smmstore: Add a key/val store facility in flash, mediated through SMM
It exposes an interface that is as generic as possible, so payloads and/or kernels can use it for their data. Change-Id: I9553922f9dfa60b9d4b3576973ad4b84d3fe2fb5 Signed-off-by: Patrick Georgi <pgeorgi@google.com> Reviewed-on: https://review.coreboot.org/25182 Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org> Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
This commit is contained in:
Patrick Georgi
parent
88607a4b10
commit
9360feaf51
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@ -0,0 +1,32 @@
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##
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## This file is part of the coreboot project.
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##
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## Copyright (C) 2018 The Chromium OS Authors. All rights reserved.
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##
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## This program is free software; you can redistribute it and/or modify
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## it under the terms of the GNU General Public License as published by
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## the Free Software Foundation; version 2 of the License.
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##
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## This program is distributed in the hope that it will be useful,
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## but WITHOUT ANY WARRANTY; without even the implied warranty of
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## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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## GNU General Public License for more details.
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##
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config SMMSTORE
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bool "Support for flash based, SMM mediated data store"
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default n
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depends on BOOT_DEVICE_SUPPORTS_WRITES
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select SPI_FLASH_SMM if BOOT_DEVICE_SPI_FLASH_RW_NOMMAP
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if SMMSTORE
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config SMMSTORE_REGION
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string "fmap region in which SMM store file is kept"
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default "RW_LEGACY" if CHROMEOS
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default "COREBOOT"
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config SMMSTORE_FILENAME
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string "SMM store file name"
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default "smm store"
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endif
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@ -0,0 +1,3 @@
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ramstage-$(CONFIG_SMMSTORE) += store.c
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smm-$(CONFIG_SMMSTORE) += store.c smi.c
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@ -0,0 +1,83 @@
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/*
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* This file is part of the coreboot project.
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*
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* Copyright (C) 2018 The Chromium OS Authors. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <console/console.h>
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#include <smmstore.h>
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#include <stddef.h>
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#include <stdint.h>
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/*
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* Check that the given range is legal.
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*
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* Legal means:
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* - not pointing into SMRAM
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* - ...?
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*
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* returns 0 on success, -1 on failure
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*/
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static int range_check(void *start, size_t size)
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{
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// TODO: fill in
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return 0;
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}
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/* Param is usually EBX, ret in EAX */
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uint32_t smmstore_exec(uint8_t command, void *param)
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{
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uint32_t ret = SMMSTORE_RET_FAILURE;
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switch (command) {
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case SMMSTORE_CMD_READ: {
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printk(BIOS_DEBUG, "Reading from SMM store\n");
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struct smmstore_params_read *params = param;
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if (range_check(params->buf, params->bufsize) != 0)
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break;
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if (smmstore_read_region(params->buf, ¶ms->bufsize) == 0)
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ret = SMMSTORE_RET_SUCCESS;
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break;
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}
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case SMMSTORE_CMD_APPEND: {
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printk(BIOS_DEBUG, "Appending into SMM store\n");
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struct smmstore_params_append *params = param;
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if (range_check(params->key, params->keysize) != 0)
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break;
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if (range_check(params->val, params->valsize) != 0)
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break;
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if (smmstore_append_data(params->key, params->keysize,
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params->val, params->valsize) == 0)
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ret = SMMSTORE_RET_SUCCESS;
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break;
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}
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case SMMSTORE_CMD_CLEAR: {
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if (smmstore_clear_region() == 0)
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ret = SMMSTORE_RET_SUCCESS;
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break;
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}
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default:
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printk(BIOS_DEBUG,
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"Unknown SMM store command: 0x%02x\n", command);
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ret = SMMSTORE_RET_UNSUPPORTED;
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break;
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}
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return ret;
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}
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@ -0,0 +1,225 @@
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/*
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* This file is part of the coreboot project.
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*
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* Copyright (C) 2018 The Chromium OS Authors. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <boot_device.h>
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#include <cbfs.h>
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#include <commonlib/region.h>
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#include <console/console.h>
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#include <smmstore.h>
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#include <string.h>
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/*
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* The region format is still not finalized, but so far it looks like this:
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* (
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* uint32le_t key_sz
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* uint32le_t value_sz
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* uint8_t key[key_sz]
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* uint8_t value[value_sz]
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* uint8_t active
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* align to 4 bytes
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* )*
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* uint32le_t endmarker = 0xffffffff
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*
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* active needs to be set to 0x00 for the entry to be valid. This satisfies
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* the constraint that entries are either complete or will be ignored, as long
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* as flash is written sequentially and into a fully erased block.
