xref: /openbmc/linux/arch/arm64/mm/proc.S (revision d6869352) 
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 <asm/assembler.h>
13#include <asm/asm-offsets.h>
14#include <asm/hwcap.h>
15#include <asm/pgtable.h>
16#include <asm/pgtable-hwdef.h>
17#include <asm/cpufeature.h>
18#include <asm/alternative.h>
19
20#ifdef CONFIG_ARM64_64K_PAGES
21#define TCR_TG_FLAGS	TCR_TG0_64K | TCR_TG1_64K
22#elif defined(CONFIG_ARM64_16K_PAGES)
23#define TCR_TG_FLAGS	TCR_TG0_16K | TCR_TG1_16K
24#else /* CONFIG_ARM64_4K_PAGES */
25#define TCR_TG_FLAGS	TCR_TG0_4K | TCR_TG1_4K
26#endif
27
28#ifdef CONFIG_RANDOMIZE_BASE
29#define TCR_KASLR_FLAGS	TCR_NFD1
30#else
31#define TCR_KASLR_FLAGS	0
32#endif
33
34#define TCR_SMP_FLAGS	TCR_SHARED
35
36/* PTWs cacheable, inner/outer WBWA */
37#define TCR_CACHE_FLAGS	TCR_IRGN_WBWA | TCR_ORGN_WBWA
38
39#ifdef CONFIG_KASAN_SW_TAGS
40#define TCR_KASAN_FLAGS TCR_TBI1
41#else
42#define TCR_KASAN_FLAGS 0
43#endif
44
45#define MAIR(attr, mt)	((attr) << ((mt) * 8))
46
47#ifdef CONFIG_CPU_PM
48/**
49 * cpu_do_suspend - save CPU registers context
50 *
51 * x0: virtual address of context pointer
52 */
53ENTRY(cpu_do_suspend)
54	mrs	x2, tpidr_el0
55	mrs	x3, tpidrro_el0
56	mrs	x4, contextidr_el1
57	mrs	x5, osdlr_el1
58	mrs	x6, cpacr_el1
59	mrs	x7, tcr_el1
60	mrs	x8, vbar_el1
61	mrs	x9, mdscr_el1
62	mrs	x10, oslsr_el1
63	mrs	x11, sctlr_el1
64alternative_if_not ARM64_HAS_VIRT_HOST_EXTN
65	mrs	x12, tpidr_el1
66alternative_else
67	mrs	x12, tpidr_el2
68alternative_endif
69	mrs	x13, sp_el0
70	stp	x2, x3, [x0]
71	stp	x4, x5, [x0, #16]
72	stp	x6, x7, [x0, #32]
73	stp	x8, x9, [x0, #48]
74	stp	x10, x11, [x0, #64]
75	stp	x12, x13, [x0, #80]
76	ret
77ENDPROC(cpu_do_suspend)
78
79/**
80 * cpu_do_resume - restore CPU register context
81 *
82 * x0: Address of context pointer
83 */
84	.pushsection ".idmap.text", "awx"
85ENTRY(cpu_do_resume)
86	ldp	x2, x3, [x0]
87	ldp	x4, x5, [x0, #16]
88	ldp	x6, x8, [x0, #32]
89	ldp	x9, x10, [x0, #48]
90	ldp	x11, x12, [x0, #64]
91	ldp	x13, x14, [x0, #80]
92	msr	tpidr_el0, x2
93	msr	tpidrro_el0, x3
94	msr	contextidr_el1, x4
95	msr	cpacr_el1, x6
96
97	/* Don't change t0sz here, mask those bits when restoring */
98	mrs	x7, tcr_el1
99	bfi	x8, x7, TCR_T0SZ_OFFSET, TCR_TxSZ_WIDTH
100
101	msr	tcr_el1, x8
102	msr	vbar_el1, x9
103
104	/*
105	 * __cpu_setup() cleared MDSCR_EL1.MDE and friends, before unmasking
106	 * debug exceptions. By restoring MDSCR_EL1 here, we may take a debug
107	 * exception. Mask them until local_daif_restore() in cpu_suspend()
108	 * resets them.
