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1// SPDX-License-Identifier: GPL-2.0+
2//
3// Security related flags and so on.
4//
5// Copyright 2018, Michael Ellerman, IBM Corporation.
6
7#include <linux/cpu.h>
8#include <linux/kernel.h>
9#include <linux/device.h>
10#include <linux/memblock.h>
11#include <linux/nospec.h>
12#include <linux/prctl.h>
13#include <linux/seq_buf.h>
14
15#include <asm/asm-prototypes.h>
16#include <asm/code-patching.h>
17#include <asm/debugfs.h>
18#include <asm/security_features.h>
19#include <asm/setup.h>
20#include <asm/inst.h>
21
22#include "setup.h"
23
24u64 powerpc_security_features __read_mostly = SEC_FTR_DEFAULT;
25
26enum branch_cache_flush_type {
27 BRANCH_CACHE_FLUSH_NONE = 0x1,
28 BRANCH_CACHE_FLUSH_SW = 0x2,
29 BRANCH_CACHE_FLUSH_HW = 0x4,
30};
31static enum branch_cache_flush_type count_cache_flush_type = BRANCH_CACHE_FLUSH_NONE;
32static enum branch_cache_flush_type link_stack_flush_type = BRANCH_CACHE_FLUSH_NONE;
33
34bool barrier_nospec_enabled;
35static bool no_nospec;
36static bool btb_flush_enabled;
37#if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_BOOK3S_64)
38static bool no_spectrev2;
39#endif
40
41static void enable_barrier_nospec(bool enable)
42{
43 barrier_nospec_enabled = enable;
44 do_barrier_nospec_fixups(enable);
45}
46
47void setup_barrier_nospec(void)
48{
49 bool enable;
50
51 /*
52 * It would make sense to check SEC_FTR_SPEC_BAR_ORI31 below as well.
53 * But there's a good reason not to. The two flags we check below are
54 * both are enabled by default in the kernel, so if the hcall is not
55 * functional they will be enabled.
56 * On a system where the host firmware has been updated (so the ori
57 * functions as a barrier), but on which the hypervisor (KVM/Qemu) has
58 * not been updated, we would like to enable the barrier. Dropping the
59 * check for SEC_FTR_SPEC_BAR_ORI31 achieves that. The only downside is
60 * we potentially enable the barrier on systems where the host firmware
61 * is not updated, but that's harmless as it's a no-op.
62 */
63 enable = security_ftr_enabled(SEC_FTR_FAVOUR_SECURITY) &&
64 security_ftr_enabled(SEC_FTR_BNDS_CHK_SPEC_BAR);
65
66 if (!no_nospec && !cpu_mitigations_off())
67 enable_barrier_nospec(enable);
68}
69
70static int __init handle_nospectre_v1(char *p)
71{
72 no_nospec = true;
73
74 return 0;
75}
76early_param("nospectre_v1", handle_nospectre_v1);
77
78#ifdef CONFIG_DEBUG_FS
79static int barrier_nospec_set(void *data, u64 val)
80{
81 switch (val) {
82 case 0:
83 case 1:
84 break;
85 default:
86 return -EINVAL;
87 }
88
89 if (!!val == !!barrier_nospec_enabled)
90 return 0;
91
92 enable_barrier_nospec(!!val);
93
94 return 0;
95}
96
97static int barrier_nospec_get(void *data, u64 *val)
98{
99 *val = barrier_nospec_enabled ? 1 : 0;
100 return 0;
101}
102
103DEFINE_DEBUGFS_ATTRIBUTE(fops_barrier_nospec, barrier_nospec_get,
104 barrier_nospec_set, "%llu\n");
105
106static __init int barrier_nospec_debugfs_init(void)
107{
108 debugfs_create_file_unsafe("barrier_nospec", 0600,
109 powerpc_debugfs_root, NULL,
110 &fops_barrier_nospec);
111 return 0;
112}
113device_initcall(barrier_nospec_debugfs_init);
114
115static __init int security_feature_debugfs_init(void)
116{
117 debugfs_create_x64("security_features", 0400, powerpc_debugfs_root,
118 &powerpc_security_features);
119 return 0;
120}
121device_initcall(security_feature_debugfs_init);
122#endif /* CONFIG_DEBUG_FS */
123
124#if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_BOOK3S_64)
125static int __init handle_nospectre_v2(char *p)
126{
127 no_spectrev2 = true;
128
129 return 0;
130}
131early_param("nospectre_v2", handle_nospectre_v2);
132#endif /* CONFIG_PPC_FSL_BOOK3E || CONFIG_PPC_BOOK3S_64 */
133
134#ifdef CONFIG_PPC_FSL_BOOK3E
135void setup_spectre_v2(void)
136{
137 if (no_spectrev2 || cpu_mitigations_off())
138 do_btb_flush_fixups();
139 else
140 btb_flush_enabled = true;
141}
142#endif /* CONFIG_PPC_FSL_BOOK3E */
143
144#ifdef CONFIG_PPC_BOOK3S_64
145ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf)
146{
147 bool thread_priv;
148
149 thread_priv = security_ftr_enabled(SEC_FTR_L1D_THREAD_PRIV);
150
151 if (rfi_flush) {
152 struct seq_buf s;
153 seq_buf_init(&s, buf, PAGE_SIZE - 1);
154
155 seq_buf_printf(&s, "Mitigation: RFI Flush");
156 if (thread_priv)
157 seq_buf_printf(&s, ", L1D private per thread");
158
159 seq_buf_printf(&s, "\n");
160
161 return s.len;
162 }
163
164 if (thread_priv)
165 return sprintf(buf, "Vulnerable: L1D private per thread\n");
166
167 if (!security_ftr_enabled(SEC_FTR_L1D_FLUSH_HV) &&
168 !security_ftr_enabled(SEC_FTR_L1D_FLUSH_PR))
169 return sprintf(buf, "Not affected\n");
170
171 return sprintf(buf, "Vulnerable\n");
172}
173
174ssize_t cpu_show_l1tf(struct device *dev, struct device_attribute *attr, char *buf)
175{
176 return cpu_show_meltdown(dev, attr, buf);
177}
178#endif
179
180ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr, char *buf)
181{
182 struct seq_buf s;
183
184 seq_buf_init(&s, buf, PAGE_SIZE - 1);
185
186 if (security_ftr_enabled(SEC_FTR_BNDS_CHK_SPEC_BAR)) {
187 if (barrier_nospec_enabled)
188 seq_buf_printf(&s, "Mitigation: __user pointer sanitization");
189 else
190 seq_buf_printf(&s, "Vulnerable");
191
192 if (security_ftr_enabled(SEC_FTR_SPEC_BAR_ORI31))
193 seq_buf_printf(&s, ", ori31 speculation barrier enabled");
194
195 seq_buf_printf(&s, "\n");
196 } else
197 seq_buf_printf(&s, "Not affected\n");
198
199 return s.len;
200}
201
202ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, char *buf)
203{
204 struct seq_buf s;
205 bool bcs, ccd;
206
207 seq_buf_init(&s, buf, PAGE_SIZE - 1);
208
209 bcs = security_ftr_enabled(SEC_FTR_BCCTRL_SERIALISED);
210 ccd = security_ftr_enabled(SEC_FTR_COUNT_CACHE_DISABLED);
211
212 if (bcs || ccd) {
213 seq_buf_printf(&s, "Mitigation: ");
214
215 if (bcs)
216 seq_buf_printf(&s, "Indirect branch serialisation (kernel only)");
217
218 if (bcs && ccd)
219 seq_buf_printf(&s, ", ");
220
221 if (ccd)
222 seq_buf_printf(&s, "Indirect branch cache disabled");
223
224 } else if (count_cache_flush_type != BRANCH_CACHE_FLUSH_NONE) {
225 seq_buf_printf(&s, "Mitigation: Software count cache flush");
226
227 if (count_cache_flush_type == BRANCH_CACHE_FLUSH_HW)
228 seq_buf_printf(&s, " (hardware accelerated)");
229
230 } else if (btb_flush_enabled) {
231 seq_buf_printf(&s, "Mitigation: Branch predictor state flush");
232 } else {
233 seq_buf_printf(&s, "Vulnerable");
234 }
235
236 if (bcs || ccd || count_cache_flush_type != BRANCH_CACHE_FLUSH_NONE) {
237 if (link_stack_flush_type != BRANCH_CACHE_FLUSH_NONE)
238 seq_buf_printf(&s, ", Software link stack flush");
239 if (link_stack_flush_type == BRANCH_CACHE_FLUSH_HW)
240 seq_buf_printf(&s, " (hardware accelerated)");
241 }
242
243 seq_buf_printf(&s, "\n");
244
245 return s.len;
246}
247
248#ifdef CONFIG_PPC_BOOK3S_64
249/*
250 * Store-forwarding barrier support.
