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1/*
2 * Based on arch/arm/kernel/signal.c
3 *
4 * Copyright (C) 1995-2009 Russell King
5 * Copyright (C) 2012 ARM Ltd.
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
18 */
19
20#include <linux/compat.h>
21#include <linux/errno.h>
22#include <linux/signal.h>
23#include <linux/personality.h>
24#include <linux/freezer.h>
25#include <linux/uaccess.h>
26#include <linux/tracehook.h>
27#include <linux/ratelimit.h>
28
29#include <asm/debug-monitors.h>
30#include <asm/elf.h>
31#include <asm/cacheflush.h>
32#include <asm/ucontext.h>
33#include <asm/unistd.h>
34#include <asm/fpsimd.h>
35#include <asm/signal32.h>
36#include <asm/vdso.h>
37
38/*
39 * Do a signal return; undo the signal stack. These are aligned to 128-bit.
40 */
41struct rt_sigframe {
42 struct siginfo info;
43 struct ucontext uc;
44 u64 fp;
45 u64 lr;
46};
47
48static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
49{
50 struct fpsimd_state *fpsimd = ¤t->thread.fpsimd_state;
51 int err;
52
53 /* dump the hardware registers to the fpsimd_state structure */
54 fpsimd_preserve_current_state();
55
56 /* copy the FP and status/control registers */
57 err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs));
58 __put_user_error(fpsimd->fpsr, &ctx->fpsr, err);
59 __put_user_error(fpsimd->fpcr, &ctx->fpcr, err);
60
61 /* copy the magic/size information */
62 __put_user_error(FPSIMD_MAGIC, &ctx->head.magic, err);
63 __put_user_error(sizeof(struct fpsimd_context), &ctx->head.size, err);
64
65 return err ? -EFAULT : 0;
66}
67
68static int restore_fpsimd_context(struct fpsimd_context __user *ctx)
69{
70 struct fpsimd_state fpsimd;
71 __u32 magic, size;
72 int err = 0;
73
74 /* check the magic/size information */
75 __get_user_error(magic, &ctx->head.magic, err);
76 __get_user_error(size, &ctx->head.size, err);
77 if (err)
78 return -EFAULT;
79 if (magic != FPSIMD_MAGIC || size != sizeof(struct fpsimd_context))
80 return -EINVAL;
81
82 /* copy the FP and status/control registers */
83 err = __copy_from_user(fpsimd.vregs, ctx->vregs,
84 sizeof(fpsimd.vregs));
85 __get_user_error(fpsimd.fpsr, &ctx->fpsr, err);
86 __get_user_error(fpsimd.fpcr, &ctx->fpcr, err);
87
88 /* load the hardware registers from the fpsimd_state structure */
89 if (!err)
90 fpsimd_update_current_state(&fpsimd);
91
92 return err ? -EFAULT : 0;
93}
94
95static int restore_sigframe(struct pt_regs *regs,
96 struct rt_sigframe __user *sf)
97{
98 sigset_t set;
99 int i, err;
100 void *aux = sf->uc.uc_mcontext.__reserved;
101
102 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
103 if (err == 0)
104 set_current_blocked(&set);
105
106 for (i = 0; i < 31; i++)
107 __get_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
108 err);
109 __get_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
110 __get_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
111 __get_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
112
113 /*
114 * Avoid sys_rt_sigreturn() restarting.
115 */
116 regs->syscallno = ~0UL;
117
118 err |= !valid_user_regs(®s->user_regs, current);
119
120 if (err == 0) {
121 struct fpsimd_context *fpsimd_ctx =
122 container_of(aux, struct fpsimd_context, head);
123 err |= restore_fpsimd_context(fpsimd_ctx);
124 }
125
126 return err;
127}
128
129asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
130{
131 struct rt_sigframe __user *frame;
132
133 /* Always make any pending restarted system calls return -EINTR */
134 current->restart_block.fn = do_no_restart_syscall;
135
136 /*
137 * Since we stacked the signal on a 128-bit boundary, then 'sp' should
138 * be word aligned here.
