| /**************************************************************************** |
| * * |
| * GNAT COMPILER COMPONENTS * |
| * * |
| * T R A C E B A C K - A l p h a / V M S * |
| * * |
| * C Implementation File * |
| * * |
| * Copyright (C) 2003 Ada Core Technologies, Inc * |
| * * |
| * GNAT is free software; you can redistribute it and/or modify it under * |
| * terms of the GNU General Public License as published by the Free Soft- * |
| * ware Foundation; either version 2, or (at your option) any later ver- * |
| * sion. GNAT is distributed in the hope that it will be useful, but WITH- * |
| * OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY * |
| * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * |
| * for more details. You should have received a copy of the GNU General * |
| * Public License distributed with GNAT; see file COPYING. If not, write * |
| * to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, * |
| * MA 02111-1307, USA. * |
| * * |
| * As a special exception, if you link this file with other files to * |
| * produce an executable, this file does not by itself cause the resulting * |
| * executable to be covered by the GNU General Public License. This except- * |
| * ion does not however invalidate any other reasons why the executable * |
| * file might be covered by the GNU Public License. * |
| * * |
| * GNAT was originally developed by the GNAT team at New York University. * |
| * Extensive contributions were provided by Ada Core Technologies Inc. * |
| * * |
| ****************************************************************************/ |
| |
| |
| /* Alpha VMS requires a special treatment due to the complexity of the ABI. |
| What is here is along the lines of what the MD_FALLBACK_FRAME_STATE_FOR |
| macro does for frame unwinding during exception propagation. This file is |
| #included within tracebak.c in the appropriate case. |
| |
| Most of the contents is directed by the OpenVMS/Alpha Conventions (ABI) |
| document, sections of which we will refer to as ABI-<section_number>. */ |
| |
| #include <pdscdef.h> |
| #include <libicb.h> |
| #include <chfctxdef.h> |
| #include <chfdef.h> |
| |
| /* A couple of items missing from the header file included above. */ |
| extern void * SYS$GL_CALL_HANDL; |
| #define PDSC$M_BASE_FRAME (1 << 10) |
| |
| /* Registers are 64bit wide and addresses are 32bit wide on alpha-vms. */ |
| typedef void * ADDR; |
| typedef unsigned long long REG; |
| |
| #define REG_AT(addr) (*(REG *)(addr)) |
| |
| #define AS_REG(addr) ((REG)(unsigned long)(addr)) |
| #define AS_ADDR(reg) ((ADDR)(unsigned long)(reg)) |
| #define ADDR_IN(reg) (AS_ADDR(reg)) |
| |
| /* The following structure defines the state maintained during the |
| unwinding process. */ |
| typedef struct |
| { |
| ADDR pc; /* Address of the call insn involved in the chain. */ |
| ADDR sp; /* Stack Pointer at the time of this call. */ |
| ADDR fp; /* Frame Pointer at the time of this call. */ |
| |
| /* The values above are fetched as saved REGisters on the stack. They are |
| typed ADDR because this is what the values in those registers are. */ |
| |
| /* Values of the registers saved by the functions in the chain, |
| incrementally updated through consecutive calls to the "unwind" function |
| below. */ |
| REG saved_regs [32]; |
| } frame_state_t; |
| |
| /* Shortcuts for saved_regs of specific interest: |
| |
| Frame Pointer is r29, |
| Stack Pointer is r30, |
| Return Address is r26, |
