1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/arch/x86_64/ia32/ia32_signal.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 *
7 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
8 * 2000-06-20 Pentium III FXSR, SSE support by Gareth Hughes
9 * 2000-12-* x86-64 compatibility mode signal handling by Andi Kleen
10 */
11
12#include <linux/sched.h>
13#include <linux/sched/task_stack.h>
14#include <linux/mm.h>
15#include <linux/smp.h>
16#include <linux/kernel.h>
17#include <linux/errno.h>
18#include <linux/wait.h>
19#include <linux/unistd.h>
20#include <linux/stddef.h>
21#include <linux/personality.h>
22#include <linux/compat.h>
23#include <linux/binfmts.h>
24#include <asm/ucontext.h>
25#include <linux/uaccess.h>
26#include <asm/fpu/internal.h>
27#include <asm/fpu/signal.h>
28#include <asm/ptrace.h>
29#include <asm/ia32_unistd.h>
30#include <asm/user32.h>
31#include <uapi/asm/sigcontext.h>
32#include <asm/proto.h>
33#include <asm/vdso.h>
34#include <asm/sigframe.h>
35#include <asm/sighandling.h>
36#include <asm/smap.h>
37
38/*
39 * Do a signal return; undo the signal stack.
40 */
41#define loadsegment_gs(v) load_gs_index(v)
42#define loadsegment_fs(v) loadsegment(fs, v)
43#define loadsegment_ds(v) loadsegment(ds, v)
44#define loadsegment_es(v) loadsegment(es, v)
45
46#define get_user_seg(seg) ({ unsigned int v; savesegment(seg, v); v; })
47#define set_user_seg(seg, v) loadsegment_##seg(v)
48
49#define COPY(x) { \
50 get_user_ex(regs->x, &sc->x); \
51}
52
53#define GET_SEG(seg) ({ \
54 unsigned short tmp; \
55 get_user_ex(tmp, &sc->seg); \
56 tmp; \
57})
58
59#define COPY_SEG_CPL3(seg) do { \
60 regs->seg = GET_SEG(seg) | 3; \
61} while (0)
62
63#define RELOAD_SEG(seg) { \
64 unsigned int pre = GET_SEG(seg); \
65 unsigned int cur = get_user_seg(seg); \
66 pre |= 3; \
67 if (pre != cur) \
68 set_user_seg(seg, pre); \
69}
70
71static int ia32_restore_sigcontext(struct pt_regs *regs,
72 struct sigcontext_32 __user *sc)
73{
74 unsigned int tmpflags, err = 0;
75 void __user *buf;
76 u32 tmp;
77
78 /* Always make any pending restarted system calls return -EINTR */
79 current->restart_block.fn = do_no_restart_syscall;
80
81 get_user_try {
82 /*
83 * Reload fs and gs if they have changed in the signal
84 * handler. This does not handle long fs/gs base changes in
85 * the handler, but does not clobber them at least in the
86 * normal case.
87 */
88 RELOAD_SEG(gs);
89 RELOAD_SEG(fs);
90 RELOAD_SEG(ds);
91 RELOAD_SEG(es);
92
93 COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
94 COPY(dx); COPY(cx); COPY(ip); COPY(ax);
95 /* Don't touch extended registers */
96
97 COPY_SEG_CPL3(cs);
98 COPY_SEG_CPL3(ss);
99
100 get_user_ex(tmpflags, &sc->flags);
101 regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
102 /* disable syscall checks */
103 regs->orig_ax = -1;
104
105 get_user_ex(tmp, &sc->fpstate);
106 buf = compat_ptr(tmp);
107 } get_user_catch(err);
108
109 err |= fpu__restore_sig(buf, 1);
110
111 force_iret();
112
113 return err;
114}
115
116asmlinkage long sys32_sigreturn(void)
117{
118 struct pt_regs *regs = current_pt_regs();
119 struct sigframe_ia32 __user *frame = (struct sigframe_ia32 __user *)(regs->sp-8);
120 sigset_t set;
121
122 if (!access_ok(frame, sizeof(*frame)))
123 goto badframe;
124 if (__get_user(set.sig[0], &frame->sc.oldmask)
125 || (_COMPAT_NSIG_WORDS > 1
126 && __copy_from_user((((char *) &set.sig) + 4),
127 &frame->extramask,
128 sizeof(frame->extramask))))
129 goto badframe;
130
131 set_current_blocked(&set);
132
133 if (ia32_restore_sigcontext(regs, &frame->sc))
134 goto badframe;
135 return regs->ax;
136
137badframe:
138 signal_fault(regs, frame, "32bit sigreturn");
139 return 0;
140}
141
142asmlinkage long sys32_rt_sigreturn(void)
143{
144 struct pt_regs *regs = current_pt_regs();
145 struct rt_sigframe_ia32 __user *frame;
146 sigset_t set;
147
148 frame = (struct rt_sigframe_ia32 __user *)(regs->sp - 4);
149
150 if (!access_ok(frame, sizeof(*frame)))
151 goto badframe;
152 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
153 goto badframe;
154
155 set_current_blocked(&set);
156
157 if (ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext))
158 goto badframe;
159
160 if (compat_restore_altstack(&frame->uc.uc_stack))
161 goto badframe;
162
163 return regs->ax;
164
165badframe:
166 signal_fault(regs, frame, "32bit rt sigreturn");
167 return 0;
168}
169
170/*
171 * Set up a signal frame.
