1/*
2 * PowerPC64 SLB support.
3 *
4 * Copyright (C) 2004 David Gibson <dwg@au.ibm.com>, IBM
5 * Based on earlier code written by:
6 * Dave Engebretsen and Mike Corrigan {engebret|mikejc}@us.ibm.com
7 *    Copyright (c) 2001 Dave Engebretsen
8 * Copyright (C) 2002 Anton Blanchard <anton@au.ibm.com>, IBM
9 *
10 *
11 *      This program is free software; you can redistribute it and/or
12 *      modify it under the terms of the GNU General Public License
13 *      as published by the Free Software Foundation; either version
14 *      2 of the License, or (at your option) any later version.
15 */
16
17#include <asm/pgtable.h>
18#include <asm/mmu.h>
19#include <asm/mmu_context.h>
20#include <asm/paca.h>
21#include <asm/cputable.h>
22#include <asm/cacheflush.h>
23#include <asm/smp.h>
24#include <linux/compiler.h>
25#include <asm/udbg.h>
26#include <asm/code-patching.h>
27
28enum slb_index {
29	LINEAR_INDEX	= 0, /* Kernel linear map  (0xc000000000000000) */
30	VMALLOC_INDEX	= 1, /* Kernel virtual map (0xd000000000000000) */
31	KSTACK_INDEX	= 2, /* Kernel stack map */
32};
33
34extern void slb_allocate_realmode(unsigned long ea);
35extern void slb_allocate_user(unsigned long ea);
36
37static void slb_allocate(unsigned long ea)
38{
39	/* Currently, we do real mode for all SLBs including user, but
40	 * that will change if we bring back dynamic VSIDs
41	 */
42	slb_allocate_realmode(ea);
43}
44
45#define slb_esid_mask(ssize)	\
46	(((ssize) == MMU_SEGSIZE_256M)? ESID_MASK: ESID_MASK_1T)
47
48static inline unsigned long mk_esid_data(unsigned long ea, int ssize,
49					 enum slb_index index)
50{
51	return (ea & slb_esid_mask(ssize)) | SLB_ESID_V | index;
52}
53
54static inline unsigned long mk_vsid_data(unsigned long ea, int ssize,
55					 unsigned long flags)
56{
57	return (get_kernel_vsid(ea, ssize) << slb_vsid_shift(ssize)) | flags |
58		((unsigned long) ssize << SLB_VSID_SSIZE_SHIFT);
59}
60
61static inline void slb_shadow_update(unsigned long ea, int ssize,
62				     unsigned long flags,
63				     enum slb_index index)
64{
65	struct slb_shadow *p = get_slb_shadow();
66
67	/*
68	 * Clear the ESID first so the entry is not valid while we are
69	 * updating it.  No write barriers are needed here, provided
70	 * we only update the current CPU's SLB shadow buffer.
71	 */
72	p->save_area[index].esid = 0;
73	p->save_area[index].vsid = cpu_to_be64(mk_vsid_data(ea, ssize, flags));
74	p->save_area[index].esid = cpu_to_be64(mk_esid_data(ea, ssize, index));
75}
76
77static inline void slb_shadow_clear(enum slb_index index)
78{
79	get_slb_shadow()->save_area[index].esid = 0;
80}
81
82static inline void create_shadowed_slbe(unsigned long ea, int ssize,
83					unsigned long flags,
84					enum slb_index index)
85{
86	/*
87	 * Updating the shadow buffer before writing the SLB ensures
88	 * we don't get a stale entry here if we get preempted by PHYP
89	 * between these two statements.
90	 */
91	slb_shadow_update(ea, ssize, flags, index);
92
93	asm volatile("slbmte  %0,%1" :
94		     : "r" (mk_vsid_data(ea, ssize, flags)),
95		       "r" (mk_esid_data(ea, ssize, index))
96		     : "memory" );
97}
98
99static void __slb_flush_and_rebolt(void)
100{
101	/* If you change this make sure you change SLB_NUM_BOLTED
102	 * and PR KVM appropriately too. */
103	unsigned long linear_llp, vmalloc_llp, lflags, vflags;
104	unsigned long ksp_esid_data, ksp_vsid_data;
105
106	linear_llp = mmu_psize_defs[mmu_linear_psize].sllp;
107	vmalloc_llp = mmu_psize_defs[mmu_vmalloc_psize].sllp;
108	lflags = SLB_VSID_KERNEL | linear_llp;
109	vflags = SLB_VSID_KERNEL | vmalloc_llp;
110
111	ksp_esid_data = mk_esid_data(get_paca()->kstack, mmu_kernel_ssize, KSTACK_INDEX);
112	if ((ksp_esid_data & ~0xfffffffUL) <= PAGE_OFFSET) {
113		ksp_esid_data &= ~SLB_ESID_V;
114		ksp_vsid_data = 0;
115		slb_shadow_clear(KSTACK_INDEX);
116	} else {
117		/* Update stack entry; others don't change */
118		slb_shadow_update(get_paca()->kstack, mmu_kernel_ssize, lflags, KSTACK_INDEX);
119		ksp_vsid_data =
120			be64_to_cpu(get_slb_shadow()->save_area[KSTACK_INDEX].vsid);
121	}
122
123	/* We need to do this all in asm, so we're sure we don't touch
124	 * the stack between the slbia and rebolting it. */
125	asm volatile("isync\n"
126		     "slbia\n"
127		     /* Slot 1 - first VMALLOC segment */
128		     "slbmte	%0,%1\n"
129		     /* Slot 2 - kernel stack */
130		     "slbmte	%2,%3\n"
131		     "isync"
132		     :: "r"(mk_vsid_data(VMALLOC_START, mmu_kernel_ssize, vflags)),
133		        "r"(mk_esid_data(VMALLOC_START, mmu_kernel_ssize, 1)),
134		        "r"(ksp_vsid_data),
135		        "r"(ksp_esid_data)
136		     : "memory");
137}
138
139void slb_flush_and_rebolt(void)
140{
141
142	WARN_ON(!irqs_disabled());
143
144	/*
145	 * We can't take a PMU exception in the following code, so hard
146	 * disable interrupts.
