* Re: [RFA] Prevent runaway (infinite loop) in mips-tdep.c
2004-04-21 17:58 ` Michael Snyder
@ 2004-04-21 19:18 ` Daniel Jacobowitz
2004-04-21 19:23 ` Andrew Cagney
1 sibling, 0 replies; 6+ messages in thread
From: Daniel Jacobowitz @ 2004-04-21 19:18 UTC (permalink / raw)
To: Michael Snyder; +Cc: gdb-patches
On Wed, Apr 21, 2004 at 05:58:09PM +0000, Michael Snyder wrote:
> Daniel Jacobowitz wrote:
> >On Wed, Apr 21, 2004 at 12:20:53AM +0000, Michael Snyder wrote:
> >
> >>Hi Andrew,
> >>
> >>This change will prevent the caller(s) of mips_mdebug_frame_id from
> >>infinite-looping when we get badly lost on the stack frame.
> >>
> >
> >
> >>2004-04-21 Michael Snyder <msnyder@redhat.com>
> >>
> >> * mips-tdep.c (mips_mdebug_frame_cache): Call error to prevent
> >> infinite looping by caller.
> >> (heuristic_proc_start): Warning() already prefixes "Warning: ".
> >
> >
> >Since I have some patches to make this "I'm not sure how" case into a
> >working part of the unwinder, I don't much like this. They got hung up
> >on the question of how to trust proc_desc's when we might be in the
> >prologue.
> >
> >One time where this case occurs is in backtracing from a NULL pointer
> >dereference, which happens in the GDB testsuite now.
>
> OK -- can I see your patches? Maybe they'll solve the runaway condition
> I'm experiencing, and if not, maybe I can fix it in a way that's
> consistant with what you're doing.
What I've attached is a diff against GDB 6.1. No promises about
quality or "correctness".
diff -urp -x objdir -x '*~' gdb-2004-03-01-cvs.orig/gdb/mips-linux-tdep.c gdb-2004-03-01-cvs/gdb/mips-linux-tdep.c
--- gdb-2004-03-01-cvs.orig/gdb/mips-linux-tdep.c 2004-03-02 16:56:42.000000000 -0500
+++ gdb-2004-03-01-cvs/gdb/mips-linux-tdep.c 2004-03-03 18:29:25.000000000 -0500
@@ -85,7 +85,7 @@ mips_linux_get_longjmp_target (CORE_ADDR
buf, TARGET_PTR_BIT / TARGET_CHAR_BIT))
return 0;
- *pc = extract_unsigned_integer (buf, TARGET_PTR_BIT / TARGET_CHAR_BIT);
+ *pc = extract_signed_integer (buf, TARGET_PTR_BIT / TARGET_CHAR_BIT);
return 1;
}
@@ -379,7 +379,7 @@ mips64_linux_get_longjmp_target (CORE_AD
buf, TARGET_PTR_BIT / TARGET_CHAR_BIT))
return 0;
- *pc = extract_unsigned_integer (buf, TARGET_PTR_BIT / TARGET_CHAR_BIT);
+ *pc = extract_signed_integer (buf, TARGET_PTR_BIT / TARGET_CHAR_BIT);
return 1;
}
@@ -866,11 +866,8 @@ static void
set_reg_offset (struct trad_frame_saved_reg *saved_regs,
int regno, CORE_ADDR offset)
{
- if (saved_regs[regno].addr == 0)
- {
- saved_regs[regno + 0 * NUM_REGS].addr = offset;
- saved_regs[regno + 1 * NUM_REGS].addr = offset;
- }
+ saved_regs[regno + 0 * NUM_REGS].addr = offset;
+ saved_regs[regno + 1 * NUM_REGS].addr = offset;
}
/* There are two possible layouts for a signal frame:
@@ -945,7 +942,7 @@ mips_linux_sigframe_find_saved_regs (COR
int sigframe_kind)
{
int ireg, reg_position;
- CORE_ADDR sigcontext_base = frame - SIGFRAME_CODE_OFFSET;
+ CORE_ADDR sigcontext_base = frame;
const struct mips_regnum *regs;
if (sigframe_kind == 1)
@@ -1067,7 +1064,7 @@ mips64_linux_sigframe_find_saved_regs (C
{
const struct mips_regnum *regs;
int ireg, reg_position;
- CORE_ADDR sigcontext_base = frame - SIGFRAME_CODE_OFFSET;
+ CORE_ADDR sigcontext_base = frame;
if (sigframe_kind == 3)
sigcontext_base += N64_SIGFRAME_SIGCONTEXT_OFFSET;
@@ -1191,7 +1188,7 @@ mips_make_sigtramp_cache (struct frame_i
cache = frame_obstack_zalloc (sizeof (struct mips_prologue_cache));
- cache->prev_sp = frame_unwind_register_unsigned (next_frame, SP_REGNUM);
+ cache->prev_sp = frame_unwind_register_signed (next_frame, NUM_REGS + SP_REGNUM);
cache->saved_regs = trad_frame_alloc_saved_regs (next_frame);
@@ -1201,10 +1198,14 @@ mips_make_sigtramp_cache (struct frame_i
mips_linux_sigframe_find_saved_regs (cache->prev_sp, cache->saved_regs,
cache->kind);
+#if 0
/* Is this right? */
cache->prev_sp
= read_memory_integer (cache->saved_regs[SP_REGNUM].addr,
- DEPRECATED_REGISTER_RAW_SIZE (SP_REGNUM));
+ register_size (current_gdbarch, SP_REGNUM));
