Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2024 Rivos Inc.
4 */
5
6#include <linux/cpu.h>
7#include <linux/device.h>
8#include <linux/sprintf.h>
9
10#include <asm/bugs.h>
11#include <asm/vendor_extensions/thead.h>
12
13static enum mitigation_state ghostwrite_state;
14
15void ghostwrite_set_vulnerable(void)
16{
17 ghostwrite_state = VULNERABLE;
18}
19
20/*
21 * Vendor extension alternatives will use the value set at the time of boot
22 * alternative patching, thus this must be called before boot alternatives are
23 * patched (and after extension probing) to be effective.
24 *
25 * Returns true if mitgated, false otherwise.
26 */
27bool ghostwrite_enable_mitigation(void)
28{
29 if (IS_ENABLED(CONFIG_RISCV_ISA_XTHEADVECTOR) &&
30 ghostwrite_state == VULNERABLE && !cpu_mitigations_off()) {
31 disable_xtheadvector();
32 ghostwrite_state = MITIGATED;
33 return true;
34 }
35
36 return false;
37}
38
39enum mitigation_state ghostwrite_get_state(void)
40{
41 return ghostwrite_state;
42}
43
44ssize_t cpu_show_ghostwrite(struct device *dev, struct device_attribute *attr, char *buf)
45{
46 if (IS_ENABLED(CONFIG_RISCV_ISA_XTHEADVECTOR)) {
47 switch (ghostwrite_state) {
48 case UNAFFECTED:
49 return sprintf(buf, "Not affected\n");
50 case MITIGATED:
51 return sprintf(buf, "Mitigation: xtheadvector disabled\n");
52 case VULNERABLE:
53 fallthrough;
54 default:
55 return sprintf(buf, "Vulnerable\n");
56 }
57 } else {
58 return sprintf(buf, "Not affected\n");
59 }
60}