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_compat_32.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_save_and_flush_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 if (err)
173 return -EFAULT;
174
175 /*
176 * We don't need to touch the exception register, so
177 * reload the hardware state.
178 */
179 fpsimd_save_and_flush_current_state();
180 current->thread.uw.fpsimd_state = fpsimd;
181
182 return 0;
183}
184
185static int compat_restore_sigframe(struct pt_regs *regs,
186 struct compat_sigframe __user *sf)
187{
188 int err;
189 sigset_t set;
190 struct compat_aux_sigframe __user *aux;
191 unsigned long psr;
192
193 err = get_sigset_t(set: &set, uset: &sf->uc.uc_sigmask);
194 if (err == 0)
195 set_current_blocked(&set);
196
197 __get_user_error(regs->regs[0], &sf->uc.uc_mcontext.arm_r0, err);
198 __get_user_error(regs->regs[1], &sf->uc.uc_mcontext.arm_r1, err);
199 __get_user_error(regs->regs[2], &sf->uc.uc_mcontext.arm_r2, err);
200 __get_user_error(regs->regs[3], &sf->uc.uc_mcontext.arm_r3, err);
201 __get_user_error(regs->regs[4], &sf->uc.uc_mcontext.arm_r4, err);
202 __get_user_error(regs->regs[5], &sf->uc.uc_mcontext.arm_r5, err);
203 __get_user_error(regs->regs[6], &sf->uc.uc_mcontext.arm_r6, err);
204 __get_user_error(regs->regs[7], &sf->uc.uc_mcontext.arm_r7, err);
205 __get_user_error(regs->regs[8], &sf->uc.uc_mcontext.arm_r8, err);
206 __get_user_error(regs->regs[9], &sf->uc.uc_mcontext.arm_r9, err);
207 __get_user_error(regs->regs[10], &sf->uc.uc_mcontext.arm_r10, err);
208 __get_user_error(regs->regs[11], &sf->uc.uc_mcontext.arm_fp, err);
209 __get_user_error(regs->regs[12], &sf->uc.uc_mcontext.arm_ip, err);
210 __get_user_error(regs->compat_sp, &sf->uc.uc_mcontext.arm_sp, err);
211 __get_user_error(regs->compat_lr, &sf->uc.uc_mcontext.arm_lr, err);
212 __get_user_error(regs->pc, &sf->uc.uc_mcontext.arm_pc, err);
213 __get_user_error(psr, &sf->uc.uc_mcontext.arm_cpsr, err);
214
215 regs->pstate = compat_psr_to_pstate(psr);
216
217 /*
218 * Avoid compat_sys_sigreturn() restarting.
219 */
220 forget_syscall(regs);
221
222 err |= !valid_user_regs(&regs->user_regs, current);
223
224 aux = (struct compat_aux_sigframe __user *) sf->uc.uc_regspace;
225 if (err == 0 && system_supports_fpsimd())
226 err |= compat_restore_vfp_context(frame: &aux->vfp);
227
228 return err;
229}
230
231COMPAT_SYSCALL_DEFINE0(sigreturn)
232{
233 struct pt_regs *regs = current_pt_regs();
234 struct compat_sigframe __user *frame;
235
236 /* Always make any pending restarted system calls return -EINTR */
237 current->restart_block.fn = do_no_restart_syscall;
238
239 /*
240 * Since we stacked the signal on a 64-bit boundary,
241 * then 'sp' should be word aligned here. If it's
242 * not, then the user is trying to mess with us.
243 */
244 if (regs->compat_sp & 7)
245 goto badframe;
246
247 frame = (struct compat_sigframe __user *)regs->compat_sp;
248
249 if (!access_ok(frame, sizeof (*frame)))
250 goto badframe;
251
252 if (compat_restore_sigframe(regs, sf: frame))
253 goto badframe;
254
255 return regs->regs[0];
256
257badframe:
258 arm64_notify_segfault(regs->compat_sp);
259 return 0;
260}
261
262COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
263{
264 struct pt_regs *regs = current_pt_regs();
265 struct compat_rt_sigframe __user *frame;
266
267 /* Always make any pending restarted system calls return -EINTR */
268 current->restart_block.fn = do_no_restart_syscall;
269
270 /*
271 * Since we stacked the signal on a 64-bit boundary,
272 * then 'sp' should be word aligned here. If it's
273 * not, then the user is trying to mess with us.
