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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 (!system_supports_fpsimd())
375 goto invalid;
376 if (user->fpsimd)
377 goto invalid;
378
379 if (size < sizeof(*user->fpsimd))
380 goto invalid;
381
382 user->fpsimd = (struct fpsimd_context __user *)head;
383 break;
384
385 case ESR_MAGIC:
386 /* ignore */
387 break;
388
389 case SVE_MAGIC:
390 if (!system_supports_sve())
391 goto invalid;
392
393 if (user->sve)
394 goto invalid;
395
396 if (size < sizeof(*user->sve))
397 goto invalid;
398
399 user->sve = (struct sve_context __user *)head;
400 break;
401
402 case EXTRA_MAGIC:
403 if (have_extra_context)
404 goto invalid;
405
406 if (size < sizeof(*extra))
407 goto invalid;
408
409 userp = (char const __user *)head;
410
411 extra = (struct extra_context const __user *)userp;
412 userp += size;
413
414 __get_user_error(extra_datap, &extra->datap, err);
415 __get_user_error(extra_size, &extra->size, err);
416 if (err)
417 return err;
418
419 /* Check for the dummy terminator in __reserved[]: */
420
421 if (limit - offset - size < TERMINATOR_SIZE)
422 goto invalid;
423
424 end = (struct _aarch64_ctx const __user *)userp;
425 userp += TERMINATOR_SIZE;
426
427 __get_user_error(end_magic, &end->magic, err);
428 __get_user_error(end_size, &end->size, err);
429 if (err)
430 return err;
431
432 if (end_magic || end_size)
433 goto invalid;
434
435 /* Prevent looping/repeated parsing of extra_context */
436 have_extra_context = true;
437
438 base = (__force void __user *)extra_datap;
439 if (!IS_ALIGNED((unsigned long)base, 16))
440 goto invalid;
441
442 if (!IS_ALIGNED(extra_size, 16))
443 goto invalid;
444
445 if (base != userp)
446 goto invalid;
447
448 /* Reject "unreasonably large" frames: */
449 if (extra_size > sfp + SIGFRAME_MAXSZ - userp)
450 goto invalid;
451
452 /*
453 * Ignore trailing terminator in __reserved[]
454 * and start parsing extra data:
455 */
456 offset = 0;
457 limit = extra_size;
458
459 if (!access_ok(base, limit))
460 goto invalid;
461
462 continue;
463
464 default:
465 goto invalid;
466 }
467
468 if (size < sizeof(*head))
469 goto invalid;
470
471 if (limit - offset < size)
472 goto invalid;
473
474 offset += size;
475 }
476
477done:
478 return 0;
479
480invalid:
481 return -EINVAL;
482}
483
484static int restore_sigframe(struct pt_regs *regs,
485 struct rt_sigframe __user *sf)
486{
487 sigset_t set;
488 int i, err;
489 struct user_ctxs user;
490
491 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
492 if (err == 0)
493 set_current_blocked(&set);
494
495 for (i = 0; i < 31; i++)
496 __get_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
497 err);
498 __get_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
499 __get_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
500 __get_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
501
502 /*
503 * Avoid sys_rt_sigreturn() restarting.
504 */
505 forget_syscall(regs);
506
507 err |= !valid_user_regs(®s->user_regs, current);
508 if (err == 0)
509 err = parse_user_sigframe(&user, sf);
510
511 if (err == 0 && system_supports_fpsimd()) {
512 if (!user.fpsimd)
513 return -EINVAL;
514
515 if (user.sve) {
516 if (!system_supports_sve())
517 return -EINVAL;
518
519 err = restore_sve_fpsimd_context(&user);
520 } else {
521 err = restore_fpsimd_context(user.fpsimd);
522 }
523 }
524
525 return err;
526}
527
528SYSCALL_DEFINE0(rt_sigreturn)
529{
530 struct pt_regs *regs = current_pt_regs();
531 struct rt_sigframe __user *frame;
532
533 /* Always make any pending restarted system calls return -EINTR */
534 current->restart_block.fn = do_no_restart_syscall;
535
536 /*
537 * Since we stacked the signal on a 128-bit boundary, then 'sp' should
538 * be word aligned here.
539 */
540 if (regs->sp & 15)
541 goto badframe;
542
543 frame = (struct rt_sigframe __user *)regs->sp;
544
545 if (!access_ok(frame, sizeof (*frame)))
546 goto badframe;
547
548 if (restore_sigframe(regs, frame))
549 goto badframe;
550
551 if (restore_altstack(&frame->uc.uc_stack))
552 goto badframe;
553
554 return regs->regs[0];
555
556badframe:
557 arm64_notify_segfault(regs->sp);
558 return 0;
559}
560
561/*
562 * Determine the layout of optional records in the signal frame
563 *
564 * add_all: if true, lays out the biggest possible signal frame for
565 * this task; otherwise, generates a layout for the current state
566 * of the task.
