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 * Modified by Will Deacon <will.deacon@arm.com>
8 */
9
10#include <linux/compat.h>
11#include <linux/signal.h>
12#include <linux/syscalls.h>
13#include <linux/ratelimit.h>
14
15#include <asm/esr.h>
16#include <asm/fpsimd.h>
17#include <asm/signal32.h>
18#include <asm/traps.h>
19#include <linux/uaccess.h>
20#include <asm/unistd.h>
21#include <asm/vdso.h>
22
23struct compat_vfp_sigframe {
24 compat_ulong_t magic;
25 compat_ulong_t size;
26 struct compat_user_vfp {
27 compat_u64 fpregs[32];
28 compat_ulong_t fpscr;
29 } ufp;
30 struct compat_user_vfp_exc {
31 compat_ulong_t fpexc;
32 compat_ulong_t fpinst;
33 compat_ulong_t fpinst2;
34 } ufp_exc;
35} __attribute__((__aligned__(8)));
36
37#define VFP_MAGIC 0x56465001
38#define VFP_STORAGE_SIZE sizeof(struct compat_vfp_sigframe)
39
40#define FSR_WRITE_SHIFT (11)
41
42struct compat_aux_sigframe {
43 struct compat_vfp_sigframe vfp;
44
45 /* Something that isn't a valid magic number for any coprocessor. */
46 unsigned long end_magic;
47} __attribute__((__aligned__(8)));
48
49static inline int put_sigset_t(compat_sigset_t __user *uset, sigset_t *set)
50{
51 compat_sigset_t cset;
52
53 cset.sig[0] = set->sig[0] & 0xffffffffull;
54 cset.sig[1] = set->sig[0] >> 32;
55
56 return copy_to_user(to: uset, from: &cset, n: sizeof(*uset));
57}
58
59static inline int get_sigset_t(sigset_t *set,
60 const compat_sigset_t __user *uset)
61{
62 compat_sigset_t s32;
63
64 if (copy_from_user(to: &s32, from: uset, n: sizeof(*uset)))
65 return -EFAULT;
66
67 set->sig[0] = s32.sig[0] | (((long)s32.sig[1]) << 32);
68 return 0;
69}
70
71/*
72 * VFP save/restore code.
73 *
74 * We have to be careful with endianness, since the fpsimd context-switch
75 * code operates on 128-bit (Q) register values whereas the compat ABI
76 * uses an array of 64-bit (D) registers. Consequently, we need to swap
77 * the two halves of each Q register when running on a big-endian CPU.
78 */
79union __fpsimd_vreg {
80 __uint128_t raw;
81 struct {
82#ifdef __AARCH64EB__
83 u64 hi;
84 u64 lo;
85#else
86 u64 lo;
87 u64 hi;
88#endif
89 };
90};
91
92static int compat_preserve_vfp_context(struct compat_vfp_sigframe __user *frame)
93{
94 struct user_fpsimd_state const *fpsimd =
95 &current->thread.uw.fpsimd_state;
96 compat_ulong_t magic = VFP_MAGIC;
97 compat_ulong_t size = VFP_STORAGE_SIZE;
98 compat_ulong_t fpscr, fpexc;
99 int i, err = 0;
100
101 /*
102 * Save the hardware registers to the fpsimd_state structure.
103 * Note that this also saves V16-31, which aren't visible
104 * in AArch32.
105 */
106 fpsimd_signal_preserve_current_state();
107
108 /* Place structure header on the stack */
109 __put_user_error(magic, &frame->magic, err);
110 __put_user_error(size, &frame->size, err);
111
112 /*
113 * Now copy the FP registers. Since the registers are packed,
114 * we can copy the prefix we want (V0-V15) as it is.
115 */
116 for (i = 0; i < ARRAY_SIZE(frame->ufp.fpregs); i += 2) {
117 union __fpsimd_vreg vreg = {
118 .raw = fpsimd->vregs[i >> 1],
119 };
120
121 __put_user_error(vreg.lo, &frame->ufp.fpregs[i], err);
122 __put_user_error(vreg.hi, &frame->ufp.fpregs[i + 1], err);
123 }
124
125 /* Create an AArch32 fpscr from the fpsr and the fpcr. */
126 fpscr = (fpsimd->fpsr & VFP_FPSCR_STAT_MASK) |
127 (fpsimd->fpcr & VFP_FPSCR_CTRL_MASK);
128 __put_user_error(fpscr, &frame->ufp.fpscr, err);
129
130 /*
131 * The exception register aren't available so we fake up a
132 * basic FPEXC and zero everything else.
