xref: /openbmc/linux/arch/arm64/mm/proc.S (revision ed1666f6) 
1/*
2 * Based on arch/arm/mm/proc.S
3 *
4 * Copyright (C) 2001 Deep Blue Solutions Ltd.
5 * Copyright (C) 2012 ARM Ltd.
6 * Author: Catalin Marinas <catalin.marinas@arm.com>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
19 */
20
21#include <linux/init.h>
22#include <linux/linkage.h>
23#include <asm/assembler.h>
24#include <asm/asm-offsets.h>
25#include <asm/hwcap.h>
26#include <asm/pgtable.h>
27#include <asm/pgtable-hwdef.h>
28#include <asm/cpufeature.h>
29#include <asm/alternative.h>
30
31#ifdef CONFIG_ARM64_64K_PAGES
32#define TCR_TG_FLAGS	TCR_TG0_64K | TCR_TG1_64K
33#elif defined(CONFIG_ARM64_16K_PAGES)
34#define TCR_TG_FLAGS	TCR_TG0_16K | TCR_TG1_16K
35#else /* CONFIG_ARM64_4K_PAGES */
36#define TCR_TG_FLAGS	TCR_TG0_4K | TCR_TG1_4K
37#endif
38
39#ifdef CONFIG_RANDOMIZE_BASE
40#define TCR_KASLR_FLAGS	TCR_NFD1
41#else
42#define TCR_KASLR_FLAGS	0
43#endif
44
45#define TCR_SMP_FLAGS	TCR_SHARED
46
47/* PTWs cacheable, inner/outer WBWA */
48#define TCR_CACHE_FLAGS	TCR_IRGN_WBWA | TCR_ORGN_WBWA
49
50#ifdef CONFIG_KASAN_SW_TAGS
51#define TCR_KASAN_FLAGS TCR_TBI1
52#else
53#define TCR_KASAN_FLAGS 0
54#endif
55
56#define MAIR(attr, mt)	((attr) << ((mt) * 8))
57
58#ifdef CONFIG_CPU_PM
59/**
60 * cpu_do_suspend - save CPU registers context
61 *
62 * x0: virtual address of context pointer
63 */
64ENTRY(cpu_do_suspend)
65	mrs	x2, tpidr_el0
66	mrs	x3, tpidrro_el0
67	mrs	x4, contextidr_el1
68	mrs	x5, cpacr_el1
69	mrs	x6, tcr_el1
70	mrs	x7, vbar_el1
71	mrs	x8, mdscr_el1
72	mrs	x9, oslsr_el1
73	mrs	x10, sctlr_el1
74alternative_if_not ARM64_HAS_VIRT_HOST_EXTN
75	mrs	x11, tpidr_el1
76alternative_else
77	mrs	x11, tpidr_el2
78alternative_endif
79	mrs	x12, sp_el0
80	stp	x2, x3, [x0]
81	stp	x4, xzr, [x0, #16]
82	stp	x5, x6, [x0, #32]
83	stp	x7, x8, [x0, #48]
84	stp	x9, x10, [x0, #64]
85	stp	x11, x12, [x0, #80]
86	ret
87ENDPROC(cpu_do_suspend)
88
89/**
90 * cpu_do_resume - restore CPU register context
91 *
92 * x0: Address of context pointer
93 */
94	.pushsection ".idmap.text", "awx"
95ENTRY(cpu_do_resume)
96	ldp	x2, x3, [x0]
97	ldp	x4, x5, [x0, #16]
98	ldp	x6, x8, [x0, #32]
99	ldp	x9, x10, [x0, #48]
100	ldp	x11, x12, [x0, #64]
101	ldp	x13, x14, [x0, #80]
102	msr	tpidr_el0, x2
103	msr	tpidrro_el0, x3
104	msr	contextidr_el1, x4
105	msr	cpacr_el1, x6
106
107	/* Don't change t0sz here, mask those bits when restoring */
108	mrs	x5, tcr_el1
109	bfi	x8, x5, TCR_T0SZ_OFFSET, TCR_TxSZ_WIDTH
110
111	msr	tcr_el1, x8
112	msr	vbar_el1, x9
113
114	/*
115	 * __cpu_setup() cleared MDSCR_EL1.MDE and friends, before unmasking
116	 * debug exceptions. By restoring MDSCR_EL1 here, we may take a debug
117	 * exception. Mask them until local_daif_restore() in cpu_suspend()
118	 * resets them.
