1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- S Y S T E M . T R A C E B A C K -- 6-- (HP/UX Version) -- 7-- -- 8-- B o d y -- 9-- -- 10-- Copyright (C) 2009-2015, Free Software Foundation, Inc. -- 11-- -- 12-- GNAT is free software; you can redistribute it and/or modify it under -- 13-- terms of the GNU General Public License as published by the Free Soft- -- 14-- ware Foundation; either version 3, or (at your option) any later ver- -- 15-- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- 16-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- 17-- or FITNESS FOR A PARTICULAR PURPOSE. -- 18-- -- 19-- As a special exception under Section 7 of GPL version 3, you are granted -- 20-- additional permissions described in the GCC Runtime Library Exception, -- 21-- version 3.1, as published by the Free Software Foundation. -- 22-- -- 23-- You should have received a copy of the GNU General Public License and -- 24-- a copy of the GCC Runtime Library Exception along with this program; -- 25-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- 26-- <http://www.gnu.org/licenses/>. -- 27-- -- 28-- GNAT was originally developed by the GNAT team at New York University. -- 29-- Extensive contributions were provided by Ada Core Technologies Inc. -- 30-- -- 31------------------------------------------------------------------------------ 32 33with Ada.Unchecked_Conversion; 34 35package body System.Traceback is 36 37 -- This package implements the backtracing facility by way of a dedicated 38 -- HP library for stack unwinding described in the "Runtime Architecture 39 -- Document". 40 41 pragma Linker_Options ("/usr/lib/libcl.a"); 42 43 -- The library basically offers services to fetch information about a 44 -- "previous" frame based on information about a "current" one. 45 46 type Current_Frame_Descriptor is record 47 cur_fsz : Address; -- Frame size of current routine. 48 cur_sp : Address; -- The current value of stack pointer. 49 cur_rls : Address; -- PC-space of the caller. 50 cur_rlo : Address; -- PC-offset of the caller. 51 cur_dp : Address; -- Data Pointer of the current routine. 52 top_rp : Address; -- Initial value of RP. 53 top_mrp : Address; -- Initial value of MRP. 54 top_sr0 : Address; -- Initial value of sr0. 55 top_sr4 : Address; -- Initial value of sr4. 56 top_r3 : Address; -- Initial value of gr3. 57 cur_r19 : Address; -- GR19 value of the calling routine. 58 top_r4 : Address; -- Initial value of gr4. 59 dummy : Address; -- Reserved. 60 out_rlo : Address; -- PC-offset of the caller after get_previous. 61 end record; 62 63 type Previous_Frame_Descriptor is record 64 prev_fsz : Address; -- frame size of calling routine. 65 prev_sp : Address; -- SP of calling routine. 66 prev_rls : Address; -- PC_space of calling routine's caller. 67 prev_rlo : Address; -- PC_offset of calling routine's caller. 68 prev_dp : Address; -- DP of calling routine. 69 udescr0 : Address; -- low word of calling routine's unwind desc. 70 udescr1 : Address; -- high word of calling routine's unwind desc. 71 ustart : Address; -- start of the unwind region. 72 uend : Address; -- end of the unwind region. 73 uw_index : Address; -- index into the unwind table. 74 prev_r19 : Address; -- GR19 value of the caller's caller. 75 top_r3 : Address; -- Caller's initial gr3. 76 top_r4 : Address; -- Caller's initial gr4. 77 end record; 78 79 -- Provide useful shortcuts for the names 80 81 subtype CFD is Current_Frame_Descriptor; 82 subtype PFD is Previous_Frame_Descriptor; 83 84 -- Frames with dynamic stack allocation are handled using the associated 85 -- frame pointer, but HP compilers and GCC setup this pointer differently. 