xref: /openbmc/linux/arch/arm64/mm/proc.S (revision 2a954832) 
1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Based on arch/arm/mm/proc.S
4 *
5 * Copyright (C) 2001 Deep Blue Solutions Ltd.
6 * Copyright (C) 2012 ARM Ltd.
7 * Author: Catalin Marinas <catalin.marinas@arm.com>
8 */
9
10#include <linux/init.h>
11#include <linux/linkage.h>
12#include <linux/pgtable.h>
13#include <linux/cfi_types.h>
14#include <asm/assembler.h>
15#include <asm/asm-offsets.h>
16#include <asm/asm_pointer_auth.h>
17#include <asm/hwcap.h>
18#include <asm/kernel-pgtable.h>
19#include <asm/pgtable-hwdef.h>
20#include <asm/cpufeature.h>
21#include <asm/alternative.h>
22#include <asm/smp.h>
23#include <asm/sysreg.h>
24
25#ifdef CONFIG_ARM64_64K_PAGES
26#define TCR_TG_FLAGS	TCR_TG0_64K | TCR_TG1_64K
27#elif defined(CONFIG_ARM64_16K_PAGES)
28#define TCR_TG_FLAGS	TCR_TG0_16K | TCR_TG1_16K
29#else /* CONFIG_ARM64_4K_PAGES */
30#define TCR_TG_FLAGS	TCR_TG0_4K | TCR_TG1_4K
31#endif
32
33#ifdef CONFIG_RANDOMIZE_BASE
34#define TCR_KASLR_FLAGS	TCR_NFD1
35#else
36#define TCR_KASLR_FLAGS	0
37#endif
38
39#define TCR_SMP_FLAGS	TCR_SHARED
40
41/* PTWs cacheable, inner/outer WBWA */
42#define TCR_CACHE_FLAGS	TCR_IRGN_WBWA | TCR_ORGN_WBWA
43
44#ifdef CONFIG_KASAN_SW_TAGS
45#define TCR_KASAN_SW_FLAGS TCR_TBI1 | TCR_TBID1
46#else
47#define TCR_KASAN_SW_FLAGS 0
48#endif
49
50#ifdef CONFIG_KASAN_HW_TAGS
51#define TCR_MTE_FLAGS TCR_TCMA1 | TCR_TBI1 | TCR_TBID1
52#elif defined(CONFIG_ARM64_MTE)
53/*
54 * The mte_zero_clear_page_tags() implementation uses DC GZVA, which relies on
55 * TBI being enabled at EL1.
56 */
57#define TCR_MTE_FLAGS TCR_TBI1 | TCR_TBID1
58#else
59#define TCR_MTE_FLAGS 0
60#endif
61
62/*
63 * Default MAIR_EL1. MT_NORMAL_TAGGED is initially mapped as Normal memory and
64 * changed during mte_cpu_setup to Normal Tagged if the system supports MTE.
65 */
66#define MAIR_EL1_SET							\
67	(MAIR_ATTRIDX(MAIR_ATTR_DEVICE_nGnRnE, MT_DEVICE_nGnRnE) |	\
68	 MAIR_ATTRIDX(MAIR_ATTR_DEVICE_nGnRE, MT_DEVICE_nGnRE) |	\
69	 MAIR_ATTRIDX(MAIR_ATTR_NORMAL_NC, MT_NORMAL_NC) |		\
70	 MAIR_ATTRIDX(MAIR_ATTR_NORMAL, MT_NORMAL) |			\
71	 MAIR_ATTRIDX(MAIR_ATTR_NORMAL, MT_NORMAL_TAGGED))
72
73#ifdef CONFIG_CPU_PM
74/**
75 * cpu_do_suspend - save CPU registers context
76 *
77 * x0: virtual address of context pointer
78 *
79 * This must be kept in sync with struct cpu_suspend_ctx in <asm/suspend.h>.
80 */
81SYM_FUNC_START(cpu_do_suspend)
82	mrs	x2, tpidr_el0
83	mrs	x3, tpidrro_el0
84	mrs	x4, contextidr_el1
85	mrs	x5, osdlr_el1
86	mrs	x6, cpacr_el1
87	mrs	x7, tcr_el1
88	mrs	x8, vbar_el1
89	mrs	x9, mdscr_el1
90	mrs	x10, oslsr_el1
91	mrs	x11, sctlr_el1
92	get_this_cpu_offset x12
93	mrs	x13, sp_el0
94	stp	x2, x3, [x0]
95	stp	x4, x5, [x0, #16]
96	stp	x6, x7, [x0, #32]
97	stp	x8, x9, [x0, #48]
98	stp	x10, x11, [x0, #64]
99	stp	x12, x13, [x0, #80]
100	/*
101	 * Save x18 as it may be used as a platform register, e.g. by shadow
102	 * call stack.