172 */
173
174static int ia32_setup_sigcontext(struct sigcontext_32 __user *sc,
175 void __user *fpstate,
176 struct pt_regs *regs, unsigned int mask)
177{
178 int err = 0;
179
180 put_user_try {
181 put_user_ex(get_user_seg(gs), (unsigned int __user *)&sc->gs);
182 put_user_ex(get_user_seg(fs), (unsigned int __user *)&sc->fs);
183 put_user_ex(get_user_seg(ds), (unsigned int __user *)&sc->ds);
184 put_user_ex(get_user_seg(es), (unsigned int __user *)&sc->es);
185
186 put_user_ex(regs->di, &sc->di);
187 put_user_ex(regs->si, &sc->si);
188 put_user_ex(regs->bp, &sc->bp);
189 put_user_ex(regs->sp, &sc->sp);
190 put_user_ex(regs->bx, &sc->bx);
191 put_user_ex(regs->dx, &sc->dx);
192 put_user_ex(regs->cx, &sc->cx);
193 put_user_ex(regs->ax, &sc->ax);
194 put_user_ex(current->thread.trap_nr, &sc->trapno);
195 put_user_ex(current->thread.error_code, &sc->err);
196 put_user_ex(regs->ip, &sc->ip);
197 put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
198 put_user_ex(regs->flags, &sc->flags);
199 put_user_ex(regs->sp, &sc->sp_at_signal);
200 put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
201
202 put_user_ex(ptr_to_compat(fpstate), &sc->fpstate);
203
204 /* non-iBCS2 extensions.. */
205 put_user_ex(mask, &sc->oldmask);
206 put_user_ex(current->thread.cr2, &sc->cr2);
207 } put_user_catch(err);
208
209 return err;
210}
211
212/*
213 * Determine which stack to use..
214 */
215static void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
216 size_t frame_size,
217 void __user **fpstate)
218{
219 struct fpu *fpu = &current->thread.fpu;
220 unsigned long sp;
221
222 /* Default to using normal stack */
223 sp = regs->sp;
224
225 /* This is the X/Open sanctioned signal stack switching. */
226 if (ksig->ka.sa.sa_flags & SA_ONSTACK)
227 sp = sigsp(sp, ksig);
228 /* This is the legacy signal stack switching. */
229 else if (regs->ss != __USER32_DS &&
230 !(ksig->ka.sa.sa_flags & SA_RESTORER) &&
231 ksig->ka.sa.sa_restorer)
232 sp = (unsigned long) ksig->ka.sa.sa_restorer;
233
234 if (fpu->initialized) {
235 unsigned long fx_aligned, math_size;
236
237 sp = fpu__alloc_mathframe(sp, 1, &fx_aligned, &math_size);
238 *fpstate = (struct _fpstate_32 __user *) sp;
239 if (copy_fpstate_to_sigframe(*fpstate, (void __user *)fx_aligned,
240 math_size) < 0)
241 return (void __user *) -1L;
242 }
243
244 sp -= frame_size;
245 /* Align the stack pointer according to the i386 ABI,
246 * i.e. so that on function entry ((sp + 4) & 15) == 0. */
247 sp = ((sp + 4) & -16ul) - 4;
248 return (void __user *) sp;
249}
250
251int ia32_setup_frame(int sig, struct ksignal *ksig,
252 compat_sigset_t *set, struct pt_regs *regs)
253{
254 struct sigframe_ia32 __user *frame;
255 void __user *restorer;
256 int err = 0;
257 void __user *fpstate = NULL;
258
259 /* copy_to_user optimizes that into a single 8 byte store */
260 static const struct {
261 u16 poplmovl;
262 u32 val;
263 u16 int80;
264 } __attribute__((packed)) code = {
265 0xb858, /* popl %eax ; movl $...,%eax */
266 __NR_ia32_sigreturn,
267 0x80cd, /* int $0x80 */
268 };
269
270 frame = get_sigframe(ksig, regs, sizeof(*frame), &fpstate);
271
272 if (!access_ok(frame, sizeof(*frame)))
273 return -EFAULT;
274
275 if (__put_user(sig, &frame->sig))
276 return -EFAULT;
277
278 if (ia32_setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
279 return -EFAULT;
280
281 if (_COMPAT_NSIG_WORDS > 1) {
282 if (__copy_to_user(frame->extramask, &set->sig[1],
283 sizeof(frame->extramask)))
284 return -EFAULT;
285 }
286
287 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
288 restorer = ksig->ka.sa.sa_restorer;
289 } else {
290 /* Return stub is in 32bit vsyscall page */
291 if (current->mm->context.vdso)
292 restorer = current->mm->context.vdso +
293 vdso_image_32.sym___kernel_sigreturn;
294 else
295 restorer = &frame->retcode;
296 }
297
298 put_user_try {
299 put_user_ex(ptr_to_compat(restorer), &frame->pretcode);
300
301 /*
302 * These are actually not used anymore, but left because some
303 * gdb versions depend on them as a marker.