567 */
568static int setup_sigframe_layout(struct rt_sigframe_user_layout *user,
569 bool add_all)
570{
571 int err;
572
573 err = sigframe_alloc(user, &user->fpsimd_offset,
574 sizeof(struct fpsimd_context));
575 if (err)
576 return err;
577
578 /* fault information, if valid */
579 if (add_all || current->thread.fault_code) {
580 err = sigframe_alloc(user, &user->esr_offset,
581 sizeof(struct esr_context));
582 if (err)
583 return err;
584 }
585
586 if (system_supports_sve()) {
587 unsigned int vq = 0;
588
589 if (add_all || test_thread_flag(TIF_SVE)) {
590 int vl = sve_max_vl;
591
592 if (!add_all)
593 vl = current->thread.sve_vl;
594
595 vq = sve_vq_from_vl(vl);
596 }
597
598 err = sigframe_alloc(user, &user->sve_offset,
599 SVE_SIG_CONTEXT_SIZE(vq));
600 if (err)
601 return err;
602 }
603
604 return sigframe_alloc_end(user);
605}
606
607static int setup_sigframe(struct rt_sigframe_user_layout *user,
608 struct pt_regs *regs, sigset_t *set)
609{
610 int i, err = 0;
611 struct rt_sigframe __user *sf = user->sigframe;
612
613 /* set up the stack frame for unwinding */
614 __put_user_error(regs->regs[29], &user->next_frame->fp, err);
615 __put_user_error(regs->regs[30], &user->next_frame->lr, err);
616
617 for (i = 0; i < 31; i++)
618 __put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
619 err);
620 __put_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
621 __put_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
622 __put_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
623
624 __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
625
626 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
627
628 if (err == 0 && system_supports_fpsimd()) {
629 struct fpsimd_context __user *fpsimd_ctx =
630 apply_user_offset(user, user->fpsimd_offset);
631 err |= preserve_fpsimd_context(fpsimd_ctx);
632 }
633
634 /* fault information, if valid */
635 if (err == 0 && user->esr_offset) {
636 struct esr_context __user *esr_ctx =
637 apply_user_offset(user, user->esr_offset);
638
639 __put_user_error(ESR_MAGIC, &esr_ctx->head.magic, err);
640 __put_user_error(sizeof(*esr_ctx), &esr_ctx->head.size, err);
641 __put_user_error(current->thread.fault_code, &esr_ctx->esr, err);
642 }
643
644 /* Scalable Vector Extension state, if present */
645 if (system_supports_sve() && err == 0 && user->sve_offset) {
646 struct sve_context __user *sve_ctx =
647 apply_user_offset(user, user->sve_offset);
648 err |= preserve_sve_context(sve_ctx);
649 }
650
651 if (err == 0 && user->extra_offset) {
652 char __user *sfp = (char __user *)user->sigframe;
653 char __user *userp =
654 apply_user_offset(user, user->extra_offset);
655
656 struct extra_context __user *extra;
657 struct _aarch64_ctx __user *end;
658 u64 extra_datap;
659 u32 extra_size;
660
661 extra = (struct extra_context __user *)userp;
662 userp += EXTRA_CONTEXT_SIZE;
663
664 end = (struct _aarch64_ctx __user *)userp;
665 userp += TERMINATOR_SIZE;
666
667 /*
668 * extra_datap is just written to the signal frame.
669 * The value gets cast back to a void __user *
670 * during sigreturn.
671 */
672 extra_datap = (__force u64)userp;
673 extra_size = sfp + round_up(user->size, 16) - userp;
674
675 __put_user_error(EXTRA_MAGIC, &extra->head.magic, err);
676 __put_user_error(EXTRA_CONTEXT_SIZE, &extra->head.size, err);
677 __put_user_error(extra_datap, &extra->datap, err);
678 __put_user_error(extra_size, &extra->size, err);
679
680 /* Add the terminator */
681 __put_user_error(0, &end->magic, err);
682 __put_user_error(0, &end->size, err);
683 }
684
685 /* set the "end" magic */
686 if (err == 0) {
687 struct _aarch64_ctx __user *end =
688 apply_user_offset(user, user->end_offset);
689
690 __put_user_error(0, &end->magic, err);
691 __put_user_error(0, &end->size, err);
692 }
693
694 return err;
695}
696
697static int get_sigframe(struct rt_sigframe_user_layout *user,
698 struct ksignal *ksig, struct pt_regs *regs)
699{
700 unsigned long sp, sp_top;
701 int err;
702
703 init_user_layout(user);
704 err = setup_sigframe_layout(user, false);
705 if (err)
706 return err;
707
708 sp = sp_top = sigsp(regs->sp, ksig);
709
710 sp = round_down(sp - sizeof(struct frame_record), 16);
711 user->next_frame = (struct frame_record __user *)sp;
712
713 sp = round_down(sp, 16) - sigframe_size(user);
714 user->sigframe = (struct rt_sigframe __user *)sp;
715
716 /*
717 * Check that we can actually write to the signal frame.