103	 */
104	str	x18, [x0, #96]
105	ret
106SYM_FUNC_END(cpu_do_suspend)
107
108/**
109 * cpu_do_resume - restore CPU register context
110 *
111 * x0: Address of context pointer
112 */
113SYM_FUNC_START(cpu_do_resume)
114	ldp	x2, x3, [x0]
115	ldp	x4, x5, [x0, #16]
116	ldp	x6, x8, [x0, #32]
117	ldp	x9, x10, [x0, #48]
118	ldp	x11, x12, [x0, #64]
119	ldp	x13, x14, [x0, #80]
120	/*
121	 * Restore x18, as it may be used as a platform register, and clear
122	 * the buffer to minimize the risk of exposure when used for shadow
123	 * call stack.
124	 */
125	ldr	x18, [x0, #96]
126	str	xzr, [x0, #96]
127	msr	tpidr_el0, x2
128	msr	tpidrro_el0, x3
129	msr	contextidr_el1, x4
130	msr	cpacr_el1, x6
131
132	/* Don't change t0sz here, mask those bits when restoring */
133	mrs	x7, tcr_el1
134	bfi	x8, x7, TCR_T0SZ_OFFSET, TCR_TxSZ_WIDTH
135
136	msr	tcr_el1, x8
137	msr	vbar_el1, x9
138
139	/*
140	 * __cpu_setup() cleared MDSCR_EL1.MDE and friends, before unmasking
141	 * debug exceptions. By restoring MDSCR_EL1 here, we may take a debug
142	 * exception. Mask them until local_daif_restore() in cpu_suspend()
143	 * resets them.
144	 */
145	disable_daif
146	msr	mdscr_el1, x10
147
148	msr	sctlr_el1, x12
149	set_this_cpu_offset x13
150	msr	sp_el0, x14
151	/*
152	 * Restore oslsr_el1 by writing oslar_el1
153	 */
154	msr	osdlr_el1, x5
155	ubfx	x11, x11, #1, #1
156	msr	oslar_el1, x11
157	reset_pmuserenr_el0 x0			// Disable PMU access from EL0
158	reset_amuserenr_el0 x0			// Disable AMU access from EL0
159
160alternative_if ARM64_HAS_RAS_EXTN
161	msr_s	SYS_DISR_EL1, xzr
162alternative_else_nop_endif
163
164	ptrauth_keys_install_kernel_nosync x14, x1, x2, x3
165	isb
166	ret
167SYM_FUNC_END(cpu_do_resume)
168#endif
169
170	.pushsection ".idmap.text", "a"
171
172.macro	__idmap_cpu_set_reserved_ttbr1, tmp1, tmp2
173	adrp	\tmp1, reserved_pg_dir
174	phys_to_ttbr \tmp2, \tmp1
175	offset_ttbr1 \tmp2, \tmp1
176	msr	ttbr1_el1, \tmp2
177	isb
178	tlbi	vmalle1
179	dsb	nsh
180	isb
181.endm
182
183/*
184 * void idmap_cpu_replace_ttbr1(phys_addr_t ttbr1)
185 *
186 * This is the low-level counterpart to cpu_replace_ttbr1, and should not be
187 * called by anything else. It can only be executed from a TTBR0 mapping.
188 */
189SYM_TYPED_FUNC_START(idmap_cpu_replace_ttbr1)
190	__idmap_cpu_set_reserved_ttbr1 x1, x3
191
192	offset_ttbr1 x0, x3
193	msr	ttbr1_el1, x0
194	isb
195
196	ret
197SYM_FUNC_END(idmap_cpu_replace_ttbr1)
198	.popsection
199
200#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
201
202#define KPTI_NG_PTE_FLAGS	(PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS)
203
204	.pushsection ".idmap.text", "a"
205
206	.macro	kpti_mk_tbl_ng, type, num_entries
207	add	end_\type\()p, cur_\type\()p, #\num_entries * 8
208.Ldo_\type:
209	ldr	\type, [cur_\type\()p]		// Load the entry
210	tbz	\type, #0, .Lnext_\type		// Skip invalid and
211	tbnz	\type, #11, .Lnext_\type	// non-global entries
212	orr	\type, \type, #PTE_NG		// Same bit for blocks and pages
213	str	\type, [cur_\type\()p]		// Update the entry
214	.ifnc	\type, pte
215	tbnz	\type, #1, .Lderef_\type
216	.endif
217.Lnext_\type:
218	add	cur_\type\()p, cur_\type\()p, #8
219	cmp	cur_\type\()p, end_\type\()p
220	b.ne	.Ldo_\type
221	.endm
222
223	/*
224	 * Dereference the current table entry and map it into the temporary
225	 * fixmap slot associated with the current level.
