[Bug symtab/9807] New: _SDA_BASE_+_SDA2_BASE_ not valid for symbols resolving

["jan dot kratochvil at redhat dot com" <sourceware-bugzilla at sourceware dot org>]

GDB testsuite reported a regression on:
gdb.mi/mi2-disassemble.exp: data-disassemble range assembly mixed

It was due to unfortunate prelink address and a bogus _SDA_BASE_ address:
  [Nr] Name              Type            Addr     Off    Size   ES Flg Lk Inf
Al
  [21] .bss              NOBITS          00028a60 018960 000030 00  WA  0   0 
4
0x00028a60 + 0x000030 == 0x28a90
  [18] .sdata            PROGBITS        00028530 018530 000430 00  WA  0   0 
8
Symbol table '.symtab' contains 723 entries:
   600: 00030530     0 OBJECT  LOCAL  DEFAULT   18 _SDA_BASE_

0x30530 > 0x28a90 - symbol being behind the end of file.
In fact it should not be out of the range of its section number 18.

Steps to Reproduce:
Prelink /lib/ld.so.1 to 0x0ffd0000
cat >cmd <<EOH
# 0x1000053c is $pc after `start'
info line *0x1000053c
start
info line *0x1000053c
q
EOH
gdb -nx -x ./cmd gdb-6.3.0.0-1.160.el4.src/gdb-6.3/gdb/testsuite/gdb.mi/basics

Actual results:
Line 54 of "./gdb.mi/basics.c" starts at address 0x1000053c <main+20> and ends
at 0x10000558 <main+48>.
Breakpoint 1 at 0x1000053c: file ./gdb.mi/basics.c, line 54.
main () at ./gdb.mi/basics.c:54
54   callee1 (2, "A string argument.", 3.5);
Line 54 of "./gdb.mi/basics.c" is at address 0x1000053c <main+20> but contains
no code.

Expected results:
Line 54 of "./gdb.mi/basics.c" starts at address 0x1000053c <main+20> and ends
at 0x10000558 <main+48>.
Breakpoint 1 at 0x1000053c: file ./gdb.mi/basics.c, line 54.
main () at ./gdb.mi/basics.c:54
54   callee1 (2, "A string argument.", 3.5);
Line 54 of "./gdb.mi/basics.c" starts at address 0x1000053c <main+20> and ends
at 0x10000558 <main+48>.

Additional info:
The problem affects only debugging (GDB) as _SDA_BASE_ is just in `.symtab'.

Comment From Roland McGrath 2009-01-25 14:57:03 EDT
_SDA_BASE_ is a special-case symbol on ppc.  elflint does have checks for
symbols being out of their section bounds, but there are machine-dependent
special exceptions.  _SDA_BASE_ is set to .sdata+0x8000 because it's used for
ppc insns where there is a -0x8000 bias applied to constants (or something like
that).  Also _SDA2_BASE_ is .sdata2+0x8000.

->

_SDA_BASE_ and _SDA2_BASE_ should be ignored for addresses resolving.

-- 
           Summary: _SDA_BASE_+_SDA2_BASE_ not valid for symbols resolving
           Product: gdb
           Version: unknown
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: symtab
        AssignedTo: unassigned at sourceware dot org
        ReportedBy: jan dot kratochvil at redhat dot com
                CC: gdb-prs at sourceware dot org
  GCC host triplet: ppc-unknown-linux-gnu


http://sourceware.org/bugzilla/show_bug.cgi?id=9807

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