coreboot-kgpe-d16/src/security/vboot/vboot_loader.c

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/*
* This file is part of the coreboot project.
*
* Copyright 2015 Google, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <cbfs.h>
#include <console/console.h>
#include <ec/google/chromeec/ec.h>
#include <rmodule.h>
#include <security/vboot/misc.h>
#include <security/vboot/symbols.h>
#include <security/vboot/vboot_common.h>
vboot: Disallow separate verstage after romstage, try to clarify logic No board has ever tried to combine CONFIG_SEPARATE_VERSTAGE with CONFIG_VBOOT_STARTS_IN_ROMSTAGE. There are probably many reasons why this wouldn't work (e.g. x86 CAR migration logic currently always assumes verstage code to run pre-migration). It would also not really make sense: the reason we use separate verstages is to decrease bootblock size (mitigating the boot speed cost of slow boot ROM SPI drivers) and to allow the SRAM-saving RETURN_FROM_VERSTAGE trick, neither of which would apply to the after-romstage case. It is better to just forbid that case explicitly and give programmers more guarantees about what the verstage is (e.g. now the assumption that it runs pre-RAM is always valid). Since Kconfig dependencies aren't always guaranteed in the face of 'select' statements, also add some explicit compile-time assertions to the vboot code. We can simplify some of the loader logic which now no longer needs to provide for the forbidden case. In addition, also try to make some of the loader logic more readable by writing it in a more functional style that allows us to put more assertions about which cases should be unreachable in there, which will hopefully make it more robust and fail-fast with future changes (e.g. addition of new stages). Change-Id: Iaf60040af4eff711d9b80ee0e5950ce05958b3aa Signed-off-by: Julius Werner <jwerner@chromium.org> Reviewed-on: https://review.coreboot.org/18983 Reviewed-by: Aaron Durbin <adurbin@chromium.org> Tested-by: build bot (Jenkins)
2017-03-18 00:54:48 +01:00
/* Ensure vboot configuration is valid: */
_Static_assert(CONFIG(VBOOT_STARTS_IN_BOOTBLOCK) +
CONFIG(VBOOT_STARTS_IN_ROMSTAGE) == 1,
vboot: Disallow separate verstage after romstage, try to clarify logic No board has ever tried to combine CONFIG_SEPARATE_VERSTAGE with CONFIG_VBOOT_STARTS_IN_ROMSTAGE. There are probably many reasons why this wouldn't work (e.g. x86 CAR migration logic currently always assumes verstage code to run pre-migration). It would also not really make sense: the reason we use separate verstages is to decrease bootblock size (mitigating the boot speed cost of slow boot ROM SPI drivers) and to allow the SRAM-saving RETURN_FROM_VERSTAGE trick, neither of which would apply to the after-romstage case. It is better to just forbid that case explicitly and give programmers more guarantees about what the verstage is (e.g. now the assumption that it runs pre-RAM is always valid). Since Kconfig dependencies aren't always guaranteed in the face of 'select' statements, also add some explicit compile-time assertions to the vboot code. We can simplify some of the loader logic which now no longer needs to provide for the forbidden case. In addition, also try to make some of the loader logic more readable by writing it in a more functional style that allows us to put more assertions about which cases should be unreachable in there, which will hopefully make it more robust and fail-fast with future changes (e.g. addition of new stages). Change-Id: Iaf60040af4eff711d9b80ee0e5950ce05958b3aa Signed-off-by: Julius Werner <jwerner@chromium.org> Reviewed-on: https://review.coreboot.org/18983 Reviewed-by: Aaron Durbin <adurbin@chromium.org> Tested-by: build bot (Jenkins)
2017-03-18 00:54:48 +01:00
"vboot must either start in bootblock or romstage (not both!)");
_Static_assert(!CONFIG(VBOOT_SEPARATE_VERSTAGE) ||
CONFIG(VBOOT_STARTS_IN_BOOTBLOCK),
