xref: /openbmc/linux/arch/mips/kernel/signal_n32.c (revision b56d1caf)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Copyright (C) 2003 Broadcom Corporation
4  */
5 #include <linux/cache.h>
6 #include <linux/sched.h>
7 #include <linux/mm.h>
8 #include <linux/smp.h>
9 #include <linux/kernel.h>
10 #include <linux/signal.h>
11 #include <linux/errno.h>
12 #include <linux/wait.h>
13 #include <linux/ptrace.h>
14 #include <linux/unistd.h>
15 #include <linux/compat.h>
16 #include <linux/bitops.h>
17 
18 #include <asm/abi.h>
19 #include <asm/asm.h>
20 #include <asm/cacheflush.h>
21 #include <asm/compat-signal.h>
22 #include <asm/sim.h>
23 #include <linux/uaccess.h>
24 #include <asm/ucontext.h>
25 #include <asm/fpu.h>
26 #include <asm/cpu-features.h>
27 
28 #include "signal-common.h"
29 
30 /*
31  * Including <asm/unistd.h> would give use the 64-bit syscall numbers ...
32  */
33 #define __NR_N32_restart_syscall	6214
34 
35 extern int setup_sigcontext(struct pt_regs *, struct sigcontext __user *);
36 extern int restore_sigcontext(struct pt_regs *, struct sigcontext __user *);
37 
38 struct ucontextn32 {
39 	u32		    uc_flags;
40 	s32		    uc_link;
41 	compat_stack_t      uc_stack;
42 	struct sigcontext   uc_mcontext;
43 	compat_sigset_t	    uc_sigmask;	  /* mask last for extensibility */
44 };
45 
46 struct rt_sigframe_n32 {
47 	u32 rs_ass[4];			/* argument save space for o32 */
48 	u32 rs_pad[2];			/* Was: signal trampoline */
49 	struct compat_siginfo rs_info;
50 	struct ucontextn32 rs_uc;
51 };
52 
sysn32_rt_sigreturn(void)53 asmlinkage void sysn32_rt_sigreturn(void)
54 {
55 	struct rt_sigframe_n32 __user *frame;
56 	struct pt_regs *regs;
57 	sigset_t set;
58 	int sig;
59 
60 	regs = current_pt_regs();
61 	frame = (struct rt_sigframe_n32 __user *)regs->regs[29];
62 	if (!access_ok(frame, sizeof(*frame)))
63 		goto badframe;
64 	if (__copy_conv_sigset_from_user(&set, &frame->rs_uc.uc_sigmask))
65 		goto badframe;
66 
67 	set_current_blocked(&set);
68 
69 	sig = restore_sigcontext(regs, &frame->rs_uc.uc_mcontext);
70 	if (sig < 0)
71 		goto badframe;
72 	else if (sig)
73 		force_sig(sig);
74 
75 	if (compat_restore_altstack(&frame->rs_uc.uc_stack))
76 		goto badframe;
77 
78 	/*
79 	 * Don't let your children do this ...
80 	 */
81 	__asm__ __volatile__(
82 		"move\t$29, %0\n\t"
83 		"j\tsyscall_exit"
84 		: /* no outputs */
85 		: "r" (regs));
86 	/* Unreached */
87 
88 badframe:
89 	force_sig(SIGSEGV);
90 }
91 
setup_rt_frame_n32(void * sig_return,struct ksignal * ksig,struct pt_regs * regs,sigset_t * set)92 static int setup_rt_frame_n32(void *sig_return, struct ksignal *ksig,
93 			      struct pt_regs *regs, sigset_t *set)
94 {
95 	struct rt_sigframe_n32 __user *frame;
96 	int err = 0;
97 
98 	frame = get_sigframe(ksig, regs, sizeof(*frame));
99 	if (!access_ok(frame, sizeof (*frame)))
100 		return -EFAULT;
101 
102 	/* Create siginfo.  */
103 	err |= copy_siginfo_to_user32(&frame->rs_info, &ksig->info);
104 
105 	/* Create the ucontext.	 */
106 	err |= __put_user(0, &frame->rs_uc.uc_flags);
107 	err |= __put_user(0, &frame->rs_uc.uc_link);
108 	err |= __compat_save_altstack(&frame->rs_uc.uc_stack, regs->regs[29]);
109 	err |= setup_sigcontext(regs, &frame->rs_uc.uc_mcontext);
110 	err |= __copy_conv_sigset_to_user(&frame->rs_uc.uc_sigmask, set);
111 
112 	if (err)
113 		return -EFAULT;
114 
115 	/*
116 	 * Arguments to signal handler:
117 	 *
118 	 *   a0 = signal number
119 	 *   a1 = 0 (should be cause)
120 	 *   a2 = pointer to ucontext
121 	 *
122 	 * $25 and c0_epc point to the signal handler, $29 points to
123 	 * the struct rt_sigframe.
124 	 */
125 	regs->regs[ 4] = ksig->sig;
126 	regs->regs[ 5] = (unsigned long) &frame->rs_info;
127 	regs->regs[ 6] = (unsigned long) &frame->rs_uc;
128 	regs->regs[29] = (unsigned long) frame;
129 	regs->regs[31] = (unsigned long) sig_return;
130 	regs->cp0_epc = regs->regs[25] = (unsigned long) ksig->ka.sa.sa_handler;
131 
132 	DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
133 	       current->comm, current->pid,
134 	       frame, regs->cp0_epc, regs->regs[31]);
135 
136 	return 0;
137 }
138 
139 struct mips_abi mips_abi_n32 = {
140 	.setup_rt_frame = setup_rt_frame_n32,
141 	.restart	= __NR_N32_restart_syscall,
142 
143 	.off_sc_fpregs = offsetof(struct sigcontext, sc_fpregs),
144 	.off_sc_fpc_csr = offsetof(struct sigcontext, sc_fpc_csr),
145 	.off_sc_used_math = offsetof(struct sigcontext, sc_used_math),
146 
147 	.vdso		= &vdso_image_n32,
148 };
149