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1/*
2 * User-space Probes (UProbes) for s390
3 *
4 * Copyright IBM Corp. 2014
5 * Author(s): Jan Willeke,
6 */
7
8#include <linux/uaccess.h>
9#include <linux/uprobes.h>
10#include <linux/compat.h>
11#include <linux/kdebug.h>
12#include <asm/switch_to.h>
13#include <asm/facility.h>
14#include <asm/kprobes.h>
15#include <asm/dis.h>
16#include "entry.h"
17
18#define UPROBE_TRAP_NR UINT_MAX
19
20int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
21 unsigned long addr)
22{
23 return probe_is_prohibited_opcode(auprobe->insn);
24}
25
26int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
27{
28 if (psw_bits(regs->psw).eaba == PSW_AMODE_24BIT)
29 return -EINVAL;
30 if (!is_compat_task() && psw_bits(regs->psw).eaba == PSW_AMODE_31BIT)
31 return -EINVAL;
32 clear_pt_regs_flag(regs, PIF_PER_TRAP);
33 auprobe->saved_per = psw_bits(regs->psw).r;
34 auprobe->saved_int_code = regs->int_code;
35 regs->int_code = UPROBE_TRAP_NR;
36 regs->psw.addr = current->utask->xol_vaddr;
37 set_tsk_thread_flag(current, TIF_UPROBE_SINGLESTEP);
38 update_cr_regs(current);
39 return 0;
40}
41
42bool arch_uprobe_xol_was_trapped(struct task_struct *tsk)
43{
44 struct pt_regs *regs = task_pt_regs(tsk);
45
46 if (regs->int_code != UPROBE_TRAP_NR)
47 return true;
48 return false;
49}
50
51static int check_per_event(unsigned short cause, unsigned long control,
52 struct pt_regs *regs)
53{
54 if (!(regs->psw.mask & PSW_MASK_PER))
55 return 0;
56 /* user space single step */
57 if (control == 0)
58 return 1;
59 /* over indication for storage alteration */
60 if ((control & 0x20200000) && (cause & 0x2000))
61 return 1;
62 if (cause & 0x8000) {
63 /* all branches */
64 if ((control & 0x80800000) == 0x80000000)
65 return 1;
66 /* branch into selected range */
67 if (((control & 0x80800000) == 0x80800000) &&
68 regs->psw.addr >= current->thread.per_user.start &&
69 regs->psw.addr <= current->thread.per_user.end)
70 return 1;
71 }
72 return 0;
73}
74
75int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
76{
77 int fixup = probe_get_fixup_type(auprobe->insn);
78 struct uprobe_task *utask = current->utask;
79
80 clear_tsk_thread_flag(current, TIF_UPROBE_SINGLESTEP);
81 update_cr_regs(current);
82 psw_bits(regs->psw).r = auprobe->saved_per;
83 regs->int_code = auprobe->saved_int_code;
84
85 if (fixup & FIXUP_PSW_NORMAL)
86 regs->psw.addr += utask->vaddr - utask->xol_vaddr;
87 if (fixup & FIXUP_RETURN_REGISTER) {
88 int reg = (auprobe->insn[0] & 0xf0) >> 4;
89
90 regs->gprs[reg] += utask->vaddr - utask->xol_vaddr;
91 }
92 if (fixup & FIXUP_BRANCH_NOT_TAKEN) {
93 int ilen = insn_length(auprobe->insn[0] >> 8);
94
95 if (regs->psw.addr - utask->xol_vaddr == ilen)
96 regs->psw.addr = utask->vaddr + ilen;
97 }
98 if (check_per_event(current->thread.per_event.cause,
99 current->thread.per_user.control, regs)) {
100 /* fix per address */
101 current->thread.per_event.address = utask->vaddr;
102 /* trigger per event */
103 set_pt_regs_flag(regs, PIF_PER_TRAP);
104 }
105 return 0;
106}
107
108int arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val,
109 void *data)
110{
111 struct die_args *args = data;
112 struct pt_regs *regs = args->regs;
113
114 if (!user_mode(regs))
115 return NOTIFY_DONE;
116 if (regs->int_code & 0x200) /* Trap during transaction */
117 return NOTIFY_DONE;
118 switch (val) {
119 case DIE_BPT:
120 if (uprobe_pre_sstep_notifier(regs))