119	 */
120	disable_daif
121	msr	mdscr_el1, x10
122
123	msr	sctlr_el1, x12
124alternative_if_not ARM64_HAS_VIRT_HOST_EXTN
125	msr	tpidr_el1, x13
126alternative_else
127	msr	tpidr_el2, x13
128alternative_endif
129	msr	sp_el0, x14
130	/*
131	 * Restore oslsr_el1 by writing oslar_el1
132	 */
133	ubfx	x11, x11, #1, #1
134	msr	oslar_el1, x11
135	reset_pmuserenr_el0 x0			// Disable PMU access from EL0
136
137alternative_if ARM64_HAS_RAS_EXTN
138	msr_s	SYS_DISR_EL1, xzr
139alternative_else_nop_endif
140
141	isb
142	ret
143ENDPROC(cpu_do_resume)
144	.popsection
145#endif
146
147/*
148 *	cpu_do_switch_mm(pgd_phys, tsk)
149 *
150 *	Set the translation table base pointer to be pgd_phys.
151 *
152 *	- pgd_phys - physical address of new TTB
153 */
154ENTRY(cpu_do_switch_mm)
155	mrs	x2, ttbr1_el1
156	mmid	x1, x1				// get mm->context.id
157	phys_to_ttbr x3, x0
158
159alternative_if ARM64_HAS_CNP
160	cbz     x1, 1f                          // skip CNP for reserved ASID
161	orr     x3, x3, #TTBR_CNP_BIT
1621:
163alternative_else_nop_endif
164#ifdef CONFIG_ARM64_SW_TTBR0_PAN
165	bfi	x3, x1, #48, #16		// set the ASID field in TTBR0
166#endif
167	bfi	x2, x1, #48, #16		// set the ASID
168	msr	ttbr1_el1, x2			// in TTBR1 (since TCR.A1 is set)
169	isb
170	msr	ttbr0_el1, x3			// now update TTBR0
171	isb
172	b	post_ttbr_update_workaround	// Back to C code...
173ENDPROC(cpu_do_switch_mm)
174
175	.pushsection ".idmap.text", "awx"
176
177.macro	__idmap_cpu_set_reserved_ttbr1, tmp1, tmp2
178	adrp	\tmp1, empty_zero_page
179	phys_to_ttbr \tmp2, \tmp1
180	offset_ttbr1 \tmp2
181	msr	ttbr1_el1, \tmp2
182	isb
183	tlbi	vmalle1
184	dsb	nsh
185	isb
186.endm
187
188/*
189 * void idmap_cpu_replace_ttbr1(phys_addr_t ttbr1)
190 *
191 * This is the low-level counterpart to cpu_replace_ttbr1, and should not be
192 * called by anything else. It can only be executed from a TTBR0 mapping.
193 */
194ENTRY(idmap_cpu_replace_ttbr1)
195	save_and_disable_daif flags=x2
196
197	__idmap_cpu_set_reserved_ttbr1 x1, x3
198
199	offset_ttbr1 x0
200	msr	ttbr1_el1, x0
201	isb
202
203	restore_daif x2
204
205	ret
206ENDPROC(idmap_cpu_replace_ttbr1)
207	.popsection
208
209#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
210	.pushsection ".idmap.text", "awx"
211
212	.macro	__idmap_kpti_get_pgtable_ent, type
213	dc	cvac, cur_\()\type\()p		// Ensure any existing dirty
214	dmb	sy				// lines are written back before
215	ldr	\type, [cur_\()\type\()p]	// loading the entry
216	tbz	\type, #0, skip_\()\type	// Skip invalid and
217	tbnz	\type, #11, skip_\()\type	// non-global entries
218	.endm
219
220	.macro __idmap_kpti_put_pgtable_ent_ng, type
221	orr	\type, \type, #PTE_NG		// Same bit for blocks and pages
222	str	\type, [cur_\()\type\()p]	// Update the entry and ensure
223	dmb	sy				// that it is visible to all
224	dc	civac, cur_\()\type\()p		// CPUs.
225	.endm
226
227/*
228 * void __kpti_install_ng_mappings(int cpu, int num_cpus, phys_addr_t swapper)
229 *
230 * Called exactly once from stop_machine context by each CPU found during boot.