| Procedure Value is r27. |
| |
| This is from ABI-3.1.1 [Integer Registers]. */ |
| |
| #define saved_fpr saved_regs[29] |
| #define saved_spr saved_regs[30] |
| #define saved_rar saved_regs[26] |
| #define saved_pvr saved_regs[27] |
| |
| /* Special values for saved_rar, used to control the overall unwinding |
| process. */ |
| #define RA_UNKNOWN ((REG)~0) |
| #define RA_STOP ((REG)0) |
| |
| /* We still use a number of macros similar to the ones for the generic |
| __gnat_backtrace implementation. */ |
| #define PC_ADJUST 4 |
| #define STOP_FRAME (frame_state.saved_rar == RA_STOP) |
| |
| /* Compute Procedure Value from Frame Pointer value. This follows the rules |
| in ABI-3.6.1 [Current Procedure]. */ |
| #define PV_FOR(FP) \ |
| (((FP) != 0) \ |
| ? (((REG_AT (FP) & 0x7) == 0) ? *(PDSCDEF **)(FP) : (PDSCDEF *)(FP)) : 0) |
| |
| |
| /********** |
| * unwind * |
| **********/ |
| |
| /* Helper for __gnat_backtrace. |
| |
| FS represents some call frame, identified by a pc and associated frame |
| pointer in FS->pc and FS->fp. FS->saved_regs contains the state of the |
| general registers upon entry in this frame. Of most interest in this set |
| are the saved return address and frame pointer registers, which actually |
| allow identifying the caller's frame. |
| |
| This routine "unwinds" the input frame state by adjusting it to eventually |
| represent its caller's frame. The basic principle is to shift the fp and pc |
| saved values into the current state, and then compute the corresponding new |
| saved registers set. |
| |
| If the call chain goes through a signal handler, special processing is |
| required when we process the kernel frame which has called the handler, to |
| switch it to the interrupted context frame. */ |
| |
| #define K_HANDLER_FRAME(fs) (PV_FOR ((fs)->fp) == SYS$GL_CALL_HANDL) |
| |
| static void unwind_regular_code (frame_state_t * fs); |
| static void unwind_kernel_handler (frame_state_t * fs); |
| |
| void |
| unwind (frame_state_t * fs) |
| { |
| /* Don't do anything if requested so. */ |
| if (fs->saved_rar == RA_STOP) |
| return; |
| |
| /* Retrieve the values of interest computed during the previous |
| call. PC_ADJUST gets us from the return address to the call insn |
| address. */ |
| fs->pc = ADDR_IN (fs->saved_rar) - PC_ADJUST; |
| fs->sp = ADDR_IN (fs->saved_spr); |
| fs->fp = ADDR_IN (fs->saved_fpr); |
| |
| /* Unless we are able to determine otherwise, set the frame state's |
| saved return address such that the unwinding process will stop. */ |
| fs->saved_rar = RA_STOP; |
| |
| /* Now we want to update fs->saved_regs to reflect the state of the caller |
| of the procedure described by pc/fp. |
| |
| The condition to check for a special kernel frame which has called a |
| signal handler is stated in ABI-6.7.1 [Signaler's Registers] : "The frame |
| of the call to the handler can be identified by the return address of |
| SYS$CALL_HANDL+4". We use the equivalent procedure value identification |
| here because SYS$CALL_HANDL appears to be undefined. */ |
| |
| if (K_HANDLER_FRAME (fs)) |
| unwind_kernel_handler (fs); |
| else |
| unwind_regular_code (fs); |
| } |
| |
| /*********************** |
| * unwind_regular_code * |
| ***********************/ |
| |
| /* Helper for unwind, for the case of unwinding through regular code which |
| is not a signal handler. */ |
| |
| static void |
| unwind_regular_code (frame_state_t * fs) |
| { |
