap being mapped.
> >
> > Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
> > Suggested-by: James Morse <james.morse at arm.com>
> > Suggested-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
> > Reported-by and Tested-by: Bhupesh Sharma <bhsharma at redhat.com>
> > ---
> > arch/arm64/include/asm/acpi.h | 23 ++++++++++++++++-------
> > arch/arm64/kernel/acpi.c | 11 +++--------
>
> Split into two patches --here-- please
Sure, but only if this patch is a favorable approach over [1].
[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2018-January/553098.html
Thanks,
-Takahiro AKASHI
>
> > drivers/firmware/efi/arm-runtime.c | 15 ++++++---------
> > init/main.c | 3 +++
> > 4 files changed, 28 insertions(+), 24 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..35702c5e58d2 100644
> > --- a/arch/arm64/kernel/acpi.c
> > +++ b/arch/arm64/kernel/acpi.c
> > @@ -18,6 +18,7 @@
> > #include <linux/acpi.h>
> > #include <linux/bootmem.h>
> > #include <linux/cpumask.h>
> > +# include <linux/efi.h>
> > #include <linux/efi-bgrt.h>
> > #include <linux/init.h>
> > #include <linux/irq.h>
> > @@ -29,12 +30,8 @@
> >
> > #include <asm/cputype.h>
> > #include <asm/cpu_ops.h>
> > -#include <asm/smp_plat.h>
> > -
> > -#ifdef CONFIG_ACPI_APEI
> > -# include <linux/efi.h>
> > # include <asm/pgtable.h>
> > -#endif
> > +#include <asm/smp_plat.h>
> >
> > int acpi_noirq = 1; /* skip ACPI IRQ initialization */
> > int acpi_disabled = 1;
> > @@ -239,8 +236,7 @@ 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 +257,3 @@ 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/drivers/firmware/efi/arm-runtime.c b/drivers/firmware/efi/arm-runtime.c
> > index 1cc41c3d6315..16dd8a2d0237 100644
> > --- a/drivers/firmware/efi/arm-runtime.c
> > +++ b/drivers/firmware/efi/arm-runtime.c
> > @@ -115,23 +115,23 @@ static bool __init efi_virtmap_init(void)
> > * non-early mapping of the UEFI system table and virtual mappings for all
> > * EFI_MEMORY_RUNTIME regions.
> > */
> > -static int __init arm_enable_runtime_services(void)
> > +void __init efi_enter_virtual_mode(void)
> > {
> > u64 mapsize;
> >
> > if (!efi_enabled(EFI_BOOT)) {
> > pr_info("EFI services will not be available.\n");
> > - return 0;
> > + return;
> > }
> >
> > if (efi_runtime_disabled()) {
> > pr_info("EFI runtime services will be disabled.\n");
> > - return 0;
> > + return;
> > }
> >
> > if (efi_enabled(EFI_RUNTIME_SERVICES)) {
> > pr_info("EFI runtime services access via paravirt.\n");
> > - return 0;
> > + return;
> > }
> >
> > pr_info("Remapping and enabling EFI services.\n");
> > @@ -140,21 +140,18 @@ static int __init arm_enable_runtime_services(void)
> >
> > if (efi_memmap_init_late(efi.memmap.phys_map, mapsize)) {
> > pr_err("Failed to remap EFI memory map\n");
> > - return -ENOMEM;
> > + return;
> > }
> >
> > if (!efi_virtmap_init()) {
> > pr_err("UEFI virtual mapping missing or invalid -- runtime services will not be available\n");
> > - return -ENOMEM;
> > + return;
> > }
> >
> > /* Set up runtime services function pointers */
> > efi_native_runtime_setup();
> > set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
> > -
> > - return 0;
> > }
> > -early_initcall(arm_enable_runtime_services);
> >
> > void efi_virtmap_load(void)
> > {
> > diff --git a/init/main.c b/init/main.c
> > index a8100b954839..2d0927768e2d 100644
> > --- a/init/main.c
> > +++ b/init/main.c
> > @@ -674,6 +674,9 @@ asmlinkage __visible void __init start_kernel(void)
> > debug_objects_mem_init();
> > setup_per_cpu_pageset();
> > numa_policy_init();
> > + if (IS_ENABLED(CONFIG_EFI) &&
> > + (IS_ENABLED(CONFIG_ARM64) || IS_ENABLED(CONFIG_ARM)))
> > + efi_enter_virtual_mode();
> > acpi_early_init();
> > if (late_time_init)
> > late_time_init();
> > --
> > 2.15.1
> >
More information about the linux-arm-kernel
mailing list