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Date: Mon, 18 Jun 2018 15:44:14 +0900
From: AKASHI Takahiro <takahiro.akashi@...aro.org>
To: James Morse <james.morse@....com>
Cc: catalin.marinas@....com, will.deacon@....com,
akpm@...ux-foundation.org, ard.biesheuvel@...aro.org,
tbaicar@...eaurora.org, bhsharma@...hat.com, dyoung@...hat.com,
mark.rutland@....com, al.stone@...aro.org,
graeme.gregory@...aro.org, hanjun.guo@...aro.org,
lorenzo.pieralisi@....com, sudeep.holla@....com,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
kexec@...ts.infradead.org
Subject: Re: [PATCH 2/3] arm64: acpi,efi: fix alignment fault in accessing
ACPI tables at kdump
James,
On Fri, Jun 15, 2018 at 05:30:08PM +0100, James Morse wrote:
> Hi Akashi,
>
> On 15/06/18 08:56, 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."
> >
> > (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 memory attribute
> > information provided by the firmware (EFI) and retaining cacheability
> > allows the kernel safe access to ACPI tables.
>
>
> > Please note that arm_enable_runtime_services() is now renamed to
> > efi_enter_virtual_mode() due to the similarity to x86's.
>
> Just a rename?:
and maps EFI memory map whether or not runtime service is enabled.
> > drivers/firmware/efi/arm-runtime.c | 27 ++++++++++++---------------
>
>
>
> > 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
> > @@ -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.
> > */
>
> (Even without kdump we would still need this. Regions ACPI wants mapped may not
> be covered by the linear map. In this case we need to use the attributes
> firmware described in the UEFI memory map. Kdump exacerbates this by
> artificially reducing the range of the linear map.)
>
>
> > - if (!memblock_is_memory(phys))
> > - return ioremap(phys, size);
> > -
> > - return ioremap_cache(phys, size);
> > + return __ioremap(phys, size, __acpi_get_mem_attribute(phys));
> > }
>
>
>
> > diff --git a/drivers/firmware/efi/arm-runtime.c b/drivers/firmware/efi/arm-runtime.c
> > index 5889cbea60b8..566ef0a9edb5 100644
> > --- a/drivers/firmware/efi/arm-runtime.c
> > +++ b/drivers/firmware/efi/arm-runtime.c
> > @@ -106,46 +106,43 @@ 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;
> > + }
> > +
> > + mapsize = efi.memmap.desc_size * efi.memmap.nr_map;
> > +
> > + if (efi_memmap_init_late(efi.memmap.phys_map, mapsize)) {
> > + pr_err("Failed to remap EFI memory map\n");
> > + 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");
> >
> > - mapsize = efi.memmap.desc_size * efi.memmap.nr_map;
> > -
> > - if (efi_memmap_init_late(efi.memmap.phys_map, mapsize)) {
> > - pr_err("Failed to remap EFI memory map\n");
> > - return -ENOMEM;
> > - }
> > -
> > 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;
> > }
>
> Please have the drivers/firmware/efi/arm-runtime.c changes in a separate patch
> (maybe combine it with patch 3). The 'efi/arm: ' prefix is more likely to catch
> the maintainers attention.
>
> I think this is what Ard meant by:
> | Could you please move the changes to this file and init/main.c into a
> | separate patch?
>
> https://patchwork.kernel.org/patch/10361761/
>
>
> > -early_initcall(arm_enable_runtime_services);
>
> With just this patch, surely nothing ever calls arm_enable_runtime_services(),
> and now acpi_os_ioremap() will return device memory for anything that isn't part
> of the linear region. (This breaks RAS).
Actually I noticed the issue.
> This will make it difficult to bisect through for any RAS or
> efi-runtime-services issue. Its easily fixed: please put the efi+init changes in
> a patch before the acpi_os_ioremap() changes.
I was reluctant to put different part of code changes into one.
But if nobody cares, I will do so in three patches.
* change arm_enable_runtime_services() with renaming
* move this function earlier in start_kernel()
* modify acpi_os_ioremap()
Thanks,
-Takahiro AKASHI
> Otherwise, looks good to me!
>
>
> Thanks,
>
> James
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