1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4  */
5 
6 #include <stddef.h>
7 #include <unistd.h>
8 #include <errno.h>
9 #include <string.h>
10 #include <sys/mman.h>
11 #include <init.h>
12 #include <as-layout.h>
13 #include <mm_id.h>
14 #include <os.h>
15 #include <ptrace_user.h>
16 #include <registers.h>
17 #include <skas.h>
18 #include <sysdep/ptrace.h>
19 #include <sysdep/stub.h>
20 
21 extern char batch_syscall_stub[], __syscall_stub_start[];
22 
23 extern void wait_stub_done(int pid);
24 
check_init_stack(struct mm_id * mm_idp,unsigned long * stack)25 static inline unsigned long *check_init_stack(struct mm_id * mm_idp,
26 					      unsigned long *stack)
27 {
28 	if (stack == NULL) {
29 		stack = (unsigned long *) mm_idp->stack + 2;
30 		*stack = 0;
31 	}
32 	return stack;
33 }
34 
35 static unsigned long syscall_regs[MAX_REG_NR];
36 
init_syscall_regs(void)37 static int __init init_syscall_regs(void)
38 {
39 	get_safe_registers(syscall_regs, NULL);
40 	syscall_regs[REGS_IP_INDEX] = STUB_CODE +
41 		((unsigned long) batch_syscall_stub -
42 		 (unsigned long) __syscall_stub_start);
43 	syscall_regs[REGS_SP_INDEX] = STUB_DATA;
44 
45 	return 0;
46 }
47 
48 __initcall(init_syscall_regs);
49 
do_syscall_stub(struct mm_id * mm_idp,void ** addr)50 static inline long do_syscall_stub(struct mm_id * mm_idp, void **addr)
51 {
52 	int n, i;
53 	long ret, offset;
54 	unsigned long * data;
55 	unsigned long * syscall;
56 	int err, pid = mm_idp->u.pid;
57 
58 	n = ptrace_setregs(pid, syscall_regs);
59 	if (n < 0) {
60 		printk(UM_KERN_ERR "Registers - \n");
61 		for (i = 0; i < MAX_REG_NR; i++)
62 			printk(UM_KERN_ERR "\t%d\t0x%lx\n", i, syscall_regs[i]);
63 		panic("do_syscall_stub : PTRACE_SETREGS failed, errno = %d\n",
64 		      -n);
65 	}
66 
67 	err = ptrace(PTRACE_CONT, pid, 0, 0);
68 	if (err)
69 		panic("Failed to continue stub, pid = %d, errno = %d\n", pid,
70 		      errno);
71 
72 	wait_stub_done(pid);
73 
74 	/*
75 	 * When the stub stops, we find the following values on the
76 	 * beginning of the stack:
77 	 * (long )return_value
78 	 * (long )offset to failed sycall-data (0, if no error)
79 	 */
80 	ret = *((unsigned long *) mm_idp->stack);
81 	offset = *((unsigned long *) mm_idp->stack + 1);
82 	if (offset) {
83 		data = (unsigned long *)(mm_idp->stack + offset - STUB_DATA);
84 		printk(UM_KERN_ERR "do_syscall_stub : ret = %ld, offset = %ld, "
85 		       "data = %p\n", ret, offset, data);
86 		syscall = (unsigned long *)((unsigned long)data + data[0]);
87 		printk(UM_KERN_ERR "do_syscall_stub: syscall %ld failed, "
88 		       "return value = 0x%lx, expected return value = 0x%lx\n",
89 		       syscall[0], ret, syscall[7]);
90 		printk(UM_KERN_ERR "    syscall parameters: "
91 		       "0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx\n",
92 		       syscall[1], syscall[2], syscall[3],
93 		       syscall[4], syscall[5], syscall[6]);
94 		for (n = 1; n < data[0]/sizeof(long); n++) {
95 			if (n == 1)
96 				printk(UM_KERN_ERR "    additional syscall "
97 				       "data:");
98 			if (n % 4 == 1)
99 				printk("\n" UM_KERN_ERR "      ");
100 			printk("  0x%lx", data[n]);
101 		}
102 		if (n > 1)
103 			printk("\n");
104 	}
105 	else ret = 0;
106 
107 	*addr = check_init_stack(mm_idp, NULL);
108 
109 	return ret;