139 */
140 if (regs->sp & 15)
141 goto badframe;
142
143 frame = (struct rt_sigframe __user *)regs->sp;
144
145 if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
146 goto badframe;
147
148 if (restore_sigframe(regs, frame))
149 goto badframe;
150
151 if (restore_altstack(&frame->uc.uc_stack))
152 goto badframe;
153
154 return regs->regs[0];
155
156badframe:
157 if (show_unhandled_signals)
158 pr_info_ratelimited("%s[%d]: bad frame in %s: pc=%08llx sp=%08llx\n",
159 current->comm, task_pid_nr(current), __func__,
160 regs->pc, regs->sp);
161 force_sig(SIGSEGV, current);
162 return 0;
163}
164
165static int setup_sigframe(struct rt_sigframe __user *sf,
166 struct pt_regs *regs, sigset_t *set)
167{
168 int i, err = 0;
169 void *aux = sf->uc.uc_mcontext.__reserved;
170 struct _aarch64_ctx *end;
171
172 /* set up the stack frame for unwinding */
173 __put_user_error(regs->regs[29], &sf->fp, err);
174 __put_user_error(regs->regs[30], &sf->lr, err);
175
176 for (i = 0; i < 31; i++)
177 __put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
178 err);
179 __put_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
180 __put_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
181 __put_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
182
183 __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
184
185 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
186
187 if (err == 0) {
188 struct fpsimd_context *fpsimd_ctx =
189 container_of(aux, struct fpsimd_context, head);
190 err |= preserve_fpsimd_context(fpsimd_ctx);
191 aux += sizeof(*fpsimd_ctx);
192 }
193
194 /* fault information, if valid */
195 if (current->thread.fault_code) {
196 struct esr_context *esr_ctx =
197 container_of(aux, struct esr_context, head);
198 __put_user_error(ESR_MAGIC, &esr_ctx->head.magic, err);
199 __put_user_error(sizeof(*esr_ctx), &esr_ctx->head.size, err);
200 __put_user_error(current->thread.fault_code, &esr_ctx->esr, err);
201 aux += sizeof(*esr_ctx);
202 }
203
204 /* set the "end" magic */
205 end = aux;
206 __put_user_error(0, &end->magic, err);
207 __put_user_error(0, &end->size, err);
208
209 return err;
210}
211
212static struct rt_sigframe __user *get_sigframe(struct ksignal *ksig,
213 struct pt_regs *regs)
214{
215 unsigned long sp, sp_top;
216 struct rt_sigframe __user *frame;
217
218 sp = sp_top = sigsp(regs->sp, ksig);
219
220 sp = (sp - sizeof(struct rt_sigframe)) & ~15;
221 frame = (struct rt_sigframe __user *)sp;
222
223 /*
224 * Check that we can actually write to the signal frame.
225 */
226 if (!access_ok(VERIFY_WRITE, frame, sp_top - sp))
227 frame = NULL;
228
229 return frame;
230}
231
232static void setup_return(struct pt_regs *regs, struct k_sigaction *ka,
233 void __user *frame, int usig)
234{
235 __sigrestore_t sigtramp;
236
237 regs->regs[0] = usig;
238 regs->sp = (unsigned long)frame;
239 regs->regs[29] = regs->sp + offsetof(struct rt_sigframe, fp);
240 regs->pc = (unsigned long)ka->sa.sa_handler;
241
242 if (ka->sa.sa_flags & SA_RESTORER)
243 sigtramp = ka->sa.sa_restorer;
244 else
245 sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp);
246
247 regs->regs[30] = (unsigned long)sigtramp;
248}
249
250static int setup_rt_frame(int usig, struct ksignal *ksig, sigset_t *set,
251 struct pt_regs *regs)
252{
253 struct rt_sigframe __user *frame;
254 int err = 0;
255
256 frame = get_sigframe(ksig, regs);
257 if (!frame)
258 return 1;
259
260 __put_user_error(0, &frame->uc.uc_flags, err);
261 __put_user_error(NULL, &frame->uc.uc_link, err);
262
263 err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
264 err |= setup_sigframe(frame, regs, set);
265 if (err == 0) {
266 setup_return(regs, &ksig->ka, frame, usig);
267 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
268 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
269 regs->regs[1] = (unsigned long)&frame->info;
270 regs->regs[2] = (unsigned long)&frame->uc;
271 }
272 }
273
274 return err;
275}
276
277static void setup_restart_syscall(struct pt_regs *regs)
278{
279 if (is_compat_task())
280 compat_setup_restart_syscall(regs);
281 else
282 regs->regs[8] = __NR_restart_syscall;
283}
284
285/*
286 * OK, we're invoking a handler
287 */
288static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
289{
290 struct task_struct *tsk = current;
291 sigset_t *oldset = sigmask_to_save();
292 int usig = ksig->sig;
293 int ret;
294
295 /*
296 * Set up the stack frame
297 */
298 if (is_compat_task()) {
299 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
300 ret = compat_setup_rt_frame(usig, ksig, oldset, regs);
301 else
302 ret = compat_setup_frame(usig, ksig, oldset, regs);
303 } else {
304 ret = setup_rt_frame(usig, ksig, oldset, regs);
305 }
306
307 /*
308 * Check that the resulting registers are actually sane.
309 */
310 ret |= !valid_user_regs(®s->user_regs, current);
311
312 /*
313 * Fast forward the stepping logic so we step into the signal
314 * handler.
315 */
316 if (!ret)
317 user_fastforward_single_step(tsk);
318
319 signal_setup_done(ret, ksig, 0);
320}
321
322/*
323 * Note that 'init' is a special process: it doesn't get signals it doesn't
324 * want to handle. Thus you cannot kill init even with a SIGKILL even by
325 * mistake.
326 *
327 * Note that we go through the signals twice: once to check the signals that
328 * the kernel can handle, and then we build all the user-level signal handling
329 * stack-frames in one go after that.
330 */
331static void do_signal(struct pt_regs *regs)
332{
333 unsigned long continue_addr = 0, restart_addr = 0;
334 int retval = 0;
335 int syscall = (int)regs->syscallno;
336 struct ksignal ksig;
337
338 /*
339 * If we were from a system call, check for system call restarting...
340 */
341 if (syscall >= 0) {
342 continue_addr = regs->pc;
343 restart_addr = continue_addr - (compat_thumb_mode(regs) ? 2 : 4);
344 retval = regs->regs[0];
345
346 /*
347 * Avoid additional syscall restarting via ret_to_user.
348 */
349 regs->syscallno = ~0UL;
350
351 /*
352 * Prepare for system call restart. We do this here so that a
353 * debugger will see the already changed PC.