109	 */
110	disable_daif
111	msr	mdscr_el1, x10
112
113	msr	sctlr_el1, x12
114alternative_if_not ARM64_HAS_VIRT_HOST_EXTN
115	msr	tpidr_el1, x13
116alternative_else
117	msr	tpidr_el2, x13
118alternative_endif
119	msr	sp_el0, x14
120	/*
121	 * Restore oslsr_el1 by writing oslar_el1
122	 */
123	msr	osdlr_el1, x5
124	ubfx	x11, x11, #1, #1
125	msr	oslar_el1, x11
126	reset_pmuserenr_el0 x0			// Disable PMU access from EL0
127
128alternative_if ARM64_HAS_RAS_EXTN
129	msr_s	SYS_DISR_EL1, xzr
130alternative_else_nop_endif
131
132	isb
133	ret
134ENDPROC(cpu_do_resume)
135	.popsection
136#endif
137
138/*
139 *	cpu_do_switch_mm(pgd_phys, tsk)
140 *
141 *	Set the translation table base pointer to be pgd_phys.
142 *
143 *	- pgd_phys - physical address of new TTB
144 */
145ENTRY(cpu_do_switch_mm)
146	mrs	x2, ttbr1_el1
147	mmid	x1, x1				// get mm->context.id
148	phys_to_ttbr x3, x0
149
150alternative_if ARM64_HAS_CNP
151	cbz     x1, 1f                          // skip CNP for reserved ASID
152	orr     x3, x3, #TTBR_CNP_BIT
1531:
154alternative_else_nop_endif
155#ifdef CONFIG_ARM64_SW_TTBR0_PAN
156	bfi	x3, x1, #48, #16		// set the ASID field in TTBR0
157#endif
158	bfi	x2, x1, #48, #16		// set the ASID
159	msr	ttbr1_el1, x2			// in TTBR1 (since TCR.A1 is set)
160	isb
161	msr	ttbr0_el1, x3			// now update TTBR0
162	isb
163	b	post_ttbr_update_workaround	// Back to C code...
164ENDPROC(cpu_do_switch_mm)
165
166	.pushsection ".idmap.text", "awx"
167
168.macro	__idmap_cpu_set_reserved_ttbr1, tmp1, tmp2
169	adrp	\tmp1, empty_zero_page
170	phys_to_ttbr \tmp2, \tmp1
171	offset_ttbr1 \tmp2
172	msr	ttbr1_el1, \tmp2
173	isb
174	tlbi	vmalle1
175	dsb	nsh
176	isb
177.endm
178
179/*
180 * void idmap_cpu_replace_ttbr1(phys_addr_t ttbr1)
181 *
182 * This is the low-level counterpart to cpu_replace_ttbr1, and should not be
183 * called by anything else. It can only be executed from a TTBR0 mapping.
184 */
185ENTRY(idmap_cpu_replace_ttbr1)
186	save_and_disable_daif flags=x2
187
188	__idmap_cpu_set_reserved_ttbr1 x1, x3
189
190	offset_ttbr1 x0
191	msr	ttbr1_el1, x0
192	isb
193
194	restore_daif x2
195
196	ret
197ENDPROC(idmap_cpu_replace_ttbr1)
198	.popsection
199
200#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
201	.pushsection ".idmap.text", "awx"
202
203	.macro	__idmap_kpti_get_pgtable_ent, type
204	dc	cvac, cur_\()\type\()p		// Ensure any existing dirty
205	dmb	sy				// lines are written back before
206	ldr	\type, [cur_\()\type\()p]	// loading the entry
207	tbz	\type, #0, skip_\()\type	// Skip invalid and
208	tbnz	\type, #11, skip_\()\type	// non-global entries
209	.endm
210
211	.macro __idmap_kpti_put_pgtable_ent_ng, type
212	orr	\type, \type, #PTE_NG		// Same bit for blocks and pages
213	str	\type, [cur_\()\type\()p]	// Update the entry and ensure
214	dmb	sy				// that it is visible to all
215	dc	civac, cur_\()\type\()p		// CPUs.
216	.endm
217
218/*
219 * void __kpti_install_ng_mappings(int cpu, int num_cpus, phys_addr_t swapper)
220 *
221 * Called exactly once from stop_machine context by each CPU found during boot.