718 */
719 if (!access_ok(user->sigframe, sp_top - sp))
720 return -EFAULT;
721
722 return 0;
723}
724
725static void setup_return(struct pt_regs *regs, struct k_sigaction *ka,
726 struct rt_sigframe_user_layout *user, int usig)
727{
728 __sigrestore_t sigtramp;
729
730 regs->regs[0] = usig;
731 regs->sp = (unsigned long)user->sigframe;
732 regs->regs[29] = (unsigned long)&user->next_frame->fp;
733 regs->pc = (unsigned long)ka->sa.sa_handler;
734
735 /*
736 * Signal delivery is a (wacky) indirect function call in
737 * userspace, so simulate the same setting of BTYPE as a BLR
738 * <register containing the signal handler entry point>.
739 * Signal delivery to a location in a PROT_BTI guarded page
740 * that is not a function entry point will now trigger a
741 * SIGILL in userspace.
742 *
743 * If the signal handler entry point is not in a PROT_BTI
744 * guarded page, this is harmless.
745 */
746 if (system_supports_bti()) {
747 regs->pstate &= ~PSR_BTYPE_MASK;
748 regs->pstate |= PSR_BTYPE_C;
749 }
750
751 if (ka->sa.sa_flags & SA_RESTORER)
752 sigtramp = ka->sa.sa_restorer;
753 else
754 sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp);
755
756 regs->regs[30] = (unsigned long)sigtramp;
757}
758
759static int setup_rt_frame(int usig, struct ksignal *ksig, sigset_t *set,
760 struct pt_regs *regs)
761{
762 struct rt_sigframe_user_layout user;
763 struct rt_sigframe __user *frame;
764 int err = 0;
765
766 fpsimd_signal_preserve_current_state();
767
768 if (get_sigframe(&user, ksig, regs))
769 return 1;
770
771 frame = user.sigframe;
772
773 __put_user_error(0, &frame->uc.uc_flags, err);
774 __put_user_error(NULL, &frame->uc.uc_link, err);
775
776 err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
777 err |= setup_sigframe(&user, regs, set);
778 if (err == 0) {
779 setup_return(regs, &ksig->ka, &user, usig);
780 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
781 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
782 regs->regs[1] = (unsigned long)&frame->info;
783 regs->regs[2] = (unsigned long)&frame->uc;
784 }
785 }
786
787 return err;
788}
789
790static void setup_restart_syscall(struct pt_regs *regs)
791{
792 if (is_compat_task())
793 compat_setup_restart_syscall(regs);
794 else
795 regs->regs[8] = __NR_restart_syscall;
796}
797
798/*
799 * OK, we're invoking a handler
800 */
801static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
802{
803 sigset_t *oldset = sigmask_to_save();
804 int usig = ksig->sig;
805 int ret;
806
807 rseq_signal_deliver(ksig, regs);
808
809 /*
810 * Set up the stack frame
811 */
812 if (is_compat_task()) {
813 if (ksig->ka.sa.sa_flags & SA_SIGINFO)
814 ret = compat_setup_rt_frame(usig, ksig, oldset, regs);
815 else
816 ret = compat_setup_frame(usig, ksig, oldset, regs);
817 } else {
818 ret = setup_rt_frame(usig, ksig, oldset, regs);
819 }
820
821 /*
822 * Check that the resulting registers are actually sane.
823 */
824 ret |= !valid_user_regs(®s->user_regs, current);
825
826 /* Step into the signal handler if we are stepping */
827 signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
828}
829
830/*
831 * Note that 'init' is a special process: it doesn't get signals it doesn't
832 * want to handle. Thus you cannot kill init even with a SIGKILL even by
833 * mistake.
834 *
835 * Note that we go through the signals twice: once to check the signals that
836 * the kernel can handle, and then we build all the user-level signal handling
837 * stack-frames in one go after that.