354 */
355 switch (retval) {
356 case -ERESTARTNOHAND:
357 case -ERESTARTSYS:
358 case -ERESTARTNOINTR:
359 case -ERESTART_RESTARTBLOCK:
360 regs->regs[0] = regs->orig_x0;
361 regs->pc = restart_addr;
362 break;
363 }
364 }
365
366 /*
367 * Get the signal to deliver. When running under ptrace, at this point
368 * the debugger may change all of our registers.
369 */
370 if (get_signal(&ksig)) {
371 /*
372 * Depending on the signal settings, we may need to revert the
373 * decision to restart the system call, but skip this if a
374 * debugger has chosen to restart at a different PC.
375 */
376 if (regs->pc == restart_addr &&
377 (retval == -ERESTARTNOHAND ||
378 retval == -ERESTART_RESTARTBLOCK ||
379 (retval == -ERESTARTSYS &&
380 !(ksig.ka.sa.sa_flags & SA_RESTART)))) {
381 regs->regs[0] = -EINTR;
382 regs->pc = continue_addr;
383 }
384
385 handle_signal(&ksig, regs);
386 return;
387 }
388
389 /*
390 * Handle restarting a different system call. As above, if a debugger
391 * has chosen to restart at a different PC, ignore the restart.
392 */
393 if (syscall >= 0 && regs->pc == restart_addr) {
394 if (retval == -ERESTART_RESTARTBLOCK)
395 setup_restart_syscall(regs);
396 user_rewind_single_step(current);
397 }
398
399 restore_saved_sigmask();
400}
401
402asmlinkage void do_notify_resume(struct pt_regs *regs,
403 unsigned int thread_flags)
404{
405 if (thread_flags & _TIF_SIGPENDING)
406 do_signal(regs);
407
408 if (thread_flags & _TIF_NOTIFY_RESUME) {
409 clear_thread_flag(TIF_NOTIFY_RESUME);
410 tracehook_notify_resume(regs);
411 }
412
413 if (thread_flags & _TIF_FOREIGN_FPSTATE)
414 fpsimd_restore_current_state();
415
416}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Based on arch/arm/kernel/signal.c
4 *
5 * Copyright (C) 1995-2009 Russell King
6 * Copyright (C) 2012 ARM Ltd.
7 */
8
9#include <linux/cache.h>
10#include <linux/compat.h>
11#include <linux/errno.h>
12#include <linux/kernel.h>
13#include <linux/signal.h>
14#include <linux/personality.h>
15#include <linux/freezer.h>
16#include <linux/stddef.h>
17#include <linux/uaccess.h>
18#include <linux/sizes.h>
19#include <linux/string.h>
20#include <linux/tracehook.h>
21#include <linux/ratelimit.h>
22#include <linux/syscalls.h>
23
24#include <asm/daifflags.h>
25#include <asm/debug-monitors.h>
26#include <asm/elf.h>
27#include <asm/cacheflush.h>
28#include <asm/ucontext.h>
29#include <asm/unistd.h>
30#include <asm/fpsimd.h>
31#include <asm/ptrace.h>
32#include <asm/signal32.h>
33#include <asm/traps.h>
34#include <asm/vdso.h>
35
36/*
37 * Do a signal return; undo the signal stack. These are aligned to 128-bit.
38 */
39struct rt_sigframe {
40 struct siginfo info;
41 struct ucontext uc;
42};
43
44struct frame_record {
45 u64 fp;
46 u64 lr;
47};
48
49struct rt_sigframe_user_layout {
50 struct rt_sigframe __user *sigframe;
51 struct frame_record __user *next_frame;
52
53 unsigned long size; /* size of allocated sigframe data */
54 unsigned long limit; /* largest allowed size */
55
56 unsigned long fpsimd_offset;
57 unsigned long esr_offset;
58 unsigned long sve_offset;
59 unsigned long extra_offset;
60 unsigned long end_offset;
61};
62
63#define BASE_SIGFRAME_SIZE round_up(sizeof(struct rt_sigframe), 16)
64#define TERMINATOR_SIZE round_up(sizeof(struct _aarch64_ctx), 16)
65#define EXTRA_CONTEXT_SIZE round_up(sizeof(struct extra_context), 16)
66
67static void init_user_layout(struct rt_sigframe_user_layout *user)
68{
69 const size_t reserved_size =
70 sizeof(user->sigframe->uc.uc_mcontext.__reserved);
71
72 memset(user, 0, sizeof(*user));
73 user->size = offsetof(struct rt_sigframe, uc.uc_mcontext.__reserved);
74
75 user->limit = user->size + reserved_size;
76
77 user->limit -= TERMINATOR_SIZE;
78 user->limit -= EXTRA_CONTEXT_SIZE;
79 /* Reserve space for extension and terminator ^ */
80}
81
82static size_t sigframe_size(struct rt_sigframe_user_layout const *user)
83{
84 return round_up(max(user->size, sizeof(struct rt_sigframe)), 16);
85}
86
87/*
88 * Sanity limit on the approximate maximum size of signal frame we'll
89 * try to generate. Stack alignment padding and the frame record are
90 * not taken into account. This limit is not a guarantee and is
91 * NOT ABI.
