kernel/entry/common.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 #include <linux/context_tracking.h>
   4 #include <linux/entry-common.h>
   5
   6 #define CREATE_TRACE_POINTS
   7 #include <trace/events/syscalls.h>
   8
   9 /**
  10  * enter_from_user_mode - Establish state when coming from user mode
  11  *
  12  * Syscall/interrupt entry disables interrupts, but user mode is traced as
  13  * interrupts enabled. Also with NO_HZ_FULL RCU might be idle.
  14  *
  15  * 1) Tell lockdep that interrupts are disabled
  16  * 2) Invoke context tracking if enabled to reactivate RCU
  17  * 3) Trace interrupts off state
  18  */
  19 static __always_inline void enter_from_user_mode(struct pt_regs *regs)
  20 {
  21         arch_check_user_regs(regs);
  22         lockdep_hardirqs_off(CALLER_ADDR0);
  23
  24         CT_WARN_ON(ct_state() != CONTEXT_USER);
  25         user_exit_irqoff();
  26
  27         instrumentation_begin();
  28         trace_hardirqs_off_finish();
  29         instrumentation_end();
  30 }
  31
  32 static inline void syscall_enter_audit(struct pt_regs *regs, long syscall)
  33 {
  34         if (unlikely(audit_context())) {
  35                 unsigned long args[6];
  36
  37                 syscall_get_arguments(current, regs, args);
  38                 audit_syscall_entry(syscall, args[0], args[1], args[2], args[3]);
  39         }
  40 }
  41
  42 static long syscall_trace_enter(struct pt_regs *regs, long syscall,
  43                                 unsigned long ti_work)
  44 {
  45         long ret = 0;
  46
  47         /* Handle ptrace */
  48         if (ti_work & (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU)) {
  49                 ret = arch_syscall_enter_tracehook(regs);
  50                 if (ret || (ti_work & _TIF_SYSCALL_EMU))
  51                         return -1L;
  52         }
  53
  54         /* Do seccomp after ptrace, to catch any tracer changes. */
  55         if (ti_work & _TIF_SECCOMP) {
  56                 ret = __secure_computing(NULL);
  57                 if (ret == -1L)
  58                         return ret;
  59         }
  60
  61         if (unlikely(ti_work & _TIF_SYSCALL_TRACEPOINT))
  62                 trace_sys_enter(regs, syscall);
  63
  64         syscall_enter_audit(regs, syscall);
  65
  66         return ret ? : syscall;
  67 }
  68
  69 noinstr long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall)
  70 {
  71         unsigned long ti_work;
  72
  73         enter_from_user_mode(regs);
  74         instrumentation_begin();
  75
  76         local_irq_enable();
  77         ti_work = READ_ONCE(current_thread_info()->flags);
  78         if (ti_work & SYSCALL_ENTER_WORK)
  79                 syscall = syscall_trace_enter(regs, syscall, ti_work);
  80         instrumentation_end();
  81
  82         return syscall;
  83 }
  84
  85 noinstr void irqentry_enter_from_user_mode(struct pt_regs *regs)
  86 {
  87         enter_from_user_mode(regs);
  88 }