1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) 4 */ 5 6 #include <linux/kernel.h> 7 #include <linux/ptrace.h> 8 #include <linux/seccomp.h> 9 #include <kern_util.h> 10 #include <sysdep/ptrace.h> 11 #include <sysdep/ptrace_user.h> 12 #include <sysdep/syscalls.h> 13 #include <linux/time-internal.h> 14 #include <asm/unistd.h> 15 #include <asm/delay.h> 16 17 void handle_syscall(struct uml_pt_regs *r) 18 { 19 struct pt_regs *regs = container_of(r, struct pt_regs, regs); 20 int syscall; 21 22 /* Initialize the syscall number and default return value. */ 23 UPT_SYSCALL_NR(r) = PT_SYSCALL_NR(r->gp); 24 PT_REGS_SET_SYSCALL_RETURN(regs, -ENOSYS); 25 26 if (syscall_trace_enter(regs)) 27 goto out; 28 29 /* Do the seccomp check after ptrace; failures should be fast. */ 30 if (secure_computing() == -1) 31 goto out; 32 33 syscall = UPT_SYSCALL_NR(r); 34 35 /* 36 * If no time passes, then sched_yield may not actually yield, causing 37 * broken spinlock implementations in userspace (ASAN) to hang for long 38 * periods of time. 39 */ 40 if ((time_travel_mode == TT_MODE_INFCPU || 41 time_travel_mode == TT_MODE_EXTERNAL) && 42 syscall == __NR_sched_yield) 43 tt_extra_sched_jiffies += 1; 44 45 if (syscall >= 0 && syscall < __NR_syscalls) { 46 unsigned long ret = EXECUTE_SYSCALL(syscall, regs); 47 48 PT_REGS_SET_SYSCALL_RETURN(regs, ret); 49 50 /* 51 * An error value here can be some form of -ERESTARTSYS 52 * and then we'd just loop. Make any error syscalls take 53 * some time, so that it won't just loop if something is 54 * not ready, and hopefully other things will make some 55 * progress. 56 */ 57 if (IS_ERR_VALUE(ret) && 58 (time_travel_mode == TT_MODE_INFCPU || 59 time_travel_mode == TT_MODE_EXTERNAL)) { 60 um_udelay(1); 61 schedule(); 62 } 63 } 64 65 out: 66 syscall_trace_leave(regs); 67 } 68