222 */
223__idmap_kpti_flag:
224	.long	1
225ENTRY(idmap_kpti_install_ng_mappings)
226	cpu		.req	w0
227	num_cpus	.req	w1
228	swapper_pa	.req	x2
229	swapper_ttb	.req	x3
230	flag_ptr	.req	x4
231	cur_pgdp	.req	x5
232	end_pgdp	.req	x6
233	pgd		.req	x7
234	cur_pudp	.req	x8
235	end_pudp	.req	x9
236	pud		.req	x10
237	cur_pmdp	.req	x11
238	end_pmdp	.req	x12
239	pmd		.req	x13
240	cur_ptep	.req	x14
241	end_ptep	.req	x15
242	pte		.req	x16
243
244	mrs	swapper_ttb, ttbr1_el1
245	restore_ttbr1	swapper_ttb
246	adr	flag_ptr, __idmap_kpti_flag
247
248	cbnz	cpu, __idmap_kpti_secondary
249
250	/* We're the boot CPU. Wait for the others to catch up */
251	sevl
2521:	wfe
253	ldaxr	w18, [flag_ptr]
254	eor	w18, w18, num_cpus
255	cbnz	w18, 1b
256
257	/* We need to walk swapper, so turn off the MMU. */
258	pre_disable_mmu_workaround
259	mrs	x18, sctlr_el1
260	bic	x18, x18, #SCTLR_ELx_M
261	msr	sctlr_el1, x18
262	isb
263
264	/* Everybody is enjoying the idmap, so we can rewrite swapper. */
265	/* PGD */
266	mov	cur_pgdp, swapper_pa
267	add	end_pgdp, cur_pgdp, #(PTRS_PER_PGD * 8)
268do_pgd:	__idmap_kpti_get_pgtable_ent	pgd
269	tbnz	pgd, #1, walk_puds
270next_pgd:
271	__idmap_kpti_put_pgtable_ent_ng	pgd
272skip_pgd:
273	add	cur_pgdp, cur_pgdp, #8
274	cmp	cur_pgdp, end_pgdp
275	b.ne	do_pgd
276
277	/* Publish the updated tables and nuke all the TLBs */
278	dsb	sy
279	tlbi	vmalle1is
280	dsb	ish
281	isb
282
283	/* We're done: fire up the MMU again */
284	mrs	x18, sctlr_el1
285	orr	x18, x18, #SCTLR_ELx_M
286	msr	sctlr_el1, x18
287	isb
288
289	/* Set the flag to zero to indicate that we're all done */
290	str	wzr, [flag_ptr]
291	ret
292
293	/* PUD */
294walk_puds:
295	.if CONFIG_PGTABLE_LEVELS > 3
296	pte_to_phys	cur_pudp, pgd
297	add	end_pudp, cur_pudp, #(PTRS_PER_PUD * 8)
298do_pud:	__idmap_kpti_get_pgtable_ent	pud
299	tbnz	pud, #1, walk_pmds
300next_pud:
301	__idmap_kpti_put_pgtable_ent_ng	pud
302skip_pud:
303	add	cur_pudp, cur_pudp, 8
304	cmp	cur_pudp, end_pudp
305	b.ne	do_pud
306	b	next_pgd
307	.else /* CONFIG_PGTABLE_LEVELS <= 3 */
308	mov	pud, pgd
309	b	walk_pmds
310next_pud:
311	b	next_pgd
312	.endif
313
314	/* PMD */
315walk_pmds:
316	.if CONFIG_PGTABLE_LEVELS > 2
317	pte_to_phys	cur_pmdp, pud
318	add	end_pmdp, cur_pmdp, #(PTRS_PER_PMD * 8)
319do_pmd:	__idmap_kpti_get_pgtable_ent	pmd
320	tbnz	pmd, #1, walk_ptes
321next_pmd:
322	__idmap_kpti_put_pgtable_ent_ng	pmd
323skip_pmd:
324	add	cur_pmdp, cur_pmdp, #8
325	cmp	cur_pmdp, end_pmdp
326	b.ne	do_pmd
327	b	next_pud
328	.else /* CONFIG_PGTABLE_LEVELS <= 2 */
329	mov	pmd, pud
330	b	walk_ptes
331next_pmd:
332	b	next_pud
333	.endif
334
335	/* PTE */
336walk_ptes:
337	pte_to_phys	cur_ptep, pmd
338	add	end_ptep, cur_ptep, #(PTRS_PER_PTE * 8)
339do_pte:	__idmap_kpti_get_pgtable_ent	pte
340	__idmap_kpti_put_pgtable_ent_ng	pte
341skip_pte:
342	add	cur_ptep, cur_ptep, #8
343	cmp	cur_ptep, end_ptep
344	b.ne	do_pte
345	b	next_pmd
346
347	/* Secondary CPUs end up here */
348__idmap_kpti_secondary:
349	/* Uninstall swapper before surgery begins */
350	__idmap_cpu_set_reserved_ttbr1 x18, x17
351
352	/* Increment the flag to let the boot CPU we're ready */
3531:	ldxr	w18, [flag_ptr]
354	add	w18, w18, #1
355	stxr	w17, w18, [flag_ptr]
356	cbnz	w17, 1b
357
358	/* Wait for the boot CPU to finish messing around with swapper */
359	sevl
3601:	wfe
361	ldxr	w18, [flag_ptr]
362	cbnz	w18, 1b
363
364	/* All done, act like nothing happened */
365	offset_ttbr1 swapper_ttb
366	msr	ttbr1_el1, swapper_ttb
367	isb
368	ret
369
370	.unreq	cpu
371	.unreq	num_cpus
372	.unreq	swapper_pa
373	.unreq	swapper_ttb
374	.unreq	flag_ptr
375	.unreq	cur_pgdp
376	.unreq	end_pgdp
377	.unreq	pgd
378	.unreq	cur_pudp
379	.unreq	end_pudp
380	.unreq	pud
381	.unreq	cur_pmdp
382	.unreq	end_pmdp
383	.unreq	pmd
384	.unreq	cur_ptep
385	.unreq	end_ptep
386	.unreq	pte
387ENDPROC(idmap_kpti_install_ng_mappings)
388	.popsection
389#endif
390
391/*
392 *	__cpu_setup
393 *
394 *	Initialise the processor for turning the MMU on.  Return in x0 the
395 *	value of the SCTLR_EL1 register.