92 */
93#define SIGFRAME_MAXSZ SZ_64K
94
95static int __sigframe_alloc(struct rt_sigframe_user_layout *user,
96 unsigned long *offset, size_t size, bool extend)
97{
98 size_t padded_size = round_up(size, 16);
99
100 if (padded_size > user->limit - user->size &&
101 !user->extra_offset &&
102 extend) {
103 int ret;
104
105 user->limit += EXTRA_CONTEXT_SIZE;
106 ret = __sigframe_alloc(user, &user->extra_offset,
107 sizeof(struct extra_context), false);
108 if (ret) {
109 user->limit -= EXTRA_CONTEXT_SIZE;
110 return ret;
111 }
112
113 /* Reserve space for the __reserved[] terminator */
114 user->size += TERMINATOR_SIZE;
115
116 /*
117 * Allow expansion up to SIGFRAME_MAXSZ, ensuring space for
118 * the terminator:
119 */
120 user->limit = SIGFRAME_MAXSZ - TERMINATOR_SIZE;
121 }
122
123 /* Still not enough space? Bad luck! */
124 if (padded_size > user->limit - user->size)
125 return -ENOMEM;
126
127 *offset = user->size;
128 user->size += padded_size;
129
130 return 0;
131}
132
133/*
134 * Allocate space for an optional record of <size> bytes in the user
135 * signal frame. The offset from the signal frame base address to the
136 * allocated block is assigned to *offset.
137 */
138static int sigframe_alloc(struct rt_sigframe_user_layout *user,
139 unsigned long *offset, size_t size)
140{
141 return __sigframe_alloc(user, offset, size, true);
142}
143
144/* Allocate the null terminator record and prevent further allocations */
145static int sigframe_alloc_end(struct rt_sigframe_user_layout *user)
146{
147 int ret;
148
149 /* Un-reserve the space reserved for the terminator: */
150 user->limit += TERMINATOR_SIZE;
151
152 ret = sigframe_alloc(user, &user->end_offset,
153 sizeof(struct _aarch64_ctx));
154 if (ret)
155 return ret;
156
157 /* Prevent further allocation: */
158 user->limit = user->size;
159 return 0;
160}
161
162static void __user *apply_user_offset(
163 struct rt_sigframe_user_layout const *user, unsigned long offset)
164{
165 char __user *base = (char __user *)user->sigframe;
166
167 return base + offset;
168}
169
170static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
171{
172 struct user_fpsimd_state const *fpsimd =
173 ¤t->thread.uw.fpsimd_state;
174 int err;
175
176 /* copy the FP and status/control registers */
177 err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs));
178 __put_user_error(fpsimd->fpsr, &ctx->fpsr, err);
179 __put_user_error(fpsimd->fpcr, &ctx->fpcr, err);
180
181 /* copy the magic/size information */
182 __put_user_error(FPSIMD_MAGIC, &ctx->head.magic, err);
183 __put_user_error(sizeof(struct fpsimd_context), &ctx->head.size, err);
184
185 return err ? -EFAULT : 0;
186}
187
188static int restore_fpsimd_context(struct fpsimd_context __user *ctx)
189{
190 struct user_fpsimd_state fpsimd;
191 __u32 magic, size;
192 int err = 0;
193
194 /* check the magic/size information */
195 __get_user_error(magic, &ctx->head.magic, err);
196 __get_user_error(size, &ctx->head.size, err);
197 if (err)
198 return -EFAULT;
199 if (magic != FPSIMD_MAGIC || size != sizeof(struct fpsimd_context))
200 return -EINVAL;
201
202 /* copy the FP and status/control registers */
203 err = __copy_from_user(fpsimd.vregs, ctx->vregs,
204 sizeof(fpsimd.vregs));
205 __get_user_error(fpsimd.fpsr, &ctx->fpsr, err);
206 __get_user_error(fpsimd.fpcr, &ctx->fpcr, err);
207
208 clear_thread_flag(TIF_SVE);
209
210 /* load the hardware registers from the fpsimd_state structure */
211 if (!err)
212 fpsimd_update_current_state(&fpsimd);
213
214 return err ? -EFAULT : 0;
215}
216
217
218struct user_ctxs {
219 struct fpsimd_context __user *fpsimd;
220 struct sve_context __user *sve;
221};
222
223#ifdef CONFIG_ARM64_SVE
224
225static int preserve_sve_context(struct sve_context __user *ctx)
226{
227 int err = 0;
228 u16 reserved[ARRAY_SIZE(ctx->__reserved)];
229 unsigned int vl = current->thread.sve_vl;
230 unsigned int vq = 0;
231
232 if (test_thread_flag(TIF_SVE))
233 vq = sve_vq_from_vl(vl);
234
235 memset(reserved, 0, sizeof(reserved));
236
237 __put_user_error(SVE_MAGIC, &ctx->head.magic, err);
238 __put_user_error(round_up(SVE_SIG_CONTEXT_SIZE(vq), 16),
239 &ctx->head.size, err);
240 __put_user_error(vl, &ctx->vl, err);
241 BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved));
242 err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved));
243
244 if (vq) {
245 /*
246 * This assumes that the SVE state has already been saved to
247 * the task struct by calling preserve_fpsimd_context().