251 */
252
253static enum stf_barrier_type stf_enabled_flush_types;
254static bool no_stf_barrier;
255static bool stf_barrier;
256
257static int __init handle_no_stf_barrier(char *p)
258{
259 pr_info("stf-barrier: disabled on command line.");
260 no_stf_barrier = true;
261 return 0;
262}
263
264early_param("no_stf_barrier", handle_no_stf_barrier);
265
266enum stf_barrier_type stf_barrier_type_get(void)
267{
268 return stf_enabled_flush_types;
269}
270
271/* This is the generic flag used by other architectures */
272static int __init handle_ssbd(char *p)
273{
274 if (!p || strncmp(p, "auto", 5) == 0 || strncmp(p, "on", 2) == 0 ) {
275 /* Until firmware tells us, we have the barrier with auto */
276 return 0;
277 } else if (strncmp(p, "off", 3) == 0) {
278 handle_no_stf_barrier(NULL);
279 return 0;
280 } else
281 return 1;
282
283 return 0;
284}
285early_param("spec_store_bypass_disable", handle_ssbd);
286
287/* This is the generic flag used by other architectures */
288static int __init handle_no_ssbd(char *p)
289{
290 handle_no_stf_barrier(NULL);
291 return 0;
292}
293early_param("nospec_store_bypass_disable", handle_no_ssbd);
294
295static void stf_barrier_enable(bool enable)
296{
297 if (enable)
298 do_stf_barrier_fixups(stf_enabled_flush_types);
299 else
300 do_stf_barrier_fixups(STF_BARRIER_NONE);
301
302 stf_barrier = enable;
303}
304
305void setup_stf_barrier(void)
306{
307 enum stf_barrier_type type;
308 bool enable;
309
310 /* Default to fallback in case fw-features are not available */
311 if (cpu_has_feature(CPU_FTR_ARCH_300))
312 type = STF_BARRIER_EIEIO;
313 else if (cpu_has_feature(CPU_FTR_ARCH_207S))
314 type = STF_BARRIER_SYNC_ORI;
315 else if (cpu_has_feature(CPU_FTR_ARCH_206))
316 type = STF_BARRIER_FALLBACK;
317 else
318 type = STF_BARRIER_NONE;
319
320 enable = security_ftr_enabled(SEC_FTR_FAVOUR_SECURITY) &&
321 security_ftr_enabled(SEC_FTR_STF_BARRIER);
322
323 if (type == STF_BARRIER_FALLBACK) {
324 pr_info("stf-barrier: fallback barrier available\n");
325 } else if (type == STF_BARRIER_SYNC_ORI) {
326 pr_info("stf-barrier: hwsync barrier available\n");
327 } else if (type == STF_BARRIER_EIEIO) {
328 pr_info("stf-barrier: eieio barrier available\n");
329 }
330
331 stf_enabled_flush_types = type;
332
333 if (!no_stf_barrier && !cpu_mitigations_off())
334 stf_barrier_enable(enable);
335}
336
337ssize_t cpu_show_spec_store_bypass(struct device *dev, struct device_attribute *attr, char *buf)
338{
339 if (stf_barrier && stf_enabled_flush_types != STF_BARRIER_NONE) {
340 const char *type;
341 switch (stf_enabled_flush_types) {
342 case STF_BARRIER_EIEIO:
343 type = "eieio";
344 break;
345 case STF_BARRIER_SYNC_ORI:
346 type = "hwsync";
347 break;
348 case STF_BARRIER_FALLBACK:
349 type = "fallback";
350 break;
351 default:
352 type = "unknown";
353 }
354 return sprintf(buf, "Mitigation: Kernel entry/exit barrier (%s)\n", type);
355 }
356
357 if (!security_ftr_enabled(SEC_FTR_L1D_FLUSH_HV) &&
358 !security_ftr_enabled(SEC_FTR_L1D_FLUSH_PR))
359 return sprintf(buf, "Not affected\n");
360
361 return sprintf(buf, "Vulnerable\n");
362}
363
364static int ssb_prctl_get(struct task_struct *task)
365{
366 if (stf_enabled_flush_types == STF_BARRIER_NONE)
367 /*
368 * We don't have an explicit signal from firmware that we're
369 * vulnerable or not, we only have certain CPU revisions that
370 * are known to be vulnerable.
371 *
372 * We assume that if we're on another CPU, where the barrier is
373 * NONE, then we are not vulnerable.
374 */
375 return PR_SPEC_NOT_AFFECTED;
376 else
377 /*
378 * If we do have a barrier type then we are vulnerable. The
379 * barrier is not a global or per-process mitigation, so the
380 * only value we can report here is PR_SPEC_ENABLE, which
381 * appears as "vulnerable" in /proc.