396 */
397	.pushsection ".idmap.text", "awx"
398ENTRY(__cpu_setup)
399	tlbi	vmalle1				// Invalidate local TLB
400	dsb	nsh
401
402	mov	x0, #3 << 20
403	msr	cpacr_el1, x0			// Enable FP/ASIMD
404	mov	x0, #1 << 12			// Reset mdscr_el1 and disable
405	msr	mdscr_el1, x0			// access to the DCC from EL0
406	isb					// Unmask debug exceptions now,
407	enable_dbg				// since this is per-cpu
408	reset_pmuserenr_el0 x0			// Disable PMU access from EL0
409	/*
410	 * Memory region attributes for LPAE:
411	 *
412	 *   n = AttrIndx[2:0]
413	 *			n	MAIR
414	 *   DEVICE_nGnRnE	000	00000000
415	 *   DEVICE_nGnRE	001	00000100
416	 *   DEVICE_GRE		010	00001100
417	 *   NORMAL_NC		011	01000100
418	 *   NORMAL		100	11111111
419	 *   NORMAL_WT		101	10111011
420	 */
421	ldr	x5, =MAIR(0x00, MT_DEVICE_nGnRnE) | \
422		     MAIR(0x04, MT_DEVICE_nGnRE) | \
423		     MAIR(0x0c, MT_DEVICE_GRE) | \
424		     MAIR(0x44, MT_NORMAL_NC) | \
425		     MAIR(0xff, MT_NORMAL) | \
426		     MAIR(0xbb, MT_NORMAL_WT)
427	msr	mair_el1, x5
428	/*
429	 * Prepare SCTLR
430	 */
431	mov_q	x0, SCTLR_EL1_SET
432	/*
433	 * Set/prepare TCR and TTBR. We use 512GB (39-bit) address range for
434	 * both user and kernel.
435	 */
436	ldr	x10, =TCR_TxSZ(VA_BITS) | TCR_CACHE_FLAGS | TCR_SMP_FLAGS | \
437			TCR_TG_FLAGS | TCR_KASLR_FLAGS | TCR_ASID16 | \
438			TCR_TBI0 | TCR_A1 | TCR_KASAN_FLAGS
439	tcr_clear_errata_bits x10, x9, x5
440
441#ifdef CONFIG_ARM64_USER_VA_BITS_52
442	ldr_l		x9, vabits_user
443	sub		x9, xzr, x9
444	add		x9, x9, #64
445#else
446	ldr_l		x9, idmap_t0sz
447#endif
448	tcr_set_t0sz	x10, x9
449
450	/*
451	 * Set the IPS bits in TCR_EL1.
452	 */
453	tcr_compute_pa_size x10, #TCR_IPS_SHIFT, x5, x6
454#ifdef CONFIG_ARM64_HW_AFDBM
455	/*
456	 * Enable hardware update of the Access Flags bit.
457	 * Hardware dirty bit management is enabled later,
458	 * via capabilities.
459	 */
460	mrs	x9, ID_AA64MMFR1_EL1
461	and	x9, x9, #0xf
462	cbz	x9, 1f
463	orr	x10, x10, #TCR_HA		// hardware Access flag update
4641:
465#endif	/* CONFIG_ARM64_HW_AFDBM */
466	msr	tcr_el1, x10
467	ret					// return to head.S
468ENDPROC(__cpu_setup)
469