On 1 March 2017 at 23:24, Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> wrote:
> Wire up the existing support for SMBIOS tables (aka DMI), by moving the
> arm64 init code to drivers/firmware/efi/arm-runtime.c, which is shared
> between ARM and arm64, and adding a asm/dmi.h header to ARM that defines
> the mapping routines for the firmware tables.
>
> This allows userspace to access these tables to discover system information
> exposed by the firmware. It also sets the hardware name used in crash
> dumps, e.g.,
>
> Unable to handle kernel NULL pointer dereference at virtual address 00000000
> pgd = ed3c0000
> [00000000] *pgd=bf1f3835
> Internal error: Oops: 817 [#1] SMP THUMB2
> Modules linked in:
> CPU: 0 PID: 759 Comm: bash Not tainted 4.10.0-09601-g0e8f38792120-dirty #112
> Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
> ^^^
>
> NOTE: This does *NOT* enable or encourage the use of DMI quirks, i.e., the
> the practice of identifying the platform via DMI to decide whether
> certain workarounds for buggy hardware and/or firmware need to be
> enabled. This would require the DMI subsystem to be enabled much
> earlier than we do on ARM, which is non-trivial.
>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
If there are no concerns with this patch, I would like to queue it for
v4.12 in the EFI tree.
Russell, do you have any objections?
Thanks,
Ard.
> ---
> arch/arm/Kconfig | 11 +++++++++++
> arch/arm/include/asm/dmi.h | 19 +++++++++++++++++++
> arch/arm64/kernel/efi.c | 15 ---------------
> drivers/firmware/efi/arm-runtime.c | 15 +++++++++++++++
> 4 files changed, 45 insertions(+), 15 deletions(-)
> create mode 100644 arch/arm/include/asm/dmi.h
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index fda6a46d27cf..8214ea99b2f3 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -2089,6 +2089,17 @@ config EFI
> is only useful for kernels that may run on systems that have
> UEFI firmware.
>
> +config DMI
> + bool "Enable support for SMBIOS (DMI) tables"
> + depends on EFI
> + default y
> + help
> + This enables SMBIOS/DMI feature for systems.
> +
> + This option is only useful on systems that have UEFI firmware.
> + However, even with this option, the resultant kernel should
> + continue to boot on existing non-UEFI platforms.
> +
> endmenu
>
> menu "CPU Power Management"
> diff --git a/arch/arm/include/asm/dmi.h b/arch/arm/include/asm/dmi.h
> new file mode 100644
> index 000000000000..df2d2ff06f5b
> --- /dev/null
> +++ b/arch/arm/include/asm/dmi.h
> @@ -0,0 +1,19 @@
> +/*
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#ifndef __ASM_DMI_H
> +#define __ASM_DMI_H
> +
> +#include <linux/io.h>
> +#include <linux/slab.h>
> +
> +#define dmi_early_remap(x, l) memremap(x, l, MEMREMAP_WB)
> +#define dmi_early_unmap(x, l) memunmap(x)
> +#define dmi_remap(x, l) memremap(x, l, MEMREMAP_WB)
> +#define dmi_unmap(x) memunmap(x)
> +#define dmi_alloc(l) kzalloc(l, GFP_KERNEL)
> +
> +#endif
> diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
> index 5d17f377d905..82cd07592519 100644
> --- a/arch/arm64/kernel/efi.c
> +++ b/arch/arm64/kernel/efi.c
> @@ -11,7 +11,6 @@
> *
> */
>
> -#include <linux/dmi.h>
> #include <linux/efi.h>
> #include <linux/init.h>
>
> @@ -117,20 +116,6 @@ int __init efi_set_mapping_permissions(struct mm_struct *mm,
> set_permissions, md);
> }
>
> -static int __init arm64_dmi_init(void)
> -{
> - /*
> - * On arm64, DMI depends on UEFI, and dmi_scan_machine() needs to
> - * be called early because dmi_id_init(), which is an arch_initcall
> - * itself, depends on dmi_scan_machine() having been called already.
> - */
> - dmi_scan_machine();
> - if (dmi_available)
> - dmi_set_dump_stack_arch_desc();
> - return 0;
> -}
> -core_initcall(arm64_dmi_init);
> -
> /*
> * UpdateCapsule() depends on the system being shutdown via
> * ResetSystem().
> diff --git a/drivers/firmware/efi/arm-runtime.c b/drivers/firmware/efi/arm-runtime.c
> index 349dc3e1e52e..7149d2f48bb1 100644
> --- a/drivers/firmware/efi/arm-runtime.c
> +++ b/drivers/firmware/efi/arm-runtime.c
> @@ -165,3 +165,18 @@ void efi_virtmap_unload(void)
> efi_set_pgd(current->active_mm);
> preempt_enable();
> }
> +
> +
> +static int __init arm_dmi_init(void)
> +{
> + /*
> + * On arm64/ARM, DMI depends on UEFI, and dmi_scan_machine() needs to
> + * be called early because dmi_id_init(), which is an arch_initcall
> + * itself, depends on dmi_scan_machine() having been called already.
> + */
> + dmi_scan_machine();
> + if (dmi_available)
> + dmi_set_dump_stack_arch_desc();
> + return 0;
> +}
> +core_initcall(arm_dmi_init);
> --
> 2.7.4
>
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