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