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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2024 Rivos Inc.
*/
#include <linux/cpu.h>
#include <linux/device.h>
#include <linux/sprintf.h>
#include <asm/bugs.h>
#include <asm/vendor_extensions/thead.h>
static enum mitigation_state ghostwrite_state;
void ghostwrite_set_vulnerable(void)
{
ghostwrite_state = VULNERABLE;
}
/*
* Vendor extension alternatives will use the value set at the time of boot
* alternative patching, thus this must be called before boot alternatives are
* patched (and after extension probing) to be effective.
*
* Returns true if mitgated, false otherwise.
*/
bool ghostwrite_enable_mitigation(void)
{
if (IS_ENABLED(CONFIG_RISCV_ISA_XTHEADVECTOR) &&
ghostwrite_state == VULNERABLE && !cpu_mitigations_off()) {
disable_xtheadvector();
ghostwrite_state = MITIGATED;
return true;
}
return false;
}
enum mitigation_state ghostwrite_get_state(void)
{
return ghostwrite_state;
}
ssize_t cpu_show_ghostwrite(struct device *dev, struct device_attribute *attr, char *buf)
{
if (IS_ENABLED(CONFIG_RISCV_ISA_XTHEADVECTOR)) {
switch (ghostwrite_state) {
case UNAFFECTED:
return sprintf(buf, "Not affected\n");
case MITIGATED:
return sprintf(buf, "Mitigation: xtheadvector disabled\n");
case VULNERABLE:
fallthrough;
default:
return sprintf(buf, "Vulnerable\n");
}
} else {
return sprintf(buf, "Not affected\n");
}
}
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