86 -- HP compilers set it to point at the top (highest address) of the static 87 -- part of the frame, whereas GCC sets it to point at the bottom of this 88 -- region. We have to fake the unwinder to compensate for this difference, 89 -- for which we'll need to access some subprograms unwind descriptors. 90 91 type Bits_2_Value is mod 2 ** 2; 92 for Bits_2_Value'Size use 2; 93 94 type Bits_4_Value is mod 2 ** 4; 95 for Bits_4_Value'Size use 4; 96 97 type Bits_5_Value is mod 2 ** 5; 98 for Bits_5_Value'Size use 5; 99 100 type Bits_27_Value is mod 2 ** 27; 101 for Bits_27_Value'Size use 27; 102 103 type Unwind_Descriptor is record 104 cannot_unwind : Boolean; 105 mcode : Boolean; 106 mcode_save_restore : Boolean; 107 region_desc : Bits_2_Value; 108 reserved0 : Boolean; 109 entry_sr : Boolean; 110 entry_fr : Bits_4_Value; 111 entry_gr : Bits_5_Value; 112 113 args_stored : Boolean; 114 variable_frame : Boolean; 115 separate_package_body : Boolean; 116 frame_extension_mcode : Boolean; 117 118 stack_overflow_check : Boolean; 119 two_steps_sp_adjust : Boolean; 120 sr4_export : Boolean; 121 cxx_info : Boolean; 122 123 cxx_try_catch : Boolean; 124 sched_entry_seq : Boolean; 125 reserved1 : Boolean; 126 save_sp : Boolean; 127 128 save_rp : Boolean; 129 save_mrp : Boolean; 130 save_r19 : Boolean; 131 cleanups : Boolean; 132 133 hpe_interrupt_marker : Boolean; 134 hpux_interrupt_marker : Boolean; 135 large_frame : Boolean; 136 alloca_frame : Boolean; 137 138 reserved2 : Boolean; 139 frame_size : Bits_27_Value; 140 end record; 141 142 for Unwind_Descriptor'Size use 64; 143 144 for Unwind_Descriptor use record 145 cannot_unwind at 0 range 0 .. 0; 146 mcode at 0 range 1 .. 1; 147 mcode_save_restore at 0 range 2 .. 2; 148 region_desc at 0 range 3 .. 4; 149 reserved0 at 0 range 5 .. 5; 150 entry_sr at 0 range 6 .. 6; 151 entry_fr at 0 range 7 .. 10; 152 153 entry_gr at 1 range 3 .. 7; 154 155 args_stored at 2 range 0 .. 0; 156 variable_frame at 2 range 1 .. 1; 157 separate_package_body at 2 range 2 .. 2; 158 frame_extension_mcode at 2 range 3 .. 3; 159 stack_overflow_check at 2 range 4 .. 4; 160 two_steps_sp_adjust at 2 range 5 .. 5; 161 sr4_export at 2 range 6 .. 6; 162 cxx_info at 2 range 7 .. 7; 163 164 cxx_try_catch at 3 range 0 .. 0; 165 sched_entry_seq at 3 range 1 .. 1; 166 reserved1 at 3 range 2 .. 2; 167 save_sp at 3 range 3 .. 3; 168 save_rp at 3 range 4 .. 4; 169 save_mrp at 3 range 5 .. 5; 170 save_r19 at 3 range 6 .. 6; 171 cleanups at 3 range 7 .. 7; 172 173 hpe_interrupt_marker at 4 range 0 .. 0; 174 hpux_interrupt_marker at 4 range 1 .. 1; 175 large_frame at 4 range 2 .. 2; 176 alloca_frame at 4 range 3 .. 3; 177 178 reserved2 at 4 range 4 .. 4; 179 frame_size at 4 range 5 .. 31; 180 end record; 181 182 subtype UWD is Unwind_Descriptor; 183 type UWD_Ptr is access all UWD; 184 185 function To_UWD_Access is new Ada.Unchecked_Conversion (Address, UWD_Ptr); 186 187 -- The descriptor associated with a given code location is retrieved 188 -- using functions imported from the HP library, requiring the definition 189 -- of additional structures. 190 191 type Unwind_Table_Region is record 192 Table_Start : Address; 193 Table_End : Address; 194 end record; 195 -- An Unwind Table region, which is a memory area containing Unwind 196 -- Descriptors. 197 198 subtype UWT is Unwind_Table_Region; 199 200 -- The subprograms imported below are provided by the HP library 201 202 function U_get_unwind_table return UWT; 203 pragma Import (C, U_get_unwind_table, "U_get_unwind_table"); 204 -- Get the unwind table region associated with the current executable. 