[PATCH v8 0/8] efi/firmware/platform-x86: Add EFI embedded fw support

[PATCH v8 0/8] efi/firmware/platform-x86: Add EFI embedded fw support

[Hans de Goede]

Here is v8 of my patch-set to add support for EFI embedded fw to the kernel.
This new version should address the few small remarks Luis had for v7,
see below for the full changelog.

I believe that this patch-set is ready for merging now. I believe it
would be best to merge patches 1-6 through Greg's driver-core tree
where firmware-loader changes go. Dmitry already gave his Acked-by
for doing this with patches 5 and 6.

Ard, you already gave your Acked-by for the changes in patches 1-2
to indicate you are ok with the changes in general, are you also ok
with merging these changes through Greg's driver-core tree?

Patches 7-8 touch a quirks file under drivers/platform/x86 which sees
multipe updates each cycle. So my proposal is that once 1-6 has landed
Greg creates an immutable branch with those changes and then
Andy and/or Darren can merge in that branch and then apply 7 and 8.

Regards,

Hans


Changes in v8:
- Add pr_warn if there are mode then EFI_DEBUGFS_MAX_BLOBS boot service segments
- Document how the EFI debugfs boot_service_code? files can be used to check for
  embedded firmware
- Properly deal with the case of an EFI segment being smaller then the fw we
  are looking for
- Log a warning when efi_get_embedded_fw get called while we did not (yet)
  check for embedded firmwares
- Only build fallback_platform.c if CONFIG_EFI_EMBEDDED_FIRMWARE is defined,
  otherwise make firmware_fallback_platform() a static inline stub

Changes in v7:
- Split drivers/firmware/efi and drivers/base/firmware_loader changes into
  2 patches
- Use new, standalone, lib/crypto/sha256.c code
- Address kdoc comments from Randy Dunlap
- Add new FW_OPT_FALLBACK_PLATFORM flag and firmware_request_platform()
  _request_firmware() wrapper, as requested by Luis R. Rodriguez
- Stop using "efi-embedded-firmware" device-property, now that drivers need to
  use the new firmware_request_platform() to enable fallback to a device fw
  copy embedded in the platform's main firmware, we no longer need a property
  on the device to trigger this behavior
- Use security_kernel_load_data instead of calling
  security_kernel_read_file with a NULL file pointer argument
- Move the docs to Documentation/driver-api/firmware/fallback-mechanisms.rst
- Document the new firmware_request_platform() function in
  Documentation/driver-api/firmware/request_firmware.rst
- Add 2 new patches for the silead and chipone-icn8505 touchscreen drivers
  to use the new firmware_request_platform() method
- Rebased on top of 5.4-rc1

Changes in v6:
-Rework code to remove casts from if (prefix == mem) comparison
-Use SHA256 hashes instead of crc32 sums
-Add new READING_FIRMWARE_EFI_EMBEDDED read_file_id and use it
-Call security_kernel_read_file(NULL, READING_FIRMWARE_EFI_EMBEDDED)
 to check if this is allowed before looking at EFI embedded fw
-Document why we are not using the PI Firmware Volume protocol

Changes in v5:
-Rename the EFI_BOOT_SERVICES flag to EFI_PRESERVE_BS_REGIONS

Changes in v4:
-Drop note in docs about EFI_FIRMWARE_VOLUME_PROTOCOL, it is not part of
 UEFI proper, so the EFI maintainers don't want us referring people to it
-Use new EFI_BOOT_SERVICES flag
-Put the new fw_get_efi_embedded_fw() function in its own fallback_efi.c
 file which only gets built when EFI_EMBEDDED_FIRMWARE is selected
-Define an empty stub for fw_get_efi_embedded_fw() in fallback.h hwen
 EFI_EMBEDDED_FIRMWARE is not selected, to avoid the need for #ifdefs
 in firmware_loader/main.c
-Properly call security_kernel_post_read_file() on the firmware returned
 by efi_get_embedded_fw() to make sure that we are allowed to use it

Changes in v2:
-Rebased on driver-core/driver-core-next
-Add documentation describing the EFI embedded firmware mechanism to:
 Documentation/driver-api/firmware/request_firmware.rst
-Add a new EFI_EMBEDDED_FIRMWARE Kconfig bool and only build the embedded
 fw support if this is set. This is an invisible option which should be
 selected by drivers which need this
-Remove the efi_embedded_fw_desc and dmi_system_id-s for known devices
 from the efi-embedded-fw code, instead drivers using this are expected to
 export a dmi_system_id array, with each entries' driver_data pointing to a
 efi_embedded_fw_desc struct and register this with the efi-embedded-fw code
-Use kmemdup to make a copy instead of efi_mem_reserve()-ing the firmware,
 this avoids us messing with the EFI memmap and avoids the need to make
 changes to efi_mem_desc_lookup()
-Make the firmware-loader code only fallback to efi_get_embedded_fw() if the
 passed in device has the "efi-embedded-firmware" device-property bool set
-Skip usermodehelper fallback when "efi-embedded-firmware" device-property
 is set

[PATCH v8 1/8] efi: Export boot-services code and data as debugfs-blobs

[Hans de Goede]

Sometimes it is useful to be able to dump the efi boot-services code and
data. This commit adds these as debugfs-blobs to /sys/kernel/debug/efi,
but only if efi=debug is passed on the kernel-commandline as this requires
not freeing those memory-regions, which costs 20+ MB of RAM.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
Changes in v8:
-Add pr_warn if there are mode then EFI_DEBUGFS_MAX_BLOBS boot service segments
-Document how the boot_service_code? files can be used to check for embedded
 firmware. Note since this is related to the firmware EFI embedded fw support,
 these docs are added in the 4th patch of this patch-set, not in this one.

Changes in v5:
-Rename the EFI_BOOT_SERVICES flag to EFI_PRESERVE_BS_REGIONS

Changes in v4:
-Add new EFI_BOOT_SERVICES flag and use it to determine if the boot-services
 memory segments are available (and thus if it makes sense to register the
 debugfs bits for them)

Changes in v2:
-Do not call pr_err on debugfs call failures
---
 arch/x86/platform/efi/efi.c    |  1 +
 arch/x86/platform/efi/quirks.c |  4 +++
 drivers/firmware/efi/efi.c     | 57 ++++++++++++++++++++++++++++++++++
 include/linux/efi.h            |  1 +
 4 files changed, 63 insertions(+)

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 425e025341db..f8a9f5230aaf 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -232,6 +232,7 @@ int __init efi_memblock_x86_reserve_range(void)
 	     efi.memmap.desc_version);
 
 	memblock_reserve(pmap, efi.memmap.nr_map * efi.memmap.desc_size);
+	set_bit(EFI_PRESERVE_BS_REGIONS, &efi.flags);
 
 	return 0;
 }
diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
index 3b9fd679cea9..fab12ebf0ada 100644
--- a/arch/x86/platform/efi/quirks.c
+++ b/arch/x86/platform/efi/quirks.c
@@ -411,6 +411,10 @@ void __init efi_free_boot_services(void)
 	int num_entries = 0;
 	void *new, *new_md;
 
+	/* Keep all regions for /sys/kernel/debug/efi */
+	if (efi_enabled(EFI_DBG))
+		return;
+
 	for_each_efi_memory_desc(md) {
 		unsigned long long start = md->phys_addr;
 		unsigned long long size = md->num_pages << EFI_PAGE_SHIFT;
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index e98bbf8e56d9..bee809b337de 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -17,6 +17,7 @@
 #include <linux/kobject.h>
 #include <linux/module.h>
 #include <linux/init.h>
+#include <linux/debugfs.h>
 #include <linux/device.h>
 #include <linux/efi.h>
 #include <linux/of.h>
@@ -317,6 +318,59 @@ static __init int efivar_ssdt_load(void)
 static inline int efivar_ssdt_load(void) { return 0; }
 #endif
 
+#ifdef CONFIG_DEBUG_FS
+
+#define EFI_DEBUGFS_MAX_BLOBS 32
+
+static struct debugfs_blob_wrapper debugfs_blob[EFI_DEBUGFS_MAX_BLOBS];
+
+static void __init efi_debugfs_init(void)
+{
+	struct dentry *efi_debugfs;
+	efi_memory_desc_t *md;
+	char name[32];
+	int type_count[EFI_BOOT_SERVICES_DATA + 1] = {};
+	int i = 0;
+
+	efi_debugfs = debugfs_create_dir("efi", NULL);
+	if (IS_ERR_OR_NULL(efi_debugfs))
+		return;
+
+	for_each_efi_memory_desc(md) {
+		switch (md->type) {
+		case EFI_BOOT_SERVICES_CODE:
+			snprintf(name, sizeof(name), "boot_services_code%d",
+				 type_count[md->type]++);
+			break;
+		case EFI_BOOT_SERVICES_DATA:
+			snprintf(name, sizeof(name), "boot_services_data%d",
+				 type_count[md->type]++);
+			break;
+		default:
+			continue;
+		}
+
+		if (i >= EFI_DEBUGFS_MAX_BLOBS) {
+			pr_warn("More then %d EFI boot service segments, only showing first %d in debugfs\n",
+				EFI_DEBUGFS_MAX_BLOBS, EFI_DEBUGFS_MAX_BLOBS);
+			break;
+		}
+
+		debugfs_blob[i].size = md->num_pages << EFI_PAGE_SHIFT;
+		debugfs_blob[i].data = memremap(md->phys_addr,
+						debugfs_blob[i].size,
+						MEMREMAP_WB);
+		if (!debugfs_blob[i].data)
+			continue;
+
+		debugfs_create_blob(name, 0400, efi_debugfs, &debugfs_blob[i]);
+		i++;
+	}
+}
+#else
+static inline void efi_debugfs_init(void) {}
+#endif
+
 /*
  * We register the efi subsystem with the firmware subsystem and the
  * efivars subsystem with the efi subsystem, if the system was booted with
@@ -373,6 +427,9 @@ static int __init efisubsys_init(void)
 		goto err_remove_group;
 	}
 
+	if (efi_enabled(EFI_DBG) && efi_enabled(EFI_PRESERVE_BS_REGIONS))
+		efi_debugfs_init();
+
 	return 0;
 
 err_remove_group:
diff --git a/include/linux/efi.h b/include/linux/efi.h
index d87acf62958e..2929abb1e3c0 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -1202,6 +1202,7 @@ extern int __init efi_setup_pcdp_console(char *);
 #define EFI_DBG			8	/* Print additional debug info at runtime */
 #define EFI_NX_PE_DATA		9	/* Can runtime data regions be mapped non-executable? */
 #define EFI_MEM_ATTR		10	/* Did firmware publish an EFI_MEMORY_ATTRIBUTES table? */
+#define EFI_PRESERVE_BS_REGIONS	11	/* Are EFI boot-services memory segments available? */
 
 #ifdef CONFIG_EFI
 /*
-- 
2.23.0

[PATCH v8 2/8] efi: Add embedded peripheral firmware support

[Hans de Goede]

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>
---
Changes in v8:
- Properly deal with the (theoretical?) case of an EFI segment being
  smaller then the fw we are looking for
- Log a warning when efi_get_embedded_fw get called while we did not (yet)
  check for embedded firmwares

Changes in v7:
- Split drivers/firmware/efi and drivers/base/firmware_loader changes into
  2 patches
- Use new, standalone, lib/crypto/sha256.c code

Changes in v6:
- Rework code to remove casts from if (prefix == mem) comparison
- Use SHA256 hashes instead of crc32 sums
- Add new READING_FIRMWARE_EFI_EMBEDDED read_file_id and use it
- Call security_kernel_read_file(NULL, READING_FIRMWARE_EFI_EMBEDDED)
  to check if this is allowed before looking at EFI embedded fw
- Document why we are not using the UEFI PI Firmware Volume protocol

Changes in v5:
- Rename the EFI_BOOT_SERVICES flag to EFI_PRESERVE_BS_REGIONS

Changes in v4:
- Drop note in docs about EFI_FIRMWARE_VOLUME_PROTOCOL, it is not part of
  UEFI proper, so the EFI maintainers don't want us referring people to it
- Use new EFI_BOOT_SERVICES flag
- Put the new fw_get_efi_embedded_fw() function in its own fallback_efi.c
  file which only gets built when EFI_EMBEDDED_FIRMWARE is selected
- Define an empty stub for fw_get_efi_embedded_fw() in fallback.h hwen
  EFI_EMBEDDED_FIRMWARE is not selected, to avoid the need for #ifdefs
  in firmware_loader/main.c
- Properly call security_kernel_post_read_file() on the firmware returned
  by efi_get_embedded_fw() to make sure that we are allowed to use it

Changes in v3:
- Fix the docs using "efi-embedded-fw" as property name instead of
  "efi-embedded-firmware"

Changes in v2:
- Rebased on driver-core/driver-core-next
- Add documentation describing the EFI embedded firmware mechanism to:
  Documentation/driver-api/firmware/request_firmware.rst
- Add a new EFI_EMBEDDED_FIRMWARE Kconfig bool and only build the embedded
  fw support if this is set. This is an invisible option which should be
  selected by drivers which need this
- Remove the efi_embedded_fw_desc and dmi_system_id-s for known devices
  from the efi-embedded-fw code, instead drivers using this are expected to
  export a dmi_system_id array, with each entries' driver_data pointing to a
  efi_embedded_fw_desc struct and register this with the efi-embedded-fw code
- Use kmemdup to make a copy instead of efi_mem_reserve()-ing the firmware,
  this avoids us messing with the EFI memmap and avoids the need to make
  changes to efi_mem_desc_lookup()
- Make the firmware-loader code only fallback to efi_get_embedded_fw() if the
  passed in device has the "efi-embedded-firmware" device-property bool set
- Skip usermodehelper fallback when "efi-embedded-firmware" device-property
  is set
---
 arch/x86/platform/efi/efi.c              |   1 +
 drivers/firmware/efi/Kconfig             |   4 +
 drivers/firmware/efi/Makefile            |   1 +
 drivers/firmware/efi/embedded-firmware.c | 151 +++++++++++++++++++++++
 include/linux/efi.h                      |   6 +
 include/linux/efi_embedded_fw.h          |  25 ++++
 6 files changed, 188 insertions(+)
 create mode 100644 drivers/firmware/efi/embedded-firmware.c
 create mode 100644 include/linux/efi_embedded_fw.h

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index f8a9f5230aaf..4e4b5ac3ce65 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -1016,6 +1016,7 @@ static void __init __efi_enter_virtual_mode(void)
 		panic("EFI call to SetVirtualAddressMap() failed!");
 	}
 
+	efi_check_for_embedded_firmwares();
 	efi_free_boot_services();
 
 	/*
diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
index b248870a9806..657f958365ee 100644
--- a/drivers/firmware/efi/Kconfig
+++ b/drivers/firmware/efi/Kconfig
@@ -194,6 +194,10 @@ config EFI_RCI2_TABLE
 
 	  Say Y here for Dell EMC PowerEdge systems.
 