133 */
134 fpexc = (1 << 30);
135 __put_user_error(fpexc, &frame->ufp_exc.fpexc, err);
136 __put_user_error(0, &frame->ufp_exc.fpinst, err);
137 __put_user_error(0, &frame->ufp_exc.fpinst2, err);
138
139 return err ? -EFAULT : 0;
140}
141
142static int compat_restore_vfp_context(struct compat_vfp_sigframe __user *frame)
143{
144 struct user_fpsimd_state fpsimd;
145 compat_ulong_t magic = VFP_MAGIC;
146 compat_ulong_t size = VFP_STORAGE_SIZE;
147 compat_ulong_t fpscr;
148 int i, err = 0;
149
150 __get_user_error(magic, &frame->magic, err);
151 __get_user_error(size, &frame->size, err);
152
153 if (err)
154 return -EFAULT;
155 if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE)
156 return -EINVAL;
157
158 /* Copy the FP registers into the start of the fpsimd_state. */
159 for (i = 0; i < ARRAY_SIZE(frame->ufp.fpregs); i += 2) {
160 union __fpsimd_vreg vreg;
161
162 __get_user_error(vreg.lo, &frame->ufp.fpregs[i], err);
163 __get_user_error(vreg.hi, &frame->ufp.fpregs[i + 1], err);
164 fpsimd.vregs[i >> 1] = vreg.raw;
165 }
166
167 /* Extract the fpsr and the fpcr from the fpscr */
168 __get_user_error(fpscr, &frame->ufp.fpscr, err);
169 fpsimd.fpsr = fpscr & VFP_FPSCR_STAT_MASK;
170 fpsimd.fpcr = fpscr & VFP_FPSCR_CTRL_MASK;
171
172 /*
173 * We don't need to touch the exception register, so
174 * reload the hardware state.
175 */
176 if (!err)
177 fpsimd_update_current_state(&fpsimd);
178
179 return err ? -EFAULT : 0;
180}
181
182static int compat_restore_sigframe(struct pt_regs *regs,
183 struct compat_sigframe __user *sf)
184{
185 int err;
186 sigset_t set;
187 struct compat_aux_sigframe __user *aux;
188 unsigned long psr;
189
190 err = get_sigset_t(set: &set, uset: &sf->uc.uc_sigmask);
191 if (err == 0)
192 set_current_blocked(&set);
193
194 __get_user_error(regs->regs[0], &sf->uc.uc_mcontext.arm_r0, err);
195 __get_user_error(regs->regs[1], &sf->uc.uc_mcontext.arm_r1, err);
196 __get_user_error(regs->regs[2], &sf->uc.uc_mcontext.arm_r2, err);
197 __get_user_error(regs->regs[3], &sf->uc.uc_mcontext.arm_r3, err);
198 __get_user_error(regs->regs[4], &sf->uc.uc_mcontext.arm_r4, err);
199 __get_user_error(regs->regs[5], &sf->uc.uc_mcontext.arm_r5, err);
200 __get_user_error(regs->regs[6], &sf->uc.uc_mcontext.arm_r6, err);
201 __get_user_error(regs->regs[7], &sf->uc.uc_mcontext.arm_r7, err);
202 __get_user_error(regs->regs[8], &sf->uc.uc_mcontext.arm_r8, err);
203 __get_user_error(regs->regs[9], &sf->uc.uc_mcontext.arm_r9, err);
204 __get_user_error(regs->regs[10], &sf->uc.uc_mcontext.arm_r10, err);
205 __get_user_error(regs->regs[11], &sf->uc.uc_mcontext.arm_fp, err);
206 __get_user_error(regs->regs[12], &sf->uc.uc_mcontext.arm_ip, err);
207 __get_user_error(regs->compat_sp, &sf->uc.uc_mcontext.arm_sp, err);
208 __get_user_error(regs->compat_lr, &sf->uc.uc_mcontext.arm_lr, err);
209 __get_user_error(regs->pc, &sf->uc.uc_mcontext.arm_pc, err);
210 __get_user_error(psr, &sf->uc.uc_mcontext.arm_cpsr, err);
211
212 regs->pstate = compat_psr_to_pstate(psr);
213
214 /*
215 * Avoid compat_sys_sigreturn() restarting.
