d777d86ab2
There are some fun rules C compilers can use to optimize their code. One of them is the assumption that two symbols point to two different addresses. In this case this wasn't true, resulting in unintended code execution (and later, a crash) with a clang build. Change-Id: I1496b22e1d1869ed0610e321b6ec6a83252e9d8b Signed-off-by: Patrick Georgi <patrick@georgi-clan.de> Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com> Reviewed-on: http://review.coreboot.org/4719 Tested-by: build bot (Jenkins)
105 lines
2.8 KiB
C
105 lines
2.8 KiB
C
/*
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* This file is part of the coreboot project.
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*
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* Copyright (C) 2013 Google, Inc.
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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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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <string.h>
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#include <stddef.h>
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#include <console/console.h>
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#include <cbmem.h>
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#include <arch/early_variables.h>
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typedef void (* const car_migration_func_t)(void);
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extern car_migration_func_t _car_migrate_start;
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extern char _car_data_start[];
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extern char _car_data_end[];
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/*
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* The car_migrated global variable determines if the cache-as-ram space has
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* been migrated to real RAM. It does this by assuming the following things:
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* 1. cache-as-ram space is zero'd out once it is set up.
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* 2. Either the cache-as-ram space is memory-backed after getting torn down
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* or the space returns 0xff's for each byte read.
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* Based on these 2 attributes there is the ability to tell when the
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* cache-as-ram region has been migrated.
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*/
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static int car_migrated CAR_GLOBAL;
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void *car_get_var_ptr(void *var)
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{
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char *migrated_base;
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int offset;
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void * _car_start = &_car_data_start;
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void * _car_end = &_car_data_end;
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/* If the cache-as-ram has not been migrated return the pointer
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* passed in. */
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if (!car_migrated)
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return var;
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if (var < _car_start || var >= _car_end) {
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printk(BIOS_ERR,
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"Requesting CAR variable outside of CAR region: %p\n",
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var);
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return var;
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}
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migrated_base = cbmem_find(CBMEM_ID_CAR_GLOBALS);
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if (migrated_base == NULL) {
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printk(BIOS_ERR, "CAR: Could not find migration base!\n");
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return var;
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}
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offset = (char *)var - (char *)_car_start;
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return &migrated_base[offset];
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}
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void car_migrate_variables(void)
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{
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void *migrated_base;
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car_migration_func_t *migrate_func;
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size_t car_data_size = &_car_data_end[0] - &_car_data_start[0];
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/* Check if already migrated. */
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if (car_migrated)
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return;
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migrated_base = cbmem_add(CBMEM_ID_CAR_GLOBALS, car_data_size);
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if (migrated_base == NULL) {
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printk(BIOS_ERR, "Could not migrate CAR data!\n");
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return;
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}
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memcpy(migrated_base, &_car_data_start[0], car_data_size);
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/* Mark that the data has been moved. */
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car_migrated = ~0;
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/* Call all the migration functions. */
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migrate_func = &_car_migrate_start;
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while (*migrate_func != NULL) {
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(*migrate_func)();
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migrate_func++;
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}
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}
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