| PDSCDEF * pv = PV_FOR (fs->fp); |
| |
| ADDR frame_base; |
| |
| /* Use the procedure value to unwind, in a way depending on the kind of |
| procedure at hand. See ABI-3.3 [Procedure Representation] and ABI-3.4 |
| [Procedure Types]. */ |
| |
| if (pv == 0 |
| || pv->pdsc$w_flags & PDSC$M_BASE_FRAME) |
| return; |
| |
| frame_base |
| = (pv->pdsc$w_flags & PDSC$M_BASE_REG_IS_FP) ? fs->fp : fs->sp; |
| |
| switch (pv->pdsc$w_flags & 0xf) |
| { |
| case PDSC$K_KIND_FP_STACK: |
| /* Stack Frame Procedure (ABI-3.4.1). Retrieve the necessary registers |
| from the Register Save Area in the frame. */ |
| { |
| ADDR rsa_base = frame_base + pv->pdsc$w_rsa_offset; |
| int i, j; |
| |
| fs->saved_rar = REG_AT (rsa_base); |
| fs->saved_pvr = REG_AT (frame_base); |
| |
| for (i = 0, j = 0; i < 32; i++) |
| if (pv->pdsc$l_ireg_mask & (1 << i)) |
| fs->saved_regs[i] = REG_AT (rsa_base + 8 * ++j); |
| |
| /* Note that the loop above is guaranteed to set fs->saved_fpr, |
| because "The preserved register set must always include R29(FP) |
| since it will always be used." (ABI-3.4.3.4 [Register Save Area for |
| All Stack Frames]). |
| |
| Also note that we need to run through all the registers to ensure |
| that unwinding through register procedures (see below) gets the |
| right values out of the saved_regs array. */ |
| } |
| break; |
| |
| case PDSC$K_KIND_FP_REGISTER: |
| /* Register Procedure (ABI-3.4.4). Retrieve the necessary registers from |
| the registers where they have been saved. */ |
| { |
| fs->saved_rar = fs->saved_regs[pv->pdsc$b_save_ra]; |
| fs->saved_fpr = fs->saved_regs[pv->pdsc$b_save_fp]; |
| } |
| break; |
| |
| default: |
| /* ??? Are we supposed to ever get here ? Don't think so. */ |
| break; |
| } |
| |
| /* SP is actually never part of the saved registers area, so we use the |
| corresponding entry in the saved_regs array to manually keep track of |
| it's evolution. */ |
| fs->saved_spr = AS_REG (frame_base) + pv->pdsc$l_size; |
| } |
| |
| /************************* |
| * unwind_kernel_handler * |
| *************************/ |
| |
| /* Helper for unwind, for the specific case of unwinding through a signal |
| handler. |
| |
| The input frame state describes the kernel frame which has called a signal |
| handler. We fill the corresponding saved_regs to have it's "caller" frame |
| represented as the interrupted context. */ |
| |
| static void |
| unwind_kernel_handler (frame_state_t * fs) |
| { |
| PDSCDEF * pv = PV_FOR (fs->fp); |
| |
| CHFDEF1 *sigargs; |
| CHFDEF2 *mechargs; |
| |
| /* Retrieve the arguments passed to the handler, by way of a VMS service |
| providing the corresponding "Invocation Context Block". */ |
| { |
| long handler_ivhandle; |
| INVO_CONTEXT_BLK handler_ivcb; |
| |
| CHFCTX *chfctx; |
| |
| handler_ivcb.libicb$q_ireg [29] = AS_REG (fs->fp); |
| handler_ivcb.libicb$q_ireg [30] = 0; |
| |
| handler_ivhandle = LIB$GET_INVO_HANDLE (&handler_ivcb); |
| |
| if ((LIB$GET_INVO_CONTEXT (handler_ivhandle, &handler_ivcb) & 1) != 1) |
| return; |
| |
| chfctx = (CHFCTX *) AS_ADDR (handler_ivcb.libicb$ph_chfctx_addr); |
| |
| sigargs = (CHFDEF1 *) AS_ADDR (chfctx->chfctx$q_sigarglst); |
| mechargs = (CHFDEF2 *) AS_ADDR (chfctx->chfctx$q_mcharglst); |
| } |
| |
| /* Compute the saved return address as the PC of the instruction causing the |
| condition, accounting for the fact that it will be adjusted by the next |
| call to "unwind" as if it was an actual call return address. */ |
| { |