+config EFI_EMBEDDED_FIRMWARE
+	bool
+	select CRYPTO_LIB_SHA256
+
 endmenu
 
 config UEFI_CPER
diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
index 4ac2de4dfa72..42bd310657f4 100644
--- a/drivers/firmware/efi/Makefile
+++ b/drivers/firmware/efi/Makefile
@@ -26,6 +26,7 @@ obj-$(CONFIG_EFI_TEST)			+= test/
 obj-$(CONFIG_EFI_DEV_PATH_PARSER)	+= dev-path-parser.o
 obj-$(CONFIG_APPLE_PROPERTIES)		+= apple-properties.o
 obj-$(CONFIG_EFI_RCI2_TABLE)		+= rci2-table.o
+obj-$(CONFIG_EFI_EMBEDDED_FIRMWARE)	+= embedded-firmware.o
 
 arm-obj-$(CONFIG_EFI)			:= arm-init.o arm-runtime.o
 obj-$(CONFIG_ARM)			+= $(arm-obj-y)
diff --git a/drivers/firmware/efi/embedded-firmware.c b/drivers/firmware/efi/embedded-firmware.c
new file mode 100644
index 000000000000..7fa18b6bf354
--- /dev/null
+++ b/drivers/firmware/efi/embedded-firmware.c
@@ -0,0 +1,151 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Support for extracting embedded firmware for peripherals from EFI code,
+ *
+ * Copyright (c) 2018 Hans de Goede <hdegoede@redhat.com>
+ */
+
+#include <linux/dmi.h>
+#include <linux/efi.h>
+#include <linux/efi_embedded_fw.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/vmalloc.h>
+#include <crypto/sha.h>
+
+struct embedded_fw {
+	struct list_head list;
+	const char *name;
+	void *data;
+	size_t length;
+};
+
+static bool checked_for_fw;
+static LIST_HEAD(found_fw_list);
+
+static const struct dmi_system_id * const embedded_fw_table[] = {
+	NULL
+};
+
+/*
+ * Note the efi_check_for_embedded_firmwares() code currently makes the
+ * following 2 assumptions. This may needs to be revisited if embedded firmware
+ * is found where this is not true:
+ * 1) The firmware is only found in EFI_BOOT_SERVICES_CODE memory segments
+ * 2) The firmware always starts at an offset which is a multiple of 8 bytes
+ */
+static int __init efi_check_md_for_embedded_firmware(
+	efi_memory_desc_t *md, const struct efi_embedded_fw_desc *desc)
+{
+	const u64 prefix = *((u64 *)desc->prefix);
+	struct sha256_state sctx;
+	struct embedded_fw *fw;
+	u8 sha256[32];
+	u64 i, size;
+	void *map;
+
+	size = md->num_pages << EFI_PAGE_SHIFT;
+	map = memremap(md->phys_addr, size, MEMREMAP_WB);
+	if (!map) {
+		pr_err("Error mapping EFI mem at %#llx\n", md->phys_addr);
+		return -ENOMEM;
+	}
+
+	for (i = 0; (i + desc->length) <= size; i += 8) {
+		u64 *mem = map + i;
+
+		if (*mem != prefix)
+			continue;
+
+		sha256_init(&sctx);
+		sha256_update(&sctx, map + i, desc->length);
+		sha256_final(&sctx, sha256);
+		if (memcmp(sha256, desc->sha256, 32) == 0)
+			break;
+	}
+	if ((i + desc->length) > size) {
+		memunmap(map);
+		return -ENOENT;
+	}
+
+	pr_info("Found EFI embedded fw '%s'\n", desc->name);
+
+	fw = kmalloc(sizeof(*fw), GFP_KERNEL);
+	if (!fw) {
+		memunmap(map);
+		return -ENOMEM;
+	}
+
+	fw->data = kmemdup(map + i, desc->length, GFP_KERNEL);
+	memunmap(map);
+	if (!fw->data) {
+		kfree(fw);
+		return -ENOMEM;
+	}
+
+	fw->name = desc->name;
+	fw->length = desc->length;
+	list_add(&fw->list, &found_fw_list);
+
+	return 0;
+}
+
+void __init efi_check_for_embedded_firmwares(void)
+{
+	const struct efi_embedded_fw_desc *fw_desc;
+	const struct dmi_system_id *dmi_id;
+	efi_memory_desc_t *md;
+	int i, r;
+
+	for (i = 0; embedded_fw_table[i]; i++) {
+		dmi_id = dmi_first_match(embedded_fw_table[i]);
+		if (!dmi_id)
+			continue;
+
+		fw_desc = dmi_id->driver_data;
+		for_each_efi_memory_desc(md) {
+			if (md->type != EFI_BOOT_SERVICES_CODE)
+				continue;
+
+			r = efi_check_md_for_embedded_firmware(md, fw_desc);
+			if (r == 0)
+				break;
+		}
+	}
+
+	checked_for_fw = true;
+}
+
+int efi_get_embedded_fw(const char *name, void **data, size_t *size)
+{
+	struct embedded_fw *iter, *fw = NULL;
+	void *buf = *data;
+
+	if (!checked_for_fw) {
+		pr_warn("Warning %s called while we did not check for embedded fw\n",
+			__func__);
+		return -ENOENT;
+	}
+
+	list_for_each_entry(iter, &found_fw_list, list) {
+		if (strcmp(name, iter->name) == 0) {
+			fw = iter;
+			break;
+		}
+	}
+
+	if (!fw)
+		return -ENOENT;
+
+	buf = vmalloc(fw->length);
+	if (!buf)
+		return -ENOMEM;
+
+	memcpy(buf, fw->data, fw->length);
+	*size = fw->length;
+	*data = buf;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(efi_get_embedded_fw);
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 2929abb1e3c0..d5d4caf44f2a 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -1646,6 +1646,12 @@ static inline void
 efi_enable_reset_attack_mitigation(efi_system_table_t *sys_table_arg) { }
 #endif
 
+#ifdef CONFIG_EFI_EMBEDDED_FIRMWARE
+void efi_check_for_embedded_firmwares(void);
+#else
+static inline void efi_check_for_embedded_firmwares(void) { }
+#endif
+
 void efi_retrieve_tpm2_eventlog(efi_system_table_t *sys_table);
 
 /*
diff --git a/include/linux/efi_embedded_fw.h b/include/linux/efi_embedded_fw.h
new file mode 100644
index 000000000000..ac70ff146d58
--- /dev/null
+++ b/include/linux/efi_embedded_fw.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_EFI_EMBEDDED_FW_H
+#define _LINUX_EFI_EMBEDDED_FW_H
+
+#include <linux/mod_devicetable.h>
+
+/**
+ * struct efi_embedded_fw_desc - This struct is used by the EFI embedded-fw
+ *                               code to search for embedded firmwares.
+ *
+ * @name:   Name to register the firmware with if found
+ * @prefix: First 8 bytes of the firmware
+ * @length: Length of the firmware in bytes including prefix
+ * @sha256: SHA256 of the firmware
+ */
+struct efi_embedded_fw_desc {
+	const char *name;
+	u8 prefix[8];
+	u32 length;
+	u8 sha256[32];
+};
+
+int efi_get_embedded_fw(const char *name, void **dat, size_t *sz);
+
+#endif
-- 
2.23.0

[PATCH v8 3/8] firmware: Rename FW_OPT_NOFALLBACK to FW_OPT_NOFALLBACK_SYSFS

[Hans de Goede]

This is a preparation patch for adding a new platform fallback mechanism,
which will have its own enable/disable FW_OPT_xxx option.

Note this also fixes a typo in one of the re-wordwrapped comments:
enfoce -> enforce.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/base/firmware_loader/fallback.c | 11 ++++++-----
 drivers/base/firmware_loader/firmware.h | 16 ++++++++--------
 drivers/base/firmware_loader/main.c     |  2 +-
 3 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/drivers/base/firmware_loader/fallback.c b/drivers/base/firmware_loader/fallback.c
index 62ee90b4db56..8704e1bae175 100644
--- a/drivers/base/firmware_loader/fallback.c
+++ b/drivers/base/firmware_loader/fallback.c
@@ -606,7 +606,7 @@ static bool fw_run_sysfs_fallback(enum fw_opt opt_flags)
 		return false;
 	}
 
-	if ((opt_flags & FW_OPT_NOFALLBACK))
+	if ((opt_flags & FW_OPT_NOFALLBACK_SYSFS))
 		return false;
 
 	/* Also permit LSMs and IMA to fail firmware sysfs fallback */
@@ -630,10 +630,11 @@ static bool fw_run_sysfs_fallback(enum fw_opt opt_flags)
  * interface. Userspace is in charge of loading the firmware through the sysfs
  * loading interface. This sysfs fallback mechanism may be disabled completely
  * on a system by setting the proc sysctl value ignore_sysfs_fallback to true.
- * If this false we check if the internal API caller set the @FW_OPT_NOFALLBACK
- * flag, if so it would also disable the fallback mechanism. A system may want
- * to enfoce the sysfs fallback mechanism at all times, it can do this by
- * setting ignore_sysfs_fallback to false and force_sysfs_fallback to true.
+ * If this is false we check if the internal API caller set the
+ * @FW_OPT_NOFALLBACK_SYSFS flag, if so it would also disable the fallback
+ * mechanism. A system may want to enforce the sysfs fallback mechanism at all
+ * times, it can do this by setting ignore_sysfs_fallback to false and
+ * force_sysfs_fallback to true.
  * Enabling force_sysfs_fallback is functionally equivalent to build a kernel
  * with CONFIG_FW_LOADER_USER_HELPER_FALLBACK.
  **/
diff --git a/drivers/base/firmware_loader/firmware.h b/drivers/base/firmware_loader/firmware.h
index 7ecd590e67fe..8656e5239a80 100644
--- a/drivers/base/firmware_loader/firmware.h
+++ b/drivers/base/firmware_loader/firmware.h
@@ -27,16 +27,16 @@
  *	firmware file lookup on storage is avoided. Used for calls where the
  *	file may be too big, or where the driver takes charge of its own
  *	firmware caching mechanism.
- * @FW_OPT_NOFALLBACK: Disable the fallback mechanism. Takes precedence over
- *	&FW_OPT_UEVENT and &FW_OPT_USERHELPER.
+ * @FW_OPT_NOFALLBACK_SYSFS: Disable the sysfs fallback mechanism. Takes
+ *	precedence over &FW_OPT_UEVENT and &FW_OPT_USERHELPER.
  */
 enum fw_opt {
-	FW_OPT_UEVENT =         BIT(0),
-	FW_OPT_NOWAIT =         BIT(1),
-	FW_OPT_USERHELPER =     BIT(2),
-	FW_OPT_NO_WARN =        BIT(3),
-	FW_OPT_NOCACHE =        BIT(4),
-	FW_OPT_NOFALLBACK =     BIT(5),
+	FW_OPT_UEVENT			= BIT(0),
+	FW_OPT_NOWAIT			= BIT(1),
+	FW_OPT_USERHELPER		= BIT(2),
+	FW_OPT_NO_WARN			= BIT(3),
+	FW_OPT_NOCACHE			= BIT(4),
+	FW_OPT_NOFALLBACK_SYSFS		= BIT(5),
 };
 
 enum fw_status {
diff --git a/drivers/base/firmware_loader/main.c b/drivers/base/firmware_loader/main.c
index bf44c79beae9..08f8995a530a 100644
--- a/drivers/base/firmware_loader/main.c
+++ b/drivers/base/firmware_loader/main.c
@@ -876,7 +876,7 @@ int request_firmware_direct(const struct firmware **firmware_p,
 	__module_get(THIS_MODULE);
 	ret = _request_firmware(firmware_p, name, device, NULL, 0,
 				FW_OPT_UEVENT | FW_OPT_NO_WARN |
-				FW_OPT_NOFALLBACK);
+				FW_OPT_NOFALLBACK_SYSFS);
 	module_put(THIS_MODULE);
 	return ret;
 }
-- 
2.23.0

[PATCH v8 4/8] firmware: Add new platform fallback mechanism and firmware_request_platform()

[Hans de Goede]

In some cases the platform's main firmware (e.g. the UEFI fw) may contain
an embedded copy of device 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 a new platform fallback mechanism to the firmware loader
which will try to lookup a device fw copy embedded in the platform's main
firmware if direct filesystem lookup fails.

