1 // SPDX-License-Identifier: GPL-2.0+
3 // Security related flags and so on.
5 // Copyright 2018, Michael Ellerman, IBM Corporation.
7 #include <linux/kernel.h>
8 #include <linux/debugfs.h>
9 #include <linux/device.h>
10 #include <linux/seq_buf.h>
12 #include <asm/debug.h>
13 #include <asm/security_features.h>
14 #include <asm/setup.h>
17 unsigned long powerpc_security_features __read_mostly
= SEC_FTR_DEFAULT
;
19 bool barrier_nospec_enabled
;
21 static void enable_barrier_nospec(bool enable
)
23 barrier_nospec_enabled
= enable
;
24 do_barrier_nospec_fixups(enable
);
27 void setup_barrier_nospec(void)
32 * It would make sense to check SEC_FTR_SPEC_BAR_ORI31 below as well.
33 * But there's a good reason not to. The two flags we check below are
34 * both are enabled by default in the kernel, so if the hcall is not
35 * functional they will be enabled.
36 * On a system where the host firmware has been updated (so the ori
37 * functions as a barrier), but on which the hypervisor (KVM/Qemu) has
38 * not been updated, we would like to enable the barrier. Dropping the
39 * check for SEC_FTR_SPEC_BAR_ORI31 achieves that. The only downside is
40 * we potentially enable the barrier on systems where the host firmware
41 * is not updated, but that's harmless as it's a no-op.
43 enable
= security_ftr_enabled(SEC_FTR_FAVOUR_SECURITY
) &&
44 security_ftr_enabled(SEC_FTR_BNDS_CHK_SPEC_BAR
);
46 enable_barrier_nospec(enable
);
49 #ifdef CONFIG_DEBUG_FS
50 static int barrier_nospec_set(void *data
, u64 val
)
60 if (!!val
== !!barrier_nospec_enabled
)
63 enable_barrier_nospec(!!val
);
68 static int barrier_nospec_get(void *data
, u64
*val
)
70 *val
= barrier_nospec_enabled
? 1 : 0;
74 DEFINE_SIMPLE_ATTRIBUTE(fops_barrier_nospec
,
75 barrier_nospec_get
, barrier_nospec_set
, "%llu\n");
77 static __init
int barrier_nospec_debugfs_init(void)
79 debugfs_create_file("barrier_nospec", 0600, powerpc_debugfs_root
, NULL
,
80 &fops_barrier_nospec
);
83 device_initcall(barrier_nospec_debugfs_init
);
84 #endif /* CONFIG_DEBUG_FS */
86 ssize_t
cpu_show_meltdown(struct device
*dev
, struct device_attribute
*attr
, char *buf
)
90 thread_priv
= security_ftr_enabled(SEC_FTR_L1D_THREAD_PRIV
);
92 if (rfi_flush
|| thread_priv
) {
94 seq_buf_init(&s
, buf
, PAGE_SIZE
- 1);
96 seq_buf_printf(&s
, "Mitigation: ");
99 seq_buf_printf(&s
, "RFI Flush");
101 if (rfi_flush
&& thread_priv
)
102 seq_buf_printf(&s
, ", ");
105 seq_buf_printf(&s
, "L1D private per thread");
107 seq_buf_printf(&s
, "\n");
112 if (!security_ftr_enabled(SEC_FTR_L1D_FLUSH_HV
) &&
113 !security_ftr_enabled(SEC_FTR_L1D_FLUSH_PR
))
114 return sprintf(buf
, "Not affected\n");
116 return sprintf(buf
, "Vulnerable\n");
119 ssize_t
cpu_show_spectre_v1(struct device
*dev
, struct device_attribute
*attr
, char *buf
)
121 if (!security_ftr_enabled(SEC_FTR_BNDS_CHK_SPEC_BAR
))
122 return sprintf(buf
, "Not affected\n");
124 return sprintf(buf
, "Vulnerable\n");
127 ssize_t
cpu_show_spectre_v2(struct device
*dev
, struct device_attribute
*attr
, char *buf
)
132 seq_buf_init(&s
, buf
, PAGE_SIZE
- 1);
134 bcs
= security_ftr_enabled(SEC_FTR_BCCTRL_SERIALISED
);
135 ccd
= security_ftr_enabled(SEC_FTR_COUNT_CACHE_DISABLED
);
136 ori
= security_ftr_enabled(SEC_FTR_SPEC_BAR_ORI31
);
139 seq_buf_printf(&s
, "Mitigation: ");
142 seq_buf_printf(&s
, "Indirect branch serialisation (kernel only)");
145 seq_buf_printf(&s
, ", ");
148 seq_buf_printf(&s
, "Indirect branch cache disabled");
150 seq_buf_printf(&s
, "Vulnerable");
153 seq_buf_printf(&s
, ", ori31 speculation barrier enabled");
155 seq_buf_printf(&s
, "\n");
161 * Store-forwarding barrier support.
