On Thu, Feb 01, 2018 at 05:34:26PM +0000, Ard Biesheuvel wrote: > On 1 February 2018 at 09:04, AKASHI Takahiro <takahiro.aka...@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.aka...@linaro.org> > > Suggested-by: James Morse <james.mo...@arm.com> > > Suggested-by: Ard Biesheuvel <ard.biesheu...@linaro.org> > > Reported-by and Tested-by: Bhupesh Sharma <bhsha...@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 > >