Drivers which need such embedded fw copies can enable this fallback
mechanism by using the new firmware_request_platform() function.

Note that for now this is only supported on EFI platforms and even on
these platforms firmware_fallback_platform() only works if
CONFIG_EFI_EMBEDDED_FIRMWARE is enabled (this gets selected by drivers
which need this), in all other cases firmware_fallback_platform() simply
always returns -ENOENT.

Reported-by: Dave Olsthoorn <dave@bewaar.me>
Suggested-by: Peter Jones <pjones@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
Changes in v8:
- Only build fallback_platform.c if CONFIG_EFI_EMBEDDED_FIRMWARE is defined,
  otherwise make firmware_fallback_platform() a static inline stub
- Add documentation to Documentation/driver-api/firmware/fallback-mechanisms.rst
  on how the boot_service_code? files exported by EFI debugfs can be used to
  check if there is an embedded firmware and to get the embedded firmware
  length and sha256sum

Changes in v7:
- Split drivers/firmware/efi and drivers/base/firmware_loader changes into
  2 patches
- Address kdoc comments from Randy Dunlap
- Add new FW_OPT_FALLBACK_PLATFORM flag and firmware_request_platform()
  _request_firmware() wrapper, as requested by Luis R. Rodriguez
- Stop using "efi-embedded-firmware" device-property, now that drivers need to
  use the new firmware_request_platform() to enable fallback to a device fw
  copy embedded in the platform's main firmware, we no longer need a property
  on the device to trigger this behavior
- Use security_kernel_load_data instead of calling
  security_kernel_read_file with a NULL file pointer argument
- Move the docs to Documentation/driver-api/firmware/fallback-mechanisms.rst
- Document the new firmware_request_platform() function in
  Documentation/driver-api/firmware/request_firmware.rst

Changes in v6:
- Rework code to remove casts from if (prefix == mem) comparison
- Use SHA256 hashes instead of crc32 sums
- Add new READING_FIRMWARE_EFI_EMBEDDED read_file_id and use it
- Call security_kernel_read_file(NULL, READING_FIRMWARE_EFI_EMBEDDED)
  to check if this is allowed before looking at EFI embedded fw
- Document why we are not using the UEFI PI Firmware Volume protocol

Changes in v5:
- Rename the EFI_BOOT_SERVICES flag to EFI_PRESERVE_BS_REGIONS

Changes in v4:
- Drop note in docs about EFI_FIRMWARE_VOLUME_PROTOCOL, it is not part of
  UEFI proper, so the EFI maintainers don't want us referring people to it
- Use new EFI_BOOT_SERVICES flag
- Put the new fw_get_efi_embedded_fw() function in its own fallback_efi.c
  file which only gets built when EFI_EMBEDDED_FIRMWARE is selected
- Define an empty stub for fw_get_efi_embedded_fw() in fallback.h hwen
  EFI_EMBEDDED_FIRMWARE is not selected, to avoid the need for #ifdefs
  in firmware_loader/main.c
- Properly call security_kernel_post_read_file() on the firmware returned
  by efi_get_embedded_fw() to make sure that we are allowed to use it

Changes in v3:
- Fix the docs using "efi-embedded-fw" as property name instead of
  "efi-embedded-firmware"

Changes in v2:
- Rebased on driver-core/driver-core-next
- Add documentation describing the EFI embedded firmware mechanism to:
  Documentation/driver-api/firmware/request_firmware.rst
- Add a new EFI_EMBEDDED_FIRMWARE Kconfig bool and only build the embedded
  fw support if this is set. This is an invisible option which should be
  selected by drivers which need this
- Remove the efi_embedded_fw_desc and dmi_system_id-s for known devices
  from the efi-embedded-fw code, instead drivers using this are expected to
  export a dmi_system_id array, with each entries' driver_data pointing to a
  efi_embedded_fw_desc struct and register this with the efi-embedded-fw code
- Use kmemdup to make a copy instead of efi_mem_reserve()-ing the firmware,
  this avoids us messing with the EFI memmap and avoids the need to make
  changes to efi_mem_desc_lookup()
- Make the firmware-loader code only fallback to efi_get_embedded_fw() if the
  passed in device has the "efi-embedded-firmware" device-property bool set
- Skip usermodehelper fallback when "efi-embedded-firmware" device-property
  is set
---
 .../firmware/fallback-mechanisms.rst          | 103 ++++++++++++++++++
 .../driver-api/firmware/lookup-order.rst      |   2 +
 .../driver-api/firmware/request_firmware.rst  |   5 +
 drivers/base/firmware_loader/Makefile         |   1 +
 drivers/base/firmware_loader/fallback.h       |  10 ++
 .../base/firmware_loader/fallback_platform.c  |  29 +++++
 drivers/base/firmware_loader/firmware.h       |   4 +
 drivers/base/firmware_loader/main.c           |  27 +++++
 include/linux/firmware.h                      |   2 +
 include/linux/fs.h                            |   1 +
 10 files changed, 184 insertions(+)
 create mode 100644 drivers/base/firmware_loader/fallback_platform.c

diff --git a/Documentation/driver-api/firmware/fallback-mechanisms.rst b/Documentation/driver-api/firmware/fallback-mechanisms.rst
index 8b041d0ab426..036383dad6d6 100644
--- a/Documentation/driver-api/firmware/fallback-mechanisms.rst
+++ b/Documentation/driver-api/firmware/fallback-mechanisms.rst
@@ -202,3 +202,106 @@ the following file:
 
 If you echo 0 into it means MAX_JIFFY_OFFSET will be used. The data type
 for the timeout is an int.
+
+EFI embedded firmware fallback mechanism
+========================================
+
+On some devices the system's EFI code / ROM may contain an embedded copy
+of firmware for some of the system's integrated peripheral devices and
+the peripheral's Linux device-driver needs to access this firmware.
+
+Device drivers which need such firmware can use the
+firmware_request_platform() function for this, note that this is a
+separate fallback mechanism from the other fallback mechanisms and
+this does not use the sysfs interface.
+
+A device driver which needs this can describe the firmware it needs
+using an efi_embedded_fw_desc struct:
+
+.. kernel-doc:: include/linux/efi_embedded_fw.h
+   :functions: efi_embedded_fw_desc
+
+The EFI embedded-fw code works by scanning all EFI_BOOT_SERVICES_CODE memory
+segments for an eight byte sequence matching prefix; if the prefix is found it
+then does a sha256 over length bytes and if that matches makes a copy of length
+bytes and adds that to its list with found firmwares.
+
+To avoid doing this somewhat expensive scan on all systems, dmi matching is
+used. Drivers are expected to export a dmi_system_id array, with each entries'
+driver_data pointing to an efi_embedded_fw_desc.
+
+To register this array with the efi-embedded-fw code, a driver needs to:
+
+1. Always be builtin to the kernel or store the dmi_system_id array in a
+   separate object file which always gets builtin.
+
+2. Add an extern declaration for the dmi_system_id array to
+   include/linux/efi_embedded_fw.h.
+
+3. Add the dmi_system_id array to the embedded_fw_table in
+   drivers/firmware/efi/embedded-firmware.c wrapped in a #ifdef testing that
+   the driver is being builtin.
+
+4. Add "select EFI_EMBEDDED_FIRMWARE if EFI_STUB" to its Kconfig entry.
+
+The firmware_request_platform() function will always first try to load firmware
+with the specified name directly from the disk, so the EFI embedded-fw can
+always be overridden by placing a file under /lib/firmware.
+
+Note that:
+
+1. The code scanning for EFI embedded-firmware runs near the end
+   of start_kernel(), just before calling rest_init(). For normal drivers and
+   subsystems using subsys_initcall() to register themselves this does not
+   matter. This means that code running earlier cannot use EFI
+   embedded-firmware.
+
+2. At the moment the EFI embedded-fw code assumes that firmwares always start at
+   an offset which is a multiple of 8 bytes, if this is not true for your case
+   send in a patch to fix this.
+
+3. At the moment the EFI embedded-fw code only works on x86 because other archs
+   free EFI_BOOT_SERVICES_CODE before the EFI embedded-fw code gets a chance to
+   scan it.
+
+4. The current brute-force scanning of EFI_BOOT_SERVICES_CODE is an ad-hoc
+   brute-force solution. There has been discussion to use the UEFI Platform
+   Initialization (PI) spec's Firmware Volume protocol. This has been rejected
+   because the FV Protocol relies on *internal* interfaces of the PI spec, and:
+   1. The PI spec does not define peripheral firmware at all
+   2. The internal interfaces of the PI spec do not guarantee any backward
+   compatibility. Any implementation details in FV may be subject to change,
+   and may vary system to system. Supporting the FV Protocol would be
+   difficult as it is purposely ambiguous.
+
+Example how to check for and extract embedded firmware
+------------------------------------------------------
+
+To check for, for example Silead touchscreen controller embedded firmware,
+do the following:
+
+1. Boot the system with efi=debug on the kernel commandline
+
+2. cp /sys/kernel/debug/efi/boot_services_code? to your home dir
+
+3. Open the boot_services_code? files in a hex-editor, search for the
+   magic prefix for Silead firmware: F0 00 00 00 02 00 00 00, this gives you
+   the beginning address of the firmware inside the boot_services_code? file.
+
+4. The firmware has a specific pattern, it starts with a 8 byte page-address,
+   typically F0 00 00 00 02 00 00 00 for the first page followed by 32-bit
+   word-address + 32-bit value pairs. With the word-address incrementing 4
+   bytes (1 word) for each pair until a page is complete. A complete page is
+   followed by a new page-address, followed by more word + value pairs. This
+   leads to a very distinct pattern. Scroll down until this pattern stops,
+   this gives you the end of the firmware inside the boot_services_code? file.
+
+5. "dd if=boot_services_code? of=firmware bs=1 skip=<begin-addr> count=<len>"
+   will extract the firmware for you. Inspect the firmware file in a
+   hexeditor to make sure you got the dd parameters correct.
+
+6. Copy it to /lib/firmware under the expected name to test it.
+
+7. If the extracted firmware works, you can use the found info to fill an
+   efi_embedded_fw_desc struct to describe it, run "sha256sum firmware"
+   to get the sha256sum to put in the sha256 field.
diff --git a/Documentation/driver-api/firmware/lookup-order.rst b/Documentation/driver-api/firmware/lookup-order.rst
index 88c81739683c..6064672a782e 100644
--- a/Documentation/driver-api/firmware/lookup-order.rst
+++ b/Documentation/driver-api/firmware/lookup-order.rst
@@ -12,6 +12,8 @@ a driver issues a firmware API call.
   return it immediately
 * The ''Direct filesystem lookup'' is performed next, if found we
   return it immediately
+* The ''Platform firmware fallback'' is performed next, but only when
+  firmware_request_platform() is used, if found we return it immediately
 * If no firmware has been found and the fallback mechanism was enabled
   the sysfs interface is created. After this either a kobject uevent
   is issued or the custom firmware loading is relied upon for firmware
diff --git a/Documentation/driver-api/firmware/request_firmware.rst b/Documentation/driver-api/firmware/request_firmware.rst
index f62bdcbfed5b..cd076462d235 100644
--- a/Documentation/driver-api/firmware/request_firmware.rst
+++ b/Documentation/driver-api/firmware/request_firmware.rst
@@ -25,6 +25,11 @@ firmware_request_nowarn
 .. kernel-doc:: drivers/base/firmware_loader/main.c
    :functions: firmware_request_nowarn
 
+firmware_request_platform
+-------------------------
+.. kernel-doc:: drivers/base/firmware_loader/main.c
+   :functions: firmware_request_platform
+
 request_firmware_direct
 -----------------------
 .. kernel-doc:: drivers/base/firmware_loader/main.c
diff --git a/drivers/base/firmware_loader/Makefile b/drivers/base/firmware_loader/Makefile
index 0b2dfa6259c9..e87843408fe6 100644
--- a/drivers/base/firmware_loader/Makefile
+++ b/drivers/base/firmware_loader/Makefile
@@ -5,5 +5,6 @@ obj-$(CONFIG_FW_LOADER_USER_HELPER) += fallback_table.o
 obj-$(CONFIG_FW_LOADER)	+= firmware_class.o
 firmware_class-objs := main.o
 firmware_class-$(CONFIG_FW_LOADER_USER_HELPER) += fallback.o
+firmware_class-$(CONFIG_EFI_EMBEDDED_FIRMWARE) += fallback_platform.o
 
 obj-y += builtin/
diff --git a/drivers/base/firmware_loader/fallback.h b/drivers/base/firmware_loader/fallback.h
index 21063503e4ea..06f4577733a8 100644
--- a/drivers/base/firmware_loader/fallback.h
+++ b/drivers/base/firmware_loader/fallback.h
@@ -66,4 +66,14 @@ static inline void unregister_sysfs_loader(void)
 }
 #endif /* CONFIG_FW_LOADER_USER_HELPER */
 
