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// SPDX-License-Identifier: GPL-2.0
/*
* shstk.c - Intel shadow stack support
*
* Copyright (c) 2021, Intel Corporation.
* Yu-cheng Yu <yu-cheng.yu@intel.com>
*/
#include <linux/sched.h>
#include <linux/bitops.h>
#include <asm/prctl.h>
void reset_thread_features(void)
{
current->thread.features = 0;
current->thread.features_locked = 0;
}
long shstk_prctl(struct task_struct *task, int option, unsigned long features)
{
if (option == ARCH_SHSTK_LOCK) {
task->thread.features_locked |= features;
return 0;
}
/* Don't allow via ptrace */
if (task != current)
return -EINVAL;
/* Do not allow to change locked features */
if (features & task->thread.features_locked)
return -EPERM;
/* Only support enabling/disabling one feature at a time. */
if (hweight_long(features) > 1)
return -EINVAL;
if (option == ARCH_SHSTK_DISABLE) {
return -EINVAL;
}
/* Handle ARCH_SHSTK_ENABLE */
return -EINVAL;
}
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