274 */
275 if (regs->compat_sp & 7)
276 goto badframe;
277
278 frame = (struct compat_rt_sigframe __user *)regs->compat_sp;
279
280 if (!access_ok(frame, sizeof (*frame)))
281 goto badframe;
282
283 if (compat_restore_sigframe(regs, sf: &frame->sig))
284 goto badframe;
285
286 if (compat_restore_altstack(uss: &frame->sig.uc.uc_stack))
287 goto badframe;
288
289 return regs->regs[0];
290
291badframe:
292 arm64_notify_segfault(regs->compat_sp);
293 return 0;
294}
295
296static void __user *compat_get_sigframe(struct ksignal *ksig,
297 struct pt_regs *regs,
298 int framesize)
299{
300 compat_ulong_t sp = sigsp(sp: regs->compat_sp, ksig);
301 void __user *frame;
302
303 /*
304 * ATPCS B01 mandates 8-byte alignment
305 */
306 frame = compat_ptr(uptr: (compat_uptr_t)((sp - framesize) & ~7));
307
308 /*
309 * Check that we can actually write to the signal frame.
310 */
311 if (!access_ok(frame, framesize))
312 frame = NULL;
313
314 return frame;
315}
316
317static void compat_setup_return(struct pt_regs *regs, struct k_sigaction *ka,
318 compat_ulong_t __user *rc, void __user *frame,
319 int usig)
320{
321 compat_ulong_t handler = ptr_to_compat(uptr: ka->sa.sa_handler);
322 compat_ulong_t retcode;
323 compat_ulong_t spsr = regs->pstate & ~(PSR_f | PSR_AA32_E_BIT);
324 int thumb;
325
326 /* Check if the handler is written for ARM or Thumb */
327 thumb = handler & 1;
328
329 if (thumb)
330 spsr |= PSR_AA32_T_BIT;
331 else
332 spsr &= ~PSR_AA32_T_BIT;
333
334 /* The IT state must be cleared for both ARM and Thumb-2 */
335 spsr &= ~PSR_AA32_IT_MASK;
336
337 /* Restore the original endianness */
338 spsr |= PSR_AA32_ENDSTATE;
339
340 if (ka->sa.sa_flags & SA_RESTORER) {
341 retcode = ptr_to_compat(uptr: ka->sa.sa_restorer);
342 } else {
343 /* Set up sigreturn pointer */
344 unsigned int idx = thumb << 1;
345
346 if (ka->sa.sa_flags & SA_SIGINFO)
347 idx += 3;
348
349 retcode = (unsigned long)current->mm->context.sigpage +
350 (idx << 2) + thumb;
351 }
352
353 regs->regs[0] = usig;
354 regs->compat_sp = ptr_to_compat(uptr: frame);
355 regs->compat_lr = retcode;
356 regs->pc = handler;
357 regs->pstate = spsr;
358}
359
360static int compat_setup_sigframe(struct compat_sigframe __user *sf,
361 struct pt_regs *regs, sigset_t *set)
362{
363 struct compat_aux_sigframe __user *aux;
364 unsigned long psr = pstate_to_compat_psr(regs->pstate);
365 int err = 0;
366
367 __put_user_error(regs->regs[0], &sf->uc.uc_mcontext.arm_r0, err);
368 __put_user_error(regs->regs[1], &sf->uc.uc_mcontext.arm_r1, err);
369 __put_user_error(regs->regs[2], &sf->uc.uc_mcontext.arm_r2, err);
370 __put_user_error(regs->regs[3], &sf->uc.uc_mcontext.arm_r3, err);
371 __put_user_error(regs->regs[4], &sf->uc.uc_mcontext.arm_r4, err);
372 __put_user_error(regs->regs[5], &sf->uc.uc_mcontext.arm_r5, err);
373 __put_user_error(regs->regs[6], &sf->uc.uc_mcontext.arm_r6, err);
374 __put_user_error(regs->regs[7], &sf->uc.uc_mcontext.arm_r7, err);
375 __put_user_error(regs->regs[8], &sf->uc.uc_mcontext.arm_r8, err);
376 __put_user_error(regs->regs[9], &sf->uc.uc_mcontext.arm_r9, err);
377 __put_user_error(regs->regs[10], &sf->uc.uc_mcontext.arm_r10, err);
378 __put_user_error(regs->regs[11], &sf->uc.uc_mcontext.arm_fp, err);
379 __put_user_error(regs->regs[12], &sf->uc.uc_mcontext.arm_ip, err);
380 __put_user_error(regs->compat_sp, &sf->uc.uc_mcontext.arm_sp, err);
381 __put_user_error(regs->compat_lr, &sf->uc.uc_mcontext.arm_lr, err);
382 __put_user_error(regs->pc, &sf->uc.uc_mcontext.arm_pc, err);
383 __put_user_error(psr, &sf->uc.uc_mcontext.arm_cpsr, err);
384
385 __put_user_error((compat_ulong_t)0, &sf->uc.uc_mcontext.trap_no, err);
386 /* set the compat FSR WnR */
387 __put_user_error(!!(current->thread.fault_code & ESR_ELx_WNR) <<
388 FSR_WRITE_SHIFT, &sf->uc.uc_mcontext.error_code, err);
389 __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
390 __put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err);
391
392 err |= put_sigset_t(uset: &sf->uc.uc_sigmask, set);
393
