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Re: [patch/rfc] signal trampoline frames
>tramp->insn is a ULONGEST. Both of these should probably be ULONGEST
>also.
changed to ->insn[0]
I was more concerned about the CORE_ADDR.
Ah, "both".
>>>+ if (tramp->insn[i] == 0)
>>>+ return func;
>
>
>So zeros in tramp->insn mark the end of the sequence? Should document
>that, zeros are valid instructions and some bizarre architecture might
>use one as a syscall trap.
Added TRAMP_SENTINEL_INSN, it _isn't_ zero.
The comment in the attached still says it's zero. Zero and -1 are just
about equally likely/unlikely, so I don't think it matters what the
value is; I like having TRAMP_SENTINEL_INSN though.
(LONGEST)-1 is typically 0xffffffffffffffffLL so unless an ISA has a
64-bit insn there won't be a clash.
I don't know.
Doesn't much matter then.
I committed the attached,
Andrew
2004-03-24 Andrew Cagney <cagney@redhat.com>
* tramp-frame.h (TRAMP_SENTINEL_INSN): Define, document.
* tramp-frame.c: Include "gdb_assert.h".
(tramp_frame_start): Use TRAMP_SENTINEL_INSN. Use ULONGEST and
correct sizeof.
(tramp_frame_append): Validate the tramp frame's instructions.
* Makefile.in (tramp-frame.o): Update dependencies.
Index: tramp-frame.c
===================================================================
RCS file: /cvs/src/src/gdb/tramp-frame.c,v
retrieving revision 1.2
diff -u -r1.2 tramp-frame.c
--- tramp-frame.c 23 Mar 2004 14:12:30 -0000 1.2
+++ tramp-frame.c 24 Mar 2004 23:13:23 -0000
@@ -28,6 +28,7 @@
#include "target.h"
#include "trad-frame.h"
#include "frame-base.h"
+#include "gdb_assert.h"
struct frame_data
{
@@ -89,15 +90,15 @@
int ti;
/* Search through the trampoline for one that matches the
instruction sequence around PC. */
- for (ti = 0; tramp->insn[ti] != 0; ti++)
+ for (ti = 0; tramp->insn[ti] != TRAMP_SENTINEL_INSN; ti++)
{
CORE_ADDR func = pc - tramp->insn_size * ti;
int i;
for (i = 0; 1; i++)
{
- bfd_byte buf[sizeof (LONGEST)];
- CORE_ADDR insn;
- if (tramp->insn[i] == 0)
+ bfd_byte buf[sizeof (tramp->insn[0])];
+ ULONGEST insn;
+ if (tramp->insn[i] == TRAMP_SENTINEL_INSN)
return func;
if (target_read_memory (func + i * tramp->insn_size, buf,
tramp->insn_size) != 0)
@@ -148,6 +149,16 @@
{
struct frame_data *data;
struct frame_unwind *unwinder;
+ int i;
+
+ /* Check that the instruction sequence contains a sentinel. */
+ for (i = 0; i < ARRAY_SIZE (tramp_frame->insn); i++)
+ {
+ if (tramp_frame->insn[i] == TRAMP_SENTINEL_INSN)
+ break;
+ }
+ gdb_assert (i < ARRAY_SIZE (tramp_frame->insn));
+ gdb_assert (tramp_frame->insn_size <= sizeof (tramp_frame->insn[0]));
data = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_data);
unwinder = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind);
Index: tramp-frame.h
===================================================================
RCS file: /cvs/src/src/gdb/tramp-frame.h,v
retrieving revision 1.2
diff -u -r1.2 tramp-frame.h
--- tramp-frame.h 23 Mar 2004 14:12:30 -0000 1.2
+++ tramp-frame.h 24 Mar 2004 23:13:23 -0000
@@ -39,6 +39,10 @@
/* A trampoline descriptor. */
+/* Magic instruction that to mark the end of the signal trampoline
+ instruction sequence. */
+#define TRAMP_SENTINEL_INSN ((LONGEST) -1)
+
struct tramp_frame
{
/* The trampoline's entire instruction sequence. Search for this in
@@ -47,7 +51,8 @@
one INSN_SIZE instruction. It is also assumed that TRAMP[0]
contains the first instruction of the trampoline and hence the
address of the instruction matching TRAMP[0] is the trampoline's
- "func" address. */
+ "func" address. The instruction sequence shall be terminated by
+ TRAMP_SENTINEL_INSN. */
int insn_size;
ULONGEST insn[8];
/* Initialize a trad-frame cache corresponding to the tramp-frame.