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- /* Fallback frame unwinding for Alpha/VMS.
- Copyright (C) 1996-2022 Free Software Foundation, Inc.
- This file is part of GCC.
- GCC is free software; you can redistribute it and/or modify it
- under the terms of the GNU General Public License as published
- by the Free Software Foundation; either version 3, or (at your
- option) any later version.
- GCC is distributed in the hope that it will be useful, but WITHOUT
- ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
- License for more details.
- Under Section 7 of GPL version 3, you are granted additional
- permissions described in the GCC Runtime Library Exception, version
- 3.1, as published by the Free Software Foundation.
- You should have received a copy of the GNU General Public License and
- a copy of the GCC Runtime Library Exception along with this program;
- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
- <http://www.gnu.org/licenses/>. */
- #include <stdlib.h>
- #include <stdio.h>
- #include <vms/pdscdef.h>
- #include <vms/libicb.h>
- #include <vms/chfctxdef.h>
- #include <vms/chfdef.h>
- #define MD_FALLBACK_FRAME_STATE_FOR alpha_vms_fallback_frame_state
- typedef void * ADDR;
- typedef unsigned long long REG;
- typedef PDSCDEF * PV;
- #define REG_AT(addr) (*(REG *)(addr))
- #define ADDR_AT(addr) (*(ADDR *)(addr))
- /* Compute pointer to procedure descriptor (Procedure Value) from Frame
- Pointer FP, according to the rules in [ABI-3.5.1 Current Procedure]. */
- #define PV_FOR(FP) \
- (((FP) != 0) \
- ? (((REG_AT (FP) & 0x7) == 0) ? *(PDSCDEF **)(FP) : (PDSCDEF *)(FP)) : 0)
- extern int SYS$GL_CALL_HANDL;
- /* This is actually defined as a "long", but in system code where longs
- are always 4bytes while GCC longs might be 8bytes. */
- #define UPDATE_FS_FOR_CFA_GR(FS, GRN, LOC, CFA) \
- do { \
- (FS)->regs.reg[GRN].how = REG_SAVED_OFFSET; \
- (FS)->regs.reg[GRN].loc.offset = (_Unwind_Sword) ((REG) (LOC) - (REG) (CFA)); \
- } while (0);
- #define GIVEUP_ON_FAILURE(STATUS) \
- { if ((((STATUS) & 1) != 1)) return _URC_END_OF_STACK; }
- #define DENOTES_EXC_DISPATCHER(PV) ((PV) == (ADDR) (REG) SYS$GL_CALL_HANDL)
- #define RA_COLUMN (__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__)
- static int
- alpha_vms_fallback_frame_state (struct _Unwind_Context *context,
- _Unwind_FrameState *fs)
- {
- static int eh_debug = -1;
- /* Our goal is to update FS to reflect the state one step up CONTEXT, that
- is: the CFA, return address and *saved* registers locations associated
- with the function designated by CONTEXT->ra. We are called when the
- libgcc unwinder has not found any dwarf FDE for this address, which
- typically happens when trying to propagate a language exception through a
- signal global vector or frame based handler.
- The CONTEXT->reg[] entries reflect the state/location of register saves
- so designate values live at the CONTEXT->ra point. Of precious value to
- us here is the frame pointer (r29), which gets us a procedure value. */
- PV pv = (context->reg[29] != 0) ? PV_FOR (ADDR_AT (context->reg[29])) : 0;
- int pkind = pv ? pv->pdsc$w_flags & 0xf : 0;
- /* VMS procedure kind, as indicated by the procedure descriptor. We only
- know how to deal with FP_STACK or FP_REGISTER here. */
- ADDR new_cfa = 0;
- /* CFA we will establish for the caller, computed in different ways,
- e.g. depending whether we cross an exception dispatcher frame. */
- CHFCTX *chfctx = 0;
- /* Pointer to the VMS CHF context associated with an exception dispatcher
- frame, if we happen to come across one. */
- int i,j;
- if (eh_debug == -1)
- {
- char * eh_debug_env = getenv ("EH_DEBUG");
- eh_debug = eh_debug_env ? atoi (eh_debug_env) : 0;
- }
- if (eh_debug)
- printf ("MD_FALLBACK running ...\n");
- /* We only know how to deal with stack or reg frame procedures, so give
- up if we're handed anything else. */
- if (pkind != PDSC$K_KIND_FP_STACK && pkind != PDSC$K_KIND_FP_REGISTER)
- return _URC_END_OF_STACK;
-
- if (eh_debug)
- printf ("FALLBACK: CTX FP = 0x%p, PV = 0x%p, EN = 0x%llx, RA = 0x%p\n",
- ADDR_AT (context->reg[29]), pv, pv->pdsc$q_entry, context->ra);
- fs->retaddr_column = RA_COLUMN;
- /* If PV designates a VMS exception vector or condition handler, we need to
- do as if the caller was the signaling point and estabish the state of the
- intermediate VMS code (CFA, RA and saved register locations) as if it was
- a single regular function. This requires special processing.