147	 */
148	hard_irq_disable();
149
150	__slb_flush_and_rebolt();
151	get_paca()->slb_cache_ptr = 0;
152}
153
154void slb_vmalloc_update(void)
155{
156	unsigned long vflags;
157
158	vflags = SLB_VSID_KERNEL | mmu_psize_defs[mmu_vmalloc_psize].sllp;
159	slb_shadow_update(VMALLOC_START, mmu_kernel_ssize, vflags, VMALLOC_INDEX);
160	slb_flush_and_rebolt();
161}
162
163/* Helper function to compare esids.  There are four cases to handle.
164 * 1. The system is not 1T segment size capable.  Use the GET_ESID compare.
165 * 2. The system is 1T capable, both addresses are < 1T, use the GET_ESID compare.
166 * 3. The system is 1T capable, only one of the two addresses is > 1T.  This is not a match.
167 * 4. The system is 1T capable, both addresses are > 1T, use the GET_ESID_1T macro to compare.
168 */
169static inline int esids_match(unsigned long addr1, unsigned long addr2)
170{
171	int esid_1t_count;
172
173	/* System is not 1T segment size capable. */
174	if (!mmu_has_feature(MMU_FTR_1T_SEGMENT))
175		return (GET_ESID(addr1) == GET_ESID(addr2));
176
177	esid_1t_count = (((addr1 >> SID_SHIFT_1T) != 0) +
178				((addr2 >> SID_SHIFT_1T) != 0));
179
180	/* both addresses are < 1T */
181	if (esid_1t_count == 0)
182		return (GET_ESID(addr1) == GET_ESID(addr2));
183
184	/* One address < 1T, the other > 1T.  Not a match */
185	if (esid_1t_count == 1)
186		return 0;
187
188	/* Both addresses are > 1T. */
189	return (GET_ESID_1T(addr1) == GET_ESID_1T(addr2));
190}
191
192/* Flush all user entries from the segment table of the current processor. */
193void switch_slb(struct task_struct *tsk, struct mm_struct *mm)
194{
195	unsigned long offset;
196	unsigned long slbie_data = 0;
197	unsigned long pc = KSTK_EIP(tsk);
198	unsigned long stack = KSTK_ESP(tsk);
199	unsigned long exec_base;
200
201	/*
202	 * We need interrupts hard-disabled here, not just soft-disabled,
203	 * so that a PMU interrupt can't occur, which might try to access
204	 * user memory (to get a stack trace) and possible cause an SLB miss
205	 * which would update the slb_cache/slb_cache_ptr fields in the PACA.
206	 */
207	hard_irq_disable();
208	offset = get_paca()->slb_cache_ptr;
209	if (!mmu_has_feature(MMU_FTR_NO_SLBIE_B) &&
210	    offset <= SLB_CACHE_ENTRIES) {
211		int i;
212		asm volatile("isync" : : : "memory");
213		for (i = 0; i < offset; i++) {
214			slbie_data = (unsigned long)get_paca()->slb_cache[i]
215				<< SID_SHIFT; /* EA */
216			slbie_data |= user_segment_size(slbie_data)
217				<< SLBIE_SSIZE_SHIFT;
218			slbie_data |= SLBIE_C; /* C set for user addresses */
219			asm volatile("slbie %0" : : "r" (slbie_data));
220		}
221		asm volatile("isync" : : : "memory");
222	} else {
223		__slb_flush_and_rebolt();
224	}
225
226	/* Workaround POWER5 < DD2.1 issue */
227	if (offset == 1 || offset > SLB_CACHE_ENTRIES)
228		asm volatile("slbie %0" : : "r" (slbie_data));
229
230	get_paca()->slb_cache_ptr = 0;
231	get_paca()->context = mm->context;
232
233	/*
234	 * preload some userspace segments into the SLB.
235	 * Almost all 32 and 64bit PowerPC executables are linked at
236	 * 0x10000000 so it makes sense to preload this segment.