231 */
232__idmap_kpti_flag:
233	.long	1
234ENTRY(idmap_kpti_install_ng_mappings)
235	cpu		.req	w0
236	num_cpus	.req	w1
237	swapper_pa	.req	x2
238	swapper_ttb	.req	x3
239	flag_ptr	.req	x4
240	cur_pgdp	.req	x5
241	end_pgdp	.req	x6
242	pgd		.req	x7
243	cur_pudp	.req	x8
244	end_pudp	.req	x9
245	pud		.req	x10
246	cur_pmdp	.req	x11
247	end_pmdp	.req	x12
248	pmd		.req	x13
249	cur_ptep	.req	x14
250	end_ptep	.req	x15
251	pte		.req	x16
252
253	mrs	swapper_ttb, ttbr1_el1
254	restore_ttbr1	swapper_ttb
255	adr	flag_ptr, __idmap_kpti_flag
256
257	cbnz	cpu, __idmap_kpti_secondary
258
259	/* We're the boot CPU. Wait for the others to catch up */
260	sevl
2611:	wfe
262	ldaxr	w18, [flag_ptr]
263	eor	w18, w18, num_cpus
264	cbnz	w18, 1b
265
266	/* We need to walk swapper, so turn off the MMU. */
267	pre_disable_mmu_workaround
268	mrs	x18, sctlr_el1
269	bic	x18, x18, #SCTLR_ELx_M
270	msr	sctlr_el1, x18
271	isb
272
273	/* Everybody is enjoying the idmap, so we can rewrite swapper. */
274	/* PGD */
275	mov	cur_pgdp, swapper_pa
276	add	end_pgdp, cur_pgdp, #(PTRS_PER_PGD * 8)
277do_pgd:	__idmap_kpti_get_pgtable_ent	pgd
278	tbnz	pgd, #1, walk_puds
279next_pgd:
280	__idmap_kpti_put_pgtable_ent_ng	pgd
281skip_pgd:
282	add	cur_pgdp, cur_pgdp, #8
283	cmp	cur_pgdp, end_pgdp
284	b.ne	do_pgd
285
286	/* Publish the updated tables and nuke all the TLBs */
287	dsb	sy
288	tlbi	vmalle1is
289	dsb	ish
290	isb
291
292	/* We're done: fire up the MMU again */
293	mrs	x18, sctlr_el1
294	orr	x18, x18, #SCTLR_ELx_M
295	msr	sctlr_el1, x18
296	isb
297
298	/* Set the flag to zero to indicate that we're all done */
299	str	wzr, [flag_ptr]
300	ret
301
302	/* PUD */
303walk_puds:
304	.if CONFIG_PGTABLE_LEVELS > 3
305	pte_to_phys	cur_pudp, pgd
306	add	end_pudp, cur_pudp, #(PTRS_PER_PUD * 8)
307do_pud:	__idmap_kpti_get_pgtable_ent	pud
308	tbnz	pud, #1, walk_pmds
309next_pud:
310	__idmap_kpti_put_pgtable_ent_ng	pud
311skip_pud:
312	add	cur_pudp, cur_pudp, 8
313	cmp	cur_pudp, end_pudp
314	b.ne	do_pud
315	b	next_pgd
316	.else /* CONFIG_PGTABLE_LEVELS <= 3 */
317	mov	pud, pgd
318	b	walk_pmds
319next_pud:
320	b	next_pgd
321	.endif
322
323	/* PMD */
324walk_pmds:
325	.if CONFIG_PGTABLE_LEVELS > 2
326	pte_to_phys	cur_pmdp, pud
327	add	end_pmdp, cur_pmdp, #(PTRS_PER_PMD * 8)
328do_pmd:	__idmap_kpti_get_pgtable_ent	pmd
329	tbnz	pmd, #1, walk_ptes
330next_pmd:
331	__idmap_kpti_put_pgtable_ent_ng	pmd
332skip_pmd:
333	add	cur_pmdp, cur_pmdp, #8
334	cmp	cur_pmdp, end_pmdp
335	b.ne	do_pmd
336	b	next_pud
337	.else /* CONFIG_PGTABLE_LEVELS <= 2 */
338	mov	pmd, pud
339	b	walk_ptes
340next_pmd:
341	b	next_pud
342	.endif
343
344	/* PTE */
345walk_ptes:
346	pte_to_phys	cur_ptep, pmd
347	add	end_ptep, cur_ptep, #(PTRS_PER_PTE * 8)
348do_pte:	__idmap_kpti_get_pgtable_ent	pte
349	__idmap_kpti_put_pgtable_ent_ng	pte
350skip_pte:
351	add	cur_ptep, cur_ptep, #8
352	cmp	cur_ptep, end_ptep
353	b.ne	do_pte
354	b	next_pmd
355
356	/* Secondary CPUs end up here */
357__idmap_kpti_secondary:
358	/* Uninstall swapper before surgery begins */
359	__idmap_cpu_set_reserved_ttbr1 x18, x17
360
361	/* Increment the flag to let the boot CPU we're ready */
3621:	ldxr	w18, [flag_ptr]
363	add	w18, w18, #1
364	stxr	w17, w18, [flag_ptr]
365	cbnz	w17, 1b
366
367	/* Wait for the boot CPU to finish messing around with swapper */
368	sevl
3691:	wfe
370	ldxr	w18, [flag_ptr]
371	cbnz	w18, 1b
372
373	/* All done, act like nothing happened */
374	offset_ttbr1 swapper_ttb
375	msr	ttbr1_el1, swapper_ttb
376	isb
377	ret
378
379	.unreq	cpu
380	.unreq	num_cpus
381	.unreq	swapper_pa
382	.unreq	swapper_ttb
383	.unreq	flag_ptr
384	.unreq	cur_pgdp
385	.unreq	end_pgdp
386	.unreq	pgd
387	.unreq	cur_pudp
388	.unreq	end_pudp
389	.unreq	pud
390	.unreq	cur_pmdp
391	.unreq	end_pmdp
392	.unreq	pmd
393	.unreq	cur_ptep
394	.unreq	end_ptep
395	.unreq	pte
396ENDPROC(idmap_kpti_install_ng_mappings)
397	.popsection
398#endif
399
400/*
401 *	__cpu_setup
402 *
403 *	Initialise the processor for turning the MMU on.  Return in x0 the
404 *	value of the SCTLR_EL1 register.