121 return NOTIFY_STOP;
122 break;
123 case DIE_SSTEP:
124 if (uprobe_post_sstep_notifier(regs))
125 return NOTIFY_STOP;
126 default:
127 break;
128 }
129 return NOTIFY_DONE;
130}
131
132void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
133{
134 clear_thread_flag(TIF_UPROBE_SINGLESTEP);
135 regs->int_code = auprobe->saved_int_code;
136 regs->psw.addr = current->utask->vaddr;
137 current->thread.per_event.address = current->utask->vaddr;
138}
139
140unsigned long arch_uretprobe_hijack_return_addr(unsigned long trampoline,
141 struct pt_regs *regs)
142{
143 unsigned long orig;
144
145 orig = regs->gprs[14];
146 regs->gprs[14] = trampoline;
147 return orig;
148}
149
150/* Instruction Emulation */
151
152static void adjust_psw_addr(psw_t *psw, unsigned long len)
153{
154 psw->addr = __rewind_psw(*psw, -len);
155}
156
157#define EMU_ILLEGAL_OP 1
158#define EMU_SPECIFICATION 2
159#define EMU_ADDRESSING 3
160
161#define emu_load_ril(ptr, output) \
162({ \
163 unsigned int mask = sizeof(*(ptr)) - 1; \
164 __typeof__(*(ptr)) input; \
165 int __rc = 0; \
166 \
167 if (!test_facility(34)) \
168 __rc = EMU_ILLEGAL_OP; \
169 else if ((u64 __force)ptr & mask) \
170 __rc = EMU_SPECIFICATION; \
171 else if (get_user(input, ptr)) \
172 __rc = EMU_ADDRESSING; \
173 else \
174 *(output) = input; \
175 __rc; \
176})
177
178#define emu_store_ril(regs, ptr, input) \
179({ \
180 unsigned int mask = sizeof(*(ptr)) - 1; \
181 __typeof__(ptr) __ptr = (ptr); \
182 int __rc = 0; \
183 \
184 if (!test_facility(34)) \
185 __rc = EMU_ILLEGAL_OP; \
186 else if ((u64 __force)__ptr & mask) \
187 __rc = EMU_SPECIFICATION; \
188 else if (put_user(*(input), __ptr)) \
189 __rc = EMU_ADDRESSING; \
190 if (__rc == 0) \
191 sim_stor_event(regs, \
192 (void __force *)__ptr, \
193 mask + 1); \
194 __rc; \
195})
196
197#define emu_cmp_ril(regs, ptr, cmp) \
198({ \
199 unsigned int mask = sizeof(*(ptr)) - 1; \
200 __typeof__(*(ptr)) input; \
201 int __rc = 0; \
202 \
203 if (!test_facility(34)) \
204 __rc = EMU_ILLEGAL_OP; \
205 else if ((u64 __force)ptr & mask) \
206 __rc = EMU_SPECIFICATION; \
207 else if (get_user(input, ptr)) \
208 __rc = EMU_ADDRESSING; \
209 else if (input > *(cmp)) \
210 psw_bits((regs)->psw).cc = 1; \
211 else if (input < *(cmp)) \
212 psw_bits((regs)->psw).cc = 2; \
213 else \
214 psw_bits((regs)->psw).cc = 0; \
215 __rc; \
216})
217
218struct insn_ril {
219 u8 opc0;
220 u8 reg : 4;
221 u8 opc1 : 4;
222 s32 disp;
223} __packed;
224
225union split_register {
226 u64 u64;
227 u32 u32[2];
228 u16 u16[4];
229 s64 s64;
230 s32 s32[2];
231 s16 s16[4];
232};
233
234/*
235 * If user per registers are setup to trace storage alterations and an
236 * emulated store took place on a fitting address a user trap is generated.
237 */
238static void sim_stor_event(struct pt_regs *regs, void *addr, int len)
239{
240 if (!(regs->psw.mask & PSW_MASK_PER))
241 return;
242 if (!(current->thread.per_user.control & PER_EVENT_STORE))
243 return;
244 if ((void *)current->thread.per_user.start > (addr + len))
245 return;
246 if ((void *)current->thread.per_user.end < addr)
247 return;
248 current->thread.per_event.address = regs->psw.addr;
249 current->thread.per_event.cause = PER_EVENT_STORE >> 16;
250 set_pt_regs_flag(regs, PIF_PER_TRAP);
251}
252
253/*
254 * pc relative instructions are emulated, since parameters may not be
255 * accessible from the xol area due to range limitations.