382 */
383 return PR_SPEC_ENABLE;
384
385 return -EINVAL;
386}
387
388int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which)
389{
390 switch (which) {
391 case PR_SPEC_STORE_BYPASS:
392 return ssb_prctl_get(task);
393 default:
394 return -ENODEV;
395 }
396}
397
398#ifdef CONFIG_DEBUG_FS
399static int stf_barrier_set(void *data, u64 val)
400{
401 bool enable;
402
403 if (val == 1)
404 enable = true;
405 else if (val == 0)
406 enable = false;
407 else
408 return -EINVAL;
409
410 /* Only do anything if we're changing state */
411 if (enable != stf_barrier)
412 stf_barrier_enable(enable);
413
414 return 0;
415}
416
417static int stf_barrier_get(void *data, u64 *val)
418{
419 *val = stf_barrier ? 1 : 0;
420 return 0;
421}
422
423DEFINE_DEBUGFS_ATTRIBUTE(fops_stf_barrier, stf_barrier_get, stf_barrier_set,
424 "%llu\n");
425
426static __init int stf_barrier_debugfs_init(void)
427{
428 debugfs_create_file_unsafe("stf_barrier", 0600, powerpc_debugfs_root,
429 NULL, &fops_stf_barrier);
430 return 0;
431}
432device_initcall(stf_barrier_debugfs_init);
433#endif /* CONFIG_DEBUG_FS */
434
435static void update_branch_cache_flush(void)
436{
437 u32 *site, __maybe_unused *site2;
438
439#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
440 site = &patch__call_kvm_flush_link_stack;
441 site2 = &patch__call_kvm_flush_link_stack_p9;
442 // This controls the branch from guest_exit_cont to kvm_flush_link_stack
443 if (link_stack_flush_type == BRANCH_CACHE_FLUSH_NONE) {
444 patch_instruction_site(site, ppc_inst(PPC_RAW_NOP()));
445 patch_instruction_site(site2, ppc_inst(PPC_RAW_NOP()));
446 } else {
447 // Could use HW flush, but that could also flush count cache
448 patch_branch_site(site, (u64)&kvm_flush_link_stack, BRANCH_SET_LINK);
449 patch_branch_site(site2, (u64)&kvm_flush_link_stack, BRANCH_SET_LINK);
450 }
451#endif
452
453 // Patch out the bcctr first, then nop the rest
454 site = &patch__call_flush_branch_caches3;
455 patch_instruction_site(site, ppc_inst(PPC_RAW_NOP()));
456 site = &patch__call_flush_branch_caches2;
457 patch_instruction_site(site, ppc_inst(PPC_RAW_NOP()));
458 site = &patch__call_flush_branch_caches1;
459 patch_instruction_site(site, ppc_inst(PPC_RAW_NOP()));
460
461 // This controls the branch from _switch to flush_branch_caches
462 if (count_cache_flush_type == BRANCH_CACHE_FLUSH_NONE &&
463 link_stack_flush_type == BRANCH_CACHE_FLUSH_NONE) {
464 // Nothing to be done
465
466 } else if (count_cache_flush_type == BRANCH_CACHE_FLUSH_HW &&
467 link_stack_flush_type == BRANCH_CACHE_FLUSH_HW) {
468 // Patch in the bcctr last
469 site = &patch__call_flush_branch_caches1;
470 patch_instruction_site(site, ppc_inst(0x39207fff)); // li r9,0x7fff
471 site = &patch__call_flush_branch_caches2;
472 patch_instruction_site(site, ppc_inst(0x7d2903a6)); // mtctr r9
473 site = &patch__call_flush_branch_caches3;
474 patch_instruction_site(site, ppc_inst(PPC_INST_BCCTR_FLUSH));
475
476 } else {
477 patch_branch_site(site, (u64)&flush_branch_caches, BRANCH_SET_LINK);
478
479 // If we just need to flush the link stack, early return
480 if (count_cache_flush_type == BRANCH_CACHE_FLUSH_NONE) {
481 patch_instruction_site(&patch__flush_link_stack_return,
482 ppc_inst(PPC_RAW_BLR()));
483
484 // If we have flush instruction, early return
485 } else if (count_cache_flush_type == BRANCH_CACHE_FLUSH_HW) {
486 patch_instruction_site(&patch__flush_count_cache_return,
487 ppc_inst(PPC_RAW_BLR()));
488 }
489 }
490}
491
492static void toggle_branch_cache_flush(bool enable)
493{
494 if (!enable || !security_ftr_enabled(SEC_FTR_FLUSH_COUNT_CACHE)) {
495 if (count_cache_flush_type != BRANCH_CACHE_FLUSH_NONE)
496 count_cache_flush_type = BRANCH_CACHE_FLUSH_NONE;
497
498 pr_info("count-cache-flush: flush disabled.\n");
499 } else {
500 if (security_ftr_enabled(SEC_FTR_BCCTR_FLUSH_ASSIST)) {
501 count_cache_flush_type = BRANCH_CACHE_FLUSH_HW;
502 pr_info("count-cache-flush: hardware flush enabled.\n");
503 } else {
504 count_cache_flush_type = BRANCH_CACHE_FLUSH_SW;
505 pr_info("count-cache-flush: software flush enabled.\n");
506 }
507 }
508
509 if (!enable || !security_ftr_enabled(SEC_FTR_FLUSH_LINK_STACK)) {
510 if (link_stack_flush_type != BRANCH_CACHE_FLUSH_NONE)
511 link_stack_flush_type = BRANCH_CACHE_FLUSH_NONE;
512
513 pr_info("link-stack-flush: flush disabled.\n");
514 } else {
515 if (security_ftr_enabled(SEC_FTR_BCCTR_LINK_FLUSH_ASSIST)) {
516 link_stack_flush_type = BRANCH_CACHE_FLUSH_HW;
517 pr_info("link-stack-flush: hardware flush enabled.\n");
518 } else {
519 link_stack_flush_type = BRANCH_CACHE_FLUSH_SW;
520 pr_info("link-stack-flush: software flush enabled.\n");
521 }
522 }
523
524 update_branch_cache_flush();
525}
526
527void setup_count_cache_flush(void)
528{
529 bool enable = true;
530
531 if (no_spectrev2 || cpu_mitigations_off()) {
532 if (security_ftr_enabled(SEC_FTR_BCCTRL_SERIALISED) ||
533 security_ftr_enabled(SEC_FTR_COUNT_CACHE_DISABLED))
534 pr_warn("Spectre v2 mitigations not fully under software control, can't disable\n");
535
536 enable = false;
537 }
538
539 /*
540 * There's no firmware feature flag/hypervisor bit to tell us we need to
541 * flush the link stack on context switch. So we set it here if we see
542 * either of the Spectre v2 mitigations that aim to protect userspace.
543 */
544 if (security_ftr_enabled(SEC_FTR_COUNT_CACHE_DISABLED) ||
545 security_ftr_enabled(SEC_FTR_FLUSH_COUNT_CACHE))
546 security_ftr_set(SEC_FTR_FLUSH_LINK_STACK);
547
548 toggle_branch_cache_flush(enable);
549}
550
551static enum l1d_flush_type enabled_flush_types;
552static void *l1d_flush_fallback_area;
553static bool no_rfi_flush;
554static bool no_entry_flush;
555static bool no_uaccess_flush;
556bool rfi_flush;
557static bool entry_flush;
558static bool uaccess_flush;
559DEFINE_STATIC_KEY_FALSE(uaccess_flush_key);
560EXPORT_SYMBOL(uaccess_flush_key);
561
562static int __init handle_no_rfi_flush(char *p)
563{
564 pr_info("rfi-flush: disabled on command line.");
565 no_rfi_flush = true;
566 return 0;
567}
568early_param("no_rfi_flush", handle_no_rfi_flush);
569
570static int __init handle_no_entry_flush(char *p)
571{
572 pr_info("entry-flush: disabled on command line.");
573 no_entry_flush = true;
574 return 0;
575}
576early_param("no_entry_flush", handle_no_entry_flush);
577
578static int __init handle_no_uaccess_flush(char *p)
579{
580 pr_info("uaccess-flush: disabled on command line.");
581 no_uaccess_flush = true;
582 return 0;
583}
584early_param("no_uaccess_flush", handle_no_uaccess_flush);
585
586/*
587 * The RFI flush is not KPTI, but because users will see doco that says to use
588 * nopti we hijack that option here to also disable the RFI flush.
589 */
590static int __init handle_no_pti(char *p)
591{
592 pr_info("rfi-flush: disabling due to 'nopti' on command line.\n");
593 handle_no_rfi_flush(NULL);
594 return 0;
595}
596early_param("nopti", handle_no_pti);
597
598static void do_nothing(void *unused)
599{
600 /*
601 * We don't need to do the flush explicitly, just enter+exit kernel is
602 * sufficient, the RFI exit handlers will do the right thing.