110 }
111 
run_syscall_stub(struct mm_id * mm_idp,int syscall,unsigned long * args,long expected,void ** addr,int done)112 long run_syscall_stub(struct mm_id * mm_idp, int syscall,
113 		      unsigned long *args, long expected, void **addr,
114 		      int done)
115 {
116 	unsigned long *stack = check_init_stack(mm_idp, *addr);
117 
118 	*stack += sizeof(long);
119 	stack += *stack / sizeof(long);
120 
121 	*stack++ = syscall;
122 	*stack++ = args[0];
123 	*stack++ = args[1];
124 	*stack++ = args[2];
125 	*stack++ = args[3];
126 	*stack++ = args[4];
127 	*stack++ = args[5];
128 	*stack++ = expected;
129 	*stack = 0;
130 
131 	if (!done && ((((unsigned long) stack) & ~UM_KERN_PAGE_MASK) <
132 		     UM_KERN_PAGE_SIZE - 10 * sizeof(long))) {
133 		*addr = stack;
134 		return 0;
135 	}
136 
137 	return do_syscall_stub(mm_idp, addr);
138 }
139 
syscall_stub_data(struct mm_id * mm_idp,unsigned long * data,int data_count,void ** addr,void ** stub_addr)140 long syscall_stub_data(struct mm_id * mm_idp,
141 		       unsigned long *data, int data_count,
142 		       void **addr, void **stub_addr)
143 {
144 	unsigned long *stack;
145 	int ret = 0;
146 
147 	/*
148 	 * If *addr still is uninitialized, it *must* contain NULL.
149 	 * Thus in this case do_syscall_stub correctly won't be called.
150 	 */
151 	if ((((unsigned long) *addr) & ~UM_KERN_PAGE_MASK) >=
152 	   UM_KERN_PAGE_SIZE - (10 + data_count) * sizeof(long)) {
153 		ret = do_syscall_stub(mm_idp, addr);
154 		/* in case of error, don't overwrite data on stack */
155 		if (ret)
156 			return ret;
157 	}
158 
159 	stack = check_init_stack(mm_idp, *addr);
160 	*addr = stack;
161 
162 	*stack = data_count * sizeof(long);
163 
164 	memcpy(stack + 1, data, data_count * sizeof(long));
165 
166 	*stub_addr = (void *)(((unsigned long)(stack + 1) &
167 			       ~UM_KERN_PAGE_MASK) + STUB_DATA);
168 
169 	return 0;
170 }
171 
map(struct mm_id * mm_idp,unsigned long virt,unsigned long len,int prot,int phys_fd,unsigned long long offset,int done,void ** data)172 int map(struct mm_id * mm_idp, unsigned long virt, unsigned long len, int prot,
173 	int phys_fd, unsigned long long offset, int done, void **data)
174 {
175 	int ret;
176 	unsigned long args[] = { virt, len, prot,
177 				 MAP_SHARED | MAP_FIXED, phys_fd,
178 				 MMAP_OFFSET(offset) };
179 
180 	ret = run_syscall_stub(mm_idp, STUB_MMAP_NR, args, virt,
181 			       data, done);
182 
183 	return ret;
184 }
185 
unmap(struct mm_id * mm_idp,unsigned long addr,unsigned long len,int done,void ** data)186 int unmap(struct mm_id * mm_idp, unsigned long addr, unsigned long len,
187 	  int done, void **data)
188 {
189 	int ret;
190 	unsigned long args[] = { (unsigned long) addr, len, 0, 0, 0,
191 				 0 };
192 
193 	ret = run_syscall_stub(mm_idp, __NR_munmap, args, 0,
194 			       data, done);
195 
196 	return ret;
197 }
198 
protect(struct mm_id * mm_idp,unsigned long addr,unsigned long len,unsigned int prot,int done,void ** data)199 int protect(struct mm_id * mm_idp, unsigned long addr, unsigned long len,
200 	    unsigned int prot, int done, void **data)
201 {
202 	int ret;
203 	unsigned long args[] = { addr, len, prot, 0, 0, 0 };
204 
205 	ret = run_syscall_stub(mm_idp, __NR_mprotect, args, 0,
206 			       data, done);
207 
208 	return ret;
209 }
210