- The datastructures available from an condition dispatcher frame (signal
- context) do not contain the values of most callee-saved registers, so
- whathever PV designates, we need to account for the registers it saves.
- Besides, we need to express all the locations with respect to a
- consistent CFA value, so we compute this first. */
- if (DENOTES_EXC_DISPATCHER (pv))
- {
- /* The CFA to establish is the signaling point's stack pointer. We
- compute it using the system invocation context unwinding services and
- save the CHF context data pointer along the way for later uses. */
- INVO_CONTEXT_BLK icb;
- int status, invo_handle;
- if (eh_debug)
- printf ("FALLBACK: SYS$HANDLER\n");
- icb.libicb$q_ireg [29] = REG_AT (context->reg[29]);
- icb.libicb$q_ireg [30] = 0;
- invo_handle = LIB$GET_INVO_HANDLE (&icb);
- status = LIB$GET_INVO_CONTEXT (invo_handle, &icb);
- GIVEUP_ON_FAILURE (status);
- chfctx = (CHFCTX *) icb.libicb$ph_chfctx_addr;
- status = LIB$GET_PREV_INVO_CONTEXT (&icb);
- GIVEUP_ON_FAILURE (status);
- new_cfa = (ADDR) icb.libicb$q_ireg[30];
- }
- else
- {
- /* The CFA to establish is the SP value on entry of the procedure
- designated by PV, which we compute as the corresponding frame base
- register value + frame size. Note that the frame base may differ
- from CONTEXT->cfa, typically if the caller has performed dynamic
- stack allocations. */
-
- int base_reg = pv->pdsc$w_flags & PDSC$M_BASE_REG_IS_FP ? 29 : 30;
- ADDR base_addr = ADDR_AT (context->reg[base_reg]);
-
- new_cfa = base_addr + pv->pdsc$l_size;
- }
- /* State to compute the caller's CFA by adding an offset to the current
- one in CONTEXT. */
- fs->regs.cfa_how = CFA_REG_OFFSET;
- fs->regs.cfa_reg = __builtin_dwarf_sp_column ();
- fs->regs.cfa_offset = new_cfa - context->cfa;
- /* Regular unwind first, accounting for the register saves performed by
- the procedure designated by PV. */
- switch (pkind)
- {
- case PDSC$K_KIND_FP_STACK:
- {
- /* The saved registers are all located in the Register Save Area,
- except for the procedure value register (R27) found at the frame
- base address. */
- int base_reg = pv->pdsc$w_flags & PDSC$M_BASE_REG_IS_FP ? 29 : 30;
- ADDR base_addr = ADDR_AT (context->reg[base_reg]);
- ADDR rsa_addr = base_addr + pv->pdsc$w_rsa_offset;
- if (eh_debug)
- printf ("FALLBACK: STACK frame procedure\n");
- UPDATE_FS_FOR_CFA_GR (fs, 27, base_addr, new_cfa);
- /* The first RSA entry is for the return address register, R26. */
- UPDATE_FS_FOR_CFA_GR (fs, 26, rsa_addr, new_cfa);
- UPDATE_FS_FOR_CFA_GR (fs, RA_COLUMN, rsa_addr, new_cfa);
- /* The following entries are for registers marked as saved according
- to ireg_mask. */
- for (i = 0, j = 0; i < 32; i++)
- if ((1 << i) & pv->pdsc$l_ireg_mask)
- UPDATE_FS_FOR_CFA_GR (fs, i, rsa_addr + 8 * ++j, new_cfa);
-
- /* ??? floating point registers ? */