248 */
249 err |= __copy_to_user((char __user *)ctx + SVE_SIG_REGS_OFFSET,
250 current->thread.sve_state,
251 SVE_SIG_REGS_SIZE(vq));
252 }
253
254 return err ? -EFAULT : 0;
255}
256
257static int restore_sve_fpsimd_context(struct user_ctxs *user)
258{
259 int err;
260 unsigned int vq;
261 struct user_fpsimd_state fpsimd;
262 struct sve_context sve;
263
264 if (__copy_from_user(&sve, user->sve, sizeof(sve)))
265 return -EFAULT;
266
267 if (sve.vl != current->thread.sve_vl)
268 return -EINVAL;
269
270 if (sve.head.size <= sizeof(*user->sve)) {
271 clear_thread_flag(TIF_SVE);
272 goto fpsimd_only;
273 }
274
275 vq = sve_vq_from_vl(sve.vl);
276
277 if (sve.head.size < SVE_SIG_CONTEXT_SIZE(vq))
278 return -EINVAL;
279
280 /*
281 * Careful: we are about __copy_from_user() directly into
282 * thread.sve_state with preemption enabled, so protection is
283 * needed to prevent a racing context switch from writing stale
284 * registers back over the new data.
285 */
286
287 fpsimd_flush_task_state(current);
288 /* From now, fpsimd_thread_switch() won't touch thread.sve_state */
289
290 sve_alloc(current);
291 err = __copy_from_user(current->thread.sve_state,
292 (char __user const *)user->sve +
293 SVE_SIG_REGS_OFFSET,
294 SVE_SIG_REGS_SIZE(vq));
295 if (err)
296 return -EFAULT;
297
298 set_thread_flag(TIF_SVE);
299
300fpsimd_only:
301 /* copy the FP and status/control registers */
302 /* restore_sigframe() already checked that user->fpsimd != NULL. */
303 err = __copy_from_user(fpsimd.vregs, user->fpsimd->vregs,
304 sizeof(fpsimd.vregs));
305 __get_user_error(fpsimd.fpsr, &user->fpsimd->fpsr, err);
306 __get_user_error(fpsimd.fpcr, &user->fpsimd->fpcr, err);
307
308 /* load the hardware registers from the fpsimd_state structure */
309 if (!err)
310 fpsimd_update_current_state(&fpsimd);
311
312 return err ? -EFAULT : 0;
313}
314
315#else /* ! CONFIG_ARM64_SVE */
316
317/* Turn any non-optimised out attempts to use these into a link error: */
318extern int preserve_sve_context(void __user *ctx);
319extern int restore_sve_fpsimd_context(struct user_ctxs *user);
320
321#endif /* ! CONFIG_ARM64_SVE */
322
323
324static int parse_user_sigframe(struct user_ctxs *user,
325 struct rt_sigframe __user *sf)
326{
327 struct sigcontext __user *const sc = &sf->uc.uc_mcontext;
328 struct _aarch64_ctx __user *head;
329 char __user *base = (char __user *)&sc->__reserved;
330 size_t offset = 0;
331 size_t limit = sizeof(sc->__reserved);
332 bool have_extra_context = false;
333 char const __user *const sfp = (char const __user *)sf;
334
335 user->fpsimd = NULL;
336 user->sve = NULL;
337
338 if (!IS_ALIGNED((unsigned long)base, 16))
339 goto invalid;
340
341 while (1) {
342 int err = 0;
343 u32 magic, size;
344 char const __user *userp;
345 struct extra_context const __user *extra;
346 u64 extra_datap;
347 u32 extra_size;
348 struct _aarch64_ctx const __user *end;
349 u32 end_magic, end_size;
350
351 if (limit - offset < sizeof(*head))
352 goto invalid;
353
354 if (!IS_ALIGNED(offset, 16))
355 goto invalid;
356
357 head = (struct _aarch64_ctx __user *)(base + offset);
358 __get_user_error(magic, &head->magic, err);
359 __get_user_error(size, &head->size, err);
360 if (err)
361 return err;
362
363 if (limit - offset < size)
364 goto invalid;
365
366 switch (magic) {
367 case 0:
368 if (size)
369 goto invalid;
370
371 goto done;
372
373 case FPSIMD_MAGIC:
374 if (user->fpsimd)
375 goto invalid;
376
377 if (size < sizeof(*user->fpsimd))
378 goto invalid;
379
380 user->fpsimd = (struct fpsimd_context __user *)head;
381 break;
382
383 case ESR_MAGIC:
384 /* ignore */
385 break;
386
387 case SVE_MAGIC:
388 if (!system_supports_sve())
389 goto invalid;
390
391 if (user->sve)
392 goto invalid;
393
394 if (size < sizeof(*user->sve))
395 goto invalid;
396
397 user->sve = (struct sve_context __user *)head;
398 break;
399
400 case EXTRA_MAGIC:
401 if (have_extra_context)
402 goto invalid;
403
404 if (size < sizeof(*extra))
405 goto invalid;
406
407 userp = (char const __user *)head;
408
409 extra = (struct extra_context const __user *)userp;
410 userp += size;
411
412 __get_user_error(extra_datap, &extra->datap, err);
413 __get_user_error(extra_size, &extra->size, err);
414 if (err)
415 return err;
416
417 /* Check for the dummy terminator in __reserved[]: */
418
419 if (limit - offset - size < TERMINATOR_SIZE)
420 goto invalid;
421
422 end = (struct _aarch64_ctx const __user *)userp;
423 userp += TERMINATOR_SIZE;
424
425 __get_user_error(end_magic, &end->magic, err);
426 __get_user_error(end_size, &end->size, err);
427 if (err)
428 return err;
429
430 if (end_magic || end_size)
431 goto invalid;
432
433 /* Prevent looping/repeated parsing of extra_context */
434 have_extra_context = true;
435
436 base = (__force void __user *)extra_datap;
437 if (!IS_ALIGNED((unsigned long)base, 16))
438 goto invalid;
439
440 if (!IS_ALIGNED(extra_size, 16))
441 goto invalid;
442
443 if (base != userp)
444 goto invalid;
445
446 /* Reject "unreasonably large" frames: */
447 if (extra_size > sfp + SIGFRAME_MAXSZ - userp)
448 goto invalid;
449
450 /*
451 * Ignore trailing terminator in __reserved[]
452 * and start parsing extra data:
453 */
454 offset = 0;
455 limit = extra_size;
456
457 if (!access_ok(base, limit))
458 goto invalid;
459
460 continue;
461
462 default:
463 goto invalid;
464 }
465
466 if (size < sizeof(*head))
467 goto invalid;
468
469 if (limit - offset < size)
470 goto invalid;
471
472 offset += size;
473 }
474
475done:
476 return 0;
477
478invalid:
479 return -EINVAL;
480}
481
482static int restore_sigframe(struct pt_regs *regs,
483 struct rt_sigframe __user *sf)
484{
485 sigset_t set;
486 int i, err;
487 struct user_ctxs user;
488
489 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
490 if (err == 0)
491 set_current_blocked(&set);
492
493 for (i = 0; i < 31; i++)
494 __get_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
495 err);
496 __get_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
497 __get_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
498 __get_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
499
500 /*
501 * Avoid sys_rt_sigreturn() restarting.
