1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Author: Hanlu Li <lihanlu@loongson.cn>
4 * Huacai Chen <chenhuacai@loongson.cn>
5 *
6 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
7 */
8 #include <linux/capability.h>
9 #include <linux/entry-common.h>
10 #include <linux/errno.h>
11 #include <linux/linkage.h>
12 #include <linux/objtool.h>
13 #include <linux/randomize_kstack.h>
14 #include <linux/syscalls.h>
15 #include <linux/unistd.h>
16
17 #include <asm/asm.h>
18 #include <asm/exception.h>
19 #include <asm/loongarch.h>
20 #include <asm/signal.h>
21 #include <asm/switch_to.h>
22 #include <asm-generic/syscalls.h>
23
24 #undef __SYSCALL
25 #define __SYSCALL(nr, call) [nr] = (call),
26 #define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, native)
27
28 SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len, unsigned long,
29 prot, unsigned long, flags, unsigned long, fd, unsigned long, offset)
30 {
31 if (offset & ~PAGE_MASK)
32 return -EINVAL;
33
34 return ksys_mmap_pgoff(addr, len, prot, flags, fd, offset >> PAGE_SHIFT);
35 }
36
37 void *sys_call_table[__NR_syscalls] = {
38 [0 ... __NR_syscalls - 1] = sys_ni_syscall,
39 #include <asm/syscall_table_64.h>
40 };
41
42 typedef long (*sys_call_fn)(unsigned long, unsigned long,
43 unsigned long, unsigned long, unsigned long, unsigned long);
44
45 void noinstr __no_stack_protector do_syscall(struct pt_regs *regs)
46 {
47 unsigned long nr;
48 sys_call_fn syscall_fn;
49
50 nr = regs->regs[11];
51 /* Set for syscall restarting */
52 if (nr < NR_syscalls)
53 regs->regs[0] = nr + 1;
54
55 regs->csr_era += 4;
56 regs->orig_a0 = regs->regs[4];
57 regs->regs[4] = -ENOSYS;
58
59 nr = syscall_enter_from_user_mode(regs, nr);
60
61 add_random_kstack_offset();
62
63 if (nr < NR_syscalls) {
64 syscall_fn = sys_call_table[nr];
65 regs->regs[4] = syscall_fn(regs->orig_a0, regs->regs[5], regs->regs[6],
66 regs->regs[7], regs->regs[8], regs->regs[9]);
67 }
68
69 /*
70 * This value will get limited by KSTACK_OFFSET_MAX(), which is 10
71 * bits. The actual entropy will be further reduced by the compiler
72 * when applying stack alignment constraints: 16-bytes (i.e. 4-bits)
73 * aligned, which will remove the 4 low bits from any entropy chosen
74 * here.
75 *
76 * The resulting 6 bits of entropy is seen in SP[9:4].
77 */
78 choose_random_kstack_offset(drdtime());
79
80 syscall_exit_to_user_mode(regs);
81 }
82
83 #ifdef CONFIG_RANDOMIZE_KSTACK_OFFSET
84 STACK_FRAME_NON_STANDARD(do_syscall);
85 #endif
86
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