gcc/ada/libgnarl/s-intman__posix.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                 GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS                 --
   4 --                                                                          --
   5 --           S Y S T E M . I N T E R R U P T _ M A N A G E M E N T          --
   6 --                                                                          --
   7 --                                  B o d y                                 --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2024, Free Software Foundation, Inc.         --
  10 --                                                                          --
  11 -- GNARL is free software; you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 3,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
  17 --                                                                          --
  18 -- As a special exception under Section 7 of GPL version 3, you are granted --
  19 -- additional permissions described in the GCC Runtime Library Exception,   --
  20 -- version 3.1, as published by the Free Software Foundation.               --
  21 --                                                                          --
  22 -- You should have received a copy of the GNU General Public License and    --
  23 -- a copy of the GCC Runtime Library Exception along with this program;     --
  24 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  25 -- <http://www.gnu.org/licenses/>.                                          --
  26 --                                                                          --
  27 -- GNARL was developed by the GNARL team at Florida State University.       --
  28 -- Extensive contributions were provided by Ada Core Technologies, Inc.     --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31
  32 --  This is the POSIX threads version of this package
  33
  34 --  Make a careful study of all signals available under the OS, to see which
  35 --  need to be reserved, kept always unmasked, or kept always unmasked. Be on
  36 --  the lookout for special signals that may be used by the thread library.
  37
  38 --  Since this is a multi target file, the signal <-> exception mapping
  39 --  is simple minded. If you need a more precise and target specific
  40 --  signal handling, create a new s-intman.adb that will fit your needs.
  41
  42 --  This file assumes that:
  43
  44 --    SIGFPE, SIGILL, SIGSEGV and SIGBUS exist. They are mapped as follows:
  45 --      SIGPFE  => Constraint_Error
  46 --      SIGILL  => Program_Error
  47 --      SIGSEGV => Storage_Error
  48 --      SIGBUS  => Storage_Error
  49
  50 --    SIGINT exists and will be kept unmasked unless the pragma
  51 --     Unreserve_All_Interrupts is specified anywhere in the application.
  52
  53 --    System.OS_Interface contains the following:
  54 --      SIGADAABORT: the signal that will be used to abort tasks.
  55 --      Unmasked: the OS specific set of signals that should be unmasked in
  56 --                all the threads. SIGADAABORT is unmasked by
  57 --                default
  58 --      Reserved: the OS specific set of signals that are reserved.
  59
  60 with System.Task_Primitives;
  61
  62 package body System.Interrupt_Management is
  63
  64    use Interfaces.C;
  65    use System.OS_Interface;
  66
  67    type Interrupt_List is array (Interrupt_ID range <>) of Interrupt_ID;
  68    Exception_Interrupts : constant Interrupt_List :=
  69      [SIGFPE, SIGILL, SIGSEGV, SIGBUS];
  70
  71    Unreserve_All_Interrupts : constant Interfaces.C.int;
  72    pragma Import
  73      (C, Unreserve_All_Interrupts, "__gl_unreserve_all_interrupts");
  74
  75    -----------------------
  76    -- Local Subprograms --
  77    -----------------------
  78
  79    function State (Int : Interrupt_ID) return Character;
  80    pragma Import (C, State, "__gnat_get_interrupt_state");
  81    --  Get interrupt state. Defined in init.c The input argument is the
  82    --  interrupt number, and the result is one of the following:
  83
  84    User    : constant Character := 'u';
  85    Runtime : constant Character := 'r';
  86    Default : constant Character := 's';
  87    --    'n'   this interrupt not set by any Interrupt_State pragma
  88    --    'u'   Interrupt_State pragma set state to User
  89    --    'r'   Interrupt_State pragma set state to Runtime
  90    --    's'   Interrupt_State pragma set state to System (use "default"
  91    --           system handler)
  92
  93    procedure Notify_Exception
  94      (signo    : Signal;
  95       siginfo  : System.Address;
  96       ucontext : System.Address);
  97    --  This function identifies the Ada exception to be raised using the
  98    --  information when the system received a synchronous signal. Since this
  99    --  function is machine and OS dependent, different code has to be provided
 100    --  for different target.
 101
 102    ----------------------
 103    -- Notify_Exception --
 104    ----------------------
 105
 106    Signal_Mask : aliased sigset_t;
 107    --  The set of signals handled by Notify_Exception
 108
 109    procedure Notify_Exception
 110      (signo    : Signal;
 111       siginfo  : System.Address;
 112       ucontext : System.Address)
 113    is
 114       pragma Unreferenced (siginfo);
 115
 116       Result : Interfaces.C.int;
 117
 118    begin
 119       --  With the __builtin_longjmp, the signal mask is not restored, so we
 120       --  need to restore it explicitly.
 121
 122       Result := pthread_sigmask (SIG_UNBLOCK, Signal_Mask'Access, null);
 123       pragma Assert (Result = 0);
 124
 125       --  Perform the necessary context adjustments prior to a raise
 126       --  from a signal handler.
 127
 128       Adjust_Context_For_Raise (signo, ucontext);
 129
 130       --  Check that treatment of exception propagation here is consistent with
 131       --  treatment of the abort signal in System.Task_Primitives.Operations.
