From patchwork Mon Aug 15 20:45:11 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jack Rosenthal X-Patchwork-Id: 12944068 Received: from mail-io1-f41.google.com (mail-io1-f41.google.com [209.85.166.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8B0C92F28 for ; Mon, 15 Aug 2022 20:45:38 +0000 (UTC) Received: by mail-io1-f41.google.com with SMTP id r141so3228798iod.4 for ; Mon, 15 Aug 2022 13:45:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc; bh=tIu5C5uMPp111gSPdwc0Dp76L1hJvvSseLDiJjEoffM=; b=OjOMTHnBF7JQvxSwuS5IlDrkhXB4ASdYWoIV0ZgNsSXXty6xl1f3qwaR7yTDBMX9g8 i+drsi5itN2ofE+HkJIQ9riLu9jDbGJKPBE1/wXV6x3UwV/Z6F8JFK5CST8ReNH2rC5v 5eMAhF4ECwEHQ8BbbSHUJVmxyAKY+WOJi8pK0= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc; bh=tIu5C5uMPp111gSPdwc0Dp76L1hJvvSseLDiJjEoffM=; b=SvoAJa0vhVd44X/DtnLeXSsQRchl18rWjDgjb5OXJYFxaZ8Yo7quDlWtXOLMsVtu3v SNYCi2DzwbQqme90GcObHxLhmoCX2wxa3YzC0MJcZ9K+jK4TmgRwEFwSwHh/71Gd+HyF ++GsSsCZq1ozquGq5nT9lb1wsljcHomm42M5RUs3m2Od87el53iVJuwlLOa7aCcKrdJ/ tvQuq9O81W+i5M0kQZnMLMenYmwqA84oUGMp9p6ldoXWZAYDokMZxIvOUASOboH3gU6k AzXNTuIkMFHtWcZCf89ubpwdtOPOC2pdB39heO5CaQswEb+b2VCB3SiAg02OgOp332Zd ecRw== X-Gm-Message-State: ACgBeo2DP7x/x3Ac5C6cvrAf0hwCPWg4333LzSFwC4AOYHjC6yscOOO+ HCQIaumUCokis6Uxmo3+3KPj7g== X-Google-Smtp-Source: AA6agR58XhABPFk1wERmMO21JeF8rkLt5CsPxCCU7eEd8uo6G/bKSTlM8uuNQh0Zxkz914v5cMLfgw== X-Received: by 2002:a05:6638:4807:b0:343:5eb7:7f7 with SMTP id cp7-20020a056638480700b003435eb707f7mr8334999jab.29.1660596337411; Mon, 15 Aug 2022 13:45:37 -0700 (PDT) Received: from jrosenth45.corp.google.com ([100.107.108.157]) by smtp.gmail.com with ESMTPSA id w8-20020a023948000000b0034366d9ff06sm3661593jae.155.2022.08.15.13.45.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 15 Aug 2022 13:45:36 -0700 (PDT) From: Jack Rosenthal To: linux-kernel@vger.kernel.org, chrome-platform@lists.linux.dev Cc: Jack Rosenthal , Stephen Boyd , Tzung-Bi Shih , Guenter Roeck , Julius Werner Subject: [PATCH v9] firmware: google: Implement cbmem in sysfs driver Date: Mon, 15 Aug 2022 14:45:11 -0600 Message-Id: <20220815204511.621569-1-jrosenth@chromium.org> X-Mailer: git-send-email 2.37.1.595.g718a3a8f04-goog Precedence: bulk X-Mailing-List: chrome-platform@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 The CBMEM area is a downward-growing memory region used by coreboot to dynamically allocate tagged data structures ("CBMEM entries") that remain resident during boot. This implements a driver which exports access to the CBMEM entries via sysfs under /sys/firmware/coreboot/cbmem/. This implementation is quite versatile. Examples of how it could be used are given below: * Tools like util/cbmem from the coreboot tree could use this driver instead of finding CBMEM in /dev/mem directly. Alternatively, firmware developers debugging an issue may find the sysfs interface more ergonomic than the cbmem tool and choose to use it directly. * The crossystem tool, which exposes verified boot variables, can use this driver to read the vboot work buffer. * Tools which read the BIOS SPI flash (e.g., flashrom) can find the flash layout in CBMEM directly, which is significantly faster than searching the flash directly. Link: https://issuetracker.google.com/239604743 Cc: Stephen Boyd Cc: Tzung-Bi Shih Reviewed-by: Guenter Roeck Reviewed-by: Julius Werner Tested-by: Jack Rosenthal Signed-off-by: Jack Rosenthal --- v9: * Removed unnecessary include linux/ctype.h. * Made /sys/firmware/coreboot/cbmem//mem provide read-only access only, and the permissions are now 0400. * Added .owner = THIS_MODULE. * Corrected coreboot_kobj -> cbmem_kobj. * Updated Kconfig help message. * Updated commit message to add much mode detail. .../ABI/testing/sysfs-firmware-coreboot | 49 ++++ drivers/firmware/google/Kconfig | 8 + drivers/firmware/google/Makefile | 3 + drivers/firmware/google/cbmem.c | 215 ++++++++++++++++++ drivers/firmware/google/coreboot_table.c | 10 + drivers/firmware/google/coreboot_table.h | 16 ++ 6 files changed, 301 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-firmware-coreboot create mode 100644 drivers/firmware/google/cbmem.c diff --git a/Documentation/ABI/testing/sysfs-firmware-coreboot b/Documentation/ABI/testing/sysfs-firmware-coreboot new file mode 100644 index 000000000000..5432dea2408c --- /dev/null +++ b/Documentation/ABI/testing/sysfs-firmware-coreboot @@ -0,0 +1,49 @@ +What: /sys/firmware/coreboot/ +Date: August 2022 +Contact: Jack Rosenthal +Description: + Kernel objects associated with the Coreboot-based BIOS firmware. + +What: /sys/firmware/coreboot/cbmem/ +Date: August 2022 +Contact: Jack Rosenthal +Description: + Coreboot provides a variety of information in CBMEM. This + directory contains each CBMEM entry, which can be found via + Coreboot tables. + +What: /sys/firmware/coreboot/cbmem// +Date: August 2022 +Contact: Jack Rosenthal +Description: + Each CBMEM entry is given a directory based on the id + corresponding to the entry. A list of ids known to coreboot can + be found in the coreboot source tree at + ``src/commonlib/bsd/include/commonlib/bsd/cbmem_id.h``. + +What: /sys/firmware/coreboot/cbmem//address +Date: August 2022 +Contact: Jack Rosenthal +Description: + The memory address that the CBMEM entry's data begins at. + +What: /sys/firmware/coreboot/cbmem//size +Date: August 2022 +Contact: Jack Rosenthal +Description: + The size of the data being stored. + +What: /sys/firmware/coreboot/cbmem//id +Date: August 2022 +Contact: Jack Rosenthal +Description: + The CBMEM id corresponding to the entry. + +What: /sys/firmware/coreboot/cbmem//mem +Date: August 2022 +Contact: Jack Rosenthal +Description: + A file exposing read-only access to the entry's data. Note + that this file does not support mmap(), and should be used for + basic data access only. Users requiring mmap() should read the + address and size files, and mmap() /dev/mem. diff --git a/drivers/firmware/google/Kconfig b/drivers/firmware/google/Kconfig index 983e07dc022e..b0f7a24fd90a 100644 --- a/drivers/firmware/google/Kconfig +++ b/drivers/firmware/google/Kconfig @@ -19,6 +19,14 @@ config GOOGLE_SMI driver provides an interface for reading and writing NVRAM variables. +config GOOGLE_CBMEM + tristate "CBMEM entries in sysfs" + depends on GOOGLE_COREBOOT_TABLE + help + This option enables the kernel to search for Coreboot CBMEM + entries, and expose the memory for each entry in sysfs under + /sys/firmware/coreboot/cbmem. + config GOOGLE_COREBOOT_TABLE tristate "Coreboot Table Access" depends on HAS_IOMEM && (ACPI || OF) diff --git a/drivers/firmware/google/Makefile b/drivers/firmware/google/Makefile index d17caded5d88..8151e323cc43 100644 --- a/drivers/firmware/google/Makefile +++ b/drivers/firmware/google/Makefile @@ -7,5 +7,8 @@ obj-$(CONFIG_GOOGLE_MEMCONSOLE) += memconsole.o obj-$(CONFIG_GOOGLE_MEMCONSOLE_COREBOOT) += memconsole-coreboot.o obj-$(CONFIG_GOOGLE_MEMCONSOLE_X86_LEGACY) += memconsole-x86-legacy.o +# Must come after coreboot_table.o, as this driver depends on that bus type. +obj-$(CONFIG_GOOGLE_CBMEM) += cbmem.o + vpd-sysfs-y := vpd.o vpd_decode.o obj-$(CONFIG_GOOGLE_VPD) += vpd-sysfs.o diff --git a/drivers/firmware/google/cbmem.c b/drivers/firmware/google/cbmem.c new file mode 100644 index 000000000000..cbfe8f388097 --- /dev/null +++ b/drivers/firmware/google/cbmem.c @@ -0,0 +1,215 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * cbmem.c + * + * Driver for exporting cbmem entries in sysfs. + * + * Copyright 2022 Google LLC + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "coreboot_table.h" + +#define LB_TAG_CBMEM_ENTRY 0x31 + +static struct kobject *cbmem_kobj; + +struct cbmem_entry; +struct cbmem_entry_attr { + struct kobj_attribute kobj_attr; + struct cbmem_entry *entry; +}; + +struct cbmem_entry { + struct kobject *kobj; + struct coreboot_device *dev; + struct bin_attribute mem_file; + char *mem_file_buf; + struct cbmem_entry_attr address_file; + struct cbmem_entry_attr size_file; + struct cbmem_entry_attr id_file; +}; + +static struct cbmem_entry_attr *to_cbmem_entry_attr(struct kobj_attribute *a) +{ + return container_of(a, struct cbmem_entry_attr, kobj_attr); +} + +static ssize_t cbmem_entry_mem_read(struct file *filp, struct kobject *kobp, + struct bin_attribute *bin_attr, char *buf, + loff_t pos, size_t count) +{ + struct cbmem_entry *entry = bin_attr->private; + + return memory_read_from_buffer(buf, count, &pos, entry->mem_file_buf, + bin_attr->size); +} + +static ssize_t cbmem_entry_address_show(struct kobject *kobj, + struct kobj_attribute *a, char *buf) +{ + struct cbmem_entry_attr *entry_attr = to_cbmem_entry_attr(a); + + return sysfs_emit(buf, "0x%llx\n", + entry_attr->entry->dev->cbmem_entry.address); +} + +static ssize_t cbmem_entry_size_show(struct kobject *kobj, + struct kobj_attribute *a, char *buf) +{ + struct cbmem_entry_attr *entry_attr = to_cbmem_entry_attr(a); + + return sysfs_emit(buf, "0x%x\n", + entry_attr->entry->dev->cbmem_entry.entry_size); +} + +static ssize_t cbmem_entry_id_show(struct kobject *kobj, + struct kobj_attribute *a, char *buf) +{ + struct cbmem_entry_attr *entry_attr = to_cbmem_entry_attr(a); + + return sysfs_emit(buf, "0x%08x\n", + entry_attr->entry->dev->cbmem_entry.id); +} + +static int cbmem_entry_setup(struct cbmem_entry *entry) +{ + int ret; + char *kobj_name; + + entry->mem_file_buf = + devm_memremap(&entry->dev->dev, entry->dev->cbmem_entry.address, + entry->dev->cbmem_entry.entry_size, MEMREMAP_WB); + if (!entry->mem_file_buf) + return -ENOMEM; + + kobj_name = devm_kasprintf(&entry->dev->dev, GFP_KERNEL, "%08x", + entry->dev->cbmem_entry.id); + if (!kobj_name) + return -ENOMEM; + + entry->kobj = kobject_create_and_add(kobj_name, cbmem_kobj); + if (!entry->kobj) + return -ENOMEM; + + sysfs_bin_attr_init(&entry->mem_file); + entry->mem_file.attr.name = "mem"; + entry->mem_file.attr.mode = 0400; + entry->mem_file.size = entry->dev->cbmem_entry.entry_size; + entry->mem_file.read = cbmem_entry_mem_read; + entry->mem_file.private = entry; + ret = sysfs_create_bin_file(entry->kobj, &entry->mem_file); + if (ret) + goto free_kobj; + + sysfs_attr_init(&entry->address_file.kobj_attr.attr); + entry->address_file.kobj_attr.attr.name = "address"; + entry->address_file.kobj_attr.attr.mode = 0444; + entry->address_file.kobj_attr.show = cbmem_entry_address_show; + entry->address_file.entry = entry; + ret = sysfs_create_file(entry->kobj, + &entry->address_file.kobj_attr.attr); + if (ret) + goto free_mem_file; + + sysfs_attr_init(&entry->size_file.kobj_attr.attr); + entry->size_file.kobj_attr.attr.name = "size"; + entry->size_file.kobj_attr.attr.mode = 0444; + entry->size_file.kobj_attr.show = cbmem_entry_size_show; + entry->size_file.entry = entry; + ret = sysfs_create_file(entry->kobj, &entry->size_file.kobj_attr.attr); + if (ret) + goto free_address_file; + + sysfs_attr_init(&entry->id_file.kobj_attr.attr); + entry->id_file.kobj_attr.attr.name = "id"; + entry->id_file.kobj_attr.attr.mode = 0444; + entry->id_file.kobj_attr.show = cbmem_entry_id_show; + entry->id_file.entry = entry; + ret = sysfs_create_file(entry->kobj, &entry->id_file.kobj_attr.attr); + if (ret) + goto free_size_file; + + return 0; + +free_size_file: + sysfs_remove_file(entry->kobj, &entry->size_file.kobj_attr.attr); +free_address_file: + sysfs_remove_file(entry->kobj, &entry->address_file.kobj_attr.attr); +free_mem_file: + sysfs_remove_bin_file(entry->kobj, &entry->mem_file); +free_kobj: + kobject_put(entry->kobj); + return ret; +} + +static int cbmem_entry_probe(struct coreboot_device *dev) +{ + struct cbmem_entry *entry; + + entry = devm_kzalloc(&dev->dev, sizeof(*entry), GFP_KERNEL); + if (!entry) + return -ENOMEM; + + dev_set_drvdata(&dev->dev, entry); + entry->dev = dev; + return cbmem_entry_setup(entry); +} + +static void cbmem_entry_remove(struct coreboot_device *dev) +{ + struct cbmem_entry *entry = dev_get_drvdata(&dev->dev); + + sysfs_remove_bin_file(entry->kobj, &entry->mem_file); + sysfs_remove_file(entry->kobj, &entry->address_file.kobj_attr.attr); + sysfs_remove_file(entry->kobj, &entry->size_file.kobj_attr.attr); + sysfs_remove_file(entry->kobj, &entry->id_file.kobj_attr.attr); + kobject_put(entry->kobj); +} + +static struct coreboot_driver cbmem_entry_driver = { + .probe = cbmem_entry_probe, + .remove = cbmem_entry_remove, + .drv = { + .name = "cbmem", + .owner = THIS_MODULE, + }, + .tag = LB_TAG_CBMEM_ENTRY, +}; + +static int __init cbmem_init(void) +{ + int ret; + + cbmem_kobj = kobject_create_and_add("cbmem", coreboot_kobj); + if (!cbmem_kobj) + return -ENOMEM; + + ret = coreboot_driver_register(&cbmem_entry_driver); + if (ret) { + kobject_put(cbmem_kobj); + return ret; + } + + return 0; +} +module_init(cbmem_init); + +static void __exit cbmem_exit(void) +{ + kobject_put(cbmem_kobj); + coreboot_driver_unregister(&cbmem_entry_driver); +} +module_exit(cbmem_exit); + +MODULE_AUTHOR("Jack Rosenthal "); +MODULE_LICENSE("GPL"); diff --git a/drivers/firmware/google/coreboot_table.c b/drivers/firmware/google/coreboot_table.c index c52bcaa9def6..a3e2720e4638 100644 --- a/drivers/firmware/google/coreboot_table.c +++ b/drivers/firmware/google/coreboot_table.c @@ -14,16 +14,21 @@ #include #include #include +#include #include #include #include #include +#include #include "coreboot_table.h" #define CB_DEV(d) container_of(d, struct coreboot_device, dev) #define CB_DRV(d) container_of(d, struct coreboot_driver, drv) +struct kobject *coreboot_kobj; +EXPORT_SYMBOL(coreboot_kobj); + static int coreboot_bus_match(struct device *dev, struct device_driver *drv) { struct coreboot_device *device = CB_DEV(dev); @@ -157,6 +162,10 @@ static int coreboot_table_probe(struct platform_device *pdev) } memunmap(ptr); + coreboot_kobj = kobject_create_and_add("coreboot", firmware_kobj); + if (!coreboot_kobj) + return -ENOMEM; + return ret; } @@ -170,6 +179,7 @@ static int coreboot_table_remove(struct platform_device *pdev) { bus_for_each_dev(&coreboot_bus_type, NULL, NULL, __cb_dev_unregister); bus_unregister(&coreboot_bus_type); + kobject_put(coreboot_kobj); return 0; } diff --git a/drivers/firmware/google/coreboot_table.h b/drivers/firmware/google/coreboot_table.h index beb778674acd..76c31e6e5376 100644 --- a/drivers/firmware/google/coreboot_table.h +++ b/drivers/firmware/google/coreboot_table.h @@ -14,6 +14,11 @@ #include +struct kobject; + +/* This is /sys/firmware/coreboot */ +extern struct kobject *coreboot_kobj; + /* Coreboot table header structure */ struct coreboot_table_header { char signature[4]; @@ -39,6 +44,16 @@ struct lb_cbmem_ref { u64 cbmem_addr; }; +/* Corresponds to LB_TAG_CBMEM_ENTRY */ +struct lb_cbmem_entry { + u32 tag; + u32 size; + + u64 address; + u32 entry_size; + u32 id; +}; + /* Describes framebuffer setup by coreboot */ struct lb_framebuffer { u32 tag; @@ -65,6 +80,7 @@ struct coreboot_device { union { struct coreboot_table_entry entry; struct lb_cbmem_ref cbmem_ref; + struct lb_cbmem_entry cbmem_entry; struct lb_framebuffer framebuffer; }; };