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 <linux/time-internal.h> 13 #include <asm/syscall.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 (!seccomp_permit_syscall()) 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. Advance the time-travel clock a bit so sched_yield() 39 * in a loop (like ping does for small intervals) also works correctly. 40 */ 41 if ((time_travel_mode == TT_MODE_INFCPU || 42 time_travel_mode == TT_MODE_EXTERNAL) && 43 syscall == __NR_sched_yield) 44 time_travel_ndelay(1000); 45 46 if (syscall >= 0 && syscall < __NR_syscalls) { 47 unsigned long ret; 48 49 ret = (*sys_call_table[syscall])(UPT_SYSCALL_ARG1(®s->regs), 50 UPT_SYSCALL_ARG2(®s->regs), 51 UPT_SYSCALL_ARG3(®s->regs), 52 UPT_SYSCALL_ARG4(®s->regs), 53 UPT_SYSCALL_ARG5(®s->regs), 54 UPT_SYSCALL_ARG6(®s->regs)); 55 56 PT_REGS_SET_SYSCALL_RETURN(regs, ret); 57 58 /* 59 * An error value here can be some form of -ERESTARTSYS 60 * and then we'd just loop. Make any error syscalls take 61 * some time, so that it won't just loop if something is 62 * not ready, and hopefully other things will make some 63 * progress. 64 */ 65 if (IS_ERR_VALUE(ret) && 66 (time_travel_mode == TT_MODE_INFCPU || 67 time_travel_mode == TT_MODE_EXTERNAL)) { 68 um_udelay(1); 69 schedule(); 70 } 71 } 72 73 out: 74 syscall_trace_leave(regs); 75 } 76