* *
* C Implementation File *
* *
- * Copyright (C) 2003 Ada Core Technologies, Inc *
+ * Copyright (C) 2003-2007, AdaCore *
* *
* 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- *
* 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. *
+ * to the Free Software Foundation, 51 Franklin Street, Fifth Floor, *
+ * Boston, MA 02110-1301, 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 *
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 <vms/pdscdef.h>
+#include <vms/libicb.h>
+#include <vms/chfctxdef.h>
+#include <vms/chfdef.h>
-/* We still use a number of macros similar to the ones for the generic
- __gnat_backtrace implementation. */
-#define SKIP_FRAME 1
-#define PC_ADJUST -4
-
-#define STOP_FRAME (frame_state.saved_ra == RA_STOP)
-
-/* Mask for PDSC$V_BASE_FRAME in procedure descriptors, missing from the
- header file included above. */
+/* A couple of items missing from the header file included above. */
+extern void * SYS$GL_CALL_HANDL;
#define PDSC$M_BASE_FRAME (1 << 10)
-typedef unsigned long REG;
+/* 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 REG_AT(address) (*(REG *)(address))
+#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
{
- void * pc; /* Address of the call insn involved in the chain. */
- void * sp; /* Stack Pointer at the time of this call. */
- void * fp; /* Frame Pointer at the time of this call. */
+ 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. */
+ incrementally updated through consecutive calls to the "unwind" function
+ below. */
REG saved_regs [32];
} frame_state_t;
This is from ABI-3.1.1 [Integer Registers]. */
-#define saved_fp saved_regs[29]
-#define saved_sp saved_regs[30]
-#define saved_ra saved_regs[26]
-#define saved_pv saved_regs[27]
+#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_ra, used to control the overall unwinding
+/* Special values for saved_rar, used to control the overall unwinding
process. */
#define RA_UNKNOWN ((REG)~0)
#define RA_STOP ((REG)0)
-/* Compute Procedure Value from a live Frame Pointer value. */
+/* 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) \
- ((REG_AT (FP) & 0x7) == 0) ? *(PDSCDEF **)(FP) : (PDSCDEF *)(FP);
+ (((FP) != 0) \
+ ? (((REG_AT (FP) & 0x7) == 0) ? *(PDSCDEF **)(FP) : (PDSCDEF *)(FP)) : 0)
+
/**********
* unwind *
**********/
-/* Helper for __gnat_backtrace. Update FS->pc/sp/fp to represent the
- state computed in FS->saved_regs during the previous call, and update
- FS->saved_regs in preparation of the next call. */
+/* 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)
{
- REG frame_base;
- PDSCDEF * pv;
-
/* Don't do anything if requested so. */
- if (fs->saved_ra == RA_STOP)
+ 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 = (void *) fs->saved_ra + PC_ADJUST;
- fs->sp = (void *) fs->saved_sp;
- fs->fp = (void *) fs->saved_fp;
+ 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_ra = RA_STOP;
+ fs->saved_rar = RA_STOP;
- /* Now we want to update fs->saved_regs to reflect what the procedure
- described by pc/fp/sp has done. */
+ /* Now we want to update fs->saved_regs to reflect the state of the caller
+ of the procedure described by pc/fp.
- /* Compute the corresponding "procedure value", following the rules in
- ABI-3.6.1 [Current Procedure]. Return immediatly if this value mandates
- us to stop. */
- if (fs->fp == 0)
- return;
+ 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);
- 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;
- /* Use the procedure value to unwind, in a way depending on the kind of
- procedure at hand. This is based on ABI-3.3 [Procedure Representation]
- and ABI-3.4 [Procedure Types]. */
frame_base
- = (REG) ((pv->pdsc$w_flags & PDSC$M_BASE_REG_IS_FP) ? fs->fp : fs->sp);
+ = (pv->pdsc$w_flags & PDSC$M_BASE_REG_IS_FP) ? fs->fp : fs->sp;
switch (pv->pdsc$w_flags & 0xf)
{
/* Stack Frame Procedure (ABI-3.4.1). Retrieve the necessary registers
from the Register Save Area in the frame. */
{
- REG rsa_base = frame_base + pv->pdsc$w_rsa_offset;
+ ADDR rsa_base = frame_base + pv->pdsc$w_rsa_offset;
int i, j;
- fs->saved_ra = REG_AT (rsa_base);
- fs->saved_pv = REG_AT (frame_base);
-
+ fs->saved_rar = REG_AT (rsa_base);
+ fs->saved_pvr = REG_AT (frame_base);
+
for (i = 0, j = 0; i < 32; i++)
if (pv->pdsc$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_fp, 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]).
-
+ /* 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. */
/* Register Procedure (ABI-3.4.4). Retrieve the necessary registers from
the registers where they have been saved. */
{
- fs->saved_ra = fs->saved_regs[pv->pdsc$b_save_ra];
- fs->saved_fp = fs->saved_regs[pv->pdsc$b_save_fp];
+ fs->saved_rar = fs->saved_regs[pv->pdsc$b_save_ra];
+ fs->saved_fpr = fs->saved_regs[pv->pdsc$b_save_fp];
}
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_sp = frame_base + pv->pdsc$l_size;
+ fs->saved_spr = AS_REG (frame_base) + pv->pdsc$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 {
- void * pc;
- void * pv;
+ ADDR pc; /* Program Counter. */
+ ADDR pv; /* Procedure Value. */
} tb_entry_t;
/********************
********************/
int
-__gnat_backtrace (array, size, exclude_min, exclude_max, skip_frames)
- void **array;
- int size;
- void *exclude_min;
- void *exclude_max;
- int skip_frames;
+__gnat_backtrace (void **array, int size,
+ void *exclude_min, void *exclude_max, int skip_frames)
{
int cnt;
register REG this_FP __asm__("$29");
register REG this_SP __asm__("$30");
- frame_state.saved_fp = this_FP;
- frame_state.saved_sp = this_SP;
- frame_state.saved_ra = RA_UNKNOWN;
+ frame_state.saved_fpr = this_FP;
+ frame_state.saved_spr = this_SP;
+ frame_state.saved_rar = RA_UNKNOWN;
unwind (&frame_state);
cnt = 0;
while (cnt < size)
{
+ /* Stop if either the frame contents or the unwinder say so. */
if (STOP_FRAME)
break;
- if (frame_state.pc < exclude_min
- || frame_state.pc > exclude_max)
+ if (! K_HANDLER_FRAME (&frame_state)
+ && (frame_state.pc < exclude_min || frame_state.pc > exclude_max))
{
- tbe->pc = frame_state.pc;
- tbe->pv = PV_FOR (frame_state.fp);
-
+ tbe->pc = (ADDR) frame_state.pc;
+ tbe->pv = (ADDR) PV_FOR (frame_state.fp);
+
cnt ++;
tbe ++;
}
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