256 */
257static void handle_insn_ril(struct arch_uprobe *auprobe, struct pt_regs *regs)
258{
259 union split_register *rx;
260 struct insn_ril *insn;
261 unsigned int ilen;
262 void *uptr;
263 int rc = 0;
264
265 insn = (struct insn_ril *) &auprobe->insn;
266 rx = (union split_register *) ®s->gprs[insn->reg];
267 uptr = (void *)(regs->psw.addr + (insn->disp * 2));
268 ilen = insn_length(insn->opc0);
269
270 switch (insn->opc0) {
271 case 0xc0:
272 switch (insn->opc1) {
273 case 0x00: /* larl */
274 rx->u64 = (unsigned long)uptr;
275 break;
276 }
277 break;
278 case 0xc4:
279 switch (insn->opc1) {
280 case 0x02: /* llhrl */
281 rc = emu_load_ril((u16 __user *)uptr, &rx->u32[1]);
282 break;
283 case 0x04: /* lghrl */
284 rc = emu_load_ril((s16 __user *)uptr, &rx->u64);
285 break;
286 case 0x05: /* lhrl */
287 rc = emu_load_ril((s16 __user *)uptr, &rx->u32[1]);
288 break;
289 case 0x06: /* llghrl */
290 rc = emu_load_ril((u16 __user *)uptr, &rx->u64);
291 break;
292 case 0x08: /* lgrl */
293 rc = emu_load_ril((u64 __user *)uptr, &rx->u64);
294 break;
295 case 0x0c: /* lgfrl */
296 rc = emu_load_ril((s32 __user *)uptr, &rx->u64);
297 break;
298 case 0x0d: /* lrl */
299 rc = emu_load_ril((u32 __user *)uptr, &rx->u32[1]);
300 break;
301 case 0x0e: /* llgfrl */
302 rc = emu_load_ril((u32 __user *)uptr, &rx->u64);
303 break;
304 case 0x07: /* sthrl */
305 rc = emu_store_ril(regs, (u16 __user *)uptr, &rx->u16[3]);
306 break;
307 case 0x0b: /* stgrl */
308 rc = emu_store_ril(regs, (u64 __user *)uptr, &rx->u64);
309 break;
310 case 0x0f: /* strl */
311 rc = emu_store_ril(regs, (u32 __user *)uptr, &rx->u32[1]);
312 break;
313 }
314 break;
315 case 0xc6:
316 switch (insn->opc1) {
317 case 0x02: /* pfdrl */
318 if (!test_facility(34))
319 rc = EMU_ILLEGAL_OP;
320 break;
321 case 0x04: /* cghrl */
322 rc = emu_cmp_ril(regs, (s16 __user *)uptr, &rx->s64);
323 break;
324 case 0x05: /* chrl */
325 rc = emu_cmp_ril(regs, (s16 __user *)uptr, &rx->s32[1]);
326 break;
327 case 0x06: /* clghrl */
328 rc = emu_cmp_ril(regs, (u16 __user *)uptr, &rx->u64);
329 break;
330 case 0x07: /* clhrl */
331 rc = emu_cmp_ril(regs, (u16 __user *)uptr, &rx->u32[1]);
332 break;
333 case 0x08: /* cgrl */
334 rc = emu_cmp_ril(regs, (s64 __user *)uptr, &rx->s64);
335 break;
336 case 0x0a: /* clgrl */
337 rc = emu_cmp_ril(regs, (u64 __user *)uptr, &rx->u64);
338 break;
339 case 0x0c: /* cgfrl */
340 rc = emu_cmp_ril(regs, (s32 __user *)uptr, &rx->s64);
341 break;
342 case 0x0d: /* crl */
343 rc = emu_cmp_ril(regs, (s32 __user *)uptr, &rx->s32[1]);
344 break;
345 case 0x0e: /* clgfrl */
346 rc = emu_cmp_ril(regs, (u32 __user *)uptr, &rx->u64);
347 break;
348 case 0x0f: /* clrl */
349 rc = emu_cmp_ril(regs, (u32 __user *)uptr, &rx->u32[1]);
350 break;
351 }
352 break;
353 }
354 adjust_psw_addr(®s->psw, ilen);
355 switch (rc) {
356 case EMU_ILLEGAL_OP:
357 regs->int_code = ilen << 16 | 0x0001;
358 do_report_trap(regs, SIGILL, ILL_ILLOPC, NULL);
359 break;
360 case EMU_SPECIFICATION:
361 regs->int_code = ilen << 16 | 0x0006;
362 do_report_trap(regs, SIGILL, ILL_ILLOPC , NULL);
363 break;
364 case EMU_ADDRESSING:
365 regs->int_code = ilen << 16 | 0x0005;
366 do_report_trap(regs, SIGSEGV, SEGV_MAPERR, NULL);
367 break;
368 }
369}
370
371bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
372{
373 if ((psw_bits(regs->psw).eaba == PSW_AMODE_24BIT) ||
374 ((psw_bits(regs->psw).eaba == PSW_AMODE_31BIT) &&
375 !is_compat_task())) {
376 regs->psw.addr = __rewind_psw(regs->psw, UPROBE_SWBP_INSN_SIZE);
377 do_report_trap(regs, SIGILL, ILL_ILLADR, NULL);
378 return true;
379 }
380 if (probe_is_insn_relative_long(auprobe->insn)) {
381 handle_insn_ril(auprobe, regs);
382 return true;
383 }
384 return false;
385}