xref: /openbmc/linux/arch/mips/kernel/signal_o32.c (revision 3cf5d076)
1 /*
2  * This file is subject to the terms and conditions of the GNU General Public
3  * License.  See the file "COPYING" in the main directory of this archive
4  * for more details.
5  *
6  * Copyright (C) 1991, 1992  Linus Torvalds
7  * Copyright (C) 1994 - 2000, 2006  Ralf Baechle
8  * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
9  * Copyright (C) 2016, Imagination Technologies Ltd.
10  */
11 #include <linux/compiler.h>
12 #include <linux/errno.h>
13 #include <linux/signal.h>
14 #include <linux/sched/signal.h>
15 #include <linux/uaccess.h>
16 
17 #include <asm/abi.h>
18 #include <asm/compat-signal.h>
19 #include <asm/dsp.h>
20 #include <asm/sim.h>
21 #include <asm/unistd.h>
22 
23 #include "signal-common.h"
24 
25 /*
26  * Including <asm/unistd.h> would give use the 64-bit syscall numbers ...
27  */
28 #define __NR_O32_restart_syscall	4253
29 
30 struct sigframe32 {
31 	u32 sf_ass[4];		/* argument save space for o32 */
32 	u32 sf_pad[2];		/* Was: signal trampoline */
33 	struct sigcontext32 sf_sc;
34 	compat_sigset_t sf_mask;
35 };
36 
37 struct ucontext32 {
38 	u32		    uc_flags;
39 	s32		    uc_link;
40 	compat_stack_t      uc_stack;
41 	struct sigcontext32 uc_mcontext;
42 	compat_sigset_t	    uc_sigmask;	  /* mask last for extensibility */
43 };
44 
45 struct rt_sigframe32 {
46 	u32 rs_ass[4];			/* argument save space for o32 */
47 	u32 rs_pad[2];			/* Was: signal trampoline */
48 	compat_siginfo_t rs_info;
49 	struct ucontext32 rs_uc;
50 };
51 
setup_sigcontext32(struct pt_regs * regs,struct sigcontext32 __user * sc)52 static int setup_sigcontext32(struct pt_regs *regs,
53 			      struct sigcontext32 __user *sc)
54 {
55 	int err = 0;
56 	int i;
57 
58 	err |= __put_user(regs->cp0_epc, &sc->sc_pc);
59 
60 	err |= __put_user(0, &sc->sc_regs[0]);
61 	for (i = 1; i < 32; i++)
62 		err |= __put_user(regs->regs[i], &sc->sc_regs[i]);
63 
64 	err |= __put_user(regs->hi, &sc->sc_mdhi);
65 	err |= __put_user(regs->lo, &sc->sc_mdlo);
66 	if (cpu_has_dsp) {
67 		err |= __put_user(rddsp(DSP_MASK), &sc->sc_dsp);
68 		err |= __put_user(mfhi1(), &sc->sc_hi1);
69 		err |= __put_user(mflo1(), &sc->sc_lo1);
70 		err |= __put_user(mfhi2(), &sc->sc_hi2);
71 		err |= __put_user(mflo2(), &sc->sc_lo2);
72 		err |= __put_user(mfhi3(), &sc->sc_hi3);
73 		err |= __put_user(mflo3(), &sc->sc_lo3);
74 	}
75 
76 	/*
77 	 * Save FPU state to signal context.  Signal handler
78 	 * will "inherit" current FPU state.