226	 */
227	.macro	kpti_map_pgtbl, type, level
228	str	xzr, [temp_pte, #8 * (\level + 1)]	// break before make
229	dsb	nshst
230	add	pte, temp_pte, #PAGE_SIZE * (\level + 1)
231	lsr	pte, pte, #12
232	tlbi	vaae1, pte
233	dsb	nsh
234	isb
235
236	phys_to_pte pte, cur_\type\()p
237	add	cur_\type\()p, temp_pte, #PAGE_SIZE * (\level + 1)
238	orr	pte, pte, pte_flags
239	str	pte, [temp_pte, #8 * (\level + 1)]
240	dsb	nshst
241	.endm
242
243/*
244 * void __kpti_install_ng_mappings(int cpu, int num_secondaries, phys_addr_t temp_pgd,
245 *				   unsigned long temp_pte_va)
246 *
247 * Called exactly once from stop_machine context by each CPU found during boot.
248 */
249	.pushsection	".data", "aw", %progbits
250SYM_DATA(__idmap_kpti_flag, .long 1)
251	.popsection
252
253SYM_TYPED_FUNC_START(idmap_kpti_install_ng_mappings)
254	cpu		.req	w0
255	temp_pte	.req	x0
256	num_cpus	.req	w1
257	pte_flags	.req	x1
258	temp_pgd_phys	.req	x2
259	swapper_ttb	.req	x3
260	flag_ptr	.req	x4
261	cur_pgdp	.req	x5
262	end_pgdp	.req	x6
263	pgd		.req	x7
264	cur_pudp	.req	x8
265	end_pudp	.req	x9
266	cur_pmdp	.req	x11
267	end_pmdp	.req	x12
268	cur_ptep	.req	x14
269	end_ptep	.req	x15
270	pte		.req	x16
271	valid		.req	x17
272
273	mov	x5, x3				// preserve temp_pte arg
274	mrs	swapper_ttb, ttbr1_el1
275	adr_l	flag_ptr, __idmap_kpti_flag
276
277	cbnz	cpu, __idmap_kpti_secondary
278
279	/* We're the boot CPU. Wait for the others to catch up */
280	sevl
2811:	wfe
282	ldaxr	w17, [flag_ptr]
283	eor	w17, w17, num_cpus
284	cbnz	w17, 1b
285
286	/* Switch to the temporary page tables on this CPU only */
287	__idmap_cpu_set_reserved_ttbr1 x8, x9
288	offset_ttbr1 temp_pgd_phys, x8
289	msr	ttbr1_el1, temp_pgd_phys
290	isb
291
292	mov	temp_pte, x5
293	mov	pte_flags, #KPTI_NG_PTE_FLAGS
294
295	/* Everybody is enjoying the idmap, so we can rewrite swapper. */
296	/* PGD */
297	adrp		cur_pgdp, swapper_pg_dir
298	kpti_map_pgtbl	pgd, 0
299	kpti_mk_tbl_ng	pgd, PTRS_PER_PGD
300
301	/* Ensure all the updated entries are visible to secondary CPUs */
302	dsb	ishst
303
304	/* We're done: fire up swapper_pg_dir again */
305	__idmap_cpu_set_reserved_ttbr1 x8, x9
306	msr	ttbr1_el1, swapper_ttb
307	isb
308
309	/* Set the flag to zero to indicate that we're all done */
310	str	wzr, [flag_ptr]
311	ret
312
313.Lderef_pgd:
314	/* PUD */
315	.if		CONFIG_PGTABLE_LEVELS > 3
316	pud		.req	x10
317	pte_to_phys	cur_pudp, pgd
318	kpti_map_pgtbl	pud, 1
319	kpti_mk_tbl_ng	pud, PTRS_PER_PUD
320	b		.Lnext_pgd
321	.else		/* CONFIG_PGTABLE_LEVELS <= 3 */
322	pud		.req	pgd
323	.set		.Lnext_pud, .Lnext_pgd
324	.endif
325
326.Lderef_pud:
327	/* PMD */
328	.if		CONFIG_PGTABLE_LEVELS > 2
329	pmd		.req	x13
330	pte_to_phys	cur_pmdp, pud
331	kpti_map_pgtbl	pmd, 2
332	kpti_mk_tbl_ng	pmd, PTRS_PER_PMD
333	b		.Lnext_pud
334	.else		/* CONFIG_PGTABLE_LEVELS <= 2 */
335	pmd		.req	pgd
336	.set		.Lnext_pmd, .Lnext_pgd
337	.endif
338
339.Lderef_pmd:
340	/* PTE */
341	pte_to_phys	cur_ptep, pmd
342	kpti_map_pgtbl	pte, 3
343	kpti_mk_tbl_ng	pte, PTRS_PER_PTE
344	b		.Lnext_pmd
345
346	.unreq	cpu