216 */
217 forget_syscall(regs);
218
219 err |= !valid_user_regs(&regs->user_regs, current);
220
221 aux = (struct compat_aux_sigframe __user *) sf->uc.uc_regspace;
222 if (err == 0 && system_supports_fpsimd())
223 err |= compat_restore_vfp_context(frame: &aux->vfp);
224
225 return err;
226}
227
228COMPAT_SYSCALL_DEFINE0(sigreturn)
229{
230 struct pt_regs *regs = current_pt_regs();
231 struct compat_sigframe __user *frame;
232
233 /* Always make any pending restarted system calls return -EINTR */
234 current->restart_block.fn = do_no_restart_syscall;
235
236 /*
237 * Since we stacked the signal on a 64-bit boundary,
238 * then 'sp' should be word aligned here. If it's
239 * not, then the user is trying to mess with us.
240 */
241 if (regs->compat_sp & 7)
242 goto badframe;
243
244 frame = (struct compat_sigframe __user *)regs->compat_sp;
245
246 if (!access_ok(frame, sizeof (*frame)))
247 goto badframe;
248
249 if (compat_restore_sigframe(regs, sf: frame))
250 goto badframe;
251
252 return regs->regs[0];
253
254badframe:
255 arm64_notify_segfault(regs->compat_sp);
256 return 0;
257}
258
259COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
260{
261 struct pt_regs *regs = current_pt_regs();
262 struct compat_rt_sigframe __user *frame;
263
264 /* Always make any pending restarted system calls return -EINTR */
265 current->restart_block.fn = do_no_restart_syscall;
266
267 /*
268 * Since we stacked the signal on a 64-bit boundary,
269 * then 'sp' should be word aligned here. If it's
270 * not, then the user is trying to mess with us.
271 */
272 if (regs->compat_sp & 7)
273 goto badframe;
274
275 frame = (struct compat_rt_sigframe __user *)regs->compat_sp;
276
277 if (!access_ok(frame, sizeof (*frame)))
278 goto badframe;
279
280 if (compat_restore_sigframe(regs, sf: &frame->sig))
281 goto badframe;
282
283 if (compat_restore_altstack(uss: &frame->sig.uc.uc_stack))
284 goto badframe;
285
286 return regs->regs[0];
287
288badframe:
289 arm64_notify_segfault(regs->compat_sp);
290 return 0;
291}
292
293static void __user *compat_get_sigframe(struct ksignal *ksig,
294 struct pt_regs *regs,
295 int framesize)
296{
297 compat_ulong_t sp = sigsp(sp: regs->compat_sp, ksig);
298 void __user *frame;
299
300 /*
301 * ATPCS B01 mandates 8-byte alignment
302 */
303 frame = compat_ptr(uptr: (compat_uptr_t)((sp - framesize) & ~7));
304
305 /*
306 * Check that we can actually write to the signal frame.