+#ifdef CONFIG_EFI_EMBEDDED_FIRMWARE
+int firmware_fallback_platform(struct fw_priv *fw_priv, enum fw_opt opt_flags);
+#else
+static inline int firmware_fallback_platform(struct fw_priv *fw_priv,
+					     enum fw_opt opt_flags)
+{
+	return -ENOENT;
+}
+#endif
+
 #endif /* __FIRMWARE_FALLBACK_H */
diff --git a/drivers/base/firmware_loader/fallback_platform.c b/drivers/base/firmware_loader/fallback_platform.c
new file mode 100644
index 000000000000..37746efaf8e3
--- /dev/null
+++ b/drivers/base/firmware_loader/fallback_platform.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/efi_embedded_fw.h>
+#include <linux/property.h>
+#include <linux/security.h>
+#include <linux/vmalloc.h>
+
+#include "fallback.h"
+#include "firmware.h"
+
+int firmware_fallback_platform(struct fw_priv *fw_priv, enum fw_opt opt_flags)
+{
+	int rc;
+
+	if (!(opt_flags & FW_OPT_FALLBACK_PLATFORM))
+		return -ENOENT;
+
+	rc = security_kernel_load_data(LOADING_FIRMWARE_EFI_EMBEDDED);
+	if (rc)
+		return rc;
+
+	rc = efi_get_embedded_fw(fw_priv->fw_name, &fw_priv->data,
+				 &fw_priv->size);
+	if (rc)
+		return rc; /* rc == -ENOENT when the fw was not found */
+
+	fw_state_done(fw_priv);
+	return 0;
+}
diff --git a/drivers/base/firmware_loader/firmware.h b/drivers/base/firmware_loader/firmware.h
index 8656e5239a80..25836a6afc9f 100644
--- a/drivers/base/firmware_loader/firmware.h
+++ b/drivers/base/firmware_loader/firmware.h
@@ -29,6 +29,9 @@
  *	firmware caching mechanism.
  * @FW_OPT_NOFALLBACK_SYSFS: Disable the sysfs fallback mechanism. Takes
  *	precedence over &FW_OPT_UEVENT and &FW_OPT_USERHELPER.
+ * @FW_OPT_FALLBACK_PLATFORM: Enable fallback to device fw copy embedded in
+ *	the platform's main firmware. If both this fallback and the sysfs
+ *      fallback are enabled, then this fallback will be tried first.
  */
 enum fw_opt {
 	FW_OPT_UEVENT			= BIT(0),
@@ -37,6 +40,7 @@ enum fw_opt {
 	FW_OPT_NO_WARN			= BIT(3),
 	FW_OPT_NOCACHE			= BIT(4),
 	FW_OPT_NOFALLBACK_SYSFS		= BIT(5),
+	FW_OPT_FALLBACK_PLATFORM	= BIT(6),
 };
 
 enum fw_status {
diff --git a/drivers/base/firmware_loader/main.c b/drivers/base/firmware_loader/main.c
index 08f8995a530a..006ff71458b1 100644
--- a/drivers/base/firmware_loader/main.c
+++ b/drivers/base/firmware_loader/main.c
@@ -775,6 +775,9 @@ _request_firmware(const struct firmware **firmware_p, const char *name,
 						 fw_decompress_xz);
 #endif
 
+	if (ret == -ENOENT)
+		ret = firmware_fallback_platform(fw->priv, opt_flags);
+
 	if (ret) {
 		if (!(opt_flags & FW_OPT_NO_WARN))
 			dev_warn(device,
@@ -882,6 +885,30 @@ int request_firmware_direct(const struct firmware **firmware_p,
 }
 EXPORT_SYMBOL_GPL(request_firmware_direct);
 
+/**
+ * firmware_request_platform() - request firmware with platform-fw fallback
+ * @firmware: pointer to firmware image
+ * @name: name of firmware file
+ * @device: device for which firmware is being loaded
+ *
+ * This function is similar in behaviour to request_firmware, except that if
+ * direct filesystem lookup fails, it will fallback to looking for a copy of the
+ * requested firmware embedded in the platform's main (e.g. UEFI) firmware.
+ **/
+int firmware_request_platform(const struct firmware **firmware,
+			      const char *name, struct device *device)
+{
+	int ret;
+
+	/* Need to pin this module until return */
+	__module_get(THIS_MODULE);
+	ret = _request_firmware(firmware, name, device, NULL, 0,
+				FW_OPT_UEVENT | FW_OPT_FALLBACK_PLATFORM);
+	module_put(THIS_MODULE);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(firmware_request_platform);
+
 /**
  * firmware_request_cache() - cache firmware for suspend so resume can use it
  * @name: name of firmware file
diff --git a/include/linux/firmware.h b/include/linux/firmware.h
index 2dd566c91d44..75dbec0bcc06 100644
--- a/include/linux/firmware.h
+++ b/include/linux/firmware.h
@@ -44,6 +44,8 @@ int request_firmware(const struct firmware **fw, const char *name,
 		     struct device *device);
 int firmware_request_nowarn(const struct firmware **fw, const char *name,
 			    struct device *device);
+int firmware_request_platform(const struct firmware **fw, const char *name,
+			      struct device *device);
 int request_firmware_nowait(
 	struct module *module, bool uevent,
 	const char *name, struct device *device, gfp_t gfp, void *context,
diff --git a/include/linux/fs.h b/include/linux/fs.h
index e0d909d35763..3cbc955f6a1a 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2961,6 +2961,7 @@ extern int do_pipe_flags(int *, int);
 	id(UNKNOWN, unknown)		\
 	id(FIRMWARE, firmware)		\
 	id(FIRMWARE_PREALLOC_BUFFER, firmware)	\
+	id(FIRMWARE_EFI_EMBEDDED, firmware)	\
 	id(MODULE, kernel-module)		\
 	id(KEXEC_IMAGE, kexec-image)		\
 	id(KEXEC_INITRAMFS, kexec-initramfs)	\
-- 
2.23.0

[PATCH v8 5/8] Input: silead - Switch to firmware_request_platform for retreiving the fw

[Hans de Goede]

Unfortunately sofar we have been unable to get permission to redistribute
Silead touchscreen firmwares in linux-firmware. This means that people
need to find and install the firmware themselves before the touchscreen
will work

Some UEFI/x86 tablets with a Silead touchscreen have a copy of the fw
embedded in their UEFI boot-services code.

This commit makes the silead driver use the new firmware_request_platform
function, which will fallback to looking for such an embedded copy when
direct filesystem lookup fails. This will make the touchscreen work OOTB
on devices where there is a fw copy embedded in the UEFI code.

Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/input/touchscreen/silead.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/input/touchscreen/silead.c b/drivers/input/touchscreen/silead.c
index ad8b6a2bfd36..8fa2f3b7cfd8 100644
--- a/drivers/input/touchscreen/silead.c
+++ b/drivers/input/touchscreen/silead.c
@@ -288,7 +288,7 @@ static int silead_ts_load_fw(struct i2c_client *client)
 
 	dev_dbg(dev, "Firmware file name: %s", data->fw_name);
 
-	error = request_firmware(&fw, data->fw_name, dev);
+	error = firmware_request_platform(&fw, data->fw_name, dev);
 	if (error) {
 		dev_err(dev, "Firmware request error %d\n", error);
 		return error;
-- 
2.23.0

[PATCH v8 6/8] Input: icn8505 - Switch to firmware_request_platform for retreiving the fw

[Hans de Goede]

Unfortunately sofar we have been unable to get permission to redistribute
icn8505 touchscreen firmwares in linux-firmware. This means that people
need to find and install the firmware themselves before the touchscreen
will work

Some UEFI/x86 tablets with an icn8505 touchscreen have a copy of the fw
embedded in their UEFI boot-services code.

This commit makes the icn8505 driver use the new firmware_request_platform
function, which will fallback to looking for such an embedded copy when
direct filesystem lookup fails. This will make the touchscreen work OOTB
on devices where there is a fw copy embedded in the UEFI code.

Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/input/touchscreen/chipone_icn8505.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/input/touchscreen/chipone_icn8505.c b/drivers/input/touchscreen/chipone_icn8505.c
index c768186ce856..f9ca5502ac8c 100644
--- a/drivers/input/touchscreen/chipone_icn8505.c
+++ b/drivers/input/touchscreen/chipone_icn8505.c
@@ -288,7 +288,7 @@ static int icn8505_upload_fw(struct icn8505_data *icn8505)
 	 * we may need it at resume. Having loaded it once will make the
 	 * firmware class code cache it at suspend/resume.
 	 */
-	error = request_firmware(&fw, icn8505->firmware_name, dev);
+	error = firmware_request_platform(&fw, icn8505->firmware_name, dev);
 	if (error) {
 		dev_err(dev, "Firmware request error %d\n", error);
 		return error;
-- 
2.23.0

[PATCH v8 7/8] platform/x86: touchscreen_dmi: Add EFI embedded firmware info support

[Hans de Goede]

Sofar we have been unable to get permission from the vendors to put the
firmware for touchscreens listed in touchscreen_dmi in linux-firmware.

Some of the tablets with such a touchscreen have a touchscreen driver, and
thus a copy of the firmware, as part of their EFI code.

This commit adds the necessary info for the new EFI embedded-firmware code
to extract these firmwares, making the touchscreen work OOTB without the
user needing to manually add the firmware.

Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
Changes in v7:
- Remove adding of PROPERTY_ENTRY_BOOL("efi-embedded-firmware"), to touchscreen
  props, as this is no longer necessary

Changes in v6:
- Switch from crc sums to SHA256 hashes for the firmware hashes
---
 drivers/firmware/efi/embedded-firmware.c |  3 ++
 drivers/platform/x86/Kconfig             |  1 +
 drivers/platform/x86/touchscreen_dmi.c   | 41 +++++++++++++++++++++++-
 include/linux/efi_embedded_fw.h          |  2 ++
 4 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/efi/embedded-firmware.c b/drivers/firmware/efi/embedded-firmware.c
index 7fa18b6bf354..24487c34c879 100644
--- a/drivers/firmware/efi/embedded-firmware.c
+++ b/drivers/firmware/efi/embedded-firmware.c
@@ -25,6 +25,9 @@ static bool checked_for_fw;
 static LIST_HEAD(found_fw_list);
 
 static const struct dmi_system_id * const embedded_fw_table[] = {
+#ifdef CONFIG_TOUCHSCREEN_DMI
+	touchscreen_dmi_table,
+#endif
 	NULL
 };
 
diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index 1cab99320514..3891fd8af886 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -1250,6 +1250,7 @@ config INTEL_TURBO_MAX_3
 config TOUCHSCREEN_DMI
 	bool "DMI based touchscreen configuration info"
 	depends on ACPI && DMI && I2C=y && TOUCHSCREEN_SILEAD
+	select EFI_EMBEDDED_FIRMWARE if EFI
 	---help---
 	  Certain ACPI based tablets with e.g. Silead or Chipone touchscreens
 	  do not have enough data in ACPI tables for the touchscreen driver to
diff --git a/drivers/platform/x86/touchscreen_dmi.c b/drivers/platform/x86/touchscreen_dmi.c
index 72205771d03d..4449e4c0b26b 100644
--- a/drivers/platform/x86/touchscreen_dmi.c
+++ b/drivers/platform/x86/touchscreen_dmi.c
@@ -11,12 +11,15 @@
 #include <linux/acpi.h>
 #include <linux/device.h>
 #include <linux/dmi.h>
+#include <linux/efi_embedded_fw.h>
 #include <linux/i2c.h>
 #include <linux/notifier.h>
 #include <linux/property.h>
 #include <linux/string.h>
 
 struct ts_dmi_data {
+	/* The EFI embedded-fw code expects this to be the first member! */
+	struct efi_embedded_fw_desc embedded_fw;
 	const char *acpi_name;
 	const struct property_entry *properties;
 };
@@ -64,6 +67,15 @@ static const struct property_entry chuwi_hi8_pro_props[] = {
 };
 
 static const struct ts_dmi_data chuwi_hi8_pro_data = {
+	.embedded_fw = {
+		.name	= "silead/gsl3680-chuwi-hi8-pro.fw",
+		.prefix = { 0xf0, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, 0x00 },
+		.length	= 39864,
+		.sha256	= { 0xc0, 0x88, 0xc5, 0xef, 0xd1, 0x70, 0x77, 0x59,
+			    0x4e, 0xe9, 0xc4, 0xd8, 0x2e, 0xcd, 0xbf, 0x95,
+			    0x32, 0xd9, 0x03, 0x28, 0x0d, 0x48, 0x9f, 0x92,
+			    0x35, 0x37, 0xf6, 0x8b, 0x2a, 0xe4, 0x73, 0xff },
+	},
 	.acpi_name	= "MSSL1680:00",
 	.properties	= chuwi_hi8_pro_props,
 };
@@ -181,6 +193,15 @@ static const struct property_entry cube_iwork8_air_props[] = {
 };
 
 static const struct ts_dmi_data cube_iwork8_air_data = {
+	.embedded_fw = {
+		.name	= "silead/gsl3670-cube-iwork8-air.fw",
+		.prefix = { 0xf0, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, 0x00 },
+		.length	= 38808,
+		.sha256	= { 0xff, 0x62, 0x2d, 0xd1, 0x8a, 0x78, 0x04, 0x7b,
+			    0x33, 0x06, 0xb0, 0x4f, 0x7f, 0x02, 0x08, 0x9c,
+			    0x96, 0xd4, 0x9f, 0x04, 0xe1, 0x47, 0x25, 0x25,
+			    0x60, 0x77, 0x41, 0x33, 0xeb, 0x12, 0x82, 0xfc },
+	},
 	.acpi_name	= "MSSL1680:00",
 	.properties	= cube_iwork8_air_props,
 };
@@ -390,6 +411,15 @@ static const struct property_entry onda_v80_plus_v3_props[] = {
 };
 
 static const struct ts_dmi_data onda_v80_plus_v3_data = {
+	.embedded_fw = {
+		.name	= "silead/gsl3676-onda-v80-plus-v3.fw",
+		.prefix = { 0xf0, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, 0x00 },
+		.length	= 37224,
+		.sha256	= { 0x8f, 0xbd, 0x8f, 0x0c, 0x6b, 0xba, 0x5b, 0xf5,
+			    0xa3, 0xc7, 0xa3, 0xc0, 0x4f, 0xcd, 0xdf, 0x32,
+			    0xcc, 0xe4, 0x70, 0xd6, 0x46, 0x9c, 0xd7, 0xa7,
+			    0x4b, 0x82, 0x3f, 0xab, 0xc7, 0x90, 0xea, 0x23 },
+	},
 	.acpi_name	= "MSSL1680:00",
 	.properties	= onda_v80_plus_v3_props,
 };
@@ -456,6 +486,15 @@ static const struct property_entry pipo_w2s_props[] = {
 };
 
 static const struct ts_dmi_data pipo_w2s_data = {
+	.embedded_fw = {
+		.name	= "silead/gsl1680-pipo-w2s.fw",
+		.prefix = { 0xf0, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, 0x00 },
+		.length	= 39072,
+		.sha256	= { 0xd0, 0x58, 0xc4, 0x7d, 0x55, 0x2d, 0x62, 0x18,
+			    0xd1, 0x6a, 0x71, 0x73, 0x0b, 0x3f, 0xbe, 0x60,
+			    0xbb, 0x45, 0x8c, 0x52, 0x27, 0xb7, 0x18, 0xf4,
+			    0x31, 0x00, 0x6a, 0x49, 0x76, 0xd8, 0x7c, 0xd3 },
+	},
 	.acpi_name	= "MSSL1680:00",
 	.properties	= pipo_w2s_props,
 };
@@ -642,7 +681,7 @@ static const struct ts_dmi_data trekstor_surftab_wintron70_data = {
 };
 