603 */
604}
605
606void rfi_flush_enable(bool enable)
607{
608 if (enable) {
609 do_rfi_flush_fixups(enabled_flush_types);
610 on_each_cpu(do_nothing, NULL, 1);
611 } else
612 do_rfi_flush_fixups(L1D_FLUSH_NONE);
613
614 rfi_flush = enable;
615}
616
617static void entry_flush_enable(bool enable)
618{
619 if (enable) {
620 do_entry_flush_fixups(enabled_flush_types);
621 on_each_cpu(do_nothing, NULL, 1);
622 } else {
623 do_entry_flush_fixups(L1D_FLUSH_NONE);
624 }
625
626 entry_flush = enable;
627}
628
629static void uaccess_flush_enable(bool enable)
630{
631 if (enable) {
632 do_uaccess_flush_fixups(enabled_flush_types);
633 static_branch_enable(&uaccess_flush_key);
634 on_each_cpu(do_nothing, NULL, 1);
635 } else {
636 static_branch_disable(&uaccess_flush_key);
637 do_uaccess_flush_fixups(L1D_FLUSH_NONE);
638 }
639
640 uaccess_flush = enable;
641}
642
643static void __ref init_fallback_flush(void)
644{
645 u64 l1d_size, limit;
646 int cpu;
647
648 /* Only allocate the fallback flush area once (at boot time). */
649 if (l1d_flush_fallback_area)
650 return;
651
652 l1d_size = ppc64_caches.l1d.size;
653
654 /*
655 * If there is no d-cache-size property in the device tree, l1d_size
656 * could be zero. That leads to the loop in the asm wrapping around to
657 * 2^64-1, and then walking off the end of the fallback area and
658 * eventually causing a page fault which is fatal. Just default to
659 * something vaguely sane.
660 */
661 if (!l1d_size)
662 l1d_size = (64 * 1024);
663
664 limit = min(ppc64_bolted_size(), ppc64_rma_size);
665
666 /*
667 * Align to L1d size, and size it at 2x L1d size, to catch possible
668 * hardware prefetch runoff. We don't have a recipe for load patterns to
669 * reliably avoid the prefetcher.
670 */
671 l1d_flush_fallback_area = memblock_alloc_try_nid(l1d_size * 2,
672 l1d_size, MEMBLOCK_LOW_LIMIT,
673 limit, NUMA_NO_NODE);
674 if (!l1d_flush_fallback_area)
675 panic("%s: Failed to allocate %llu bytes align=0x%llx max_addr=%pa\n",
676 __func__, l1d_size * 2, l1d_size, &limit);
677
678
679 for_each_possible_cpu(cpu) {
680 struct paca_struct *paca = paca_ptrs[cpu];
681 paca->rfi_flush_fallback_area = l1d_flush_fallback_area;
682 paca->l1d_flush_size = l1d_size;
683 }
684}
685
686void setup_rfi_flush(enum l1d_flush_type types, bool enable)
687{
688 if (types & L1D_FLUSH_FALLBACK) {
689 pr_info("rfi-flush: fallback displacement flush available\n");
690 init_fallback_flush();
691 }
692
693 if (types & L1D_FLUSH_ORI)
694 pr_info("rfi-flush: ori type flush available\n");
695
696 if (types & L1D_FLUSH_MTTRIG)
697 pr_info("rfi-flush: mttrig type flush available\n");
698
699 enabled_flush_types = types;
700
701 if (!cpu_mitigations_off() && !no_rfi_flush)
702 rfi_flush_enable(enable);
703}
704
705void setup_entry_flush(bool enable)
706{
707 if (cpu_mitigations_off())
708 return;
709
710 if (!no_entry_flush)
711 entry_flush_enable(enable);
712}
713
714void setup_uaccess_flush(bool enable)
715{
716 if (cpu_mitigations_off())
717 return;
718
719 if (!no_uaccess_flush)
720 uaccess_flush_enable(enable);
721}
722
723#ifdef CONFIG_DEBUG_FS
724static int count_cache_flush_set(void *data, u64 val)
725{
726 bool enable;
727
728 if (val == 1)
729 enable = true;
730 else if (val == 0)
731 enable = false;
732 else
733 return -EINVAL;
734
735 toggle_branch_cache_flush(enable);
736
737 return 0;
738}
739
740static int count_cache_flush_get(void *data, u64 *val)
741{
742 if (count_cache_flush_type == BRANCH_CACHE_FLUSH_NONE)
743 *val = 0;
744 else
745 *val = 1;
746
747 return 0;
748}
749
750DEFINE_DEBUGFS_ATTRIBUTE(fops_count_cache_flush, count_cache_flush_get,
751 count_cache_flush_set, "%llu\n");
752
753static __init int count_cache_flush_debugfs_init(void)
754{
755 debugfs_create_file_unsafe("count_cache_flush", 0600,
756 powerpc_debugfs_root, NULL,
757 &fops_count_cache_flush);
758 return 0;
759}
760device_initcall(count_cache_flush_debugfs_init);
761
762static int rfi_flush_set(void *data, u64 val)
763{
764 bool enable;
765
766 if (val == 1)
767 enable = true;
768 else if (val == 0)
769 enable = false;
770 else
771 return -EINVAL;
772
773 /* Only do anything if we're changing state */
774 if (enable != rfi_flush)
775 rfi_flush_enable(enable);
776
777 return 0;
778}
779
780static int rfi_flush_get(void *data, u64 *val)
781{
782 *val = rfi_flush ? 1 : 0;
783 return 0;
784}
785
786DEFINE_SIMPLE_ATTRIBUTE(fops_rfi_flush, rfi_flush_get, rfi_flush_set, "%llu\n");
787
788static int entry_flush_set(void *data, u64 val)
789{
790 bool enable;
791
792 if (val == 1)
793 enable = true;
794 else if (val == 0)
795 enable = false;
796 else
797 return -EINVAL;
798
799 /* Only do anything if we're changing state */
800 if (enable != entry_flush)
801 entry_flush_enable(enable);
802
803 return 0;
804}
805
806static int entry_flush_get(void *data, u64 *val)
807{
808 *val = entry_flush ? 1 : 0;
809 return 0;
810}
811
812DEFINE_SIMPLE_ATTRIBUTE(fops_entry_flush, entry_flush_get, entry_flush_set, "%llu\n");
813
814static int uaccess_flush_set(void *data, u64 val)
815{
816 bool enable;
817
818 if (val == 1)
819 enable = true;
820 else if (val == 0)
821 enable = false;
822 else
823 return -EINVAL;
824
825 /* Only do anything if we're changing state */
826 if (enable != uaccess_flush)
827 uaccess_flush_enable(enable);
828
829 return 0;
830}
831
832static int uaccess_flush_get(void *data, u64 *val)
833{
834 *val = uaccess_flush ? 1 : 0;
835 return 0;
836}
837
838DEFINE_SIMPLE_ATTRIBUTE(fops_uaccess_flush, uaccess_flush_get, uaccess_flush_set, "%llu\n");
839
840static __init int rfi_flush_debugfs_init(void)
841{
842 debugfs_create_file("rfi_flush", 0600, powerpc_debugfs_root, NULL, &fops_rfi_flush);
843 debugfs_create_file("entry_flush", 0600, powerpc_debugfs_root, NULL, &fops_entry_flush);
844 debugfs_create_file("uaccess_flush", 0600, powerpc_debugfs_root, NULL, &fops_uaccess_flush);
845 return 0;
846}
847device_initcall(rfi_flush_debugfs_init);
848#endif /* CONFIG_DEBUG_FS */
849#endif /* CONFIG_PPC_BOOK3S_64 */
1// SPDX-License-Identifier: GPL-2.0+
2//
3// Security related flags and so on.
4//
5// Copyright 2018, Michael Ellerman, IBM Corporation.
