arch/loongarch/kernel/syscall.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Author: Hanlu Li <[email protected]>
   4  *         Huacai Chen <[email protected]>
   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 }