 /* NOTE: Please keep this table sorted alphabetically */
-static const struct dmi_system_id touchscreen_dmi_table[] = {
+const struct dmi_system_id touchscreen_dmi_table[] = {
 	{
 		/* Chuwi Hi8 */
 		.driver_data = (void *)&chuwi_hi8_data,
diff --git a/include/linux/efi_embedded_fw.h b/include/linux/efi_embedded_fw.h
index ac70ff146d58..1ca4206ee006 100644
--- a/include/linux/efi_embedded_fw.h
+++ b/include/linux/efi_embedded_fw.h
@@ -20,6 +20,8 @@ struct efi_embedded_fw_desc {
 	u8 sha256[32];
 };
 
+extern const struct dmi_system_id touchscreen_dmi_table[];
+
 int efi_get_embedded_fw(const char *name, void **dat, size_t *sz);
 
 #endif
-- 
2.23.0

[PATCH v8 8/8] platform/x86: touchscreen_dmi: Add info for the Chuwi Vi8 Plus tablet

[Hans de Goede]

Add touchscreen info for the Chuwi Vi8 Plus tablet. This tablet uses a
Chipone ICN8505 touchscreen controller, with the firmware used by the
touchscreen embedded in the EFI firmware.

Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
Changes in v7:
- Remove PROPERTY_ENTRY_BOOL("efi-embedded-firmware") properties entry,
  as this is no longer necessary

Changes in v6:
- Switch from crc sums to SHA256 hashes for the firmware hash
---
 drivers/platform/x86/touchscreen_dmi.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/drivers/platform/x86/touchscreen_dmi.c b/drivers/platform/x86/touchscreen_dmi.c
index 4449e4c0b26b..4a09b479cda5 100644
--- a/drivers/platform/x86/touchscreen_dmi.c
+++ b/drivers/platform/x86/touchscreen_dmi.c
@@ -132,6 +132,18 @@ static const struct ts_dmi_data chuwi_vi8_data = {
 	.properties     = chuwi_vi8_props,
 };
 
+static const struct ts_dmi_data chuwi_vi8_plus_data = {
+	.embedded_fw = {
+		.name	= "chipone/icn8505-HAMP0002.fw",
+		.prefix = { 0xb0, 0x07, 0x00, 0x00, 0xe4, 0x07, 0x00, 0x00 },
+		.length	= 35012,
+		.sha256	= { 0x93, 0xe5, 0x49, 0xe0, 0xb6, 0xa2, 0xb4, 0xb3,
+			    0x88, 0x96, 0x34, 0x97, 0x5e, 0xa8, 0x13, 0x78,
+			    0x72, 0x98, 0xb8, 0x29, 0xeb, 0x5c, 0xa7, 0xf1,
+			    0x25, 0x13, 0x43, 0xf4, 0x30, 0x7c, 0xfc, 0x7c },
+	},
+};
+
 static const struct property_entry chuwi_vi10_props[] = {
 	PROPERTY_ENTRY_U32("touchscreen-min-x", 0),
 	PROPERTY_ENTRY_U32("touchscreen-min-y", 4),
@@ -743,6 +755,15 @@ const struct dmi_system_id touchscreen_dmi_table[] = {
 			DMI_MATCH(DMI_BIOS_VERSION, "CHUWI.D86JLBNR"),
 		},
 	},
+	{
+		/* Chuwi Vi8 Plus (CWI519) */
+		.driver_data = (void *)&chuwi_vi8_plus_data,
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Hampoo"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "D2D3_Vi8A1"),
+			DMI_MATCH(DMI_BOARD_NAME, "Cherry Trail CR"),
+		},
+	},
 	{
 		/* Chuwi Vi10 (CWI505) */
 		.driver_data = (void *)&chuwi_vi10_data,
@@ -1137,6 +1158,9 @@ static int __init ts_dmi_init(void)
 		return 0; /* Not an error */
 
 	ts_data = dmi_id->driver_data;
+	/* Some dmi table entries only provide an efi_embedded_fw_desc */
+	if (!ts_data->properties)
+		return 0;
 
 	error = bus_register_notifier(&i2c_bus_type, &ts_dmi_notifier);
 	if (error)
-- 
2.23.0

Re: [PATCH v8 3/8] firmware: Rename FW_OPT_NOFALLBACK to FW_OPT_NOFALLBACK_SYSFS

[Luis Chamberlain]

On Fri, Nov 15, 2019 at 04:35:24PM +0100, Hans de Goede wrote:
> This is a preparation patch for adding a new platform fallback mechanism,
> which will have its own enable/disable FW_OPT_xxx option.
> 
> Note this also fixes a typo in one of the re-wordwrapped comments:
> enfoce -> enforce.
> 
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>

Acked-by: Luis Chamberlain <mcgrof@kernel.org>

  Luis

Re: [PATCH v8 4/8] firmware: Add new platform fallback mechanism and firmware_request_platform()

[Luis Chamberlain]

On Fri, Nov 15, 2019 at 04:35:25PM +0100, Hans de Goede wrote:
> In some cases the platform's main firmware (e.g. the UEFI fw) may contain
> an embedded copy of device 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 a new platform fallback mechanism to the firmware loader
> which will try to lookup a device fw copy embedded in the platform's main
> firmware if direct filesystem lookup fails.
> 
> Drivers which need such embedded fw copies can enable this fallback
> mechanism by using the new firmware_request_platform() function.
> 
> Note that for now this is only supported on EFI platforms and even on
> these platforms firmware_fallback_platform() only works if
> CONFIG_EFI_EMBEDDED_FIRMWARE is enabled (this gets selected by drivers
> which need this), in all other cases firmware_fallback_platform() simply
> always returns -ENOENT.
> 
> Reported-by: Dave Olsthoorn <dave@bewaar.me>
> Suggested-by: Peter Jones <pjones@redhat.com>
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>

This looks good to me now thanks!

Acked-by: Luis Chamberlain <mcgrof@kernel.org>

Just one more thing: testing. Since this requires EFI memeory, I guess
we can't mimic a fake firmware somehow to use to test the API on any x86
system? If not we'd have no test coverage through the selftests for this
new call at all, and so could not easily detect regressions. We could
perhaps *fake* an entry if a DEBUG kconfig option is enabled, which
would stuff the EFI fw entry *once*. What do you think?