205 -- This function is actually documented as having an argument, but which 206 -- is only used for the MPE/iX targets. 207 208 function U_get_shLib_unwind_table (r19 : Address) return UWT; 209 pragma Import (C, U_get_shLib_unwind_table, "U_get_shLib_unw_tbl"); 210 -- Return the unwind table region associated with a possible shared 211 -- library, as determined by the provided r19 value. 212 213 function U_get_shLib_text_addr (r19 : Address) return Address; 214 pragma Import (C, U_get_shLib_text_addr, "U_get_shLib_text_addr"); 215 -- Return the address at which the code for a shared library begins, or 216 -- -1 if the value provided for r19 does not identify shared library code. 217 218 function U_get_unwind_entry 219 (Pc : Address; 220 Space : Address; 221 Table_Start : Address; 222 Table_End : Address) return Address; 223 pragma Import (C, U_get_unwind_entry, "U_get_unwind_entry"); 224 -- Given the bounds of an unwind table, return the address of the 225 -- unwind descriptor associated with a code location/space. In the case 226 -- of shared library code, the offset from the beginning of the library 227 -- is expected as Pc. 228 229 procedure U_init_frame_record (Frame : not null access CFD); 230 pragma Import (C, U_init_frame_record, "U_init_frame_record"); 231 232 procedure U_prep_frame_rec_for_unwind (Frame : not null access CFD); 233 pragma Import (C, U_prep_frame_rec_for_unwind, 234 "U_prep_frame_rec_for_unwind"); 235 236 -- Fetch the description data of the frame in which these two procedures 237 -- are called. 238 239 function U_get_u_rlo 240 (Cur : not null access CFD; Prev : not null access PFD) return Integer; 241 pragma Import (C, U_get_u_rlo, "U_IS_STUB_OR_CALLX"); 242 -- From a complete current frame with a return location possibly located 243 -- into a linker generated stub, and basic information about the previous 244 -- frame, place the first non stub return location into the current frame. 245 -- Return -1 if something went wrong during the computation. 246 247 function U_is_shared_pc (rlo : Address; r19 : Address) return Address; 248 pragma Import (C, U_is_shared_pc, "U_is_shared_pc"); 249 -- Return 0 if the provided return location does not correspond to code 250 -- in a shared library, or something non null otherwise. 251 252 function U_get_previous_frame_x 253 (current_frame : not null access CFD; 254 previous_frame : not null access PFD; 255 previous_size : Integer) return Integer; 256 pragma Import (C, U_get_previous_frame_x, "U_get_previous_frame_x"); 257 -- Fetch the data describing the "previous" frame relatively to the 258 -- "current" one. "previous_size" should be the size of the "previous" 259 -- frame descriptor provided. 260 -- 261 -- The library provides a simpler interface without the size parameter 262 -- but it is not usable when frames with dynamically allocated space are 263 -- on the way. 264 265 procedure Call_Chain 266 (Traceback : System.Address; 267 Max_Len : Natural; 268 Len : out Natural; 269 Exclude_Min : System.Address := System.Null_Address; 270 Exclude_Max : System.Address := System.Null_Address; 271 Skip_Frames : Natural := 1); 272 -- Same as the exported version, but takes Traceback as an Address 273 274 ------------------ 275 -- C_Call_Chain -- 276 ------------------ 277 278 function C_Call_Chain 279 (Traceback : System.Address; 280 Max_Len : Natural) return Natural 281 is 282 Val : Natural; 283 begin 284 Call_Chain (Traceback, Max_Len, Val); 285 return Val; 286 end C_Call_Chain; 287 288 ---------------- 289 -- Call_Chain -- 290 ---------------- 291 292 procedure Call_Chain 293 (Traceback : System.Address; 294 Max_Len : Natural; 295 Len : out Natural; 296 Exclude_Min : System.Address := System.Null_Address; 297 Exclude_Max : System.Address := System.Null_Address; 298 Skip_Frames : Natural := 1) 299 is 300 type Tracebacks_Array is array (1 .. Max_Len) of System.Address; 301 pragma Suppress_Initialization (Tracebacks_Array); 302 303 -- The code location returned by the unwinder is a return location but 304 -- what we need is a call point. Under HP-UX call instructions are 4 305 -- bytes long and the return point they specify is 4 bytes beyond the 306 -- next instruction because of the delay slot. 307 308 Call_Size : constant := 4; 309 DSlot_Size : constant := 4; 310 Rlo_Offset : constant := Call_Size + DSlot_Size; 311 312 -- Moreover, the return point is passed via a register which two least 313 -- significant bits specify a privilege level that we will have to mask. 314 315 Priv_Mask : constant := 16#00000003#; 316 317 Frame : aliased CFD; 318 Code : System.Address; 319 J : Natural := 1; 320 Pop_Success : Boolean; 321 Trace : Tracebacks_Array; 322 for Trace'Address use Traceback; 323 324 -- The backtracing process needs a set of subprograms : 325 326 function UWD_For_RLO_Of (Frame : not null access CFD) return UWD_Ptr; 327 -- Return an access to the unwind descriptor for the caller of 328 -- a given frame, using only the provided return location. 329 330 function UWD_For_Caller_Of (Frame : not null access CFD) return UWD_Ptr; 331 -- Return an access to the unwind descriptor for the user code caller 332 -- of a given frame, or null if the information is not available. 333 334 function Pop_Frame (Frame : not null access CFD) return Boolean; 335 -- Update the provided machine state structure so that it reflects 336 -- the state one call frame "above" the initial one. 337 -- 338 -- Return True if the operation has been successful, False otherwise. 339 -- Failure typically occurs when the top of the call stack has been 340 -- reached. 341 342 function Prepare_For_Unwind_Of 343 (Frame : not null access CFD) return Boolean; 344 -- Perform the necessary adaptations to the machine state before 345 -- calling the unwinder. Currently used for the specific case of 346 -- dynamically sized previous frames. 347 -- 348 -- Return True if everything went fine, or False otherwise. 349 350 Program_UWT : constant UWT := U_get_unwind_table; 351 352 --------------- 353 -- Pop_Frame -- 354 --------------- 355 356 function Pop_Frame (Frame : not null access CFD) return Boolean is 357 Up_Frame : aliased PFD; 358 State_Ready : Boolean; 359 360 begin 361 -- Check/adapt the state before calling the unwinder and return 362 -- if anything went wrong. 363 364 State_Ready := Prepare_For_Unwind_Of (Frame); 365 366 if not State_Ready then 367 return False; 368 end if; 369 370 -- Now, safely call the unwinder and use the results 371 372 if U_get_previous_frame_x (Frame, 373 Up_Frame'Access, 374 Up_Frame'Size) /= 0 375 then 376 return False; 377 end if; 378 379 -- In case a stub is on the way, the usual previous return location 380 -- (the one in prev_rlo) is the one in the stub and the "real" one 381 -- is placed in the "current" record, so let's take this one into 382 -- account. 383 384 Frame.out_rlo := Frame.cur_rlo; 385 386 Frame.cur_fsz := Up_Frame.prev_fsz; 387 Frame.cur_sp := Up_Frame.prev_sp; 388 Frame.cur_rls := Up_Frame.prev_rls; 389 Frame.cur_rlo := Up_Frame.prev_rlo; 390 Frame.cur_dp := Up_Frame.prev_dp; 391 Frame.cur_r19 := Up_Frame.prev_r19; 392 Frame.top_r3 := Up_Frame.top_r3; 393 Frame.top_r4 := Up_Frame.top_r4; 394 395 return True; 396 end Pop_Frame; 397 398 --------------------------------- 399 -- Prepare_State_For_Unwind_Of -- 400 --------------------------------- 401 402 function Prepare_For_Unwind_Of 403 (Frame : not null access CFD) return Boolean 404 is 405 Caller_UWD : UWD_Ptr; 406 FP_Adjustment : Integer; 407 408 begin 409 -- No need to bother doing anything if the stack is already fully 410 -- unwound. 