307 */
308 if (!access_ok(frame, framesize))
309 frame = NULL;
310
311 return frame;
312}
313
314static void compat_setup_return(struct pt_regs *regs, struct k_sigaction *ka,
315 compat_ulong_t __user *rc, void __user *frame,
316 int usig)
317{
318 compat_ulong_t handler = ptr_to_compat(uptr: ka->sa.sa_handler);
319 compat_ulong_t retcode;
320 compat_ulong_t spsr = regs->pstate & ~(PSR_f | PSR_AA32_E_BIT);
321 int thumb;
322
323 /* Check if the handler is written for ARM or Thumb */
324 thumb = handler & 1;
325
326 if (thumb)
327 spsr |= PSR_AA32_T_BIT;
328 else
329 spsr &= ~PSR_AA32_T_BIT;
330
331 /* The IT state must be cleared for both ARM and Thumb-2 */
332 spsr &= ~PSR_AA32_IT_MASK;
333
334 /* Restore the original endianness */
335 spsr |= PSR_AA32_ENDSTATE;
336
337 if (ka->sa.sa_flags & SA_RESTORER) {
338 retcode = ptr_to_compat(uptr: ka->sa.sa_restorer);
339 } else {
340 /* Set up sigreturn pointer */
341 unsigned int idx = thumb << 1;
342
343 if (ka->sa.sa_flags & SA_SIGINFO)
344 idx += 3;
345
346 retcode = (unsigned long)current->mm->context.sigpage +
347 (idx << 2) + thumb;
348 }
349
350 regs->regs[0] = usig;
351 regs->compat_sp = ptr_to_compat(uptr: frame);
352 regs->compat_lr = retcode;
353 regs->pc = handler;
354 regs->pstate = spsr;
355}
356
357static int compat_setup_sigframe(struct compat_sigframe __user *sf,
358 struct pt_regs *regs, sigset_t *set)
359{
360 struct compat_aux_sigframe __user *aux;
361 unsigned long psr = pstate_to_compat_psr(regs->pstate);
362 int err = 0;
363
364 __put_user_error(regs->regs[0], &sf->uc.uc_mcontext.arm_r0, err);
365 __put_user_error(regs->regs[1], &sf->uc.uc_mcontext.arm_r1, err);
366 __put_user_error(regs->regs[2], &sf->uc.uc_mcontext.arm_r2, err);
367 __put_user_error(regs->regs[3], &sf->uc.uc_mcontext.arm_r3, err);
368 __put_user_error(regs->regs[4], &sf->uc.uc_mcontext.arm_r4, err);
369 __put_user_error(regs->regs[5], &sf->uc.uc_mcontext.arm_r5, err);
370 __put_user_error(regs->regs[6], &sf->uc.uc_mcontext.arm_r6, err);
371 __put_user_error(regs->regs[7], &sf->uc.uc_mcontext.arm_r7, err);
372 __put_user_error(regs->regs[8], &sf->uc.uc_mcontext.arm_r8, err);
373 __put_user_error(regs->regs[9], &sf->uc.uc_mcontext.arm_r9, err);
374 __put_user_error(regs->regs[10], &sf->uc.uc_mcontext.arm_r10, err);
375 __put_user_error(regs->regs[11], &sf->uc.uc_mcontext.arm_fp, err);
376 __put_user_error(regs->regs[12], &sf->uc.uc_mcontext.arm_ip, err);
377 __put_user_error(regs->compat_sp, &sf->uc.uc_mcontext.arm_sp, err);
378 __put_user_error(regs->compat_lr, &sf->uc.uc_mcontext.arm_lr, err);
379 __put_user_error(regs->pc, &sf->uc.uc_mcontext.arm_pc, err);
380 __put_user_error(psr, &sf->uc.uc_mcontext.arm_cpsr, err);
381
382 __put_user_error((compat_ulong_t)0, &sf->uc.uc_mcontext.trap_no, err);
383 /* set the compat FSR WnR */
384 __put_user_error(!!(current->thread.fault_code & ESR_ELx_WNR) <<
385 FSR_WRITE_SHIFT, &sf->uc.uc_mcontext.error_code, err);
386 __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
387 __put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err);
388
389 err |= put_sigset_t(uset: &sf->uc.uc_sigmask, set);
390
391 aux = (struct compat_aux_sigframe __user *) sf->uc.uc_regspace;
392
393 if (err == 0 && system_supports_fpsimd())
394 err |= compat_preserve_vfp_context(frame: &aux->vfp);
395 __put_user_error(0, &aux->end_magic, err);
396
397 return err;
398}
399
400/*
401 * 32-bit signal handling routines called from signal.c
402 */
403int compat_setup_rt_frame(int usig, struct ksignal *ksig,
404 sigset_t *set, struct pt_regs *regs)
405{
406 struct compat_rt_sigframe __user *frame;