405 */
406	.pushsection ".idmap.text", "awx"
407ENTRY(__cpu_setup)
408	tlbi	vmalle1				// Invalidate local TLB
409	dsb	nsh
410
411	mov	x0, #3 << 20
412	msr	cpacr_el1, x0			// Enable FP/ASIMD
413	mov	x0, #1 << 12			// Reset mdscr_el1 and disable
414	msr	mdscr_el1, x0			// access to the DCC from EL0
415	isb					// Unmask debug exceptions now,
416	enable_dbg				// since this is per-cpu
417	reset_pmuserenr_el0 x0			// Disable PMU access from EL0
418	/*
419	 * Memory region attributes for LPAE:
420	 *
421	 *   n = AttrIndx[2:0]
422	 *			n	MAIR
423	 *   DEVICE_nGnRnE	000	00000000
424	 *   DEVICE_nGnRE	001	00000100
425	 *   DEVICE_GRE		010	00001100
426	 *   NORMAL_NC		011	01000100
427	 *   NORMAL		100	11111111
428	 *   NORMAL_WT		101	10111011
429	 */
430	ldr	x5, =MAIR(0x00, MT_DEVICE_nGnRnE) | \
431		     MAIR(0x04, MT_DEVICE_nGnRE) | \
432		     MAIR(0x0c, MT_DEVICE_GRE) | \
433		     MAIR(0x44, MT_NORMAL_NC) | \
434		     MAIR(0xff, MT_NORMAL) | \
435		     MAIR(0xbb, MT_NORMAL_WT)
436	msr	mair_el1, x5
437	/*
438	 * Prepare SCTLR
439	 */
440	mov_q	x0, SCTLR_EL1_SET
441	/*
442	 * Set/prepare TCR and TTBR. We use 512GB (39-bit) address range for
443	 * both user and kernel.
444	 */
445	ldr	x10, =TCR_TxSZ(VA_BITS) | TCR_CACHE_FLAGS | TCR_SMP_FLAGS | \
446			TCR_TG_FLAGS | TCR_KASLR_FLAGS | TCR_ASID16 | \
447			TCR_TBI0 | TCR_A1 | TCR_KASAN_FLAGS
448	tcr_clear_errata_bits x10, x9, x5
449
450#ifdef CONFIG_ARM64_USER_VA_BITS_52
451	ldr_l		x9, vabits_user
452	sub		x9, xzr, x9
453	add		x9, x9, #64
454#else
455	ldr_l		x9, idmap_t0sz
456#endif
457	tcr_set_t0sz	x10, x9
458
459	/*
460	 * Set the IPS bits in TCR_EL1.
461	 */
462	tcr_compute_pa_size x10, #TCR_IPS_SHIFT, x5, x6
463#ifdef CONFIG_ARM64_HW_AFDBM
464	/*
465	 * Enable hardware update of the Access Flags bit.
466	 * Hardware dirty bit management is enabled later,
467	 * via capabilities.
468	 */
469	mrs	x9, ID_AA64MMFR1_EL1
470	and	x9, x9, #0xf
471	cbz	x9, 1f
472	orr	x10, x10, #TCR_HA		// hardware Access flag update
4731:
474#endif	/* CONFIG_ARM64_HW_AFDBM */
475	msr	tcr_el1, x10
476	ret					// return to head.S
477ENDPROC(__cpu_setup)
478