| /* ABI-6.5.1.1 [Signal Argument Vector]: The signal occurrence address |
| is available from the sigargs argument to the handler, designed to |
| support both 32 and 64 bit addresses. The initial reference we get |
| is a pointer to the 32bit form, from which one may extract a pointer |
| to the 64bit version if need be. We work directly from the 32bit |
| form here. */ |
| |
| /* The sigargs vector structure for 32bits addresses is: |
| |
| <......32bit......> |
| +-----------------+ |
| | Vsize | :chf$is_sig_args |
| +-----------------+ -+- |
| | Condition Value | : [0] |
| +-----------------+ : |
| | ... | : |
| +-----------------+ : vector of Vsize entries |
| | Signal PC | : |
| +-----------------+ : |
| | PS | : [Vsize - 1] |
| +-----------------+ -+- |
| |
| */ |
| |
| unsigned long * sigargs_vector |
| = ((unsigned long *) (&sigargs->chf$is_sig_args)) + 1; |
| |
| long sigargs_vsize |
| = sigargs->chf$is_sig_args; |
| |
| fs->saved_rar = (REG) sigargs_vector [sigargs_vsize - 2] + PC_ADJUST; |
| } |
| |
| fs->saved_spr = RA_UNKNOWN; |
| fs->saved_fpr = (REG) mechargs->chf$q_mch_frame; |
| fs->saved_pvr = (REG) mechargs->chf$q_mch_savr27; |
| |
| fs->saved_regs[16] = (REG) mechargs->chf$q_mch_savr16; |
| fs->saved_regs[17] = (REG) mechargs->chf$q_mch_savr17; |
| fs->saved_regs[18] = (REG) mechargs->chf$q_mch_savr18; |
| fs->saved_regs[19] = (REG) mechargs->chf$q_mch_savr19; |
| fs->saved_regs[20] = (REG) mechargs->chf$q_mch_savr20; |
| } |
| |
| /* Structure representing a traceback entry in the tracebacks array to be |
| filled by __gnat_backtrace below. |
| |
| !! This should match what is in System.Traceback_Entries, so beware of |
| !! the REG/ADDR difference here. |
| |
| The use of a structure is motivated by the potential necessity of having |
| several fields to fill for each entry, for instance if later calls to VMS |
| system functions need more than just a mere PC to compute info on a frame |
| (e.g. for non-symbolic->symbolic translation purposes). */ |
| typedef struct { |
| ADDR pc; |
| ADDR pv; |
| } tb_entry_t; |
| |
| /******************** |
| * __gnat_backtrace * |
| ********************/ |
| |
| int |
| __gnat_backtrace (void **array, int size, |
| void *exclude_min, void *exclude_max, int skip_frames) |
| { |
| int cnt; |
| |
| tb_entry_t * tbe = (tb_entry_t *)&array [0]; |
| |
| frame_state_t frame_state; |
| |
| /* Setup the frame state before initiating the unwinding sequence. */ |
| register REG this_FP __asm__("$29"); |
| register REG this_SP __asm__("$30"); |
| |
| frame_state.saved_fpr = this_FP; |
| frame_state.saved_spr = this_SP; |
| frame_state.saved_rar = RA_UNKNOWN; |
| |
| unwind (&frame_state); |
| |
| /* At this point frame_state describes this very function. Skip the |
| requested number of calls. */ |
| for (cnt = 0; cnt < skip_frames; cnt ++) |
| unwind (&frame_state); |
| |
| /* Now consider each frame as a potential candidate for insertion inside |
| the provided array. */ |
| cnt = 0; |
| while (cnt < size) |
| { |
| PDSCDEF * pv = PV_FOR (frame_state.fp); |
| |
| /* Stop if either the frame contents or the unwinder say so. */ |
| if (STOP_FRAME) |
| break; |
| |
| if (! K_HANDLER_FRAME (&frame_state) |
| && (frame_state.pc < exclude_min || frame_state.pc > exclude_max)) |
| { |
| tbe->pc = (ADDR) frame_state.pc; |
| tbe->pv = (ADDR) PV_FOR (frame_state.fp); |
| |
| cnt ++; |
| tbe ++; |
| } |
| |
| unwind (&frame_state); |
| } |
| |
| return cnt; |
| } |