79 	 */
80 	err |= protected_save_fp_context(sc);
81 
82 	return err;
83 }
84 
restore_sigcontext32(struct pt_regs * regs,struct sigcontext32 __user * sc)85 static int restore_sigcontext32(struct pt_regs *regs,
86 				struct sigcontext32 __user *sc)
87 {
88 	int err = 0;
89 	s32 treg;
90 	int i;
91 
92 	/* Always make any pending restarted system calls return -EINTR */
93 	current->restart_block.fn = do_no_restart_syscall;
94 
95 	err |= __get_user(regs->cp0_epc, &sc->sc_pc);
96 	err |= __get_user(regs->hi, &sc->sc_mdhi);
97 	err |= __get_user(regs->lo, &sc->sc_mdlo);
98 	if (cpu_has_dsp) {
99 		err |= __get_user(treg, &sc->sc_hi1); mthi1(treg);
100 		err |= __get_user(treg, &sc->sc_lo1); mtlo1(treg);
101 		err |= __get_user(treg, &sc->sc_hi2); mthi2(treg);
102 		err |= __get_user(treg, &sc->sc_lo2); mtlo2(treg);
103 		err |= __get_user(treg, &sc->sc_hi3); mthi3(treg);
104 		err |= __get_user(treg, &sc->sc_lo3); mtlo3(treg);
105 		err |= __get_user(treg, &sc->sc_dsp); wrdsp(treg, DSP_MASK);
106 	}
107 
108 	for (i = 1; i < 32; i++)
109 		err |= __get_user(regs->regs[i], &sc->sc_regs[i]);
110 
111 	return err ?: protected_restore_fp_context(sc);
112 }
113 
setup_frame_32(void * sig_return,struct ksignal * ksig,struct pt_regs * regs,sigset_t * set)114 static int setup_frame_32(void *sig_return, struct ksignal *ksig,
115 			  struct pt_regs *regs, sigset_t *set)
116 {
117 	struct sigframe32 __user *frame;
118 	int err = 0;
119 
120 	frame = get_sigframe(ksig, regs, sizeof(*frame));
121 	if (!access_ok(frame, sizeof (*frame)))
122 		return -EFAULT;
123 
124 	err |= setup_sigcontext32(regs, &frame->sf_sc);
125 	err |= __copy_conv_sigset_to_user(&frame->sf_mask, set);
126 
127 	if (err)
128 		return -EFAULT;
129 
130 	/*
131 	 * Arguments to signal handler:
132 	 *
133 	 *   a0 = signal number
134 	 *   a1 = 0 (should be cause)
135 	 *   a2 = pointer to struct sigcontext
136 	 *
137 	 * $25 and c0_epc point to the signal handler, $29 points to the
138 	 * struct sigframe.
139 	 */
140 	regs->regs[ 4] = ksig->sig;
141 	regs->regs[ 5] = 0;
142 	regs->regs[ 6] = (unsigned long) &frame->sf_sc;
143 	regs->regs[29] = (unsigned long) frame;
144 	regs->regs[31] = (unsigned long) sig_return;
145 	regs->cp0_epc = regs->regs[25] = (unsigned long) ksig->ka.sa.sa_handler;
146 
147 	DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
148 	       current->comm, current->pid,
149 	       frame, regs->cp0_epc, regs->regs[31]);
150 
151 	return 0;
152 }
153 
sys32_rt_sigreturn(void)154 asmlinkage void sys32_rt_sigreturn(void)
155 {
156 	struct rt_sigframe32 __user *frame;
157 	struct pt_regs *regs;
158 	sigset_t set;
159 	int sig;
160 
161 	regs = current_pt_regs();
162 	frame = (struct rt_sigframe32 __user *)regs->regs[29];
163 	if (!access_ok(frame, sizeof(*frame)))
164 		goto badframe;
165 	if (__copy_conv_sigset_from_user(&set, &frame->rs_uc.uc_sigmask))
166 		goto badframe;
167 
168 	set_current_blocked(&set);
169 
170 	sig = restore_sigcontext32(regs, &frame->rs_uc.uc_mcontext);
171 	if (sig < 0)
172 		goto badframe;
173 	else if (sig)
174 		force_sig(sig);
175 
176 	if (compat_restore_altstack(&frame->rs_uc.uc_stack))
177 		goto badframe;
178 
179 	/*
180 	 * Don't let your children do this ...