394 aux = (struct compat_aux_sigframe __user *) sf->uc.uc_regspace;
395
396 if (err == 0 && system_supports_fpsimd())
397 err |= compat_preserve_vfp_context(frame: &aux->vfp);
398 __put_user_error(0, &aux->end_magic, err);
399
400 return err;
401}
402
403/*
404 * 32-bit signal handling routines called from signal.c
405 */
406int compat_setup_rt_frame(int usig, struct ksignal *ksig,
407 sigset_t *set, struct pt_regs *regs)
408{
409 struct compat_rt_sigframe __user *frame;
410 int err = 0;
411
412 frame = compat_get_sigframe(ksig, regs, sizeof(*frame));
413
414 if (!frame)
415 return 1;
416
417 err |= copy_siginfo_to_user32(to: &frame->info, from: &ksig->info);
418
419 __put_user_error(0, &frame->sig.uc.uc_flags, err);
420 __put_user_error(0, &frame->sig.uc.uc_link, err);
421
422 err |= __compat_save_altstack(&frame->sig.uc.uc_stack, regs->compat_sp);
423
424 err |= compat_setup_sigframe(sf: &frame->sig, regs, set);
425
426 if (err == 0) {
427 compat_setup_return(regs, ka: &ksig->ka, rc: frame->sig.retcode, frame, usig);
428 regs->regs[1] = (compat_ulong_t)(unsigned long)&frame->info;
429 regs->regs[2] = (compat_ulong_t)(unsigned long)&frame->sig.uc;
430 }
431
432 return err;
433}
434
435int compat_setup_frame(int usig, struct ksignal *ksig, sigset_t *set,
436 struct pt_regs *regs)
437{
438 struct compat_sigframe __user *frame;
439 int err = 0;
440
441 frame = compat_get_sigframe(ksig, regs, sizeof(*frame));
442
443 if (!frame)
444 return 1;
445
446 __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err);
447
448 err |= compat_setup_sigframe(sf: frame, regs, set);
449 if (err == 0)
450 compat_setup_return(regs, ka: &ksig->ka, rc: frame->retcode, frame, usig);
451
452 return err;
453}
454
455void compat_setup_restart_syscall(struct pt_regs *regs)
456{
457 regs->regs[7] = __NR_compat32_restart_syscall;
458}
459
460/*
461 * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as
462 * changes likely come with new fields that should be added below.
463 */
464static_assert(NSIGILL == 11);
465static_assert(NSIGFPE == 15);
466static_assert(NSIGSEGV == 10);
467static_assert(NSIGBUS == 5);
468static_assert(NSIGTRAP == 6);
469static_assert(NSIGCHLD == 6);
470static_assert(NSIGSYS == 2);
471static_assert(sizeof(compat_siginfo_t) == 128);
472static_assert(__alignof__(compat_siginfo_t) == 4);
473static_assert(offsetof(compat_siginfo_t, si_signo) == 0x00);
474static_assert(offsetof(compat_siginfo_t, si_errno) == 0x04);
475static_assert(offsetof(compat_siginfo_t, si_code) == 0x08);
476static_assert(offsetof(compat_siginfo_t, si_pid) == 0x0c);
477static_assert(offsetof(compat_siginfo_t, si_uid) == 0x10);
478static_assert(offsetof(compat_siginfo_t, si_tid) == 0x0c);
479static_assert(offsetof(compat_siginfo_t, si_overrun) == 0x10);
480static_assert(offsetof(compat_siginfo_t, si_status) == 0x14);
481static_assert(offsetof(compat_siginfo_t, si_utime) == 0x18);
482static_assert(offsetof(compat_siginfo_t, si_stime) == 0x1c);
483static_assert(offsetof(compat_siginfo_t, si_value) == 0x14);
484static_assert(offsetof(compat_siginfo_t, si_int) == 0x14);
485static_assert(offsetof(compat_siginfo_t, si_ptr) == 0x14);
486static_assert(offsetof(compat_siginfo_t, si_addr) == 0x0c);
487static_assert(offsetof(compat_siginfo_t, si_addr_lsb) == 0x10);
488static_assert(offsetof(compat_siginfo_t, si_lower) == 0x14);
489static_assert(offsetof(compat_siginfo_t, si_upper) == 0x18);
490static_assert(offsetof(compat_siginfo_t, si_pkey) == 0x14);
491static_assert(offsetof(compat_siginfo_t, si_perf_data) == 0x10);
492static_assert(offsetof(compat_siginfo_t, si_perf_type) == 0x14);
493static_assert(offsetof(compat_siginfo_t, si_perf_flags) == 0x18);
494static_assert(offsetof(compat_siginfo_t, si_band) == 0x0c);
495static_assert(offsetof(compat_siginfo_t, si_fd) == 0x10);
496static_assert(offsetof(compat_siginfo_t, si_call_addr) == 0x0c);
497static_assert(offsetof(compat_siginfo_t, si_syscall) == 0x10);
498static_assert(offsetof(compat_siginfo_t, si_arch) == 0x14);
499

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