502 */
503 forget_syscall(regs);
504
505 err |= !valid_user_regs(®s->user_regs, current);
506 if (err == 0)
507 err = parse_user_sigframe(&user, sf);
508
509 if (err == 0) {
510 if (!user.fpsimd)
511 return -EINVAL;
512
513 if (user.sve) {
514 if (!system_supports_sve())
515 return -EINVAL;
516
517 err = restore_sve_fpsimd_context(&user);
518 } else {
519 err = restore_fpsimd_context(user.fpsimd);
520 }
521 }
522
523 return err;
524}
525
526SYSCALL_DEFINE0(rt_sigreturn)
527{
528 struct pt_regs *regs = current_pt_regs();
529 struct rt_sigframe __user *frame;
530
531 /* Always make any pending restarted system calls return -EINTR */
532 current->restart_block.fn = do_no_restart_syscall;
533
534 /*
535 * Since we stacked the signal on a 128-bit boundary, then 'sp' should
536 * be word aligned here.
537 */
538 if (regs->sp & 15)
539 goto badframe;
540
541 frame = (struct rt_sigframe __user *)regs->sp;
542
543 if (!access_ok(frame, sizeof (*frame)))
544 goto badframe;
545
546 if (restore_sigframe(regs, frame))
547 goto badframe;
548
549 if (restore_altstack(&frame->uc.uc_stack))
550 goto badframe;
551
552 return regs->regs[0];
553
554badframe:
555 arm64_notify_segfault(regs->sp);
556 return 0;
557}
558
559/*
560 * Determine the layout of optional records in the signal frame
561 *
562 * add_all: if true, lays out the biggest possible signal frame for
563 * this task; otherwise, generates a layout for the current state
564 * of the task.
565 */
566static int setup_sigframe_layout(struct rt_sigframe_user_layout *user,
567 bool add_all)
568{
569 int err;
570
571 err = sigframe_alloc(user, &user->fpsimd_offset,
572 sizeof(struct fpsimd_context));
573 if (err)
574 return err;
575
576 /* fault information, if valid */
577 if (add_all || current->thread.fault_code) {
578 err = sigframe_alloc(user, &user->esr_offset,
579 sizeof(struct esr_context));
580 if (err)
581 return err;
582 }
583
584 if (system_supports_sve()) {
585 unsigned int vq = 0;
586
587 if (add_all || test_thread_flag(TIF_SVE)) {
588 int vl = sve_max_vl;
589
590 if (!add_all)
591 vl = current->thread.sve_vl;
592
593 vq = sve_vq_from_vl(vl);
594 }
595
596 err = sigframe_alloc(user, &user->sve_offset,
597 SVE_SIG_CONTEXT_SIZE(vq));
598 if (err)
599 return err;
600 }
601
602 return sigframe_alloc_end(user);
603}
604
605static int setup_sigframe(struct rt_sigframe_user_layout *user,
606 struct pt_regs *regs, sigset_t *set)
607{
608 int i, err = 0;
609 struct rt_sigframe __user *sf = user->sigframe;
610
611 /* set up the stack frame for unwinding */
612 __put_user_error(regs->regs[29], &user->next_frame->fp, err);
613 __put_user_error(regs->regs[30], &user->next_frame->lr, err);
614
615 for (i = 0; i < 31; i++)
616 __put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
617 err);
618 __put_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
619 __put_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
620 __put_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
621
622 __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
623
624 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
625
626 if (err == 0) {
627 struct fpsimd_context __user *fpsimd_ctx =
628 apply_user_offset(user, user->fpsimd_offset);
629 err |= preserve_fpsimd_context(fpsimd_ctx);
630 }
631
632 /* fault information, if valid */
633 if (err == 0 && user->esr_offset) {
634 struct esr_context __user *esr_ctx =
635 apply_user_offset(user, user->esr_offset);
636
637 __put_user_error(ESR_MAGIC, &esr_ctx->head.magic, err);
638 __put_user_error(sizeof(*esr_ctx), &esr_ctx->head.size, err);
639 __put_user_error(current->thread.fault_code, &esr_ctx->esr, err);
640 }
641
642 /* Scalable Vector Extension state, if present */
643 if (system_supports_sve() && err == 0 && user->sve_offset) {
644 struct sve_context __user *sve_ctx =
645 apply_user_offset(user, user->sve_offset);
646 err |= preserve_sve_context(sve_ctx);
647 }
648
649 if (err == 0 && user->extra_offset) {
650 char __user *sfp = (char __user *)user->sigframe;
651 char __user *userp =
652 apply_user_offset(user, user->extra_offset);
653
654 struct extra_context __user *extra;
655 struct _aarch64_ctx __user *end;
656 u64 extra_datap;
657 u32 extra_size;
658
659 extra = (struct extra_context __user *)userp;
660 userp += EXTRA_CONTEXT_SIZE;
661
662 end = (struct _aarch64_ctx __user *)userp;
663 userp += TERMINATOR_SIZE;
664
665 /*
666 * extra_datap is just written to the signal frame.
