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f16d6e43d3
The jittery clock and trng security features require high permissions to be initialized. In the future these initializations and the permission level drop may be moved to RO. This change adds permission level checks before trying to access any registers that require high permission, so when we update RO to change the permission RW can still function fine. BUG=chrome-os-partner:59107 BRANCH=none TEST=Move the permission drop to the beginning of main and verify the system still boots. Change-Id: I5b7cb856decd0640288ad3476f875ec9edc42635 Signed-off-by: Mary Ruthven <mruthven@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/405840
50 lines
1.4 KiB
C
50 lines
1.4 KiB
C
/* Copyright 2016 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#include "init_chip.h"
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#include "registers.h"
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/* Drop run level to at least medium. */
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void init_runlevel(const enum permission_level desired_level)
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{
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volatile uint32_t *const reg_addrs[] = {
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/* CPU's use of the system peripheral bus */
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GREG32_ADDR(GLOBALSEC, CPU0_S_PERMISSION),
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/* CPU's use of the system bus via the debug access port */
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GREG32_ADDR(GLOBALSEC, CPU0_S_DAP_PERMISSION),
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/* DMA's use of the system peripheral bus */
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GREG32_ADDR(GLOBALSEC, DDMA0_PERMISSION),
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/*
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* Current software level affects which (if any) scratch
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* registers can be used for a warm boot hardware-verified
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* jump.
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*/
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GREG32_ADDR(GLOBALSEC, SOFTWARE_LVL),
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};
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int i;
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/* Permission registers drop by 1 level (e.g. HIGHEST -> HIGH)
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* each time a write is encountered (the value written does
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* not matter). So we repeat writes and reads, until the
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* desired level is reached.
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*/
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for (i = 0; i < ARRAY_SIZE(reg_addrs); i++) {
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uint32_t current_level;
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while (1) {
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current_level = *reg_addrs[i];
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if (current_level <= desired_level)
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break;
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*reg_addrs[i] = desired_level;
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}
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}
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}
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int runlevel_is_high(void)
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{
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return ((GREAD(GLOBALSEC, CPU0_S_PERMISSION) == PERMISSION_HIGH) ||
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(GREAD(GLOBALSEC, CPU0_S_PERMISSION) == PERMISSION_HIGHEST));
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}
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