407 int err = 0;
408
409 frame = compat_get_sigframe(ksig, regs, sizeof(*frame));
410
411 if (!frame)
412 return 1;
413
414 err |= copy_siginfo_to_user32(to: &frame->info, from: &ksig->info);
415
416 __put_user_error(0, &frame->sig.uc.uc_flags, err);
417 __put_user_error(0, &frame->sig.uc.uc_link, err);
418
419 err |= __compat_save_altstack(&frame->sig.uc.uc_stack, regs->compat_sp);
420
421 err |= compat_setup_sigframe(sf: &frame->sig, regs, set);
422
423 if (err == 0) {
424 compat_setup_return(regs, ka: &ksig->ka, rc: frame->sig.retcode, frame, usig);
425 regs->regs[1] = (compat_ulong_t)(unsigned long)&frame->info;
426 regs->regs[2] = (compat_ulong_t)(unsigned long)&frame->sig.uc;
427 }
428
429 return err;
430}
431
432int compat_setup_frame(int usig, struct ksignal *ksig, sigset_t *set,
433 struct pt_regs *regs)
434{
435 struct compat_sigframe __user *frame;
436 int err = 0;
437
438 frame = compat_get_sigframe(ksig, regs, sizeof(*frame));
439
440 if (!frame)
441 return 1;
442
443 __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err);
444
445 err |= compat_setup_sigframe(sf: frame, regs, set);
446 if (err == 0)
447 compat_setup_return(regs, ka: &ksig->ka, rc: frame->retcode, frame, usig);
448
449 return err;
450}
451
452void compat_setup_restart_syscall(struct pt_regs *regs)
453{
454 regs->regs[7] = __NR_compat_restart_syscall;
455}
456
457/*
458 * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as
459 * changes likely come with new fields that should be added below.
460 */
461static_assert(NSIGILL == 11);
462static_assert(NSIGFPE == 15);
463static_assert(NSIGSEGV == 10);
464static_assert(NSIGBUS == 5);
465static_assert(NSIGTRAP == 6);
466static_assert(NSIGCHLD == 6);
467static_assert(NSIGSYS == 2);
468static_assert(sizeof(compat_siginfo_t) == 128);
469static_assert(__alignof__(compat_siginfo_t) == 4);
470static_assert(offsetof(compat_siginfo_t, si_signo) == 0x00);
471static_assert(offsetof(compat_siginfo_t, si_errno) == 0x04);
472static_assert(offsetof(compat_siginfo_t, si_code) == 0x08);
473static_assert(offsetof(compat_siginfo_t, si_pid) == 0x0c);
474static_assert(offsetof(compat_siginfo_t, si_uid) == 0x10);
475static_assert(offsetof(compat_siginfo_t, si_tid) == 0x0c);
476static_assert(offsetof(compat_siginfo_t, si_overrun) == 0x10);
477static_assert(offsetof(compat_siginfo_t, si_status) == 0x14);
478static_assert(offsetof(compat_siginfo_t, si_utime) == 0x18);
479static_assert(offsetof(compat_siginfo_t, si_stime) == 0x1c);
480static_assert(offsetof(compat_siginfo_t, si_value) == 0x14);
481static_assert(offsetof(compat_siginfo_t, si_int) == 0x14);
482static_assert(offsetof(compat_siginfo_t, si_ptr) == 0x14);
483static_assert(offsetof(compat_siginfo_t, si_addr) == 0x0c);
484static_assert(offsetof(compat_siginfo_t, si_addr_lsb) == 0x10);
485static_assert(offsetof(compat_siginfo_t, si_lower) == 0x14);
486static_assert(offsetof(compat_siginfo_t, si_upper) == 0x18);
487static_assert(offsetof(compat_siginfo_t, si_pkey) == 0x14);
488static_assert(offsetof(compat_siginfo_t, si_perf_data) == 0x10);
489static_assert(offsetof(compat_siginfo_t, si_perf_type) == 0x14);
490static_assert(offsetof(compat_siginfo_t, si_perf_flags) == 0x18);
491static_assert(offsetof(compat_siginfo_t, si_band) == 0x0c);
492static_assert(offsetof(compat_siginfo_t, si_fd) == 0x10);
493static_assert(offsetof(compat_siginfo_t, si_call_addr) == 0x0c);
494static_assert(offsetof(compat_siginfo_t, si_syscall) == 0x10);
495static_assert(offsetof(compat_siginfo_t, si_arch) == 0x14);
496

source code of linux/arch/arm64/kernel/signal32.c