Author: dim
Date: Sat Mar 29 17:18:23 2014
New Revision: 263915
URL: http://svnweb.freebsd.org/changeset/base/263915
Log:
MFC r260880 (by kaiw, from projects/elftoolchain):
* Make die_mem_offset() be able to handle DW_AT_data_member_location
attributes generated by Clang 3.4.
* Document how different compilers generate DW_AT_data_member_location
attributes differently.
* Document the quirks about DW_FORM_data[48].
This is a slightly modified version, adapted to work with the old
libdwarf in stable/9 and stable/10. It should fix DTrace on these
branches, when the kernel is compiled with clang 3.4.
Note that you have to build *and* install the CTF tools first, before
building the kernel. Otherwise you can possibly still get error
messages similar to "failed to copy type of 'pr_uid': Type information
is in parent and unavailable", when attempting to run dtrace(1).
Submitted by: kaiw
Modified:
stable/9/cddl/contrib/opensolaris/tools/ctf/cvt/dwarf.c
Directory Properties:
stable/9/cddl/contrib/opensolaris/ (props changed)
Changes in other areas also in this revision:
Modified:
stable/10/cddl/contrib/opensolaris/tools/ctf/cvt/dwarf.c
Directory Properties:
stable/10/ (props changed)
Modified: stable/9/cddl/contrib/opensolaris/tools/ctf/cvt/dwarf.c
==============================================================================
--- stable/9/cddl/contrib/opensolaris/tools/ctf/cvt/dwarf.c Sat Mar 29
14:35:36 2014 (r263914)
+++ stable/9/cddl/contrib/opensolaris/tools/ctf/cvt/dwarf.c Sat Mar 29
17:18:23 2014 (r263915)
@@ -489,16 +489,59 @@ die_mem_offset(dwarf_t *dw, Dwarf_Die di
{
Dwarf_Locdesc *loc = NULL;
Dwarf_Signed locnum = 0;
+ Dwarf_Attribute at;
+ Dwarf_Half form;
- if (dwarf_locdesc(die, name, &loc, &locnum, &dw->dw_err) != DW_DLV_OK)
+ if (name != DW_AT_data_member_location)
+ terminate("die %llu: can only process attribute "
+ "DW_AT_data_member_location\n", die_off(dw, die));
+
+ if ((at = die_attr(dw, die, name, 0)) == NULL)
return (0);
- if (locnum != 1 || loc->ld_s->lr_atom != DW_OP_plus_uconst) {
- terminate("die %llu: cannot parse member offset\n",
- die_off(dw, die));
- }
+ if (dwarf_whatform(at, &form, &dw->dw_err) != DW_DLV_OK)
+ return (0);
- *valp = loc->ld_s->lr_number;
+ switch (form) {
+ case DW_FORM_block:
+ case DW_FORM_block1:
+ case DW_FORM_block2:
+ case DW_FORM_block4:
+ /*
+ * GCC in base and Clang (3.3 or below) generates
+ * DW_AT_data_member_location attribute with DW_FORM_block*
+ * form. The attribute contains one DW_OP_plus_uconst
+ * operator. The member offset stores in the operand.
+ */
+ if (dwarf_locdesc(die, name, &loc, &locnum, &dw->dw_err) !=
+ DW_DLV_OK)
+ return (0);
+ if (locnum != 1 || loc->ld_s->lr_atom != DW_OP_plus_uconst) {
+ terminate("die %llu: cannot parse member offset\n",
+ die_off(dw, die));
+ }
+ *valp = loc->ld_s->lr_number;
+ break;
+
+ case DW_FORM_data1:
+ case DW_FORM_data2:
+ case DW_FORM_data4:
+ case DW_FORM_data8:
+ case DW_FORM_udata:
+ /*
+ * Clang 3.4 generates DW_AT_data_member_location attribute
+ * with DW_FORM_data* form (constant class). The attribute
+ * stores a contant value which is the member offset.
+ */
+ if (dwarf_attrval_unsigned(die, name, valp, &dw->dw_err) !=
+ DW_DLV_OK)
+ return (0);
+ break;
+
+ default:
+ terminate("die %llu: cannot parse member offset with form "
+ "%u\n", die_off(dw, die), form);
+ }
if (loc != NULL)
if (dwarf_locdesc_free(loc, &dw->dw_err) != DW_DLV_OK)
@@ -872,6 +915,9 @@ die_sou_create(dwarf_t *dw, Dwarf_Die st
int type, const char *typename)
{
Dwarf_Unsigned sz, bitsz, bitoff;
+#if BYTE_ORDER == _LITTLE_ENDIAN
+ Dwarf_Unsigned bysz;
+#endif
Dwarf_Die mem;
mlist_t *ml, **mlastp;
iidesc_t *ii;
@@ -944,8 +990,26 @@ die_sou_create(dwarf_t *dw, Dwarf_Die st
#if BYTE_ORDER == _BIG_ENDIAN
ml->ml_offset += bitoff;
#else
- ml->ml_offset += tdesc_bitsize(ml->ml_type) - bitoff -
- ml->ml_size;
+ /*
+ * Note that Clang 3.4 will sometimes generate
+ * member DIE before generating the DIE for the
+ * member's type. The code can not handle this
+ * properly so that tdesc_bitsize(ml->ml_type) will
+ * return 0 because ml->ml_type is unknown. As a
+ * result, a wrong member offset will be calculated.
+ * To workaround this, we can instead try to
+ * retrieve the value of DW_AT_byte_size attribute
+ * which stores the byte size of the space occupied
+ * by the type. If this attribute exists, its value
+ * should equal to tdesc_bitsize(ml->ml_type)/NBBY.
+ */
+ if (die_unsigned(dw, mem, DW_AT_byte_size, &bysz, 0) &&
+ bysz > 0)
+ ml->ml_offset += bysz * NBBY - bitoff -
+ ml->ml_size;
+ else
+ ml->ml_offset += tdesc_bitsize(ml->ml_type) -
+ bitoff - ml->ml_size;
#endif
}
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