+ trad_frame_set_value (cache->saved_regs, SP_REGNUM, cache->prev_sp);
+ /* What about NUM_REGS + SP_REGNUM? */
+#endif
return cache;
}
diff -urp -x objdir -x '*~' gdb-2004-03-01-cvs.orig/gdb/mips-tdep.c gdb-2004-03-01-cvs/gdb/mips-tdep.c
--- gdb-2004-03-01-cvs.orig/gdb/mips-tdep.c 2004-03-02 16:56:42.000000000 -0500
+++ gdb-2004-03-01-cvs/gdb/mips-tdep.c 2004-03-04 14:51:06.000000000 -0500
@@ -1503,19 +1505,26 @@ mips_mdebug_frame_cache (struct frame_in
/* Get the mdebug proc descriptor. */
proc_desc = find_proc_desc (frame_pc_unwind (next_frame), next_frame, 1);
if (proc_desc == NULL)
- /* I'm not sure how/whether this can happen. Normally when we
- can't find a proc_desc, we "synthesize" one using
- heuristic_proc_desc and set the saved_regs right away. */
- return cache;
-
- /* Extract the frame's base. */
- cache->base = (frame_unwind_register_signed (next_frame, NUM_REGS + PROC_FRAME_REG (proc_desc))
- + PROC_FRAME_OFFSET (proc_desc) - PROC_FRAME_ADJUST (proc_desc));
+ {
+ /* This can happen at least at PC == 0. */
+ cache->base = frame_unwind_register_signed (next_frame, NUM_REGS + SP_REGNUM);
+ cache->saved_regs[NUM_REGS + mips_regnum (current_gdbarch)->pc]
+ = cache->saved_regs[NUM_REGS + RA_REGNUM];
+ return cache;
+ }
+
+ /* Extract the frame's base. Assume that the first instruction sets it
+ up. */
+ if (frame_pc_unwind (next_frame) == PROC_LOW_ADDR (proc_desc))
+ cache->base = frame_unwind_register_signed (next_frame, NUM_REGS + SP_REGNUM);
+ else
+ cache->base = (frame_unwind_register_signed (next_frame, NUM_REGS + PROC_FRAME_REG (proc_desc))
+ + PROC_FRAME_OFFSET (proc_desc) - PROC_FRAME_ADJUST (proc_desc));
kernel_trap = PROC_REG_MASK (proc_desc) & 1;
gen_mask = kernel_trap ? 0xFFFFFFFF : PROC_REG_MASK (proc_desc);
float_mask = kernel_trap ? 0xFFFFFFFF : PROC_FREG_MASK (proc_desc);
-
+
/* In any frame other than the innermost or a frame interrupted by a
signal, we assume that all registers have been saved. This
assumes that all register saves in a function happen before the
@@ -1681,7 +1690,8 @@ mips_mdebug_frame_this_id (struct frame_
glibc syscall stubs does not work. Eventually MIPS will use
allow us to solve this with DWARF unwind information instead. */
if (frame_relative_level (next_frame) >= 0
- && !trad_frame_addr_p (info->saved_regs, PC_REGNUM))
+ && get_frame_type (next_frame) == NORMAL_FRAME
+ && !trad_frame_addr_p (info->saved_regs, NUM_REGS + PC_REGNUM))
{
(*this_id) = null_frame_id;
return;
@@ -2471,7 +2481,8 @@ find_proc_desc (CORE_ADDR pc, struct fra
*/
/* If the next frame is a signal handler trampoline, then we also
need to do this, because we might be in the prologue. */
- if (next_frame == NULL || get_frame_type (next_frame) == SIGTRAMP_FRAME)
+ if (frame_relative_level (next_frame) < 0
+ || get_frame_type (next_frame) != NORMAL_FRAME)
{
struct symtab_and_line val;
struct symbol *proc_symbol =
@@ -2489,7 +2500,10 @@ find_proc_desc (CORE_ADDR pc, struct fra
heuristic_proc_desc (PROC_LOW_ADDR (proc_desc),
pc, next_frame, cur_frame);
if (found_heuristic)
- proc_desc = found_heuristic;
+ {
+ PROC_REG_OFFSET (found_heuristic) = PROC_REG_OFFSET (proc_desc);
+ proc_desc = found_heuristic;
+ }
}
}
}
@@ -3123,6 +3137,11 @@ mips_n32n64_push_dummy_call (struct gdba
val = (char *) VALUE_CONTENTS (arg);
+ /* FIXME drow/2004-03-04: One unimplemented rule from the
+ N32/N64 ABI is that any 64-bit chunk of a structure which
+ consists of a double-precision floating point field (but not
+ a double member of a union) will be passed in an FP reg
+ instead of an integer reg. */
if (fp_register_arg_p (typecode, arg_type)
&& float_argreg <= MIPS_LAST_FP_ARG_REGNUM)
{
@@ -3147,13 +3166,6 @@ mips_n32n64_push_dummy_call (struct gdba
/* Copy the argument to general registers or the stack in
register-sized pieces. Large arguments are split between
registers and stack. */
- /* Note: structs whose size is not a multiple of
- mips_regsize() are treated specially: Irix cc passes them
- in registers where gcc sometimes puts them on the stack.
