signal32.c

  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(uset, &cset, 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(&s32, uset, 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, &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(&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, 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, &frame->sig))
284		goto badframe;
285
286	if (compat_restore_altstack(&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(regs->compat_sp, ksig);
301	void __user *frame;
302
303	/*
304	 * ATPCS B01 mandates 8-byte alignment
305	 */
306	frame = compat_ptr((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(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(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(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(&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(&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(&frame->info, &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(&frame->sig, regs, set);
425
426	if (err == 0) {
427		compat_setup_return(regs, &ksig->ka, 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(frame, regs, set);
449	if (err == 0)
450		compat_setup_return(regs, &ksig->ka, 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);