304 */
305 put_user_ex(*((u64 *)&code), (u64 __user *)frame->retcode);
306 } put_user_catch(err);
307
308 if (err)
309 return -EFAULT;
310
311 /* Set up registers for signal handler */
312 regs->sp = (unsigned long) frame;
313 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
314
315 /* Make -mregparm=3 work */
316 regs->ax = sig;
317 regs->dx = 0;
318 regs->cx = 0;
319
320 loadsegment(ds, __USER32_DS);
321 loadsegment(es, __USER32_DS);
322
323 regs->cs = __USER32_CS;
324 regs->ss = __USER32_DS;
325
326 return 0;
327}
328
329int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
330 compat_sigset_t *set, struct pt_regs *regs)
331{
332 struct rt_sigframe_ia32 __user *frame;
333 void __user *restorer;
334 int err = 0;
335 void __user *fpstate = NULL;
336
337 /* __copy_to_user optimizes that into a single 8 byte store */
338 static const struct {
339 u8 movl;
340 u32 val;
341 u16 int80;
342 u8 pad;
343 } __attribute__((packed)) code = {
344 0xb8,
345 __NR_ia32_rt_sigreturn,
346 0x80cd,
347 0,
348 };
349
350 frame = get_sigframe(ksig, regs, sizeof(*frame), &fpstate);
351
352 if (!access_ok(frame, sizeof(*frame)))
353 return -EFAULT;
354
355 put_user_try {
356 put_user_ex(sig, &frame->sig);
357 put_user_ex(ptr_to_compat(&frame->info), &frame->pinfo);
358 put_user_ex(ptr_to_compat(&frame->uc), &frame->puc);
359
360 /* Create the ucontext. */
361 if (boot_cpu_has(X86_FEATURE_XSAVE))
362 put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
363 else
364 put_user_ex(0, &frame->uc.uc_flags);
365 put_user_ex(0, &frame->uc.uc_link);
366 compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp);
367
368 if (ksig->ka.sa.sa_flags & SA_RESTORER)
369 restorer = ksig->ka.sa.sa_restorer;
370 else
371 restorer = current->mm->context.vdso +
372 vdso_image_32.sym___kernel_rt_sigreturn;
373 put_user_ex(ptr_to_compat(restorer), &frame->pretcode);
374
375 /*
376 * Not actually used anymore, but left because some gdb
377 * versions need it.
378 */
379 put_user_ex(*((u64 *)&code), (u64 __user *)frame->retcode);
380 } put_user_catch(err);
381
382 err |= __copy_siginfo_to_user32(&frame->info, &ksig->info, false);
383 err |= ia32_setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
384 regs, set->sig[0]);
385 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
386
387 if (err)
388 return -EFAULT;
389
390 /* Set up registers for signal handler */
391 regs->sp = (unsigned long) frame;
392 regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
393
394 /* Make -mregparm=3 work */
395 regs->ax = sig;
396 regs->dx = (unsigned long) &frame->info;
397 regs->cx = (unsigned long) &frame->uc;
398
399 loadsegment(ds, __USER32_DS);
400 loadsegment(es, __USER32_DS);
401
402 regs->cs = __USER32_CS;
403 regs->ss = __USER32_DS;
404
405 return 0;
406}
407