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SubjectRe: [RESEND PATCH] arm64: acpi,efi: fix alignment fault in accessing ACPI tables at kdump
On 25 April 2018 at 08:35, AKASHI Takahiro <takahiro.akashi@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.
> * 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@linaro.org>
> Suggested-by: James Morse <james.morse@arm.com>
> Suggested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Reported-by and Tested-by: Bhupesh Sharma <bhsharma@redhat.com>
> ---
> arch/arm64/include/asm/acpi.h | 23 ++++++++++++++++-------
> arch/arm64/kernel/acpi.c | 11 +++--------
> 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 7b09487ff8fb..7880076c1cf0 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>

Please drop the space after #

> #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>

And here

> -#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 5889cbea60b8..1148ea5a0faa 100644
> --- a/drivers/firmware/efi/arm-runtime.c
> +++ b/drivers/firmware/efi/arm-runtime.c
> @@ -106,23 +106,23 @@ 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;
> }
>

This is a problem. If you are booting using efi=noruntime, the routine
exits early and never sets up the mapping for the EFI memory map.
So the efi_memmap_init_late() call should be moved before the
efi_runtime_disabled() check, everything else can stay as is afaict

Could you please move the changes to this file and init/main.c into a
separate patch?

> 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");
> @@ -131,21 +131,18 @@ 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 b795aa341a3a..40d05b63960f 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -693,6 +693,9 @@ 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();
> --
> 2.17.0
>

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