 132
 133       case signo is
 134          when SIGFPE  => raise Constraint_Error;
 135          when SIGILL  => raise Program_Error;
 136          when SIGSEGV => raise Storage_Error;
 137          when SIGBUS  => raise Storage_Error;
 138          when others  => null;
 139       end case;
 140    end Notify_Exception;
 141
 142    ----------------
 143    -- Initialize --
 144    ----------------
 145
 146    Initialized : Boolean := False;
 147
 148    procedure Initialize is
 149       act     : aliased struct_sigaction;
 150       old_act : aliased struct_sigaction;
 151       Result  : System.OS_Interface.int;
 152
 153       Use_Alternate_Stack : constant Boolean :=
 154                               System.Task_Primitives.Alternate_Stack_Size /= 0;
 155       --  Whether to use an alternate signal stack for stack overflows
 156
 157    begin
 158       if Initialized then
 159          return;
 160       end if;
 161
 162       Initialized := True;
 163
 164       --  Need to call pthread_init very early because it is doing signal
 165       --  initializations.
 166
 167       pthread_init;
 168
 169       Abort_Task_Interrupt := SIGADAABORT;
 170
 171       act.sa_handler := Notify_Exception'Address;
 172
 173       --  Setting SA_SIGINFO asks the kernel to pass more than just the signal
 174       --  number argument to the handler when it is called. The set of extra
 175       --  parameters includes a pointer to the interrupted context, which the
 176       --  ZCX propagation scheme needs.
 177
 178       --  Most man pages for sigaction mention that sa_sigaction should be set
 179       --  instead of sa_handler when SA_SIGINFO is on.  In practice, the two
 180       --  fields are actually union'ed and located at the same offset.
 181
 182       --  On some targets, we set sa_flags to SA_NODEFER so that during the
 183       --  handler execution we do not change the Signal_Mask to be masked for
 184       --  the Signal.
 185
 186       --  This is a temporary fix to the problem that the Signal_Mask is not
 187       --  restored after the exception (longjmp) from the handler. The right
 188       --  fix should be made in sigsetjmp so that we save the Signal_Set and
 189       --  restore it after a longjmp.
 190
 191       --  Since SA_NODEFER is obsolete, instead we reset explicitly the mask
 192       --  in the exception handler.
 193
 194       Result := sigemptyset (Signal_Mask'Access);
 195       pragma Assert (Result = 0);
 196
 197       --  Add signals that map to Ada exceptions to the mask
 198
 199       for J in Exception_Interrupts'Range loop
 200          if State (Exception_Interrupts (J)) /= Default then
 201             Result :=
 202             sigaddset (Signal_Mask'Access, Signal (Exception_Interrupts (J)));
 203             pragma Assert (Result = 0);
 204          end if;
 205       end loop;
 206
 207       act.sa_mask := Signal_Mask;
 208
 209       pragma Assert (Keep_Unmasked = [Interrupt_ID'Range => False]);
 210       pragma Assert (Reserve = [Interrupt_ID'Range => False]);
 211
 212       --  Process state of exception signals
 213
 214       for J in Exception_Interrupts'Range loop
 215          if State (Exception_Interrupts (J)) /= User then
 216             Keep_Unmasked (Exception_Interrupts (J)) := True;
 217             Reserve (Exception_Interrupts (J)) := True;
 218
 219             if State (Exception_Interrupts (J)) /= Default then
 220                act.sa_flags := SA_SIGINFO;
 221
 222                if Use_Alternate_Stack
 223                  and then Exception_Interrupts (J) = SIGSEGV
 224                then
 225                   act.sa_flags := act.sa_flags + SA_ONSTACK;
 226                end if;
 227
 228                Result :=
 229                  sigaction
 230                    (Signal (Exception_Interrupts (J)), act'Unchecked_Access,
 231                     old_act'Unchecked_Access);
 232                pragma Assert (Result = 0);
 233             end if;
 234          end if;
 235       end loop;
 236
 237       if State (Abort_Task_Interrupt) /= User then
 238          Keep_Unmasked (Abort_Task_Interrupt) := True;
 239          Reserve (Abort_Task_Interrupt) := True;
 240       end if;
 241
 242       --  Set SIGINT to unmasked state as long as it is not in "User" state.
 243       --  Check for Unreserve_All_Interrupts last.
 244
 245       if State (SIGINT) /= User then
 246          Keep_Unmasked (SIGINT) := True;
 247          Reserve (SIGINT) := True;
 248       end if;
 249
 250       --  Check all signals for state that requires keeping them unmasked and
 251       --  reserved.
 252
 253       for J in Interrupt_ID'Range loop
 254          if State (J) = Default or else State (J) = Runtime then
 255             Keep_Unmasked (J) := True;
 256             Reserve (J) := True;
 257          end if;
 258       end loop;
 259
 260       --  Add the set of signals that must always be unmasked for this target
 261
 262       for J in Unmasked'Range loop
 263          Keep_Unmasked (Interrupt_ID (Unmasked (J))) := True;
 264          Reserve (Interrupt_ID (Unmasked (J))) := True;
 265       end loop;
 266
 267       --  Add target-specific reserved signals
 268
 269       for J in Reserved'Range loop
 270          Reserve (Interrupt_ID (Reserved (J))) := True;
 271       end loop;
 272
 273       --  Process pragma Unreserve_All_Interrupts. This overrides any settings
 274       --  due to pragma Interrupt_State:
 275
 276       if Unreserve_All_Interrupts /= 0 then
 277          Keep_Unmasked (SIGINT) := False;
 278          Reserve (SIGINT) := False;
 279       end if;
 280
 281       --  We do not really have Signal 0. We just use this value to identify
 282       --  non-existent signals (see s-intnam.ads). Therefore, Signal should not
 283       --  be used in all signal related operations hence mark it as reserved.
 284
 285       Reserve (0) := True;
 286    end Initialize;
 287
 288 end System.Interrupt_Management;