6
7#include <linux/cpu.h>
8#include <linux/kernel.h>
9#include <linux/device.h>
10#include <linux/memblock.h>
11#include <linux/nospec.h>
12#include <linux/prctl.h>
13#include <linux/seq_buf.h>
14#include <linux/debugfs.h>
15
16#include <asm/asm-prototypes.h>
17#include <asm/text-patching.h>
18#include <asm/security_features.h>
19#include <asm/sections.h>
20#include <asm/setup.h>
21#include <asm/inst.h>
22
23#include "setup.h"
24
25u64 powerpc_security_features __read_mostly = SEC_FTR_DEFAULT;
26
27enum branch_cache_flush_type {
28 BRANCH_CACHE_FLUSH_NONE = 0x1,
29 BRANCH_CACHE_FLUSH_SW = 0x2,
30 BRANCH_CACHE_FLUSH_HW = 0x4,
31};
32static enum branch_cache_flush_type count_cache_flush_type = BRANCH_CACHE_FLUSH_NONE;
33static enum branch_cache_flush_type link_stack_flush_type = BRANCH_CACHE_FLUSH_NONE;
34
35bool barrier_nospec_enabled;
36static bool no_nospec;
37static bool btb_flush_enabled;
38#if defined(CONFIG_PPC_E500) || defined(CONFIG_PPC_BOOK3S_64)
39static bool no_spectrev2;
40#endif
41
42static void enable_barrier_nospec(bool enable)
43{
44 barrier_nospec_enabled = enable;
45 do_barrier_nospec_fixups(enable);
46}
47
48void __init setup_barrier_nospec(void)
49{
50 bool enable;
51
52 /*
53 * It would make sense to check SEC_FTR_SPEC_BAR_ORI31 below as well.
54 * But there's a good reason not to. The two flags we check below are
55 * both are enabled by default in the kernel, so if the hcall is not
56 * functional they will be enabled.
57 * On a system where the host firmware has been updated (so the ori
58 * functions as a barrier), but on which the hypervisor (KVM/Qemu) has
59 * not been updated, we would like to enable the barrier. Dropping the
60 * check for SEC_FTR_SPEC_BAR_ORI31 achieves that. The only downside is
61 * we potentially enable the barrier on systems where the host firmware
62 * is not updated, but that's harmless as it's a no-op.
63 */
64 enable = security_ftr_enabled(SEC_FTR_FAVOUR_SECURITY) &&
65 security_ftr_enabled(SEC_FTR_BNDS_CHK_SPEC_BAR);
66
67 if (!no_nospec && !cpu_mitigations_off())
68 enable_barrier_nospec(enable);
69}
70
71static int __init handle_nospectre_v1(char *p)
72{
73 no_nospec = true;
74
75 return 0;
76}
77early_param("nospectre_v1", handle_nospectre_v1);
78
79#ifdef CONFIG_DEBUG_FS
80static int barrier_nospec_set(void *data, u64 val)
81{
82 switch (val) {
83 case 0:
84 case 1:
85 break;
86 default:
87 return -EINVAL;
88 }
89
90 if (!!val == !!barrier_nospec_enabled)
91 return 0;
92
93 enable_barrier_nospec(!!val);
94
95 return 0;
96}
97
98static int barrier_nospec_get(void *data, u64 *val)
99{
100 *val = barrier_nospec_enabled ? 1 : 0;
101 return 0;
102}
103
104DEFINE_DEBUGFS_ATTRIBUTE(fops_barrier_nospec, barrier_nospec_get,
105 barrier_nospec_set, "%llu\n");
106
107static __init int barrier_nospec_debugfs_init(void)
108{
109 debugfs_create_file_unsafe("barrier_nospec", 0600,
110 arch_debugfs_dir, NULL,
111 &fops_barrier_nospec);
112 return 0;
113}
114device_initcall(barrier_nospec_debugfs_init);
115
116static __init int security_feature_debugfs_init(void)
117{
118 debugfs_create_x64("security_features", 0400, arch_debugfs_dir,
119 &powerpc_security_features);
120 return 0;
121}
122device_initcall(security_feature_debugfs_init);
123#endif /* CONFIG_DEBUG_FS */
124
125#if defined(CONFIG_PPC_E500) || defined(CONFIG_PPC_BOOK3S_64)
126static int __init handle_nospectre_v2(char *p)
127{
128 no_spectrev2 = true;
129
130 return 0;
131}
132early_param("nospectre_v2", handle_nospectre_v2);
133#endif /* CONFIG_PPC_E500 || CONFIG_PPC_BOOK3S_64 */
134
135#ifdef CONFIG_PPC_E500
136void __init setup_spectre_v2(void)
137{
138 if (no_spectrev2 || cpu_mitigations_off())
139 do_btb_flush_fixups();
140 else
141 btb_flush_enabled = true;
142}
143#endif /* CONFIG_PPC_E500 */
144
145#ifdef CONFIG_PPC_BOOK3S_64
146ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf)
147{
148 bool thread_priv;
149
150 thread_priv = security_ftr_enabled(SEC_FTR_L1D_THREAD_PRIV);
151
152 if (rfi_flush) {
153 struct seq_buf s;
154 seq_buf_init(&s, buf, PAGE_SIZE - 1);
155
156 seq_buf_printf(&s, "Mitigation: RFI Flush");
157 if (thread_priv)
158 seq_buf_printf(&s, ", L1D private per thread");
159
160 seq_buf_printf(&s, "\n");
161
162 return s.len;
163 }
164
165 if (thread_priv)
166 return sprintf(buf, "Vulnerable: L1D private per thread\n");
167
168 if (!security_ftr_enabled(SEC_FTR_L1D_FLUSH_HV) &&
169 !security_ftr_enabled(SEC_FTR_L1D_FLUSH_PR))
170 return sprintf(buf, "Not affected\n");
171
172 return sprintf(buf, "Vulnerable\n");
173}
174
175ssize_t cpu_show_l1tf(struct device *dev, struct device_attribute *attr, char *buf)
176{
177 return cpu_show_meltdown(dev, attr, buf);
178}
179#endif
180
181ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr, char *buf)
182{
183 struct seq_buf s;
184
185 seq_buf_init(&s, buf, PAGE_SIZE - 1);
186
187 if (security_ftr_enabled(SEC_FTR_BNDS_CHK_SPEC_BAR)) {
188 if (barrier_nospec_enabled)
189 seq_buf_printf(&s, "Mitigation: __user pointer sanitization");
190 else
191 seq_buf_printf(&s, "Vulnerable");
192
193 if (security_ftr_enabled(SEC_FTR_SPEC_BAR_ORI31))
194 seq_buf_printf(&s, ", ori31 speculation barrier enabled");
195
196 seq_buf_printf(&s, "\n");
197 } else
198 seq_buf_printf(&s, "Not affected\n");
199
200 return s.len;
201}
202
203ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, char *buf)
204{
205 struct seq_buf s;
206 bool bcs, ccd;
207
208 seq_buf_init(&s, buf, PAGE_SIZE - 1);
209
210 bcs = security_ftr_enabled(SEC_FTR_BCCTRL_SERIALISED);
211 ccd = security_ftr_enabled(SEC_FTR_COUNT_CACHE_DISABLED);
212
213 if (bcs || ccd) {
214 seq_buf_printf(&s, "Mitigation: ");
215
216 if (bcs)
217 seq_buf_printf(&s, "Indirect branch serialisation (kernel only)");
218
219 if (bcs && ccd)
220 seq_buf_printf(&s, ", ");
221
222 if (ccd)
223 seq_buf_printf(&s, "Indirect branch cache disabled");
224
225 } else if (count_cache_flush_type != BRANCH_CACHE_FLUSH_NONE) {
226 seq_buf_printf(&s, "Mitigation: Software count cache flush");
227
228 if (count_cache_flush_type == BRANCH_CACHE_FLUSH_HW)
229 seq_buf_printf(&s, " (hardware accelerated)");
230
231 } else if (btb_flush_enabled) {
232 seq_buf_printf(&s, "Mitigation: Branch predictor state flush");
233 } else {
234 seq_buf_printf(&s, "Vulnerable");
235 }
236
237 if (bcs || ccd || count_cache_flush_type != BRANCH_CACHE_FLUSH_NONE) {
238 if (link_stack_flush_type != BRANCH_CACHE_FLUSH_NONE)
239 seq_buf_printf(&s, ", Software link stack flush");
240 if (link_stack_flush_type == BRANCH_CACHE_FLUSH_HW)
241 seq_buf_printf(&s, " (hardware accelerated)");
242 }
243
244 seq_buf_printf(&s, "\n");
245
246 return s.len;
247}
248
249#ifdef CONFIG_PPC_BOOK3S_64
250/*
251 * Store-forwarding barrier support.