- For maximum compatibility, we will put them in both
- places. */
- int odd_sized_struct = ((len > mips_saved_regsize (tdep))
- && (len % mips_saved_regsize (tdep) != 0));
/* Note: Floating-point values that didn't fit into an FP
register are only written to memory. */
while (len > 0)
@@ -3169,7 +3181,6 @@ mips_n32n64_push_dummy_call (struct gdba
/* Write this portion of the argument to the stack. */
if (argreg > MIPS_LAST_ARG_REGNUM
- || odd_sized_struct
|| fp_register_arg_p (typecode, arg_type))
{
/* Should shorter than int integer values be
@@ -3209,15 +3220,10 @@ mips_n32n64_push_dummy_call (struct gdba
}
write_memory (addr, val, partial_len);
}
-
- /* Note!!! This is NOT an else clause. Odd sized
- structs may go thru BOTH paths. Floating point
- arguments will not. */
- /* Write this portion of the argument to a general
- purpose register. */
- if (argreg <= MIPS_LAST_ARG_REGNUM
- && !fp_register_arg_p (typecode, arg_type))
+ else
{
+ /* Write this portion of the argument to a general
+ purpose register. */
LONGEST regval =
extract_unsigned_integer (val, partial_len);
@@ -3290,10 +3296,10 @@ mips_n32n64_return_value (struct gdbarch
void *readbuf, const void *writebuf)
{
struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
- if (TYPE_CODE (type) == TYPE_CODE_STRUCT
- || TYPE_CODE (type) == TYPE_CODE_UNION
- || TYPE_CODE (type) == TYPE_CODE_ARRAY
- || TYPE_LENGTH (type) > 2 * mips_saved_regsize (tdep))
+ if ((TYPE_CODE (type) == TYPE_CODE_STRUCT
+ || TYPE_CODE (type) == TYPE_CODE_UNION
+ || TYPE_CODE (type) == TYPE_CODE_ARRAY)
+ && TYPE_LENGTH (type) > 2 * mips_saved_regsize (tdep))
return RETURN_VALUE_STRUCT_CONVENTION;
else if (TYPE_CODE (type) == TYPE_CODE_FLT
&& TYPE_LENGTH (type) == 16
@@ -3366,6 +3372,29 @@ mips_n32n64_return_value (struct gdbarch
mips_xfer_lower. */
int offset;
int regnum;
+
+ /* This is... rough. If we have a non-trivial copy constructor or
+ destructor, use reference. This should be in common code. */
+ int i, j;
+ for (i = 0; i < TYPE_NFN_FIELDS (type); i++)
+ for (j = 0; j < TYPE_FN_FIELDLIST_LENGTH (type, i); j++)
+ {
+ struct fn_field *fn = TYPE_FN_FIELDLIST1 (type, i);
+ if (TYPE_FN_FIELD_ARTIFICIAL (fn, j))
+ continue;
+ if (TYPE_FN_FIELDLIST_NAME (type, i)[0] == '~')
+ return RETURN_VALUE_STRUCT_CONVENTION;
+ if (strncmp (TYPE_NAME (type),
+ TYPE_FN_FIELDLIST_NAME (type, i),
+ strlen (TYPE_NAME (type))) == 0
+ && (TYPE_FN_FIELDLIST_NAME (type, i)[strlen (TYPE_NAME (type))] == '\0'
+ || TYPE_FN_FIELDLIST_NAME (type, i)[strlen (TYPE_NAME (type))] == '<')
+ && TYPE_NFIELDS (TYPE_FN_FIELD_TYPE (fn, j)) == 2
+ && TYPE_CODE (TYPE_FIELD_TYPE (TYPE_FN_FIELD_TYPE (fn, j), 1)) == TYPE_CODE_REF
+ && TYPE_TARGET_TYPE (TYPE_FIELD_TYPE (TYPE_FN_FIELD_TYPE (fn, j), 1)) == type)
+ return RETURN_VALUE_STRUCT_CONVENTION;
+ }
+
for (offset = 0, regnum = V0_REGNUM;
offset < TYPE_LENGTH (type);
offset += register_size (current_gdbarch, regnum), regnum++)
--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer
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