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*
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* Future additions to the format will split the region in half with an active
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* block marker to allow safe compaction (ie. write the new data in the unused
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* region, mark it active after the write completed). Otherwise a well-timed
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* crash/reboot could clear out all variables.
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*/
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/*
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* Return a region device that points into the store file.
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*
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* It's the image builder's responsibility to make it block aligned so that
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* erase works without destroying other data.
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*
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* It doesn't cache the location to cope with flash changing underneath (eg
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* due to an update)
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*
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* returns 0 on success, -1 on failure
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* outputs the valid store rdev in rstore
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*/
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static int lookup_store(struct region_device *rstore)
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{
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struct cbfsf file;
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if (cbfs_locate_file_in_region(&file,
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CONFIG_SMMSTORE_REGION, CONFIG_SMMSTORE_FILENAME, NULL) < 0) {
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printk(BIOS_WARNING, "smm store: "
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"Unable to find SMM store file in region '%s'\n",
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CONFIG_SMMSTORE_REGION);
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return -1;
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}
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cbfs_file_data(rstore, &file);
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return 0;
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}
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/*
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* Read entire store into user provided buffer
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*
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* returns 0 on success, -1 on failure
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* writes up to `*bufsize` bytes into `buf` and updates `*bufsize`
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*/
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int smmstore_read_region(void *buf, ssize_t *bufsize)
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{
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struct region_device store;
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if (bufsize == NULL)
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return -1;
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*bufsize = 0;
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if (lookup_store(&store) < 0) {
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printk(BIOS_WARNING, "reading region failed\n");
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return -1;
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}
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ssize_t tx = min(*bufsize, region_device_sz(&store));
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*bufsize = rdev_readat(&store, buf, 0, tx);
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if (*bufsize < 0)
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return -1;
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return 0;
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}
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/*
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* Append data to region
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*
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* Returns 0 on success, -1 on failure
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*/
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int smmstore_append_data(void *key, uint32_t key_sz,
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void *value, uint32_t value_sz)
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{
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struct region_device store;
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if (lookup_store(&store) < 0) {
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printk(BIOS_WARNING, "reading region failed\n");
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return -1;
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}
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ssize_t data_sz = region_device_sz(&store);
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/* scan for end */
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ssize_t end = 0;
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uint32_t k_sz, v_sz;
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while (end < data_sz) {
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/* make odd corner cases identifiable, eg. invalid v_sz */
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k_sz = 0;
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if (rdev_readat(&store, &k_sz, end, sizeof(k_sz)) < 0) {
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printk(BIOS_WARNING, "failed reading key size\n");
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return -1;
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}
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/* found the end */
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if (k_sz == 0xffffffff)
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break;
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/* something is fishy here:
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* Avoid wrapping (since data_size < MAX_UINT32_T / 2) while
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* other problems are covered by the loop condition
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*/
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if (k_sz > data_sz) {
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printk(BIOS_WARNING, "key size out of bounds\n");
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return -1;
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}
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if (rdev_readat(&store, &v_sz, end + 4, sizeof(v_sz)) < 0) {
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printk(BIOS_WARNING, "failed reading value size\n");
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return -1;
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}
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if (v_sz > data_sz) {
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printk(BIOS_WARNING, "value size out of bounds\n");
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return -1;
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}
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end += 8 + k_sz + v_sz + 1;
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end = ALIGN_UP(end, sizeof(uint32_t));
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}
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printk(BIOS_WARNING, "used smm store size might be 0x%zx bytes\n", end);
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if (k_sz != 0xffffffff) {
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printk(BIOS_WARNING,
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"eof of data marker looks invalid: 0x%x\n", k_sz);
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return -1;
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}
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printk(BIOS_WARNING, "used size looks legit\n");
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printk(BIOS_WARNING, "open (%zx, %zx) for writing\n",
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region_device_offset(&store), region_device_sz(&store));
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if (boot_device_rw_subregion(&store.region, &store) < 0) {
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printk(BIOS_WARNING, "couldn't open store for writing\n");
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return -1;
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}
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uint32_t record_sz = 8 + key_sz + value_sz + 1;
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if (end + record_sz >= data_sz) {
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printk(BIOS_WARNING, "not enough space for new data\n");
