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![Hans de Goede](/assets/img/avatar_default.png)
Just like with PCI options ROMs, which we save in the setup_efi_pci* functions from arch/x86/boot/compressed/eboot.c, the EFI code / ROM itself sometimes may contain data which is useful/necessary for peripheral drivers to have access to. Specifically the EFI code may contain an embedded copy of firmware which needs to be (re)loaded into the peripheral. Normally such firmware would be part of linux-firmware, but in some cases this is not feasible, for 2 reasons: 1) The firmware is customized for a specific use-case of the chipset / use with a specific hardware model, so we cannot have a single firmware file for the chipset. E.g. touchscreen controller firmwares are compiled specifically for the hardware model they are used with, as they are calibrated for a specific model digitizer. 2) Despite repeated attempts we have failed to get permission to redistribute the firmware. This is especially a problem with customized firmwares, these get created by the chip vendor for a specific ODM and the copyright may partially belong with the ODM, so the chip vendor cannot give a blanket permission to distribute these. This commit adds support for finding peripheral firmware embedded in the EFI code and makes the found firmware available through the new efi_get_embedded_fw() function. Support for loading these firmwares through the standard firmware loading mechanism is added in a follow-up commit in this patch-series. Note we check the EFI_BOOT_SERVICES_CODE for embedded firmware near the end of start_kernel(), just before calling rest_init(), this is on purpose because the typical EFI_BOOT_SERVICES_CODE memory-segment is too large for early_memremap(), so the check must be done after mm_init(). This relies on EFI_BOOT_SERVICES_CODE not being free-ed until efi_free_boot_services() is called, which means that this will only work on x86 for now. Reported-by: Dave Olsthoorn <dave@bewaar.me> Suggested-by: Peter Jones <pjones@redhat.com> Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Hans de Goede <hdegoede@redhat.com> Link: https://lore.kernel.org/r/20200115163554.101315-3-hdegoede@redhat.com Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
41 lines
1 KiB
C
41 lines
1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_EFI_EMBEDDED_FW_H
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#define _LINUX_EFI_EMBEDDED_FW_H
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#include <linux/list.h>
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#include <linux/mod_devicetable.h>
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#define EFI_EMBEDDED_FW_PREFIX_LEN 8
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/*
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* This struct and efi_embedded_fw_list are private to the efi-embedded fw
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* implementation they are in this header for use by lib/test_firmware.c only!
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*/
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struct efi_embedded_fw {
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struct list_head list;
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const char *name;
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const u8 *data;
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size_t length;
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};
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extern struct list_head efi_embedded_fw_list;
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/**
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* struct efi_embedded_fw_desc - This struct is used by the EFI embedded-fw
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* code to search for embedded firmwares.
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*
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* @name: Name to register the firmware with if found
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* @prefix: First 8 bytes of the firmware
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* @length: Length of the firmware in bytes including prefix
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* @sha256: SHA256 of the firmware
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*/
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struct efi_embedded_fw_desc {
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const char *name;
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u8 prefix[EFI_EMBEDDED_FW_PREFIX_LEN];
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u32 length;
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u8 sha256[32];
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};
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int efi_get_embedded_fw(const char *name, const u8 **dat, size_t *sz);
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#endif
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