- break;
- }
- case PDSC$K_KIND_FP_REGISTER:
- {
- if (eh_debug)
- printf ("FALLBACK: REGISTER frame procedure\n");
- fs->regs.reg[RA_COLUMN].how = REG_SAVED_REG;
- fs->regs.reg[RA_COLUMN].loc.reg = pv->pdsc$b_save_ra;
-
- fs->regs.reg[29].how = REG_SAVED_REG;
- fs->regs.reg[29].loc.reg = pv->pdsc$b_save_fp;
-
- break;
- }
- default:
- /* Should never reach here. */
- return _URC_END_OF_STACK;
- }
- /* If PV designates an exception dispatcher, we have to adjust the return
- address column to get at the signal occurrence point, and account for
- what the CHF context contains. */
- if (DENOTES_EXC_DISPATCHER (pv))
- {
- /* The PC of the instruction causing the condition is available from the
- signal argument vector. Extra saved register values are available
- from the mechargs array. */
- CHF$SIGNAL_ARRAY *sigargs
- = (CHF$SIGNAL_ARRAY *) chfctx->chfctx$q_sigarglst;
- CHF$MECH_ARRAY *mechargs
- = (CHF$MECH_ARRAY *) chfctx->chfctx$q_mcharglst;
- ADDR condpc_addr
- = &((int *)(&sigargs->chf$l_sig_name)) [sigargs->chf$is_sig_args-2];
- ADDR rei_frame_addr = (void *) mechargs->chf$q_mch_esf_addr;
- /* Adjust the return address location. */
- UPDATE_FS_FOR_CFA_GR (fs, RA_COLUMN, condpc_addr, new_cfa);
- /* The frame pointer at the condition point is available from the
- chf context directly. */
- UPDATE_FS_FOR_CFA_GR (fs, 29, &chfctx->chfctx$q_expt_fp, new_cfa);
- /* Registers available from the mechargs array. */
- UPDATE_FS_FOR_CFA_GR (fs, 0, &mechargs->chf$q_mch_savr0, new_cfa);
- UPDATE_FS_FOR_CFA_GR (fs, 1, &mechargs->chf$q_mch_savr1, new_cfa);
- UPDATE_FS_FOR_CFA_GR (fs, 16, &mechargs->chf$q_mch_savr16, new_cfa);
- UPDATE_FS_FOR_CFA_GR (fs, 17, &mechargs->chf$q_mch_savr17, new_cfa);
- UPDATE_FS_FOR_CFA_GR (fs, 18, &mechargs->chf$q_mch_savr18, new_cfa);
- UPDATE_FS_FOR_CFA_GR (fs, 19, &mechargs->chf$q_mch_savr19, new_cfa);
- UPDATE_FS_FOR_CFA_GR (fs, 20, &mechargs->chf$q_mch_savr20, new_cfa);
- UPDATE_FS_FOR_CFA_GR (fs, 21, &mechargs->chf$q_mch_savr21, new_cfa);
- UPDATE_FS_FOR_CFA_GR (fs, 22, &mechargs->chf$q_mch_savr22, new_cfa);
- UPDATE_FS_FOR_CFA_GR (fs, 23, &mechargs->chf$q_mch_savr23, new_cfa);
- UPDATE_FS_FOR_CFA_GR (fs, 24, &mechargs->chf$q_mch_savr24, new_cfa);
- UPDATE_FS_FOR_CFA_GR (fs, 25, &mechargs->chf$q_mch_savr25, new_cfa);
- UPDATE_FS_FOR_CFA_GR (fs, 26, &mechargs->chf$q_mch_savr26, new_cfa);
- UPDATE_FS_FOR_CFA_GR (fs, 27, &mechargs->chf$q_mch_savr27, new_cfa);
- UPDATE_FS_FOR_CFA_GR (fs, 28, &mechargs->chf$q_mch_savr28, new_cfa);
-
- /* Registers R2 to R7 are available from the rei frame pointer. */
-
- for (i = 2; i <= 7; i ++)
- UPDATE_FS_FOR_CFA_GR (fs, i, rei_frame_addr+(i - 2)*8, new_cfa);
-
- /* ??? floating point registers ? */
- }
- fs->signal_frame = 1;
- return _URC_NO_REASON;
- }
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