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
28 enum 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
34 extern void slb_allocate_realmode(unsigned long ea);
35 extern void slb_allocate_user(unsigned long ea);
36
slb_allocate(unsigned long ea)37 static 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
mk_esid_data(unsigned long ea,int ssize,enum slb_index index)48 static 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
mk_vsid_data(unsigned long ea,int ssize,unsigned long flags)54 static 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
slb_shadow_update(unsigned long ea,int ssize,unsigned long flags,enum slb_index index)61 static 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 WRITE_ONCE(p->save_area[index].esid, 0);
73 WRITE_ONCE(p->save_area[index].vsid, cpu_to_be64(mk_vsid_data(ea, ssize, flags)));
74 WRITE_ONCE(p->save_area[index].esid, cpu_to_be64(mk_esid_data(ea, ssize, index)));
75 }
76
slb_shadow_clear(enum slb_index index)77 static inline void slb_shadow_clear(enum slb_index index)
78 {
79 WRITE_ONCE(get_slb_shadow()->save_area[index].esid, 0);
80 }
81
create_shadowed_slbe(unsigned long ea,int ssize,unsigned long flags,enum slb_index index)82 static 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
__slb_flush_and_rebolt(void)99 static 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
slb_flush_and_rebolt(void)139 void 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
slb_vmalloc_update(void)154 void 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 */
esids_match(unsigned long addr1,unsigned long addr2)169 static 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. */
switch_slb(struct task_struct * tsk,struct mm_struct * mm)193 void 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
patch_slb_encoding(unsigned int * insn_addr,unsigned int immed)254 static 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
275 extern u32 slb_miss_kernel_load_linear[];
276 extern u32 slb_miss_kernel_load_io[];
277 extern u32 slb_compare_rr_to_size[];
278 extern u32 slb_miss_kernel_load_vmemmap[];
279
slb_set_size(u16 size)280 void 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
slb_initialize(void)289 void 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 - 1;
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