From: Philippe Waroquiers <philippe.waroquiers@skynet.be>
Date: Sat, 6 Sep 2014 00:13:47 +0000 (+0000)
Subject: Partial bypass for 338803 Handling of dwz debug alt files or cross-CU is broken
X-Git-Tag: svn/VALGRIND_3_10_0~33
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d02c10cede30a32e1de29da4eacc8a5bad6f7260;p=thirdparty%2Fvalgrind.git

Partial bypass for 338803 Handling of dwz debug alt files or cross-CU is broken

This patch avoids dereferencing absori that are in other CUs than
the CU currently being read.
This avoids dwarf reading errors when reading inlined information.
The bypass results in inlined function being reported as
UnknownInlinedFun rather than the real correct function name.

--read-var-info=yes is still broken for unknown reasons
(probably type reading is doing some other cross-CU references ?).




git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14476
---

diff --git a/coregrind/m_debuginfo/readdwarf3.c b/coregrind/m_debuginfo/readdwarf3.c
index 3a88c5b311..825df53976 100644
--- a/coregrind/m_debuginfo/readdwarf3.c
+++ b/coregrind/m_debuginfo/readdwarf3.c
@@ -2511,7 +2511,28 @@ typedef
    D3InlParser;
 
 /* Return the function name corresponding to absori.
-   The return value is a (permanent) string in DebugInfo's .strchunks. */
+
+   absori is a 'cooked' reference to a DIE, i.e. absori can be either
+   in cc->escn_debug_info or in cc->escn_debug_info_alt.
+   get_inlFnName will uncook absori. 
+
+   The returned value is a (permanent) string in DebugInfo's .strchunks.
+
+   LIMITATION: absori must point in the CU of cc. If absori points
+   in another CU, returns "UnknownInlinedFun".
+
+   Here are the problems to retrieve the fun name if absori is in
+   another CU:  the DIE reading code cannot properly extract data from
+   another CU, as the abbv code retrieved in the other CU cannot be
+   translated in an abbreviation. Reading data from the alternate debug
+   info also gives problems as the string reference is also in the alternate
+   file, but when reading the alt DIE, the string form is a 'local' string,
+   but cannot be read in the current CU, but must be read in the alt CU.
+   See bug 338803 comment#3 and attachment for a failed attempt to handle
+   these problems (failed because with the patch, only one alt abbrev hash
+   table is kept, while we must handle all abbreviations in all CUs
+   referenced by an absori (being a reference to an alt CU, or a previous
+   or following CU). */
 static HChar* get_inlFnName (Int absori, CUConst* cc, Bool td3)
 {
    Cursor c;
@@ -2519,14 +2540,37 @@ static HChar* get_inlFnName (Int absori, CUConst* cc, Bool td3)
    ULong  atag, abbv_code;
    UInt   has_children;
    UWord  posn;
+   Bool type_flag, alt_flag;
    HChar *ret = NULL;
    FormContents cts;
    UInt nf_i;
 
-   init_Cursor (&c, cc->escn_debug_info, absori, cc->barf, 
+   posn = uncook_die( cc, absori, &type_flag, &alt_flag);
+   if (type_flag)
+      cc->barf("get_inlFnName: uncooked absori in type debug info");
+
+   /* LIMITATION: check we are in the same CU.
+      If not, return unknown inlined function name. */
+   /* if crossing between alt debug info<>normal info
+          or posn not in the cu range,
+      then it is in another CU. */
+   if (alt_flag != cc->is_alt_info
+       || posn < cc->cu_start_offset
+       || posn >= cc->cu_start_offset + cc->unit_length) {
+      static Bool reported = False;
+      if (!reported) {
+         VG_(message)(Vg_DebugMsg,
+                      "Warning: cross-CU LIMITATION: some inlined fn names\n"
+                      "might be shown as UnknownInlinedFun\n");
+         reported = True;
+      }
+      TRACE_D3(" <get_inlFnName><%lx>: cross-CU LIMITATION", posn);
+      return ML_(addStr)(cc->di, "UnknownInlinedFun", -1);
+   }
+
+   init_Cursor (&c, cc->escn_debug_info, posn, cc->barf, 
                 "Overrun get_inlFnName absori");
 
-   posn      = cook_die( cc, get_position_of_Cursor( &c ) );
    abbv_code = get_ULEB128( &c );
    abbv      = get_abbv ( cc, abbv_code);
    atag      = abbv->atag;
@@ -2562,12 +2606,19 @@ static HChar* get_inlFnName (Int absori, CUConst* cc, Bool td3)
                  DW_AT_specification. */
       }
       if (attr == DW_AT_specification) {
+         UWord cdie;
+
          if (cts.szB == 0)
             cc->barf("get_inlFnName: AT specification missing");
+
+         /* The recursive call to get_inlFnName will uncook its arg.
+            So, we need to cook it here, so as to reference the
+            correct section (e.g. the alt info). */
+         cdie = cook_die_using_form(cc, (UWord)cts.u.val, form);
+
          /* hoping that there is no loop */
-         ret = get_inlFnName (cts.u.val, cc, td3);
-         /* 
-            Unclear if having both DW_AT_specification and DW_AT_name is
+         ret = get_inlFnName (cdie, cc, td3);
+         /* Unclear if having both DW_AT_specification and DW_AT_name is
             possible but in any case, we do not break here. 
             If we find later on a DW_AT_name, it will override the name found
             in the DW_AT_specification.*/
@@ -2675,7 +2726,8 @@ static Bool parse_inl_DIE (
          }  
 
          if (attr == DW_AT_abstract_origin  && cts.szB > 0) {
-            inlinedfn_abstract_origin = cts.u.val;
+            inlinedfn_abstract_origin
+               = cook_die_using_form (cc, (UWord)cts.u.val, form);
          }
 
          if (attr == DW_AT_low_pc && cts.szB > 0) {