411 412 if Frame.cur_rlo = 0 then 413 return False; 414 end if; 415 416 -- When ALLOCA_FRAME is set in an unwind descriptor, the unwinder 417 -- uses the value provided in current.top_r3 or current.top_r4 as 418 -- a frame pointer to compute the size of the frame. What decides 419 -- between r3 or r4 is the unwind descriptor LARGE_FRAME bit, with 420 -- r4 chosen if the bit is set. 421 422 -- The size computed by the unwinder is STATIC_PART + (SP - FP), 423 -- which is correct with HP's frame pointer convention, but not 424 -- with GCC's one since we end up with the static part accounted 425 -- for twice. 426 427 -- We have to compute r4 when it is required because the unwinder 428 -- has looked for it at a place where it was not if we went through 429 -- GCC frames. 430 431 -- The size of the static part of a frame can be found in the 432 -- associated unwind descriptor. 433 434 Caller_UWD := UWD_For_Caller_Of (Frame); 435 436 -- If we cannot get it, we are unable to compute the potentially 437 -- necessary adjustments. We'd better not try to go on then. 438 439 if Caller_UWD = null then 440 return False; 441 end if; 442 443 -- If the caller frame is a GCC one, r3 is its frame pointer and 444 -- points to the bottom of the frame. The value to provide for r4 445 -- can then be computed directly from the one of r3, compensating 446 -- for the static part of the frame. 447 448 -- If the caller frame is an HP one, r3 is used to locate the 449 -- previous frame marker, that is it also points to the bottom of 450 -- the frame (this is why r3 cannot be used as the frame pointer in 451 -- the HP sense for large frames). The value to provide for r4 can 452 -- then also be computed from the one of r3 with the compensation 453 -- for the static part of the frame. 454 455 FP_Adjustment := Integer (Caller_UWD.frame_size * 8); 456 Frame.top_r4 := Address (Integer (Frame.top_r3) + FP_Adjustment); 457 458 return True; 459 end Prepare_For_Unwind_Of; 460 461 ----------------------- 462 -- UWD_For_Caller_Of -- 463 ----------------------- 464 465 function UWD_For_Caller_Of (Frame : not null access CFD) return UWD_Ptr 466 is 467 UWD_Access : UWD_Ptr; 468 469 begin 470 -- First try the most direct path, using the return location data 471 -- associated with the frame. 472 473 UWD_Access := UWD_For_RLO_Of (Frame); 474 475 if UWD_Access /= null then 476 return UWD_Access; 477 end if; 478 479 -- If we did not get a result, we might face an in-stub return 480 -- address. In this case U_get_previous_frame can tell us what the 481 -- first not-in-stub return point is. We cannot call it directly, 482 -- though, because we haven't computed the potentially necessary 483 -- frame pointer adjustments, which might lead to SEGV in some 484 -- circumstances. Instead, we directly call the libcl routine which 485 -- is called by U_get_previous_frame and which only requires few 486 -- information. Take care, however, that the information is provided 487 -- in the "current" argument, so we need to work on a copy to avoid 488 -- disturbing our caller. 