181 	 */
182 	__asm__ __volatile__(
183 		"move\t$29, %0\n\t"
184 		"j\tsyscall_exit"
185 		: /* no outputs */
186 		: "r" (regs));
187 	/* Unreached */
188 
189 badframe:
190 	force_sig(SIGSEGV);
191 }
192 
setup_rt_frame_32(void * sig_return,struct ksignal * ksig,struct pt_regs * regs,sigset_t * set)193 static int setup_rt_frame_32(void *sig_return, struct ksignal *ksig,
194 			     struct pt_regs *regs, sigset_t *set)
195 {
196 	struct rt_sigframe32 __user *frame;
197 	int err = 0;
198 
199 	frame = get_sigframe(ksig, regs, sizeof(*frame));
200 	if (!access_ok(frame, sizeof (*frame)))
201 		return -EFAULT;
202 
203 	/* Convert (siginfo_t -> compat_siginfo_t) and copy to user. */
204 	err |= copy_siginfo_to_user32(&frame->rs_info, &ksig->info);
205 
206 	/* Create the ucontext.	 */
207 	err |= __put_user(0, &frame->rs_uc.uc_flags);
208 	err |= __put_user(0, &frame->rs_uc.uc_link);
209 	err |= __compat_save_altstack(&frame->rs_uc.uc_stack, regs->regs[29]);
210 	err |= setup_sigcontext32(regs, &frame->rs_uc.uc_mcontext);
211 	err |= __copy_conv_sigset_to_user(&frame->rs_uc.uc_sigmask, set);
212 
213 	if (err)
214 		return -EFAULT;
215 
216 	/*
217 	 * Arguments to signal handler:
218 	 *
219 	 *   a0 = signal number
220 	 *   a1 = 0 (should be cause)
221 	 *   a2 = pointer to ucontext
222 	 *
223 	 * $25 and c0_epc point to the signal handler, $29 points to
224 	 * the struct rt_sigframe32.
225 	 */
226 	regs->regs[ 4] = ksig->sig;
227 	regs->regs[ 5] = (unsigned long) &frame->rs_info;
228 	regs->regs[ 6] = (unsigned long) &frame->rs_uc;
229 	regs->regs[29] = (unsigned long) frame;
230 	regs->regs[31] = (unsigned long) sig_return;
231 	regs->cp0_epc = regs->regs[25] = (unsigned long) ksig->ka.sa.sa_handler;
232 
233 	DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
234 	       current->comm, current->pid,
235 	       frame, regs->cp0_epc, regs->regs[31]);
236 
237 	return 0;
238 }
239 
240 /*
241  * o32 compatibility on 64-bit kernels, without DSP ASE
242  */
243 struct mips_abi mips_abi_32 = {
244 	.setup_frame	= setup_frame_32,
245 	.setup_rt_frame = setup_rt_frame_32,
246 	.restart	= __NR_O32_restart_syscall,
247 
248 	.off_sc_fpregs = offsetof(struct sigcontext32, sc_fpregs),
249 	.off_sc_fpc_csr = offsetof(struct sigcontext32, sc_fpc_csr),
250 	.off_sc_used_math = offsetof(struct sigcontext32, sc_used_math),
251 
252 	.vdso		= &vdso_image_o32,
253 };
254 
255 
sys32_sigreturn(void)256 asmlinkage void sys32_sigreturn(void)
257 {
258 	struct sigframe32 __user *frame;
259 	struct pt_regs *regs;
260 	sigset_t blocked;
261 	int sig;
262 
263 	regs = current_pt_regs();
264 	frame = (struct sigframe32 __user *)regs->regs[29];
265 	if (!access_ok(frame, sizeof(*frame)))
266 		goto badframe;
267 	if (__copy_conv_sigset_from_user(&blocked, &frame->sf_mask))
268 		goto badframe;
269 
270 	set_current_blocked(&blocked);
271 
272 	sig = restore_sigcontext32(regs, &frame->sf_sc);
273 	if (sig < 0)
274 		goto badframe;
275 	else if (sig)
276 		force_sig(sig);
277 
278 	/*
279 	 * Don't let your children do this ...
280 	 */
281 	__asm__ __volatile__(
282 		"move\t$29, %0\n\t"
283 		"j\tsyscall_exit"
284 		: /* no outputs */
285 		: "r" (regs));
286 	/* Unreached */
287 
288 badframe:
289 	force_sig(SIGSEGV);
290 }
291