gdbserver: Unexpected missing PT_PHDR when running break-interp.exp

[Pedro Alves <palves at redhat dot com>]

Hi Jan,

When running break-interp.exp against extended-remote gdbserver, I see several
"gdbserver: Unexpected missing PT_PHDR" warnings in gdb.log, though the
tests all pass.

GDB doesn't issue any warning in the (I think sort of) equivalent code
in solib-svr4.c:read_program_header:

 /* PT_PHDR is optional, but we really need it
     for PIE to make this work in general.  */

  if (pt_phdr_p)
    {
      /* at_phdr is real address in memory. pt_phdr is what pheader says it is.
	 Relocation offset is the difference between the two. */
      sect_addr = sect_addr + (at_phdr - pt_phdr);
    }

I'm wondering if the gdbserver warning is really useful?  Is is because
something is missing in gdbserver?  AT_ENTRY-based relocation perhaps?  And/or
can we drop the warning?

2012-03-02  Pedro Alves  <palves@redhat.com>

	* linux-low.c (get_dynamic): Don't warn when PT_PHDR isn't found.
---

 gdb/gdbserver/linux-low.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c
index 7638ca3..02cbb60 100644
--- a/gdb/gdbserver/linux-low.c
+++ b/gdb/gdbserver/linux-low.c
@@ -5243,7 +5243,7 @@ get_dynamic (const int pid, const int is_elf64)

   if (relocation == -1)
     {
-      warning ("Unexpected missing PT_PHDR");
+      /* PT_PHDR is optional, but necessary for PIE in general.  */
       return 0;
     }




Note, you need:

diff --git a/gdb/testsuite/gdb.base/break-interp.exp b/gdb/testsuite/gdb.base/break-interp.exp
index 1e47b34..272debd 100644
--- a/gdb/testsuite/gdb.base/break-interp.exp
+++ b/gdb/testsuite/gdb.base/break-interp.exp
@@ -429,6 +429,7 @@ proc test_ld {file ifmain trynosym displacement} {
        # Test no (error) message has been printed by `exec-file'.
        set escapedfile [string_to_regexp $file]
        gdb_test "exec-file $file" "exec-file $escapedfile" "load"
+ gdb_test "set remote exec-file $file" ".*" "load (remote)"

        if $ifmain {
            reach "_dl_debug_state" run $displacement


in order to run the test against gdbserver currently.

-- 
Pedro Alves