On Sat, 26 Oct 2013 23:47:04 +0200, Mark Wielaard wrote:
> On Fri, 2013-10-25 at 18:22 +0200, Jan Kratochvil wrote:
> > I have implemented all the missing ops except for:
> > + case DW_OP_GNU_encoded_addr:
> > + /* Missing support in the rest of elfutils. */
> > + case DW_OP_deref_size:
> > + /* Missing appropriate callback. */
>
> Do we need to extend the memory_read callback to take a size argument?
> Or can we do something clever (depending on byte order) with the current
> memory_read of a full word and chop it down? The size will never be
> bigger than the number of bytes in an address. So it will never be
> bigger than 8.
OK, true, implemented DW_OP_deref_size.
> > BTW elfutils should really get DW_OP_GNU_encoded_addr implemented I guess
> > as it
> > may appear in CFI.
>
> It is indeed documented (at the end of)
> https://sourceware.org/binutils/docs-2.22/as/CFI-directives.html
> .cfi_val_encoded_addr will generate a DW_OP_GNU_encoded_addr according
> to http://gcc.gnu.org/ml/gcc-patches/2008-09/msg01713.html
> But I haven't actually seen it used. Would be nice to have an example
> usage.
It is true that gcc/dwarf2cfi.c does not use it, if I read it correctly.
> If users are really interested they could do some checks on the last
> frame address to see if it actually falls inside a known Module, has a
> Dwarf/CFI and whether that CFI has a range covering the address (if they
> really cared).
OK, so left as is.
> > + case DW_OP_rot:
> > + {
> > + Dwarf_Addr val3;
> > + if (! pop (&val1) || ! pop (&val2) || ! pop (&val3)
> > + || ! push (val1) || ! push (val2) || ! push (val3))
> > + {
> > + free (stack);
> > + return false;
> > + }
> > + }
> > + break;
>
> I think that should be: push (val1), push (val3), push (val2).
That's bad, I cannot even copy the GDB code.
So I have finally run the elfutils unwinder on Jakub's
gcc/testsuite/gcc.dg/cleanup-13.c and it really found DW_OP_rot is buggy.
Besides that it found also DW_OP_pick had a bug (fixed it below).
And then it works (patched it with the simple attached patch).
Just I do not know if cleanup-13.c is covered by GPL3 or if it is public
domain but I guess the former. In such case I do not think it is compatible
with elfutils due to its LGPL option.
Thanks,
Jan
--- /home/jkratoch/t/cleanup-13.c-orig 2010-01-21 07:01:45.000000000 +0100
+++ /home/jkratoch/t/cleanup-13.c 2013-10-27 11:31:16.556145134 +0100
@@ -281,6 +281,7 @@ extern char verify_it[sizeof (cfi_arch_p
: : "i" (sizeof (cfi_arch_program)))
#endif
#endif
+#include <unistd.h>
static _Unwind_Reason_Code
force_unwind_stop (int version, _Unwind_Action actions,
_Unwind_Exception_Class exc_class,
@@ -289,7 +290,10 @@ force_unwind_stop (int version, _Unwind_
void *stop_parameter)
{
if (actions & _UA_END_OF_STACK)
+{
+pause();
abort ();
+}
return _URC_NO_REASON;
}
diff --git a/libdwfl/frame_unwind.c b/libdwfl/frame_unwind.c
index eca7a04..a875e98 100644
--- a/libdwfl/frame_unwind.c
+++ b/libdwfl/frame_unwind.c
@@ -231,8 +231,13 @@ expr_eval (Dwfl_Frame *state, Dwarf_Frame *frame, const
Dwarf_Op *ops,
}
break;
case DW_OP_pick:
- if (! pop (&val1) || stack_used <= val1
- || ! push (stack[stack_used - 1 - val1]))
+ if (stack_used <= op->number)
+ {
+ free (stack);
+ __libdwfl_seterrno (DWFL_E_INVALID_DWARF);
+ return false;
+ }
+ if (! push (stack[stack_used - 1 - op->number]))
{
free (stack);
return false;
@@ -257,7 +262,7 @@ expr_eval (Dwfl_Frame *state, Dwarf_Frame *frame, const
Dwarf_Op *ops,
{
Dwarf_Addr val3;
if (! pop (&val1) || ! pop (&val2) || ! pop (&val3)
- || ! push (val1) || ! push (val2) || ! push (val3))
+ || ! push (val1) || ! push (val3) || ! push (val2))
{
free (stack);
return false;
@@ -265,6 +270,7 @@ expr_eval (Dwfl_Frame *state, Dwarf_Frame *frame, const
Dwarf_Op *ops,
}
break;
case DW_OP_deref:
+ case DW_OP_deref_size:
if (process->callbacks->memory_read == NULL)
{
free (stack);
@@ -273,17 +279,35 @@ expr_eval (Dwfl_Frame *state, Dwarf_Frame *frame, const
Dwarf_Op *ops,
}
if (! pop (&val1)
|| ! process->callbacks->memory_read (process->dwfl, val1, &val1,
- process->callbacks_arg)
- || ! push (val1))
+ process->callbacks_arg))
+ {
+ free (stack);
+ return false;
+ }
+ if (op->atom == DW_OP_deref_size)
+ {
+ if (op->number > 8)
+ {
+ free (stack);
+ __libdwfl_seterrno (DWFL_E_INVALID_DWARF);
+ return false;
+ }
+#if BYTE_ORDER == BIG_ENDIAN
+ if (op->number == 0)
+ val1 = 0;
+ else
+ val1 >>= 64 - op->number * 8;
+#else
+ if (op->number < 8)
+ val1 &= (1 << (op->number * 8)) - 1;
+#endif
+ }
+ if (! push (val1))
{
free (stack);
return false;
}
break;
- case DW_OP_deref_size:
- /* Missing appropriate callback. */
- __libdwfl_seterrno (DWFL_E_UNSUPPORTED_DWARF);
- return false;
#define UNOP(atom, expr) \
case atom: \
if (! pop (&val1) || ! push (expr)) \
diff --git a/libdwfl/linux-pid-attach.c b/libdwfl/linux-pid-attach.c
index 0721c88..66a0814 100644
--- a/libdwfl/linux-pid-attach.c
+++ b/libdwfl/linux-pid-attach.c
@@ -122,9 +122,14 @@ pid_memory_read (Dwfl *dwfl, Dwarf_Addr addr, Dwarf_Word
*result, void *arg)
Dwfl_Process *process = dwfl->process;
if (ebl_get_elfclass (process->ebl) == ELFCLASS64)
{
+#if SIZEOF_LONG == 8
errno = 0;
*result = ptrace (PTRACE_PEEKDATA, tid, (void *) (uintptr_t) addr, NULL);
return errno == 0;
+#else /* SIZEOF_LONG != 8 */
+ /* This should not happen. */
+ return false;
+#endif /* SIZEOF_LONG != 8 */
}
#if SIZEOF_LONG == 8
/* We do not care about reads unaliged to 4 bytes boundary.