Look at: lib/test_firmware.c and tools/testing/selftests/firmware/

  Luis

> ---
> Changes in v8:
> - Only build fallback_platform.c if CONFIG_EFI_EMBEDDED_FIRMWARE is defined,
>   otherwise make firmware_fallback_platform() a static inline stub
> - Add documentation to Documentation/driver-api/firmware/fallback-mechanisms.rst
>   on how the boot_service_code? files exported by EFI debugfs can be used to
>   check if there is an embedded firmware and to get the embedded firmware
>   length and sha256sum
> 
> Changes in v7:
> - Split drivers/firmware/efi and drivers/base/firmware_loader changes into
>   2 patches
> - Address kdoc comments from Randy Dunlap
> - Add new FW_OPT_FALLBACK_PLATFORM flag and firmware_request_platform()
>   _request_firmware() wrapper, as requested by Luis R. Rodriguez
> - Stop using "efi-embedded-firmware" device-property, now that drivers need to
>   use the new firmware_request_platform() to enable fallback to a device fw
>   copy embedded in the platform's main firmware, we no longer need a property
>   on the device to trigger this behavior
> - Use security_kernel_load_data instead of calling
>   security_kernel_read_file with a NULL file pointer argument
> - Move the docs to Documentation/driver-api/firmware/fallback-mechanisms.rst
> - Document the new firmware_request_platform() function in
>   Documentation/driver-api/firmware/request_firmware.rst
> 
> Changes in v6:
> - Rework code to remove casts from if (prefix == mem) comparison
> - Use SHA256 hashes instead of crc32 sums
> - Add new READING_FIRMWARE_EFI_EMBEDDED read_file_id and use it
> - Call security_kernel_read_file(NULL, READING_FIRMWARE_EFI_EMBEDDED)
>   to check if this is allowed before looking at EFI embedded fw
> - Document why we are not using the UEFI PI Firmware Volume protocol
> 
> Changes in v5:
> - Rename the EFI_BOOT_SERVICES flag to EFI_PRESERVE_BS_REGIONS
> 
> Changes in v4:
> - Drop note in docs about EFI_FIRMWARE_VOLUME_PROTOCOL, it is not part of
>   UEFI proper, so the EFI maintainers don't want us referring people to it
> - Use new EFI_BOOT_SERVICES flag
> - Put the new fw_get_efi_embedded_fw() function in its own fallback_efi.c
>   file which only gets built when EFI_EMBEDDED_FIRMWARE is selected
> - Define an empty stub for fw_get_efi_embedded_fw() in fallback.h hwen
>   EFI_EMBEDDED_FIRMWARE is not selected, to avoid the need for #ifdefs
>   in firmware_loader/main.c
> - Properly call security_kernel_post_read_file() on the firmware returned
>   by efi_get_embedded_fw() to make sure that we are allowed to use it
> 
> Changes in v3:
> - Fix the docs using "efi-embedded-fw" as property name instead of
>   "efi-embedded-firmware"
> 
> Changes in v2:
> - Rebased on driver-core/driver-core-next
> - Add documentation describing the EFI embedded firmware mechanism to:
>   Documentation/driver-api/firmware/request_firmware.rst
> - Add a new EFI_EMBEDDED_FIRMWARE Kconfig bool and only build the embedded
>   fw support if this is set. This is an invisible option which should be
>   selected by drivers which need this
> - Remove the efi_embedded_fw_desc and dmi_system_id-s for known devices
>   from the efi-embedded-fw code, instead drivers using this are expected to
>   export a dmi_system_id array, with each entries' driver_data pointing to a
>   efi_embedded_fw_desc struct and register this with the efi-embedded-fw code
> - Use kmemdup to make a copy instead of efi_mem_reserve()-ing the firmware,
>   this avoids us messing with the EFI memmap and avoids the need to make
>   changes to efi_mem_desc_lookup()
> - Make the firmware-loader code only fallback to efi_get_embedded_fw() if the
>   passed in device has the "efi-embedded-firmware" device-property bool set
> - Skip usermodehelper fallback when "efi-embedded-firmware" device-property
>   is set
> ---
>  .../firmware/fallback-mechanisms.rst          | 103 ++++++++++++++++++
>  .../driver-api/firmware/lookup-order.rst      |   2 +
>  .../driver-api/firmware/request_firmware.rst  |   5 +
>  drivers/base/firmware_loader/Makefile         |   1 +
>  drivers/base/firmware_loader/fallback.h       |  10 ++
>  .../base/firmware_loader/fallback_platform.c  |  29 +++++
>  drivers/base/firmware_loader/firmware.h       |   4 +
>  drivers/base/firmware_loader/main.c           |  27 +++++
>  include/linux/firmware.h                      |   2 +
>  include/linux/fs.h                            |   1 +
>  10 files changed, 184 insertions(+)
>  create mode 100644 drivers/base/firmware_loader/fallback_platform.c
> 
> diff --git a/Documentation/driver-api/firmware/fallback-mechanisms.rst b/Documentation/driver-api/firmware/fallback-mechanisms.rst
> index 8b041d0ab426..036383dad6d6 100644
> --- a/Documentation/driver-api/firmware/fallback-mechanisms.rst
> +++ b/Documentation/driver-api/firmware/fallback-mechanisms.rst
> @@ -202,3 +202,106 @@ the following file:
>  
>  If you echo 0 into it means MAX_JIFFY_OFFSET will be used. The data type
>  for the timeout is an int.
> +
> +EFI embedded firmware fallback mechanism
> +========================================
> +
> +On some devices the system's EFI code / ROM may contain an embedded copy
> +of firmware for some of the system's integrated peripheral devices and
> +the peripheral's Linux device-driver needs to access this firmware.
> +
> +Device drivers which need such firmware can use the
> +firmware_request_platform() function for this, note that this is a
> +separate fallback mechanism from the other fallback mechanisms and
> +this does not use the sysfs interface.
> +
> +A device driver which needs this can describe the firmware it needs
> +using an efi_embedded_fw_desc struct:
> +
> +.. kernel-doc:: include/linux/efi_embedded_fw.h
> +   :functions: efi_embedded_fw_desc
> +
> +The EFI embedded-fw code works by scanning all EFI_BOOT_SERVICES_CODE memory
> +segments for an eight byte sequence matching prefix; if the prefix is found it
> +then does a sha256 over length bytes and if that matches makes a copy of length
> +bytes and adds that to its list with found firmwares.
> +
> +To avoid doing this somewhat expensive scan on all systems, dmi matching is
> +used. Drivers are expected to export a dmi_system_id array, with each entries'
> +driver_data pointing to an efi_embedded_fw_desc.
> +
> +To register this array with the efi-embedded-fw code, a driver needs to:
> +
> +1. Always be builtin to the kernel or store the dmi_system_id array in a
> +   separate object file which always gets builtin.
> +
> +2. Add an extern declaration for the dmi_system_id array to
> +   include/linux/efi_embedded_fw.h.
> +
> +3. Add the dmi_system_id array to the embedded_fw_table in
> +   drivers/firmware/efi/embedded-firmware.c wrapped in a #ifdef testing that
> +   the driver is being builtin.
> +
> +4. Add "select EFI_EMBEDDED_FIRMWARE if EFI_STUB" to its Kconfig entry.
> +
> +The firmware_request_platform() function will always first try to load firmware
> +with the specified name directly from the disk, so the EFI embedded-fw can
> +always be overridden by placing a file under /lib/firmware.
> +
> +Note that:
> +
> +1. The code scanning for EFI embedded-firmware runs near the end
> +   of start_kernel(), just before calling rest_init(). For normal drivers and
> +   subsystems using subsys_initcall() to register themselves this does not
> +   matter. This means that code running earlier cannot use EFI
> +   embedded-firmware.
> +
> +2. At the moment the EFI embedded-fw code assumes that firmwares always start at
> +   an offset which is a multiple of 8 bytes, if this is not true for your case
> +   send in a patch to fix this.
> +
> +3. At the moment the EFI embedded-fw code only works on x86 because other archs
> +   free EFI_BOOT_SERVICES_CODE before the EFI embedded-fw code gets a chance to
> +   scan it.
> +
> +4. The current brute-force scanning of EFI_BOOT_SERVICES_CODE is an ad-hoc
> +   brute-force solution. There has been discussion to use the UEFI Platform
> +   Initialization (PI) spec's Firmware Volume protocol. This has been rejected
> +   because the FV Protocol relies on *internal* interfaces of the PI spec, and:
> +   1. The PI spec does not define peripheral firmware at all
> +   2. The internal interfaces of the PI spec do not guarantee any backward
> +   compatibility. Any implementation details in FV may be subject to change,
> +   and may vary system to system. Supporting the FV Protocol would be
> +   difficult as it is purposely ambiguous.
> +
> +Example how to check for and extract embedded firmware
> +------------------------------------------------------
> +
> +To check for, for example Silead touchscreen controller embedded firmware,
> +do the following:
> +
> +1. Boot the system with efi=debug on the kernel commandline
> +
> +2. cp /sys/kernel/debug/efi/boot_services_code? to your home dir
> +
> +3. Open the boot_services_code? files in a hex-editor, search for the
> +   magic prefix for Silead firmware: F0 00 00 00 02 00 00 00, this gives you
> +   the beginning address of the firmware inside the boot_services_code? file.
> +
> +4. The firmware has a specific pattern, it starts with a 8 byte page-address,
> +   typically F0 00 00 00 02 00 00 00 for the first page followed by 32-bit
> +   word-address + 32-bit value pairs. With the word-address incrementing 4
> +   bytes (1 word) for each pair until a page is complete. A complete page is
> +   followed by a new page-address, followed by more word + value pairs. This
> +   leads to a very distinct pattern. Scroll down until this pattern stops,
> +   this gives you the end of the firmware inside the boot_services_code? file.
> +
> +5. "dd if=boot_services_code? of=firmware bs=1 skip=<begin-addr> count=<len>"
> +   will extract the firmware for you. Inspect the firmware file in a
> +   hexeditor to make sure you got the dd parameters correct.
> +
> +6. Copy it to /lib/firmware under the expected name to test it.
> +
> +7. If the extracted firmware works, you can use the found info to fill an
> +   efi_embedded_fw_desc struct to describe it, run "sha256sum firmware"
> +   to get the sha256sum to put in the sha256 field.
> diff --git a/Documentation/driver-api/firmware/lookup-order.rst b/Documentation/driver-api/firmware/lookup-order.rst
> index 88c81739683c..6064672a782e 100644
> --- a/Documentation/driver-api/firmware/lookup-order.rst
> +++ b/Documentation/driver-api/firmware/lookup-order.rst
> @@ -12,6 +12,8 @@ a driver issues a firmware API call.
>    return it immediately
>  * The ''Direct filesystem lookup'' is performed next, if found we
>    return it immediately
> +* The ''Platform firmware fallback'' is performed next, but only when
> +  firmware_request_platform() is used, if found we return it immediately
>  * If no firmware has been found and the fallback mechanism was enabled
>    the sysfs interface is created. After this either a kobject uevent
>    is issued or the custom firmware loading is relied upon for firmware
> diff --git a/Documentation/driver-api/firmware/request_firmware.rst b/Documentation/driver-api/firmware/request_firmware.rst
> index f62bdcbfed5b..cd076462d235 100644
> --- a/Documentation/driver-api/firmware/request_firmware.rst
> +++ b/Documentation/driver-api/firmware/request_firmware.rst
> @@ -25,6 +25,11 @@ firmware_request_nowarn
>  .. kernel-doc:: drivers/base/firmware_loader/main.c
>     :functions: firmware_request_nowarn
>  
> +firmware_request_platform
> +-------------------------
> +.. kernel-doc:: drivers/base/firmware_loader/main.c
> +   :functions: firmware_request_platform
> +
>  request_firmware_direct
>  -----------------------
>  .. kernel-doc:: drivers/base/firmware_loader/main.c
> diff --git a/drivers/base/firmware_loader/Makefile b/drivers/base/firmware_loader/Makefile
> index 0b2dfa6259c9..e87843408fe6 100644
> --- a/drivers/base/firmware_loader/Makefile
> +++ b/drivers/base/firmware_loader/Makefile
> @@ -5,5 +5,6 @@ obj-$(CONFIG_FW_LOADER_USER_HELPER) += fallback_table.o
>  obj-$(CONFIG_FW_LOADER)	+= firmware_class.o
>  firmware_class-objs := main.o
>  firmware_class-$(CONFIG_FW_LOADER_USER_HELPER) += fallback.o
> +firmware_class-$(CONFIG_EFI_EMBEDDED_FIRMWARE) += fallback_platform.o
>  
>  obj-y += builtin/
> diff --git a/drivers/base/firmware_loader/fallback.h b/drivers/base/firmware_loader/fallback.h
> index 21063503e4ea..06f4577733a8 100644
> --- a/drivers/base/firmware_loader/fallback.h
> +++ b/drivers/base/firmware_loader/fallback.h
> @@ -66,4 +66,14 @@ static inline void unregister_sysfs_loader(void)
>  }
>  #endif /* CONFIG_FW_LOADER_USER_HELPER */
>  
> +#ifdef CONFIG_EFI_EMBEDDED_FIRMWARE
> +int firmware_fallback_platform(struct fw_priv *fw_priv, enum fw_opt opt_flags);
> +#else
> +static inline int firmware_fallback_platform(struct fw_priv *fw_priv,
> +					     enum fw_opt opt_flags)
> +{
> +	return -ENOENT;
> +}
> +#endif
> +
>  #endif /* __FIRMWARE_FALLBACK_H */
> diff --git a/drivers/base/firmware_loader/fallback_platform.c b/drivers/base/firmware_loader/fallback_platform.c
> new file mode 100644
> index 000000000000..37746efaf8e3
> --- /dev/null
> +++ b/drivers/base/firmware_loader/fallback_platform.c
> @@ -0,0 +1,29 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <linux/efi_embedded_fw.h>
> +#include <linux/property.h>
> +#include <linux/security.h>
> +#include <linux/vmalloc.h>
> +
> +#include "fallback.h"
> +#include "firmware.h"
> +
> +int firmware_fallback_platform(struct fw_priv *fw_priv, enum fw_opt opt_flags)
> +{
> +	int rc;
> +
> +	if (!(opt_flags & FW_OPT_FALLBACK_PLATFORM))
> +		return -ENOENT;
> +
> +	rc = security_kernel_load_data(LOADING_FIRMWARE_EFI_EMBEDDED);
> +	if (rc)
> +		return rc;
> +
> +	rc = efi_get_embedded_fw(fw_priv->fw_name, &fw_priv->data,
> +				 &fw_priv->size);
> +	if (rc)
> +		return rc; /* rc == -ENOENT when the fw was not found */
> +
> +	fw_state_done(fw_priv);
> +	return 0;
> +}
> diff --git a/drivers/base/firmware_loader/firmware.h b/drivers/base/firmware_loader/firmware.h
> index 8656e5239a80..25836a6afc9f 100644
> --- a/drivers/base/firmware_loader/firmware.h
> +++ b/drivers/base/firmware_loader/firmware.h
> @@ -29,6 +29,9 @@
>   *	firmware caching mechanism.
>   * @FW_OPT_NOFALLBACK_SYSFS: Disable the sysfs fallback mechanism. Takes
>   *	precedence over &FW_OPT_UEVENT and &FW_OPT_USERHELPER.
> + * @FW_OPT_FALLBACK_PLATFORM: Enable fallback to device fw copy embedded in
> + *	the platform's main firmware. If both this fallback and the sysfs
> + *      fallback are enabled, then this fallback will be tried first.
>   */
>  enum fw_opt {
>  	FW_OPT_UEVENT			= BIT(0),
> @@ -37,6 +40,7 @@ enum fw_opt {
>  	FW_OPT_NO_WARN			= BIT(3),
>  	FW_OPT_NOCACHE			= BIT(4),
>  	FW_OPT_NOFALLBACK_SYSFS		= BIT(5),
> +	FW_OPT_FALLBACK_PLATFORM	= BIT(6),
>  };
>  
>  enum fw_status {
> diff --git a/drivers/base/firmware_loader/main.c b/drivers/base/firmware_loader/main.c
> index 08f8995a530a..006ff71458b1 100644
> --- a/drivers/base/firmware_loader/main.c
> +++ b/drivers/base/firmware_loader/main.c
> @@ -775,6 +775,9 @@ _request_firmware(const struct firmware **firmware_p, const char *name,
>  						 fw_decompress_xz);
>  #endif
>  
> +	if (ret == -ENOENT)
> +		ret = firmware_fallback_platform(fw->priv, opt_flags);
> +
>  	if (ret) {
>  		if (!(opt_flags & FW_OPT_NO_WARN))
>  			dev_warn(device,
> @@ -882,6 +885,30 @@ int request_firmware_direct(const struct firmware **firmware_p,
>  }
>  EXPORT_SYMBOL_GPL(request_firmware_direct);
>  
> +/**
> + * firmware_request_platform() - request firmware with platform-fw fallback
> + * @firmware: pointer to firmware image
> + * @name: name of firmware file
> + * @device: device for which firmware is being loaded
> + *
> + * This function is similar in behaviour to request_firmware, except that if
> + * direct filesystem lookup fails, it will fallback to looking for a copy of the
> + * requested firmware embedded in the platform's main (e.g. UEFI) firmware.
> + **/
> +int firmware_request_platform(const struct firmware **firmware,
> +			      const char *name, struct device *device)
> +{
> +	int ret;
> +
> +	/* Need to pin this module until return */
> +	__module_get(THIS_MODULE);
> +	ret = _request_firmware(firmware, name, device, NULL, 0,
> +				FW_OPT_UEVENT | FW_OPT_FALLBACK_PLATFORM);
> +	module_put(THIS_MODULE);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(firmware_request_platform);
> +
>  /**
>   * firmware_request_cache() - cache firmware for suspend so resume can use it
>   * @name: name of firmware file
> diff --git a/include/linux/firmware.h b/include/linux/firmware.h
> index 2dd566c91d44..75dbec0bcc06 100644
> --- a/include/linux/firmware.h
> +++ b/include/linux/firmware.h
> @@ -44,6 +44,8 @@ int request_firmware(const struct firmware **fw, const char *name,
>  		     struct device *device);
>  int firmware_request_nowarn(const struct firmware **fw, const char *name,
>  			    struct device *device);
> +int firmware_request_platform(const struct firmware **fw, const char *name,
> +			      struct device *device);
>  int request_firmware_nowait(
>  	struct module *module, bool uevent,
>  	const char *name, struct device *device, gfp_t gfp, void *context,
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index e0d909d35763..3cbc955f6a1a 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2961,6 +2961,7 @@ extern int do_pipe_flags(int *, int);
>  	id(UNKNOWN, unknown)		\
>  	id(FIRMWARE, firmware)		\
>  	id(FIRMWARE_PREALLOC_BUFFER, firmware)	\
> +	id(FIRMWARE_EFI_EMBEDDED, firmware)	\
>  	id(MODULE, kernel-module)		\
>  	id(KEXEC_IMAGE, kexec-image)		\
>  	id(KEXEC_INITRAMFS, kexec-initramfs)	\
> -- 
> 2.23.0
> 