vboot: Disallow separate verstage after romstage, try to clarify logic No board has ever tried to combine CONFIG_SEPARATE_VERSTAGE with CONFIG_VBOOT_STARTS_IN_ROMSTAGE. There are probably many reasons why this wouldn't work (e.g. x86 CAR migration logic currently always assumes verstage code to run pre-migration). It would also not really make sense: the reason we use separate verstages is to decrease bootblock size (mitigating the boot speed cost of slow boot ROM SPI drivers) and to allow the SRAM-saving RETURN_FROM_VERSTAGE trick, neither of which would apply to the after-romstage case. It is better to just forbid that case explicitly and give programmers more guarantees about what the verstage is (e.g. now the assumption that it runs pre-RAM is always valid). Since Kconfig dependencies aren't always guaranteed in the face of 'select' statements, also add some explicit compile-time assertions to the vboot code. We can simplify some of the loader logic which now no longer needs to provide for the forbidden case. In addition, also try to make some of the loader logic more readable by writing it in a more functional style that allows us to put more assertions about which cases should be unreachable in there, which will hopefully make it more robust and fail-fast with future changes (e.g. addition of new stages). Change-Id: Iaf60040af4eff711d9b80ee0e5950ce05958b3aa Signed-off-by: Julius Werner <jwerner@chromium.org> Reviewed-on: https://review.coreboot.org/18983 Reviewed-by: Aaron Durbin <adurbin@chromium.org> Tested-by: build bot (Jenkins)
2017-03-18 00:54:48 +01:00
"stand-alone verstage must start in (i.e. after) bootblock");
_Static_assert(!CONFIG(VBOOT_RETURN_FROM_VERSTAGE) ||
CONFIG(VBOOT_SEPARATE_VERSTAGE),
vboot: Disallow separate verstage after romstage, try to clarify logic No board has ever tried to combine CONFIG_SEPARATE_VERSTAGE with CONFIG_VBOOT_STARTS_IN_ROMSTAGE. There are probably many reasons why this wouldn't work (e.g. x86 CAR migration logic currently always assumes verstage code to run pre-migration). It would also not really make sense: the reason we use separate verstages is to decrease bootblock size (mitigating the boot speed cost of slow boot ROM SPI drivers) and to allow the SRAM-saving RETURN_FROM_VERSTAGE trick, neither of which would apply to the after-romstage case. It is better to just forbid that case explicitly and give programmers more guarantees about what the verstage is (e.g. now the assumption that it runs pre-RAM is always valid). Since Kconfig dependencies aren't always guaranteed in the face of 'select' statements, also add some explicit compile-time assertions to the vboot code. We can simplify some of the loader logic which now no longer needs to provide for the forbidden case. In addition, also try to make some of the loader logic more readable by writing it in a more functional style that allows us to put more assertions about which cases should be unreachable in there, which will hopefully make it more robust and fail-fast with future changes (e.g. addition of new stages). Change-Id: Iaf60040af4eff711d9b80ee0e5950ce05958b3aa Signed-off-by: Julius Werner <jwerner@chromium.org> Reviewed-on: https://review.coreboot.org/18983 Reviewed-by: Aaron Durbin <adurbin@chromium.org> Tested-by: build bot (Jenkins)
2017-03-18 00:54:48 +01:00
"return from verstage only makes sense for separate verstages");
int vboot_executed;
void vboot_run_logic(void)
{
if (verification_should_run()) {
/* Note: this path is not used for VBOOT_RETURN_FROM_VERSTAGE */
verstage_main();
vboot_executed = 1;
} else if (verstage_should_load()) {
struct cbfsf file;
struct prog verstage =
PROG_INIT(PROG_VERSTAGE,
CONFIG_CBFS_PREFIX "/verstage");
printk(BIOS_DEBUG, "VBOOT: Loading verstage.\n");
/* load verstage from RO */
if (cbfs_boot_locate(&file, prog_name(&verstage), NULL))
die("failed to load verstage");
cbfs_file_data(prog_rdev(&verstage), &file);
if (cbfs_prog_stage_load(&verstage))
die("failed to load verstage");
/* verify and select a slot */
prog_run(&verstage);
/* This is not actually possible to hit this condition at
* runtime, but this provides a hint to the compiler for dead
* code elimination below. */
if (!CONFIG(VBOOT_RETURN_FROM_VERSTAGE))
return;
vboot_executed = 1;
}
}
static int vboot_locate(struct region_device *rdev)
{
struct vb2_context *ctx;
/* Don't honor vboot results until the vboot logic has run. */
if (!vboot_logic_executed())
return -1;
ctx = vboot_get_context();
if (ctx->flags & VB2_CONTEXT_RECOVERY_MODE)
return -1;
return vboot_locate_firmware(ctx, rdev);
}
const struct cbfs_locator vboot_locator = {
.name = "VBOOT",
.locate = vboot_locate,
};