489 490 declare 491 U_Current : aliased CFD := Frame.all; 492 U_Previous : aliased PFD; 493 494 begin 495 U_Previous.prev_dp := U_Current.cur_dp; 496 U_Previous.prev_rls := U_Current.cur_rls; 497 U_Previous.prev_sp := U_Current.cur_sp - U_Current.cur_fsz; 498 499 if U_get_u_rlo (U_Current'Access, U_Previous'Access) /= -1 then 500 UWD_Access := UWD_For_RLO_Of (U_Current'Access); 501 end if; 502 end; 503 504 return UWD_Access; 505 end UWD_For_Caller_Of; 506 507 -------------------- 508 -- UWD_For_RLO_Of -- 509 -------------------- 510 511 function UWD_For_RLO_Of (Frame : not null access CFD) return UWD_Ptr 512 is 513 UWD_Address : Address; 514 515 -- The addresses returned by the library point to full descriptors 516 -- including the frame information bits but also the applicable PC 517 -- range. We need to account for this. 518 519 Frame_Info_Offset : constant := 8; 520 521 begin 522 -- First try to locate the descriptor in the program's unwind table 523 524 UWD_Address := U_get_unwind_entry (Frame.cur_rlo, 525 Frame.cur_rls, 526 Program_UWT.Table_Start, 527 Program_UWT.Table_End); 528 529 -- If we did not get it, we might have a frame from code in a 530 -- stub or shared library. For code in stub we would have to 531 -- compute the first non-stub return location but this is not 532 -- the role of this subprogram, so let's just try to see if we 533 -- can get a result from the tables in shared libraries. 534 535 if UWD_Address = -1 536 and then U_is_shared_pc (Frame.cur_rlo, Frame.cur_r19) /= 0 537 then 538 declare 539 Shlib_UWT : constant UWT := 540 U_get_shLib_unwind_table (Frame.cur_r19); 541 Shlib_Start : constant Address := 542 U_get_shLib_text_addr (Frame.cur_r19); 543 Rlo_Offset : constant Address := 544 Frame.cur_rlo - Shlib_Start; 545 begin 546 UWD_Address := U_get_unwind_entry (Rlo_Offset, 547 Frame.cur_rls, 548 Shlib_UWT.Table_Start, 549 Shlib_UWT.Table_End); 550 end; 551 end if; 552 553 if UWD_Address /= -1 then 554 return To_UWD_Access (UWD_Address + Frame_Info_Offset); 555 else 556 return null; 557 end if; 558 end UWD_For_RLO_Of; 559 560 -- Start of processing for Call_Chain 561 562 begin 563 -- Fetch the state for this subprogram's frame and pop it so that we 564 -- start with an initial out_rlo "here". 565 566 U_init_frame_record (Frame'Access); 567 Frame.top_sr0 := 0; 568 Frame.top_sr4 := 0; 569 570 U_prep_frame_rec_for_unwind (Frame'Access); 571 572 Pop_Success := Pop_Frame (Frame'Access); 573 574 -- Skip the requested number of frames 575 576 for I in 1 .. Skip_Frames loop 577 Pop_Success := Pop_Frame (Frame'Access); 578 end loop; 579 580 -- Loop popping frames and storing locations until either a problem 581 -- occurs, or the top of the call chain is reached, or the provided 582 -- array is full. 583 584 loop 585 -- We have to test some conditions against the return location 586 -- as it is returned, so get it as is first. 587 588 Code := Frame.out_rlo; 589 590 exit when not Pop_Success or else Code = 0 or else J = Max_Len + 1; 591 592 -- Compute the call point from the retrieved return location : 593 -- Mask the privilege bits and account for the delta between the 594 -- call site and the return point. 595 596 Code := (Code and not Priv_Mask) - Rlo_Offset; 597 598 if Code < Exclude_Min or else Code > Exclude_Max then 599 Trace (J) := Code; 600 J := J + 1; 601 end if; 602 603 Pop_Success := Pop_Frame (Frame'Access); 604 end loop; 605 606 Len := J - 1; 607 end Call_Chain; 608 609 procedure Call_Chain 610 (Traceback : in out System.Traceback_Entries.Tracebacks_Array; 611 Max_Len : Natural; 612 Len : out Natural; 613 Exclude_Min : System.Address := System.Null_Address; 614 Exclude_Max : System.Address := System.Null_Address; 615 Skip_Frames : Natural := 1) 616 is 617 begin 618 Call_Chain 619 (Traceback'Address, Max_Len, Len, 620 Exclude_Min, Exclude_Max, 621 622 -- Skip one extra frame to skip the other Call_Chain entry as well 623 624 Skip_Frames => Skip_Frames + 1); 625 end Call_Chain; 626 627end System.Traceback; 628