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return -1;
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}
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if (rdev_writeat(&store, &key_sz, end, 4) != 4) {
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printk(BIOS_WARNING, "failed writing key size\n");
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}
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end += 4;
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if (rdev_writeat(&store, &value_sz, end, 4) != 4) {
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printk(BIOS_WARNING, "failed writing value size\n");
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}
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end += 4;
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if (rdev_writeat(&store, key, end, key_sz) != key_sz) {
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printk(BIOS_WARNING, "failed writing key data\n");
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}
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end += key_sz;
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if (rdev_writeat(&store, value, end, value_sz) != value_sz) {
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printk(BIOS_WARNING, "failed writing value data\n");
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}
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end += value_sz;
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uint8_t nul = 0;
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if (rdev_writeat(&store, &nul, end, 1) != 1) {
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printk(BIOS_WARNING, "failed writing termination\n");
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}
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return 0;
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}
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/*
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* Clear region
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*
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* Returns 0 on success, -1 on failure, including partial erase
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*/
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int smmstore_clear_region(void)
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{
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struct region_device store;
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if (lookup_store(&store) < 0) {
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printk(BIOS_WARNING, "smm store: reading region failed\n");
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return -1;
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}
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ssize_t res = rdev_eraseat(&store, 0, region_device_sz(&store));
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if (res != region_device_sz(&store)) {
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printk(BIOS_WARNING, "smm store: erasing region failed\n");
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return -1;
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}
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return 0;
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}
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/*
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* This file is part of the coreboot project.
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*
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* Copyright (C) 2018 The Chromium OS Authors. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#ifndef _SMMSTORE_H_
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#define _SMMSTORE_H_
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#include <stddef.h>
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#include <stdint.h>
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#define SMMSTORE_APM_CNT 0xed
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#define SMMSTORE_RET_SUCCESS 0
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#define SMMSTORE_RET_FAILURE 1
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#define SMMSTORE_RET_UNSUPPORTED 2
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#define SMMSTORE_CMD_CLEAR 1
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#define SMMSTORE_CMD_READ 2
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#define SMMSTORE_CMD_APPEND 3
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struct smmstore_params_read {
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void *buf;
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ssize_t bufsize;
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};
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struct smmstore_params_append {
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void *key;
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size_t keysize;
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void *val;
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size_t valsize;
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};
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/* SMM responder */
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uint32_t smmstore_exec(uint8_t command, void *param);
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/* implementation */
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int smmstore_read_region(void *buf, ssize_t *bufsize);
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int smmstore_append_data(void *key, uint32_t key_sz,
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void *value, uint32_t value_sz);
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int smmstore_clear_region(void);
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#endif
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@ -27,6 +27,7 @@
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#include <intelblocks/pmclib.h>
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#include <intelblocks/smihandler.h>
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#include <intelblocks/uart.h>
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#include <smmstore.h>
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#include <soc/nvs.h>
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#include <soc/pm.h>
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#include <soc/gpio.h>
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@ -294,6 +295,27 @@ static void southbridge_smi_gsmi(
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save_state_ops->set_reg(io_smi, RAX, ret);
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}
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static void southbridge_smi_store(
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const struct smm_save_state_ops *save_state_ops)
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{
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u8 sub_command, ret;
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void *io_smi;
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uint32_t reg_ebx;
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io_smi = find_save_state(save_state_ops, SMMSTORE_APM_CNT);
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if (!io_smi)
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return;
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/* Command and return value in EAX */
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sub_command = (save_state_ops->get_reg(io_smi, RAX) >> 8) & 0xff;
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/* Parameter buffer in EBX */
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reg_ebx = save_state_ops->get_reg(io_smi, RBX);
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/* drivers/smmstore/smi.c */
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ret = smmstore_exec(sub_command, (void *)reg_ebx);
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save_state_ops->set_reg(io_smi, RAX, ret);
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}
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static void finalize(void)
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{
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static int finalize_done;
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@ -366,6 +388,10 @@ void smihandler_southbridge_apmc(
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if (IS_ENABLED(CONFIG_ELOG_GSMI))
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southbridge_smi_gsmi(save_state_ops);
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break;
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case SMMSTORE_APM_CNT:
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if (IS_ENABLED(CONFIG_SMMSTORE))
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southbridge_smi_store(save_state_ops);
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break;
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case APM_CNT_FINALIZE:
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finalize();
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break;
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