252 */
253
254static enum stf_barrier_type stf_enabled_flush_types;
255static bool no_stf_barrier;
256static bool stf_barrier;
257
258static int __init handle_no_stf_barrier(char *p)
259{
260 pr_info("stf-barrier: disabled on command line.");
261 no_stf_barrier = true;
262 return 0;
263}
264
265early_param("no_stf_barrier", handle_no_stf_barrier);
266
267enum stf_barrier_type stf_barrier_type_get(void)
268{
269 return stf_enabled_flush_types;
270}
271
272/* This is the generic flag used by other architectures */
273static int __init handle_ssbd(char *p)
274{
275 if (!p || strncmp(p, "auto", 5) == 0 || strncmp(p, "on", 2) == 0 ) {
276 /* Until firmware tells us, we have the barrier with auto */
277 return 0;
278 } else if (strncmp(p, "off", 3) == 0) {
279 handle_no_stf_barrier(NULL);
280 return 0;
281 } else
282 return 1;
283
284 return 0;
285}
286early_param("spec_store_bypass_disable", handle_ssbd);
287
288/* This is the generic flag used by other architectures */
289static int __init handle_no_ssbd(char *p)
290{
291 handle_no_stf_barrier(NULL);
292 return 0;
293}
294early_param("nospec_store_bypass_disable", handle_no_ssbd);
295
296static void stf_barrier_enable(bool enable)
297{
298 if (enable)
299 do_stf_barrier_fixups(stf_enabled_flush_types);
300 else
301 do_stf_barrier_fixups(STF_BARRIER_NONE);
302
303 stf_barrier = enable;
304}
305
306void setup_stf_barrier(void)
307{
308 enum stf_barrier_type type;
309 bool enable;
310
311 /* Default to fallback in case fw-features are not available */
312 if (cpu_has_feature(CPU_FTR_ARCH_300))
313 type = STF_BARRIER_EIEIO;
314 else if (cpu_has_feature(CPU_FTR_ARCH_207S))
315 type = STF_BARRIER_SYNC_ORI;
316 else if (cpu_has_feature(CPU_FTR_ARCH_206))
317 type = STF_BARRIER_FALLBACK;
318 else
319 type = STF_BARRIER_NONE;
320
321 enable = security_ftr_enabled(SEC_FTR_FAVOUR_SECURITY) &&
322 security_ftr_enabled(SEC_FTR_STF_BARRIER);
323
324 if (type == STF_BARRIER_FALLBACK) {
325 pr_info("stf-barrier: fallback barrier available\n");
326 } else if (type == STF_BARRIER_SYNC_ORI) {
327 pr_info("stf-barrier: hwsync barrier available\n");
328 } else if (type == STF_BARRIER_EIEIO) {
329 pr_info("stf-barrier: eieio barrier available\n");
330 }
331
332 stf_enabled_flush_types = type;
333
334 if (!no_stf_barrier && !cpu_mitigations_off())
335 stf_barrier_enable(enable);
336}
337
338ssize_t cpu_show_spec_store_bypass(struct device *dev, struct device_attribute *attr, char *buf)
339{
340 if (stf_barrier && stf_enabled_flush_types != STF_BARRIER_NONE) {
341 const char *type;
342 switch (stf_enabled_flush_types) {
343 case STF_BARRIER_EIEIO:
344 type = "eieio";
345 break;
346 case STF_BARRIER_SYNC_ORI:
347 type = "hwsync";
348 break;
349 case STF_BARRIER_FALLBACK:
350 type = "fallback";
351 break;
352 default:
353 type = "unknown";
354 }
355 return sprintf(buf, "Mitigation: Kernel entry/exit barrier (%s)\n", type);
356 }
357
358 if (!security_ftr_enabled(SEC_FTR_L1D_FLUSH_HV) &&
359 !security_ftr_enabled(SEC_FTR_L1D_FLUSH_PR))
360 return sprintf(buf, "Not affected\n");
361
362 return sprintf(buf, "Vulnerable\n");
363}
364
365static int ssb_prctl_get(struct task_struct *task)
366{
367 /*
368 * The STF_BARRIER feature is on by default, so if it's off that means
369 * firmware has explicitly said the CPU is not vulnerable via either
370 * the hypercall or device tree.
371 */
372 if (!security_ftr_enabled(SEC_FTR_STF_BARRIER))
373 return PR_SPEC_NOT_AFFECTED;
374
375 /*
376 * If the system's CPU has no known barrier (see setup_stf_barrier())
377 * then assume that the CPU is not vulnerable.
378 */
379 if (stf_enabled_flush_types == STF_BARRIER_NONE)
380 return PR_SPEC_NOT_AFFECTED;
381
382 /*
383 * Otherwise the CPU is vulnerable. The barrier is not a global or
384 * per-process mitigation, so the only value that can be reported here
385 * is PR_SPEC_ENABLE, which appears as "vulnerable" in /proc.