237	 */
238	exec_base = 0x10000000;
239
240	if (is_kernel_addr(pc) || is_kernel_addr(stack) ||
241	    is_kernel_addr(exec_base))
242		return;
243
244	slb_allocate(pc);
245
246	if (!esids_match(pc, stack))
247		slb_allocate(stack);
248
249	if (!esids_match(pc, exec_base) &&
250	    !esids_match(stack, exec_base))
251		slb_allocate(exec_base);
252}
253
254static inline void patch_slb_encoding(unsigned int *insn_addr,
255				      unsigned int immed)
256{
257
258	/*
259	 * This function patches either an li or a cmpldi instruction with
260	 * a new immediate value. This relies on the fact that both li
261	 * (which is actually addi) and cmpldi both take a 16-bit immediate
262	 * value, and it is situated in the same location in the instruction,
263	 * ie. bits 16-31 (Big endian bit order) or the lower 16 bits.
264	 * The signedness of the immediate operand differs between the two
265	 * instructions however this code is only ever patching a small value,
266	 * much less than 1 << 15, so we can get away with it.
267	 * To patch the value we read the existing instruction, clear the
268	 * immediate value, and or in our new value, then write the instruction
269	 * back.
270	 */
271	unsigned int insn = (*insn_addr & 0xffff0000) | immed;
272	patch_instruction(insn_addr, insn);
273}
274
275extern u32 slb_miss_kernel_load_linear[];
276extern u32 slb_miss_kernel_load_io[];
277extern u32 slb_compare_rr_to_size[];
278extern u32 slb_miss_kernel_load_vmemmap[];
279
280void slb_set_size(u16 size)
281{
282	if (mmu_slb_size == size)
283		return;
284
285	mmu_slb_size = size;
286	patch_slb_encoding(slb_compare_rr_to_size, mmu_slb_size);
287}
288
289void slb_initialize(void)
290{
291	unsigned long linear_llp, vmalloc_llp, io_llp;
292	unsigned long lflags, vflags;
293	static int slb_encoding_inited;
294#ifdef CONFIG_SPARSEMEM_VMEMMAP
295	unsigned long vmemmap_llp;
296#endif
297
298	/* Prepare our SLB miss handler based on our page size */
299	linear_llp = mmu_psize_defs[mmu_linear_psize].sllp;
300	io_llp = mmu_psize_defs[mmu_io_psize].sllp;
301	vmalloc_llp = mmu_psize_defs[mmu_vmalloc_psize].sllp;
302	get_paca()->vmalloc_sllp = SLB_VSID_KERNEL | vmalloc_llp;
303#ifdef CONFIG_SPARSEMEM_VMEMMAP
304	vmemmap_llp = mmu_psize_defs[mmu_vmemmap_psize].sllp;
305#endif
306	if (!slb_encoding_inited) {
307		slb_encoding_inited = 1;
308		patch_slb_encoding(slb_miss_kernel_load_linear,
309				   SLB_VSID_KERNEL | linear_llp);
310		patch_slb_encoding(slb_miss_kernel_load_io,
311				   SLB_VSID_KERNEL | io_llp);
312		patch_slb_encoding(slb_compare_rr_to_size,
313				   mmu_slb_size);
314
315		pr_devel("SLB: linear  LLP = %04lx\n", linear_llp);
316		pr_devel("SLB: io      LLP = %04lx\n", io_llp);
317
318#ifdef CONFIG_SPARSEMEM_VMEMMAP
319		patch_slb_encoding(slb_miss_kernel_load_vmemmap,
320				   SLB_VSID_KERNEL | vmemmap_llp);
321		pr_devel("SLB: vmemmap LLP = %04lx\n", vmemmap_llp);
322#endif
323	}
324
325	get_paca()->stab_rr = SLB_NUM_BOLTED;
326
327	lflags = SLB_VSID_KERNEL | linear_llp;
328	vflags = SLB_VSID_KERNEL | vmalloc_llp;
329
330	/* Invalidate the entire SLB (even entry 0) & all the ERATS */
331	asm volatile("isync":::"memory");
332	asm volatile("slbmte  %0,%0"::"r" (0) : "memory");
333	asm volatile("isync; slbia; isync":::"memory");
334	create_shadowed_slbe(PAGE_OFFSET, mmu_kernel_ssize, lflags, LINEAR_INDEX);
335	create_shadowed_slbe(VMALLOC_START, mmu_kernel_ssize, vflags, VMALLOC_INDEX);
336
337	/* For the boot cpu, we're running on the stack in init_thread_union,
338	 * which is in the first segment of the linear mapping, and also
339	 * get_paca()->kstack hasn't been initialized yet.
340	 * For secondary cpus, we need to bolt the kernel stack entry now.
341	 */
342	slb_shadow_clear(KSTACK_INDEX);
343	if (raw_smp_processor_id() != boot_cpuid &&
344	    (get_paca()->kstack & slb_esid_mask(mmu_kernel_ssize)) > PAGE_OFFSET)
345		create_shadowed_slbe(get_paca()->kstack,
346				     mmu_kernel_ssize, lflags, KSTACK_INDEX);
347
348	asm volatile("isync":::"memory");
349}
350