Re: [PATCH v8 4/8] firmware: Add new platform fallback mechanism and firmware_request_platform()

[Hans de Goede]

Hi,

On 18-11-2019 22:35, Luis Chamberlain wrote:
> On Fri, Nov 15, 2019 at 04:35:25PM +0100, Hans de Goede wrote:
>> In some cases the platform's main firmware (e.g. the UEFI fw) may contain
>> an embedded copy of device 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 a new platform fallback mechanism to the firmware loader
>> which will try to lookup a device fw copy embedded in the platform's main
>> firmware if direct filesystem lookup fails.
>>
>> Drivers which need such embedded fw copies can enable this fallback
>> mechanism by using the new firmware_request_platform() function.
>>
>> Note that for now this is only supported on EFI platforms and even on
>> these platforms firmware_fallback_platform() only works if
>> CONFIG_EFI_EMBEDDED_FIRMWARE is enabled (this gets selected by drivers
>> which need this), in all other cases firmware_fallback_platform() simply
>> always returns -ENOENT.
>>
>> Reported-by: Dave Olsthoorn <dave@bewaar.me>
>> Suggested-by: Peter Jones <pjones@redhat.com>
>> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> 
> This looks good to me now thanks!
> 
> Acked-by: Luis Chamberlain <mcgrof@kernel.org>
> 
> Just one more thing: testing. Since this requires EFI memeory, I guess
> we can't mimic a fake firmware somehow to use to test the API on any x86
> system? If not we'd have no test coverage through the selftests for this
> new call at all, and so could not easily detect regressions. We could
> perhaps *fake* an entry if a DEBUG kconfig option is enabled, which
> would stuff the EFI fw entry *once*. What do you think?

We could give the found_fw_list list_head from drivers/firmware/efi/embedded-firmware.c
a name which is better suited for exporting it and then actually export it.
That combined with moving the struct embedded_fw type declaration into
linux/efi_embedded_fw.h, with a note saying that it is private and should only
be used for the selftests.

Then a selftest can indeed simply add a fake fw entry to the list and then
excercise the API and check that it gets the contents of its own fake
entry back.

Hmm, I see that the tests under tools/testing/selftests/firmware
are doing everything through a special sysfs API, in case of testing
the userspace fallbacks this makes sense, but in this case I
was thinking more along the lines of writing the test itself in a
module (or add it to the lib/test_firmware.c) module rather then doing
this complex dance.

I guess this test could just be another store method for a new sysfs
attribute, which does not interact with any of the state/config, like the
trigger_request test.

I can try to write a follow up series which does this this weekend.

Regards,

Hans



> 
> Look at: lib/test_firmware.c and tools/testing/selftests/firmware/
> 
>    Luis
> 
>> ---
>> Changes in v8:
>> - Only build fallback_platform.c if CONFIG_EFI_EMBEDDED_FIRMWARE is defined,
>>    otherwise make firmware_fallback_platform() a static inline stub
>> - Add documentation to Documentation/driver-api/firmware/fallback-mechanisms.rst
>>    on how the boot_service_code? files exported by EFI debugfs can be used to
>>    check if there is an embedded firmware and to get the embedded firmware
>>    length and sha256sum
>>
>> Changes in v7:
>> - Split drivers/firmware/efi and drivers/base/firmware_loader changes into
>>    2 patches
>> - Address kdoc comments from Randy Dunlap
>> - Add new FW_OPT_FALLBACK_PLATFORM flag and firmware_request_platform()
>>    _request_firmware() wrapper, as requested by Luis R. Rodriguez
>> - Stop using "efi-embedded-firmware" device-property, now that drivers need to
>>    use the new firmware_request_platform() to enable fallback to a device fw
>>    copy embedded in the platform's main firmware, we no longer need a property
>>    on the device to trigger this behavior
>> - Use security_kernel_load_data instead of calling
>>    security_kernel_read_file with a NULL file pointer argument
>> - Move the docs to Documentation/driver-api/firmware/fallback-mechanisms.rst
>> - Document the new firmware_request_platform() function in
>>    Documentation/driver-api/firmware/request_firmware.rst
>>
>> Changes in v6:
>> - Rework code to remove casts from if (prefix == mem) comparison
>> - Use SHA256 hashes instead of crc32 sums
>> - Add new READING_FIRMWARE_EFI_EMBEDDED read_file_id and use it
>> - Call security_kernel_read_file(NULL, READING_FIRMWARE_EFI_EMBEDDED)
>>    to check if this is allowed before looking at EFI embedded fw
>> - Document why we are not using the UEFI PI Firmware Volume protocol
>>
>> Changes in v5:
>> - Rename the EFI_BOOT_SERVICES flag to EFI_PRESERVE_BS_REGIONS
>>
>> Changes in v4:
>> - Drop note in docs about EFI_FIRMWARE_VOLUME_PROTOCOL, it is not part of
>>    UEFI proper, so the EFI maintainers don't want us referring people to it
>> - Use new EFI_BOOT_SERVICES flag
>> - Put the new fw_get_efi_embedded_fw() function in its own fallback_efi.c
>>    file which only gets built when EFI_EMBEDDED_FIRMWARE is selected
>> - Define an empty stub for fw_get_efi_embedded_fw() in fallback.h hwen
>>    EFI_EMBEDDED_FIRMWARE is not selected, to avoid the need for #ifdefs
>>    in firmware_loader/main.c
>> - Properly call security_kernel_post_read_file() on the firmware returned
>>    by efi_get_embedded_fw() to make sure that we are allowed to use it
>>
>> Changes in v3:
>> - Fix the docs using "efi-embedded-fw" as property name instead of
>>    "efi-embedded-firmware"
>>
>> Changes in v2:
>> - Rebased on driver-core/driver-core-next
>> - Add documentation describing the EFI embedded firmware mechanism to:
>>    Documentation/driver-api/firmware/request_firmware.rst
>> - Add a new EFI_EMBEDDED_FIRMWARE Kconfig bool and only build the embedded
>>    fw support if this is set. This is an invisible option which should be
>>    selected by drivers which need this
>> - Remove the efi_embedded_fw_desc and dmi_system_id-s for known devices
>>    from the efi-embedded-fw code, instead drivers using this are expected to
>>    export a dmi_system_id array, with each entries' driver_data pointing to a
>>    efi_embedded_fw_desc struct and register this with the efi-embedded-fw code
>> - Use kmemdup to make a copy instead of efi_mem_reserve()-ing the firmware,
>>    this avoids us messing with the EFI memmap and avoids the need to make
>>    changes to efi_mem_desc_lookup()
>> - Make the firmware-loader code only fallback to efi_get_embedded_fw() if the
>>    passed in device has the "efi-embedded-firmware" device-property bool set
>> - Skip usermodehelper fallback when "efi-embedded-firmware" device-property
>>    is set
>> ---
>>   .../firmware/fallback-mechanisms.rst          | 103 ++++++++++++++++++
>>   .../driver-api/firmware/lookup-order.rst      |   2 +
>>   .../driver-api/firmware/request_firmware.rst  |   5 +
>>   drivers/base/firmware_loader/Makefile         |   1 +
>>   drivers/base/firmware_loader/fallback.h       |  10 ++
>>   .../base/firmware_loader/fallback_platform.c  |  29 +++++
>>   drivers/base/firmware_loader/firmware.h       |   4 +
>>   drivers/base/firmware_loader/main.c           |  27 +++++
>>   include/linux/firmware.h                      |   2 +
>>   include/linux/fs.h                            |   1 +
>>   10 files changed, 184 insertions(+)
>>   create mode 100644 drivers/base/firmware_loader/fallback_platform.c
>>
>> diff --git a/Documentation/driver-api/firmware/fallback-mechanisms.rst b/Documentation/driver-api/firmware/fallback-mechanisms.rst
>> index 8b041d0ab426..036383dad6d6 100644
>> --- a/Documentation/driver-api/firmware/fallback-mechanisms.rst
>> +++ b/Documentation/driver-api/firmware/fallback-mechanisms.rst
>> @@ -202,3 +202,106 @@ the following file:
>>   
>>   If you echo 0 into it means MAX_JIFFY_OFFSET will be used. The data type
>>   for the timeout is an int.
>> +
>> +EFI embedded firmware fallback mechanism
>> +========================================
>> +
>> +On some devices the system's EFI code / ROM may contain an embedded copy
>> +of firmware for some of the system's integrated peripheral devices and
>> +the peripheral's Linux device-driver needs to access this firmware.
>> +
>> +Device drivers which need such firmware can use the
>> +firmware_request_platform() function for this, note that this is a
>> +separate fallback mechanism from the other fallback mechanisms and
>> +this does not use the sysfs interface.
>> +
>> +A device driver which needs this can describe the firmware it needs
>> +using an efi_embedded_fw_desc struct:
>> +
>> +.. kernel-doc:: include/linux/efi_embedded_fw.h
>> +   :functions: efi_embedded_fw_desc
>> +
>> +The EFI embedded-fw code works by scanning all EFI_BOOT_SERVICES_CODE memory
>> +segments for an eight byte sequence matching prefix; if the prefix is found it
>> +then does a sha256 over length bytes and if that matches makes a copy of length
>> +bytes and adds that to its list with found firmwares.
>> +
>> +To avoid doing this somewhat expensive scan on all systems, dmi matching is
>> +used. Drivers are expected to export a dmi_system_id array, with each entries'
>> +driver_data pointing to an efi_embedded_fw_desc.
>> +
>> +To register this array with the efi-embedded-fw code, a driver needs to:
>> +
>> +1. Always be builtin to the kernel or store the dmi_system_id array in a
>> +   separate object file which always gets builtin.
>> +
>> +2. Add an extern declaration for the dmi_system_id array to
>> +   include/linux/efi_embedded_fw.h.
>> +
>> +3. Add the dmi_system_id array to the embedded_fw_table in
>> +   drivers/firmware/efi/embedded-firmware.c wrapped in a #ifdef testing that
>> +   the driver is being builtin.
>> +
>> +4. Add "select EFI_EMBEDDED_FIRMWARE if EFI_STUB" to its Kconfig entry.
>> +
>> +The firmware_request_platform() function will always first try to load firmware
>> +with the specified name directly from the disk, so the EFI embedded-fw can
>> +always be overridden by placing a file under /lib/firmware.
>> +
>> +Note that:
>> +
>> +1. The code scanning for EFI embedded-firmware runs near the end
>> +   of start_kernel(), just before calling rest_init(). For normal drivers and
>> +   subsystems using subsys_initcall() to register themselves this does not
>> +   matter. This means that code running earlier cannot use EFI
>> +   embedded-firmware.
>> +
>> +2. At the moment the EFI embedded-fw code assumes that firmwares always start at
>> +   an offset which is a multiple of 8 bytes, if this is not true for your case
>> +   send in a patch to fix this.
>> +
>> +3. At the moment the EFI embedded-fw code only works on x86 because other archs
>> +   free EFI_BOOT_SERVICES_CODE before the EFI embedded-fw code gets a chance to
>> +   scan it.
>> +
>> +4. The current brute-force scanning of EFI_BOOT_SERVICES_CODE is an ad-hoc
>> +   brute-force solution. There has been discussion to use the UEFI Platform
>> +   Initialization (PI) spec's Firmware Volume protocol. This has been rejected
>> +   because the FV Protocol relies on *internal* interfaces of the PI spec, and:
>> +   1. The PI spec does not define peripheral firmware at all
>> +   2. The internal interfaces of the PI spec do not guarantee any backward
>> +   compatibility. Any implementation details in FV may be subject to change,
>> +   and may vary system to system. Supporting the FV Protocol would be
>> +   difficult as it is purposely ambiguous.
>> +
>> +Example how to check for and extract embedded firmware
>> +------------------------------------------------------
>> +
>> +To check for, for example Silead touchscreen controller embedded firmware,
>> +do the following:
>> +
>> +1. Boot the system with efi=debug on the kernel commandline
>> +
>> +2. cp /sys/kernel/debug/efi/boot_services_code? to your home dir
>> +
>> +3. Open the boot_services_code? files in a hex-editor, search for the
>> +   magic prefix for Silead firmware: F0 00 00 00 02 00 00 00, this gives you
>> +   the beginning address of the firmware inside the boot_services_code? file.
>> +
>> +4. The firmware has a specific pattern, it starts with a 8 byte page-address,
>> +   typically F0 00 00 00 02 00 00 00 for the first page followed by 32-bit
>> +   word-address + 32-bit value pairs. With the word-address incrementing 4
>> +   bytes (1 word) for each pair until a page is complete. A complete page is
>> +   followed by a new page-address, followed by more word + value pairs. This
>> +   leads to a very distinct pattern. Scroll down until this pattern stops,
>> +   this gives you the end of the firmware inside the boot_services_code? file.
>> +
>> +5. "dd if=boot_services_code? of=firmware bs=1 skip=<begin-addr> count=<len>"
>> +   will extract the firmware for you. Inspect the firmware file in a
>> +   hexeditor to make sure you got the dd parameters correct.
>> +
>> +6. Copy it to /lib/firmware under the expected name to test it.
>> +
>> +7. If the extracted firmware works, you can use the found info to fill an
>> +   efi_embedded_fw_desc struct to describe it, run "sha256sum firmware"
>> +   to get the sha256sum to put in the sha256 field.
>> diff --git a/Documentation/driver-api/firmware/lookup-order.rst b/Documentation/driver-api/firmware/lookup-order.rst
>> index 88c81739683c..6064672a782e 100644
>> --- a/Documentation/driver-api/firmware/lookup-order.rst
>> +++ b/Documentation/driver-api/firmware/lookup-order.rst
>> @@ -12,6 +12,8 @@ a driver issues a firmware API call.
>>     return it immediately
>>   * The ''Direct filesystem lookup'' is performed next, if found we
>>     return it immediately
>> +* The ''Platform firmware fallback'' is performed next, but only when
>> +  firmware_request_platform() is used, if found we return it immediately
>>   * If no firmware has been found and the fallback mechanism was enabled
>>     the sysfs interface is created. After this either a kobject uevent
>>     is issued or the custom firmware loading is relied upon for firmware
>> diff --git a/Documentation/driver-api/firmware/request_firmware.rst b/Documentation/driver-api/firmware/request_firmware.rst
>> index f62bdcbfed5b..cd076462d235 100644
>> --- a/Documentation/driver-api/firmware/request_firmware.rst
>> +++ b/Documentation/driver-api/firmware/request_firmware.rst
>> @@ -25,6 +25,11 @@ firmware_request_nowarn
>>   .. kernel-doc:: drivers/base/firmware_loader/main.c
>>      :functions: firmware_request_nowarn
>>   
>> +firmware_request_platform
>> +-------------------------
>> +.. kernel-doc:: drivers/base/firmware_loader/main.c
>> +   :functions: firmware_request_platform
>> +
>>   request_firmware_direct
>>   -----------------------
>>   .. kernel-doc:: drivers/base/firmware_loader/main.c
>> diff --git a/drivers/base/firmware_loader/Makefile b/drivers/base/firmware_loader/Makefile
>> index 0b2dfa6259c9..e87843408fe6 100644
>> --- a/drivers/base/firmware_loader/Makefile
>> +++ b/drivers/base/firmware_loader/Makefile
>> @@ -5,5 +5,6 @@ obj-$(CONFIG_FW_LOADER_USER_HELPER) += fallback_table.o
>>   obj-$(CONFIG_FW_LOADER)	+= firmware_class.o
>>   firmware_class-objs := main.o
>>   firmware_class-$(CONFIG_FW_LOADER_USER_HELPER) += fallback.o
>> +firmware_class-$(CONFIG_EFI_EMBEDDED_FIRMWARE) += fallback_platform.o
>>   
>>   obj-y += builtin/
>> diff --git a/drivers/base/firmware_loader/fallback.h b/drivers/base/firmware_loader/fallback.h
>> index 21063503e4ea..06f4577733a8 100644
>> --- a/drivers/base/firmware_loader/fallback.h
>> +++ b/drivers/base/firmware_loader/fallback.h
>> @@ -66,4 +66,14 @@ static inline void unregister_sysfs_loader(void)
>>   }
>>   #endif /* CONFIG_FW_LOADER_USER_HELPER */
>>   
>> +#ifdef CONFIG_EFI_EMBEDDED_FIRMWARE
>> +int firmware_fallback_platform(struct fw_priv *fw_priv, enum fw_opt opt_flags);
>> +#else
>> +static inline int firmware_fallback_platform(struct fw_priv *fw_priv,
>> +					     enum fw_opt opt_flags)
>> +{
>> +	return -ENOENT;
>> +}
>> +#endif
>> +
>>   #endif /* __FIRMWARE_FALLBACK_H */
>> diff --git a/drivers/base/firmware_loader/fallback_platform.c b/drivers/base/firmware_loader/fallback_platform.c
>> new file mode 100644
>> index 000000000000..37746efaf8e3
>> --- /dev/null
>> +++ b/drivers/base/firmware_loader/fallback_platform.c
>> @@ -0,0 +1,29 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +
>> +#include <linux/efi_embedded_fw.h>
>> +#include <linux/property.h>
>> +#include <linux/security.h>
>> +#include <linux/vmalloc.h>
>> +
>> +#include "fallback.h"
>> +#include "firmware.h"
>> +
>> +int firmware_fallback_platform(struct fw_priv *fw_priv, enum fw_opt opt_flags)
>> +{
>> +	int rc;
>> +
>> +	if (!(opt_flags & FW_OPT_FALLBACK_PLATFORM))
>> +		return -ENOENT;
>> +
>> +	rc = security_kernel_load_data(LOADING_FIRMWARE_EFI_EMBEDDED);
>> +	if (rc)
>> +		return rc;
>> +
>> +	rc = efi_get_embedded_fw(fw_priv->fw_name, &fw_priv->data,
>> +				 &fw_priv->size);
>> +	if (rc)
>> +		return rc; /* rc == -ENOENT when the fw was not found */
>> +
>> +	fw_state_done(fw_priv);
>> +	return 0;
>> +}
>> diff --git a/drivers/base/firmware_loader/firmware.h b/drivers/base/firmware_loader/firmware.h
>> index 8656e5239a80..25836a6afc9f 100644
>> --- a/drivers/base/firmware_loader/firmware.h
>> +++ b/drivers/base/firmware_loader/firmware.h
>> @@ -29,6 +29,9 @@
>>    *	firmware caching mechanism.
>>    * @FW_OPT_NOFALLBACK_SYSFS: Disable the sysfs fallback mechanism. Takes
>>    *	precedence over &FW_OPT_UEVENT and &FW_OPT_USERHELPER.
>> + * @FW_OPT_FALLBACK_PLATFORM: Enable fallback to device fw copy embedded in
>> + *	the platform's main firmware. If both this fallback and the sysfs
>> + *      fallback are enabled, then this fallback will be tried first.
>>    */
>>   enum fw_opt {
>>   	FW_OPT_UEVENT			= BIT(0),
>> @@ -37,6 +40,7 @@ enum fw_opt {
>>   	FW_OPT_NO_WARN			= BIT(3),
>>   	FW_OPT_NOCACHE			= BIT(4),
>>   	FW_OPT_NOFALLBACK_SYSFS		= BIT(5),
>> +	FW_OPT_FALLBACK_PLATFORM	= BIT(6),
>>   };
>>   
>>   enum fw_status {
>> diff --git a/drivers/base/firmware_loader/main.c b/drivers/base/firmware_loader/main.c
>> index 08f8995a530a..006ff71458b1 100644
>> --- a/drivers/base/firmware_loader/main.c
>> +++ b/drivers/base/firmware_loader/main.c
>> @@ -775,6 +775,9 @@ _request_firmware(const struct firmware **firmware_p, const char *name,
>>   						 fw_decompress_xz);
>>   #endif
>>   
>> +	if (ret == -ENOENT)
>> +		ret = firmware_fallback_platform(fw->priv, opt_flags);
>> +
>>   	if (ret) {
>>   		if (!(opt_flags & FW_OPT_NO_WARN))
>>   			dev_warn(device,
>> @@ -882,6 +885,30 @@ int request_firmware_direct(const struct firmware **firmware_p,
>>   }
>>   EXPORT_SYMBOL_GPL(request_firmware_direct);
>>   
>> +/**
>> + * firmware_request_platform() - request firmware with platform-fw fallback
>> + * @firmware: pointer to firmware image
>> + * @name: name of firmware file
>> + * @device: device for which firmware is being loaded
>> + *
>> + * This function is similar in behaviour to request_firmware, except that if
>> + * direct filesystem lookup fails, it will fallback to looking for a copy of the
>> + * requested firmware embedded in the platform's main (e.g. UEFI) firmware.
>> + **/
>> +int firmware_request_platform(const struct firmware **firmware,
>> +			      const char *name, struct device *device)
>> +{
>> +	int ret;
>> +
>> +	/* Need to pin this module until return */
>> +	__module_get(THIS_MODULE);
>> +	ret = _request_firmware(firmware, name, device, NULL, 0,
>> +				FW_OPT_UEVENT | FW_OPT_FALLBACK_PLATFORM);
>> +	module_put(THIS_MODULE);
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(firmware_request_platform);
>> +
>>   /**
>>    * firmware_request_cache() - cache firmware for suspend so resume can use it
>>    * @name: name of firmware file
>> diff --git a/include/linux/firmware.h b/include/linux/firmware.h
>> index 2dd566c91d44..75dbec0bcc06 100644
>> --- a/include/linux/firmware.h
>> +++ b/include/linux/firmware.h
>> @@ -44,6 +44,8 @@ int request_firmware(const struct firmware **fw, const char *name,
>>   		     struct device *device);
>>   int firmware_request_nowarn(const struct firmware **fw, const char *name,
>>   			    struct device *device);
>> +int firmware_request_platform(const struct firmware **fw, const char *name,
>> +			      struct device *device);
>>   int request_firmware_nowait(
>>   	struct module *module, bool uevent,
>>   	const char *name, struct device *device, gfp_t gfp, void *context,
>> diff --git a/include/linux/fs.h b/include/linux/fs.h
>> index e0d909d35763..3cbc955f6a1a 100644
>> --- a/include/linux/fs.h
>> +++ b/include/linux/fs.h
>> @@ -2961,6 +2961,7 @@ extern int do_pipe_flags(int *, int);
>>   	id(UNKNOWN, unknown)		\
>>   	id(FIRMWARE, firmware)		\
>>   	id(FIRMWARE_PREALLOC_BUFFER, firmware)	\
>> +	id(FIRMWARE_EFI_EMBEDDED, firmware)	\
>>   	id(MODULE, kernel-module)		\
>>   	id(KEXEC_IMAGE, kexec-image)		\
>>   	id(KEXEC_INITRAMFS, kexec-initramfs)	\
>> -- 
>> 2.23.0
>>
> 