667 * The value gets cast back to a void __user *
668 * during sigreturn.
669 */
670 extra_datap = (__force u64)userp;
671 extra_size = sfp + round_up(user->size, 16) - userp;
672
673 __put_user_error(EXTRA_MAGIC, &extra->head.magic, err);
674 __put_user_error(EXTRA_CONTEXT_SIZE, &extra->head.size, err);
675 __put_user_error(extra_datap, &extra->datap, err);
676 __put_user_error(extra_size, &extra->size, err);
677
678 /* Add the terminator */
679 __put_user_error(0, &end->magic, err);
680 __put_user_error(0, &end->size, err);
681 }
682
683 /* set the "end" magic */
684 if (err == 0) {
685 struct _aarch64_ctx __user *end =
686 apply_user_offset(user, user->end_offset);
687
688 __put_user_error(0, &end->magic, err);
689 __put_user_error(0, &end->size, err);
690 }
691
692 return err;
693}
694
695static int get_sigframe(struct rt_sigframe_user_layout *user,
696 struct ksignal *ksig, struct pt_regs *regs)
697{
698 unsigned long sp, sp_top;
699 int err;
700
701 init_user_layout(user);
702 err = setup_sigframe_layout(user, false);
703 if (err)
704 return err;
705
706 sp = sp_top = sigsp(regs->sp, ksig);
707
708 sp = round_down(sp - sizeof(struct frame_record), 16);
709 user->next_frame = (struct frame_record __user *)sp;
710
711 sp = round_down(sp, 16) - sigframe_size(user);
712 user->sigframe = (struct rt_sigframe __user *)sp;
713
714 /*
715 * Check that we can actually write to the signal frame.
716 */
717 if (!access_ok(user->sigframe, sp_top - sp))
718 return -EFAULT;
719
720 return 0;
721}
722
723static void setup_return(struct pt_regs *regs, struct k_sigaction *ka,
724 struct rt_sigframe_user_layout *user, int usig)
725{
726 __sigrestore_t sigtramp;
727
728 regs->regs[0] = usig;
729 regs->sp = (unsigned long)user->sigframe;
730 regs->regs[29] = (unsigned long)&user->next_frame->fp;
731 regs->pc = (unsigned long)ka->sa.sa_handler;
732
733 if (ka->sa.sa_flags & SA_RESTORER)
734 sigtramp = ka->sa.sa_restorer;
735 else
736 sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp);
737
738 regs->regs[30] = (unsigned long)sigtramp;
739}
740
741static int setup_rt_frame(int usig, struct ksignal *ksig, sigset_t *set,
742 struct pt_regs *regs)
743{
744 struct rt_sigframe_user_layout user;
745 struct rt_sigframe __user *frame;
746 int err = 0;
747
748 fpsimd_signal_preserve_current_state();
749
750 if (get_sigframe(&user, ksig, regs))
751 return 1;
752
753 frame = user.sigframe;
754
755 __put_user_error(0, &frame->uc.uc_flags, err);
756 __put_user_error(NULL, &frame->uc.uc_link, err);
757
758 err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
759 err |= setup_sigframe(&user, regs, set);
760 if (err == 0) {
761 setup_return(regs, &ksig->ka, &user, usig);
762 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
763 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
764 regs->regs[1] = (unsigned long)&frame->info;
765 regs->regs[2] = (unsigned long)&frame->uc;
766 }
767 }
768
769 return err;
770}
771
772static void setup_restart_syscall(struct pt_regs *regs)
773{
774 if (is_compat_task())
775 compat_setup_restart_syscall(regs);
776 else
777 regs->regs[8] = __NR_restart_syscall;
778}
779
780/*
781 * OK, we're invoking a handler
782 */
783static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
784{
785 struct task_struct *tsk = current;
786 sigset_t *oldset = sigmask_to_save();
787 int usig = ksig->sig;
788 int ret;
789
790 rseq_signal_deliver(ksig, regs);
791
792 /*
793 * Set up the stack frame
794 */
795 if (is_compat_task()) {
796 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
797 ret = compat_setup_rt_frame(usig, ksig, oldset, regs);
798 else
799 ret = compat_setup_frame(usig, ksig, oldset, regs);
800 } else {
801 ret = setup_rt_frame(usig, ksig, oldset, regs);
802 }
803
804 /*
805 * Check that the resulting registers are actually sane.