347	.unreq	temp_pte
348	.unreq	num_cpus
349	.unreq	pte_flags
350	.unreq	temp_pgd_phys
351	.unreq	cur_pgdp
352	.unreq	end_pgdp
353	.unreq	pgd
354	.unreq	cur_pudp
355	.unreq	end_pudp
356	.unreq	pud
357	.unreq	cur_pmdp
358	.unreq	end_pmdp
359	.unreq	pmd
360	.unreq	cur_ptep
361	.unreq	end_ptep
362	.unreq	pte
363	.unreq	valid
364
365	/* Secondary CPUs end up here */
366__idmap_kpti_secondary:
367	/* Uninstall swapper before surgery begins */
368	__idmap_cpu_set_reserved_ttbr1 x16, x17
369
370	/* Increment the flag to let the boot CPU we're ready */
3711:	ldxr	w16, [flag_ptr]
372	add	w16, w16, #1
373	stxr	w17, w16, [flag_ptr]
374	cbnz	w17, 1b
375
376	/* Wait for the boot CPU to finish messing around with swapper */
377	sevl
3781:	wfe
379	ldxr	w16, [flag_ptr]
380	cbnz	w16, 1b
381
382	/* All done, act like nothing happened */
383	msr	ttbr1_el1, swapper_ttb
384	isb
385	ret
386
387	.unreq	swapper_ttb
388	.unreq	flag_ptr
389SYM_FUNC_END(idmap_kpti_install_ng_mappings)
390	.popsection
391#endif
392
393/*
394 *	__cpu_setup
395 *
396 *	Initialise the processor for turning the MMU on.
397 *
398 * Input:
399 *	x0 - actual number of VA bits (ignored unless VA_BITS > 48)
400 * Output:
401 *	Return in x0 the value of the SCTLR_EL1 register.
402 */
403	.pushsection ".idmap.text", "a"
404SYM_FUNC_START(__cpu_setup)
405	tlbi	vmalle1				// Invalidate local TLB
406	dsb	nsh
407
408	mov	x1, #3 << 20
409	msr	cpacr_el1, x1			// Enable FP/ASIMD
410	mov	x1, #1 << 12			// Reset mdscr_el1 and disable
411	msr	mdscr_el1, x1			// access to the DCC from EL0
412	isb					// Unmask debug exceptions now,
413	enable_dbg				// since this is per-cpu
414	reset_pmuserenr_el0 x1			// Disable PMU access from EL0
415	reset_amuserenr_el0 x1			// Disable AMU access from EL0
416
417	/*
418	 * Default values for VMSA control registers. These will be adjusted
419	 * below depending on detected CPU features.
420	 */
421	mair	.req	x17
422	tcr	.req	x16
423	mov_q	mair, MAIR_EL1_SET
424	mov_q	tcr, TCR_TxSZ(VA_BITS) | TCR_CACHE_FLAGS | TCR_SMP_FLAGS | \
425			TCR_TG_FLAGS | TCR_KASLR_FLAGS | TCR_ASID16 | \
426			TCR_TBI0 | TCR_A1 | TCR_KASAN_SW_FLAGS | TCR_MTE_FLAGS
427
428	tcr_clear_errata_bits tcr, x9, x5
429
430#ifdef CONFIG_ARM64_VA_BITS_52
431	sub		x9, xzr, x0
432	add		x9, x9, #64
433	tcr_set_t1sz	tcr, x9
434#else
435	idmap_get_t0sz	x9
436#endif
437	tcr_set_t0sz	tcr, x9
438
439	/*
440	 * Set the IPS bits in TCR_EL1.
441	 */
442	tcr_compute_pa_size tcr, #TCR_IPS_SHIFT, x5, x6
443#ifdef CONFIG_ARM64_HW_AFDBM
444	/*
445	 * Enable hardware update of the Access Flags bit.
446	 * Hardware dirty bit management is enabled later,
447	 * via capabilities.
448	 */
449	mrs	x9, ID_AA64MMFR1_EL1
450	and	x9, x9, #0xf
451	cbz	x9, 1f
452	orr	tcr, tcr, #TCR_HA		// hardware Access flag update
4531:
454#endif	/* CONFIG_ARM64_HW_AFDBM */
455	msr	mair_el1, mair
456	msr	tcr_el1, tcr
457	/*
458	 * Prepare SCTLR
459	 */
460	mov_q	x0, INIT_SCTLR_EL1_MMU_ON
461	ret					// return to head.S
462
463	.unreq	mair
464	.unreq	tcr
465SYM_FUNC_END(__cpu_setup)
466