164 static enum stf_barrier_type stf_enabled_flush_types
;
165 static bool no_stf_barrier
;
168 static int __init
handle_no_stf_barrier(char *p
)
170 pr_info("stf-barrier: disabled on command line.");
171 no_stf_barrier
= true;
175 early_param("no_stf_barrier", handle_no_stf_barrier
);
177 /* This is the generic flag used by other architectures */
178 static int __init
handle_ssbd(char *p
)
180 if (!p
|| strncmp(p
, "auto", 5) == 0 || strncmp(p
, "on", 2) == 0 ) {
181 /* Until firmware tells us, we have the barrier with auto */
183 } else if (strncmp(p
, "off", 3) == 0) {
184 handle_no_stf_barrier(NULL
);
191 early_param("spec_store_bypass_disable", handle_ssbd
);
193 /* This is the generic flag used by other architectures */
194 static int __init
handle_no_ssbd(char *p
)
196 handle_no_stf_barrier(NULL
);
199 early_param("nospec_store_bypass_disable", handle_no_ssbd
);
201 static void stf_barrier_enable(bool enable
)
204 do_stf_barrier_fixups(stf_enabled_flush_types
);
206 do_stf_barrier_fixups(STF_BARRIER_NONE
);
208 stf_barrier
= enable
;
211 void setup_stf_barrier(void)
213 enum stf_barrier_type type
;
216 hv
= cpu_has_feature(CPU_FTR_HVMODE
);
218 /* Default to fallback in case fw-features are not available */
219 if (cpu_has_feature(CPU_FTR_ARCH_300
))
220 type
= STF_BARRIER_EIEIO
;
221 else if (cpu_has_feature(CPU_FTR_ARCH_207S
))
222 type
= STF_BARRIER_SYNC_ORI
;
223 else if (cpu_has_feature(CPU_FTR_ARCH_206
))
224 type
= STF_BARRIER_FALLBACK
;
226 type
= STF_BARRIER_NONE
;
228 enable
= security_ftr_enabled(SEC_FTR_FAVOUR_SECURITY
) &&
229 (security_ftr_enabled(SEC_FTR_L1D_FLUSH_PR
) ||
230 (security_ftr_enabled(SEC_FTR_L1D_FLUSH_HV
) && hv
));
232 if (type
== STF_BARRIER_FALLBACK
) {
233 pr_info("stf-barrier: fallback barrier available\n");
234 } else if (type
== STF_BARRIER_SYNC_ORI
) {
235 pr_info("stf-barrier: hwsync barrier available\n");
236 } else if (type
== STF_BARRIER_EIEIO
) {
237 pr_info("stf-barrier: eieio barrier available\n");
240 stf_enabled_flush_types
= type
;
243 stf_barrier_enable(enable
);
246 ssize_t
cpu_show_spec_store_bypass(struct device
*dev
, struct device_attribute
*attr
, char *buf
)
248 if (stf_barrier
&& stf_enabled_flush_types
!= STF_BARRIER_NONE
) {
250 switch (stf_enabled_flush_types
) {
251 case STF_BARRIER_EIEIO
:
254 case STF_BARRIER_SYNC_ORI
:
257 case STF_BARRIER_FALLBACK
:
263 return sprintf(buf
, "Mitigation: Kernel entry/exit barrier (%s)\n", type
);
266 if (!security_ftr_enabled(SEC_FTR_L1D_FLUSH_HV
) &&
267 !security_ftr_enabled(SEC_FTR_L1D_FLUSH_PR
))
268 return sprintf(buf
, "Not affected\n");
270 return sprintf(buf
, "Vulnerable\n");
273 #ifdef CONFIG_DEBUG_FS
274 static int stf_barrier_set(void *data
, u64 val
)
285 /* Only do anything if we're changing state */
286 if (enable
!= stf_barrier
)
287 stf_barrier_enable(enable
);
292 static int stf_barrier_get(void *data
, u64
*val
)
294 *val
= stf_barrier
? 1 : 0;
298 DEFINE_SIMPLE_ATTRIBUTE(fops_stf_barrier
, stf_barrier_get
, stf_barrier_set
, "%llu\n");
300 static __init
int stf_barrier_debugfs_init(void)
302 debugfs_create_file("stf_barrier", 0600, powerpc_debugfs_root
, NULL
, &fops_stf_barrier
);
305 device_initcall(stf_barrier_debugfs_init
);
306 #endif /* CONFIG_DEBUG_FS */