Re: [PATCH v8 4/8] firmware: Add new platform fallback mechanism and firmware_request_platform()

[Luis Chamberlain]

On Tue, Nov 19, 2019 at 03:03:48PM +0100, Hans de Goede wrote:
> Hi,
> 
> On 18-11-2019 22:35, Luis Chamberlain wrote:
> > On Fri, Nov 15, 2019 at 04:35:25PM +0100, Hans de Goede wrote:
> > > In some cases the platform's main firmware (e.g. the UEFI fw) may contain
> > > an embedded copy of device 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 a new platform fallback mechanism to the firmware loader
> > > which will try to lookup a device fw copy embedded in the platform's main
> > > firmware if direct filesystem lookup fails.
> > > 
> > > Drivers which need such embedded fw copies can enable this fallback
> > > mechanism by using the new firmware_request_platform() function.
> > > 
> > > Note that for now this is only supported on EFI platforms and even on
> > > these platforms firmware_fallback_platform() only works if
> > > CONFIG_EFI_EMBEDDED_FIRMWARE is enabled (this gets selected by drivers
> > > which need this), in all other cases firmware_fallback_platform() simply
> > > always returns -ENOENT.
> > > 
> > > Reported-by: Dave Olsthoorn <dave@bewaar.me>
> > > Suggested-by: Peter Jones <pjones@redhat.com>
> > > Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> > 
> > This looks good to me now thanks!
> > 
> > Acked-by: Luis Chamberlain <mcgrof@kernel.org>
> > 
> > Just one more thing: testing. Since this requires EFI memeory, I guess
> > we can't mimic a fake firmware somehow to use to test the API on any x86
> > system? If not we'd have no test coverage through the selftests for this
> > new call at all, and so could not easily detect regressions. We could
> > perhaps *fake* an entry if a DEBUG kconfig option is enabled, which
> > would stuff the EFI fw entry *once*. What do you think?
> 
> We could give the found_fw_list list_head from drivers/firmware/efi/embedded-firmware.c
> a name which is better suited for exporting it and then actually export it.
> That combined with moving the struct embedded_fw type declaration into
> linux/efi_embedded_fw.h, 

Sure.

> with a note saying that it is private and should only
> be used for the selftests.

No need, we now have symbol namespaces [0]. You can use that then.

[0] https://lwn.net/Articles/759928/

> Then a selftest can indeed simply add a fake fw entry to the list and then
> excercise the API and check that it gets the contents of its own fake
> entry back.

Great.

> Hmm, I see that the tests under tools/testing/selftests/firmware
> are doing everything through a special sysfs API,

That's incorrect.

tools/testing/selftests/firmware/fw_fallback.sh - tests sysfs fallback
tools/testing/selftests/firmware/fw_filesystem.sh - tests direct loading

The fw_fallback.sh should probably be renamed to something like
fw_fallback_sysfs.sh and you could have your own script for this
new API.

> in case of testing
> the userspace fallbacks this makes sense, but in this case I
> was thinking more along the lines of writing the test itself in a
> module (or add it to the lib/test_firmware.c) module rather then doing
> this complex dance.

What the scripts do is *configure* a test type in userspace and then
trigger the test. It should pretty trivial to add an entry to enable
your API to be used. The benefit of this is that we can then tweak
*how* we test the API in userspace, and kick a trigger.

Doing a new module could be done but we'd have to answer why we can't
implement the test with the test knob interface currently used.

> I guess this test could just be another store method for a new sysfs
> attribute, which does not interact with any of the state/config, like the
> trigger_request test.

Right, the syfs for for that test driver is just to *configure* the
test in userspace, nothing to do with the firmware API. The firmware
API is then *used* once the trigger is used.

> I can try to write a follow up series which does this this weekend.

That would be fantastic, thanks!

  Luis