386 */
387 return PR_SPEC_ENABLE;
388}
389
390int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which)
391{
392 switch (which) {
393 case PR_SPEC_STORE_BYPASS:
394 return ssb_prctl_get(task);
395 default:
396 return -ENODEV;
397 }
398}
399
400#ifdef CONFIG_DEBUG_FS
401static int stf_barrier_set(void *data, u64 val)
402{
403 bool enable;
404
405 if (val == 1)
406 enable = true;
407 else if (val == 0)
408 enable = false;
409 else
410 return -EINVAL;
411
412 /* Only do anything if we're changing state */
413 if (enable != stf_barrier)
414 stf_barrier_enable(enable);
415
416 return 0;
417}
418
419static int stf_barrier_get(void *data, u64 *val)
420{
421 *val = stf_barrier ? 1 : 0;
422 return 0;
423}
424
425DEFINE_DEBUGFS_ATTRIBUTE(fops_stf_barrier, stf_barrier_get, stf_barrier_set,
426 "%llu\n");
427
428static __init int stf_barrier_debugfs_init(void)
429{
430 debugfs_create_file_unsafe("stf_barrier", 0600, arch_debugfs_dir,
431 NULL, &fops_stf_barrier);
432 return 0;
433}
434device_initcall(stf_barrier_debugfs_init);
435#endif /* CONFIG_DEBUG_FS */
436
437static void update_branch_cache_flush(void)
438{
439 u32 *site, __maybe_unused *site2;
440
441#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
442 site = &patch__call_kvm_flush_link_stack;
443 site2 = &patch__call_kvm_flush_link_stack_p9;
444 // This controls the branch from guest_exit_cont to kvm_flush_link_stack
445 if (link_stack_flush_type == BRANCH_CACHE_FLUSH_NONE) {
446 patch_instruction_site(site, ppc_inst(PPC_RAW_NOP()));
447 patch_instruction_site(site2, ppc_inst(PPC_RAW_NOP()));
448 } else {
449 // Could use HW flush, but that could also flush count cache
450 patch_branch_site(site, (u64)&kvm_flush_link_stack, BRANCH_SET_LINK);
451 patch_branch_site(site2, (u64)&kvm_flush_link_stack, BRANCH_SET_LINK);
452 }
453#endif
454
455 // Patch out the bcctr first, then nop the rest
456 site = &patch__call_flush_branch_caches3;
457 patch_instruction_site(site, ppc_inst(PPC_RAW_NOP()));
458 site = &patch__call_flush_branch_caches2;
459 patch_instruction_site(site, ppc_inst(PPC_RAW_NOP()));
460 site = &patch__call_flush_branch_caches1;
461 patch_instruction_site(site, ppc_inst(PPC_RAW_NOP()));
462
463 // This controls the branch from _switch to flush_branch_caches
464 if (count_cache_flush_type == BRANCH_CACHE_FLUSH_NONE &&
465 link_stack_flush_type == BRANCH_CACHE_FLUSH_NONE) {
466 // Nothing to be done
467
468 } else if (count_cache_flush_type == BRANCH_CACHE_FLUSH_HW &&
469 link_stack_flush_type == BRANCH_CACHE_FLUSH_HW) {
470 // Patch in the bcctr last
471 site = &patch__call_flush_branch_caches1;
472 patch_instruction_site(site, ppc_inst(0x39207fff)); // li r9,0x7fff
473 site = &patch__call_flush_branch_caches2;
474 patch_instruction_site(site, ppc_inst(0x7d2903a6)); // mtctr r9
475 site = &patch__call_flush_branch_caches3;
476 patch_instruction_site(site, ppc_inst(PPC_INST_BCCTR_FLUSH));
477
478 } else {
479 patch_branch_site(site, (u64)&flush_branch_caches, BRANCH_SET_LINK);
480
481 // If we just need to flush the link stack, early return
482 if (count_cache_flush_type == BRANCH_CACHE_FLUSH_NONE) {
483 patch_instruction_site(&patch__flush_link_stack_return,
484 ppc_inst(PPC_RAW_BLR()));
485
486 // If we have flush instruction, early return
487 } else if (count_cache_flush_type == BRANCH_CACHE_FLUSH_HW) {
488 patch_instruction_site(&patch__flush_count_cache_return,
489 ppc_inst(PPC_RAW_BLR()));
490 }
491 }
492}
493
494static void toggle_branch_cache_flush(bool enable)
495{
496 if (!enable || !security_ftr_enabled(SEC_FTR_FLUSH_COUNT_CACHE)) {
497 if (count_cache_flush_type != BRANCH_CACHE_FLUSH_NONE)
498 count_cache_flush_type = BRANCH_CACHE_FLUSH_NONE;
499
500 pr_info("count-cache-flush: flush disabled.\n");
501 } else {
502 if (security_ftr_enabled(SEC_FTR_BCCTR_FLUSH_ASSIST)) {
503 count_cache_flush_type = BRANCH_CACHE_FLUSH_HW;
504 pr_info("count-cache-flush: hardware flush enabled.\n");
505 } else {
506 count_cache_flush_type = BRANCH_CACHE_FLUSH_SW;
507 pr_info("count-cache-flush: software flush enabled.\n");
508 }
509 }
510
511 if (!enable || !security_ftr_enabled(SEC_FTR_FLUSH_LINK_STACK)) {
512 if (link_stack_flush_type != BRANCH_CACHE_FLUSH_NONE)
513 link_stack_flush_type = BRANCH_CACHE_FLUSH_NONE;
514
515 pr_info("link-stack-flush: flush disabled.\n");
516 } else {
517 if (security_ftr_enabled(SEC_FTR_BCCTR_LINK_FLUSH_ASSIST)) {
518 link_stack_flush_type = BRANCH_CACHE_FLUSH_HW;
519 pr_info("link-stack-flush: hardware flush enabled.\n");
520 } else {
521 link_stack_flush_type = BRANCH_CACHE_FLUSH_SW;
522 pr_info("link-stack-flush: software flush enabled.\n");
523 }
524 }
525
526 update_branch_cache_flush();
527}
528
529void setup_count_cache_flush(void)
530{
531 bool enable = true;
532
533 if (no_spectrev2 || cpu_mitigations_off()) {
534 if (security_ftr_enabled(SEC_FTR_BCCTRL_SERIALISED) ||
535 security_ftr_enabled(SEC_FTR_COUNT_CACHE_DISABLED))
536 pr_warn("Spectre v2 mitigations not fully under software control, can't disable\n");
537
538 enable = false;
539 }
540
541 /*
542 * There's no firmware feature flag/hypervisor bit to tell us we need to
543 * flush the link stack on context switch. So we set it here if we see
544 * either of the Spectre v2 mitigations that aim to protect userspace.
545 */
546 if (security_ftr_enabled(SEC_FTR_COUNT_CACHE_DISABLED) ||
547 security_ftr_enabled(SEC_FTR_FLUSH_COUNT_CACHE))
548 security_ftr_set(SEC_FTR_FLUSH_LINK_STACK);
549
550 toggle_branch_cache_flush(enable);
551}
552
553static enum l1d_flush_type enabled_flush_types;
554static void *l1d_flush_fallback_area;
555static bool no_rfi_flush;
556static bool no_entry_flush;
557static bool no_uaccess_flush;
558bool rfi_flush;
559static bool entry_flush;
560static bool uaccess_flush;
561DEFINE_STATIC_KEY_FALSE(uaccess_flush_key);
562EXPORT_SYMBOL(uaccess_flush_key);
563
564static int __init handle_no_rfi_flush(char *p)
565{
566 pr_info("rfi-flush: disabled on command line.");
567 no_rfi_flush = true;
568 return 0;
569}
570early_param("no_rfi_flush", handle_no_rfi_flush);
571
572static int __init handle_no_entry_flush(char *p)
573{
574 pr_info("entry-flush: disabled on command line.");
575 no_entry_flush = true;
576 return 0;
577}
578early_param("no_entry_flush", handle_no_entry_flush);
579
580static int __init handle_no_uaccess_flush(char *p)
581{
582 pr_info("uaccess-flush: disabled on command line.");
583 no_uaccess_flush = true;
584 return 0;
585}
586early_param("no_uaccess_flush", handle_no_uaccess_flush);
587
588/*
589 * The RFI flush is not KPTI, but because users will see doco that says to use
590 * nopti we hijack that option here to also disable the RFI flush.
591 */
592static int __init handle_no_pti(char *p)
593{
594 pr_info("rfi-flush: disabling due to 'nopti' on command line.\n");
595 handle_no_rfi_flush(NULL);
596 return 0;
597}
598early_param("nopti", handle_no_pti);
599
600static void do_nothing(void *unused)
601{
602 /*
603 * We don't need to do the flush explicitly, just enter+exit kernel is
604 * sufficient, the RFI exit handlers will do the right thing.