806 */
807 ret |= !valid_user_regs(®s->user_regs, current);
808
809 /*
810 * Fast forward the stepping logic so we step into the signal
811 * handler.
812 */
813 if (!ret)
814 user_fastforward_single_step(tsk);
815
816 signal_setup_done(ret, ksig, 0);
817}
818
819/*
820 * Note that 'init' is a special process: it doesn't get signals it doesn't
821 * want to handle. Thus you cannot kill init even with a SIGKILL even by
822 * mistake.
823 *
824 * Note that we go through the signals twice: once to check the signals that
825 * the kernel can handle, and then we build all the user-level signal handling
826 * stack-frames in one go after that.
827 */
828static void do_signal(struct pt_regs *regs)
829{
830 unsigned long continue_addr = 0, restart_addr = 0;
831 int retval = 0;
832 struct ksignal ksig;
833 bool syscall = in_syscall(regs);
834
835 /*
836 * If we were from a system call, check for system call restarting...
837 */
838 if (syscall) {
839 continue_addr = regs->pc;
840 restart_addr = continue_addr - (compat_thumb_mode(regs) ? 2 : 4);
841 retval = regs->regs[0];
842
843 /*
844 * Avoid additional syscall restarting via ret_to_user.
845 */
846 forget_syscall(regs);
847
848 /*
849 * Prepare for system call restart. We do this here so that a
850 * debugger will see the already changed PC.
851 */
852 switch (retval) {
853 case -ERESTARTNOHAND:
854 case -ERESTARTSYS:
855 case -ERESTARTNOINTR:
856 case -ERESTART_RESTARTBLOCK:
857 regs->regs[0] = regs->orig_x0;
858 regs->pc = restart_addr;
859 break;
860 }
861 }
862
863 /*
864 * Get the signal to deliver. When running under ptrace, at this point
865 * the debugger may change all of our registers.
866 */
867 if (get_signal(&ksig)) {
868 /*
869 * Depending on the signal settings, we may need to revert the
870 * decision to restart the system call, but skip this if a
871 * debugger has chosen to restart at a different PC.
872 */
873 if (regs->pc == restart_addr &&
874 (retval == -ERESTARTNOHAND ||
875 retval == -ERESTART_RESTARTBLOCK ||
876 (retval == -ERESTARTSYS &&
877 !(ksig.ka.sa.sa_flags & SA_RESTART)))) {
878 regs->regs[0] = -EINTR;
879 regs->pc = continue_addr;
880 }
881
882 handle_signal(&ksig, regs);
883 return;
884 }
885
886 /*
887 * Handle restarting a different system call. As above, if a debugger
888 * has chosen to restart at a different PC, ignore the restart.
889 */
890 if (syscall && regs->pc == restart_addr) {
891 if (retval == -ERESTART_RESTARTBLOCK)
892 setup_restart_syscall(regs);
893 user_rewind_single_step(current);
894 }
895
896 restore_saved_sigmask();
897}
898
899asmlinkage void do_notify_resume(struct pt_regs *regs,
900 unsigned long thread_flags)
901{
902 /*
903 * The assembly code enters us with IRQs off, but it hasn't
904 * informed the tracing code of that for efficiency reasons.
905 * Update the trace code with the current status.
906 */
907 trace_hardirqs_off();
908
909 do {
910 /* Check valid user FS if needed */
911 addr_limit_user_check();
912
913 if (thread_flags & _TIF_NEED_RESCHED) {
914 /* Unmask Debug and SError for the next task */
915 local_daif_restore(DAIF_PROCCTX_NOIRQ);
916
917 schedule();
918 } else {
919 local_daif_restore(DAIF_PROCCTX);
920
921 if (thread_flags & _TIF_UPROBE)
922 uprobe_notify_resume(regs);
923
924 if (thread_flags & _TIF_SIGPENDING)
925 do_signal(regs);
926
927 if (thread_flags & _TIF_NOTIFY_RESUME) {
928 clear_thread_flag(TIF_NOTIFY_RESUME);
929 tracehook_notify_resume(regs);
930 rseq_handle_notify_resume(NULL, regs);
931 }
932
933 if (thread_flags & _TIF_FOREIGN_FPSTATE)
934 fpsimd_restore_current_state();
935 }
936
937 local_daif_mask();
938 thread_flags = READ_ONCE(current_thread_info()->flags);
939 } while (thread_flags & _TIF_WORK_MASK);
940}
941
942unsigned long __ro_after_init signal_minsigstksz;
943
944/*
945 * Determine the stack space required for guaranteed signal devliery.
946 * This function is used to populate AT_MINSIGSTKSZ at process startup.
947 * cpufeatures setup is assumed to be complete.
948 */
949void __init minsigstksz_setup(void)
950{
951 struct rt_sigframe_user_layout user;
952
953 init_user_layout(&user);
954
955 /*
956 * If this fails, SIGFRAME_MAXSZ needs to be enlarged. It won't
957 * be big enough, but it's our best guess:
958 */
959 if (WARN_ON(setup_sigframe_layout(&user, true)))
960 return;
961
962 signal_minsigstksz = sigframe_size(&user) +
963 round_up(sizeof(struct frame_record), 16) +
964 16; /* max alignment padding */
965}