838 */
839static void do_signal(struct pt_regs *regs)
840{
841 unsigned long continue_addr = 0, restart_addr = 0;
842 int retval = 0;
843 struct ksignal ksig;
844 bool syscall = in_syscall(regs);
845
846 /*
847 * If we were from a system call, check for system call restarting...
848 */
849 if (syscall) {
850 continue_addr = regs->pc;
851 restart_addr = continue_addr - (compat_thumb_mode(regs) ? 2 : 4);
852 retval = regs->regs[0];
853
854 /*
855 * Avoid additional syscall restarting via ret_to_user.
856 */
857 forget_syscall(regs);
858
859 /*
860 * Prepare for system call restart. We do this here so that a
861 * debugger will see the already changed PC.
862 */
863 switch (retval) {
864 case -ERESTARTNOHAND:
865 case -ERESTARTSYS:
866 case -ERESTARTNOINTR:
867 case -ERESTART_RESTARTBLOCK:
868 regs->regs[0] = regs->orig_x0;
869 regs->pc = restart_addr;
870 break;
871 }
872 }
873
874 /*
875 * Get the signal to deliver. When running under ptrace, at this point
876 * the debugger may change all of our registers.
877 */
878 if (get_signal(&ksig)) {
879 /*
880 * Depending on the signal settings, we may need to revert the
881 * decision to restart the system call, but skip this if a
882 * debugger has chosen to restart at a different PC.
883 */
884 if (regs->pc == restart_addr &&
885 (retval == -ERESTARTNOHAND ||
886 retval == -ERESTART_RESTARTBLOCK ||
887 (retval == -ERESTARTSYS &&
888 !(ksig.ka.sa.sa_flags & SA_RESTART)))) {
889 regs->regs[0] = -EINTR;
890 regs->pc = continue_addr;
891 }
892
893 handle_signal(&ksig, regs);
894 return;
895 }
896
897 /*
898 * Handle restarting a different system call. As above, if a debugger
899 * has chosen to restart at a different PC, ignore the restart.
900 */
901 if (syscall && regs->pc == restart_addr) {
902 if (retval == -ERESTART_RESTARTBLOCK)
903 setup_restart_syscall(regs);
904 user_rewind_single_step(current);
905 }
906
907 restore_saved_sigmask();
908}
909
910asmlinkage void do_notify_resume(struct pt_regs *regs,
911 unsigned long thread_flags)
912{
913 /*
914 * The assembly code enters us with IRQs off, but it hasn't
915 * informed the tracing code of that for efficiency reasons.
916 * Update the trace code with the current status.
917 */
918 trace_hardirqs_off();
919
920 do {
921 /* Check valid user FS if needed */
922 addr_limit_user_check();
923
924 if (thread_flags & _TIF_NEED_RESCHED) {
925 /* Unmask Debug and SError for the next task */
926 local_daif_restore(DAIF_PROCCTX_NOIRQ);
927
928 schedule();
929 } else {
930 local_daif_restore(DAIF_PROCCTX);
931
932 if (thread_flags & _TIF_UPROBE)
933 uprobe_notify_resume(regs);
934
935 if (thread_flags & _TIF_SIGPENDING)
936 do_signal(regs);
937
938 if (thread_flags & _TIF_NOTIFY_RESUME) {
939 clear_thread_flag(TIF_NOTIFY_RESUME);
940 tracehook_notify_resume(regs);
941 rseq_handle_notify_resume(NULL, regs);
942 }
943
944 if (thread_flags & _TIF_FOREIGN_FPSTATE)
945 fpsimd_restore_current_state();
946 }
947
948 local_daif_mask();
949 thread_flags = READ_ONCE(current_thread_info()->flags);
950 } while (thread_flags & _TIF_WORK_MASK);
951}
952
953unsigned long __ro_after_init signal_minsigstksz;
954
955/*
956 * Determine the stack space required for guaranteed signal devliery.
957 * This function is used to populate AT_MINSIGSTKSZ at process startup.
958 * cpufeatures setup is assumed to be complete.
959 */
960void __init minsigstksz_setup(void)
961{
962 struct rt_sigframe_user_layout user;
963
964 init_user_layout(&user);
965
966 /*
967 * If this fails, SIGFRAME_MAXSZ needs to be enlarged. It won't
968 * be big enough, but it's our best guess:
969 */
970 if (WARN_ON(setup_sigframe_layout(&user, true)))
971 return;
972
973 signal_minsigstksz = sigframe_size(&user) +
974 round_up(sizeof(struct frame_record), 16) +
975 16; /* max alignment padding */
976}