605 */
606}
607
608void rfi_flush_enable(bool enable)
609{
610 if (enable) {
611 do_rfi_flush_fixups(enabled_flush_types);
612 on_each_cpu(do_nothing, NULL, 1);
613 } else
614 do_rfi_flush_fixups(L1D_FLUSH_NONE);
615
616 rfi_flush = enable;
617}
618
619static void entry_flush_enable(bool enable)
620{
621 if (enable) {
622 do_entry_flush_fixups(enabled_flush_types);
623 on_each_cpu(do_nothing, NULL, 1);
624 } else {
625 do_entry_flush_fixups(L1D_FLUSH_NONE);
626 }
627
628 entry_flush = enable;
629}
630
631static void uaccess_flush_enable(bool enable)
632{
633 if (enable) {
634 do_uaccess_flush_fixups(enabled_flush_types);
635 static_branch_enable(&uaccess_flush_key);
636 on_each_cpu(do_nothing, NULL, 1);
637 } else {
638 static_branch_disable(&uaccess_flush_key);
639 do_uaccess_flush_fixups(L1D_FLUSH_NONE);
640 }
641
642 uaccess_flush = enable;
643}
644
645static void __ref init_fallback_flush(void)
646{
647 u64 l1d_size, limit;
648 int cpu;
649
650 /* Only allocate the fallback flush area once (at boot time). */
651 if (l1d_flush_fallback_area)
652 return;
653
654 l1d_size = ppc64_caches.l1d.size;
655
656 /*
657 * If there is no d-cache-size property in the device tree, l1d_size
658 * could be zero. That leads to the loop in the asm wrapping around to
659 * 2^64-1, and then walking off the end of the fallback area and
660 * eventually causing a page fault which is fatal. Just default to
661 * something vaguely sane.
662 */
663 if (!l1d_size)
664 l1d_size = (64 * 1024);
665
666 limit = min(ppc64_bolted_size(), ppc64_rma_size);
667
668 /*
669 * Align to L1d size, and size it at 2x L1d size, to catch possible
670 * hardware prefetch runoff. We don't have a recipe for load patterns to
671 * reliably avoid the prefetcher.
672 */
673 l1d_flush_fallback_area = memblock_alloc_try_nid(l1d_size * 2,
674 l1d_size, MEMBLOCK_LOW_LIMIT,
675 limit, NUMA_NO_NODE);
676 if (!l1d_flush_fallback_area)
677 panic("%s: Failed to allocate %llu bytes align=0x%llx max_addr=%pa\n",
678 __func__, l1d_size * 2, l1d_size, &limit);
679
680
681 for_each_possible_cpu(cpu) {
682 struct paca_struct *paca = paca_ptrs[cpu];
683 paca->rfi_flush_fallback_area = l1d_flush_fallback_area;
684 paca->l1d_flush_size = l1d_size;
685 }
686}
687
688void setup_rfi_flush(enum l1d_flush_type types, bool enable)
689{
690 if (types & L1D_FLUSH_FALLBACK) {
691 pr_info("rfi-flush: fallback displacement flush available\n");
692 init_fallback_flush();
693 }
694
695 if (types & L1D_FLUSH_ORI)
696 pr_info("rfi-flush: ori type flush available\n");
697
698 if (types & L1D_FLUSH_MTTRIG)
699 pr_info("rfi-flush: mttrig type flush available\n");
700
701 enabled_flush_types = types;
702
703 if (!cpu_mitigations_off() && !no_rfi_flush)
704 rfi_flush_enable(enable);
705}
706
707void setup_entry_flush(bool enable)
708{
709 if (cpu_mitigations_off())
710 return;
711
712 if (!no_entry_flush)
713 entry_flush_enable(enable);
714}
715
716void setup_uaccess_flush(bool enable)
717{
718 if (cpu_mitigations_off())
719 return;
720
721 if (!no_uaccess_flush)
722 uaccess_flush_enable(enable);
723}
724
725#ifdef CONFIG_DEBUG_FS
726static int count_cache_flush_set(void *data, u64 val)
727{
728 bool enable;
729
730 if (val == 1)
731 enable = true;
732 else if (val == 0)
733 enable = false;
734 else
735 return -EINVAL;
736
737 toggle_branch_cache_flush(enable);
738
739 return 0;
740}
741
742static int count_cache_flush_get(void *data, u64 *val)
743{
744 if (count_cache_flush_type == BRANCH_CACHE_FLUSH_NONE)
745 *val = 0;
746 else
747 *val = 1;
748
749 return 0;
750}
751
752static int link_stack_flush_get(void *data, u64 *val)
753{
754 if (link_stack_flush_type == BRANCH_CACHE_FLUSH_NONE)
755 *val = 0;
756 else
757 *val = 1;
758
759 return 0;
760}
761
762DEFINE_DEBUGFS_ATTRIBUTE(fops_count_cache_flush, count_cache_flush_get,
763 count_cache_flush_set, "%llu\n");
764DEFINE_DEBUGFS_ATTRIBUTE(fops_link_stack_flush, link_stack_flush_get,
765 count_cache_flush_set, "%llu\n");
766
767static __init int count_cache_flush_debugfs_init(void)
768{
769 debugfs_create_file_unsafe("count_cache_flush", 0600,
770 arch_debugfs_dir, NULL,
771 &fops_count_cache_flush);
772 debugfs_create_file_unsafe("link_stack_flush", 0600,
773 arch_debugfs_dir, NULL,
774 &fops_link_stack_flush);
775 return 0;
776}
777device_initcall(count_cache_flush_debugfs_init);
778
779static int rfi_flush_set(void *data, u64 val)
780{
781 bool enable;
782
783 if (val == 1)
784 enable = true;
785 else if (val == 0)
786 enable = false;
787 else
788 return -EINVAL;
789
790 /* Only do anything if we're changing state */
791 if (enable != rfi_flush)
792 rfi_flush_enable(enable);
793
794 return 0;
795}
796
797static int rfi_flush_get(void *data, u64 *val)
798{
799 *val = rfi_flush ? 1 : 0;
800 return 0;
801}
802
803DEFINE_SIMPLE_ATTRIBUTE(fops_rfi_flush, rfi_flush_get, rfi_flush_set, "%llu\n");
804
805static int entry_flush_set(void *data, u64 val)
806{
807 bool enable;
808
809 if (val == 1)
810 enable = true;
811 else if (val == 0)
812 enable = false;
813 else
814 return -EINVAL;
815
816 /* Only do anything if we're changing state */
817 if (enable != entry_flush)
818 entry_flush_enable(enable);
819
820 return 0;
821}
822
823static int entry_flush_get(void *data, u64 *val)
824{
825 *val = entry_flush ? 1 : 0;
826 return 0;
827}
828
829DEFINE_SIMPLE_ATTRIBUTE(fops_entry_flush, entry_flush_get, entry_flush_set, "%llu\n");
830
831static int uaccess_flush_set(void *data, u64 val)
832{
833 bool enable;
834
835 if (val == 1)
836 enable = true;
837 else if (val == 0)
838 enable = false;
839 else
840 return -EINVAL;
841
842 /* Only do anything if we're changing state */
843 if (enable != uaccess_flush)
844 uaccess_flush_enable(enable);
845
846 return 0;
847}
848
849static int uaccess_flush_get(void *data, u64 *val)
850{
851 *val = uaccess_flush ? 1 : 0;
852 return 0;
853}
854
855DEFINE_SIMPLE_ATTRIBUTE(fops_uaccess_flush, uaccess_flush_get, uaccess_flush_set, "%llu\n");
856
857static __init int rfi_flush_debugfs_init(void)
858{
859 debugfs_create_file("rfi_flush", 0600, arch_debugfs_dir, NULL, &fops_rfi_flush);
860 debugfs_create_file("entry_flush", 0600, arch_debugfs_dir, NULL, &fops_entry_flush);
861 debugfs_create_file("uaccess_flush", 0600, arch_debugfs_dir, NULL, &fops_uaccess_flush);
862 return 0;
863}
864device_initcall(rfi_flush_debugfs_init);
865#endif /* CONFIG_DEBUG_FS */
866#endif /* CONFIG_PPC_BOOK3S_64 */