Check function is GC'ed

I see the following fail on arm-none-eabi target,

(gdb) b 24^M
Breakpoint 1 at 0x4: file
../../../../git/gdb/testsuite/gdb.base/break-on-linker-gcd-function.cc,
line 24.^M
(gdb) FAIL: gdb.base/break-on-linker-gcd-function.exp: b 24

Currently, we are using flag has_section_at_zero to determine whether
address zero in debug info means the corresponding code has been
GC'ed, like this:

	case DW_LNE_set_address:
	  address = read_address (abfd, line_ptr, cu, &bytes_read);

	  if (address == 0 && !dwarf2_per_objfile->has_section_at_zero)
	    {
	      /* This line table is for a function which has been
		 GCd by the linker.  Ignore it.  PR gdb/12528 */

However, this is incorrect on some bare metal targets, as .text
section is located at 0x0, so dwarf2_per_objfile->has_section_at_zero
is true.  If a function is GC'ed by linker, the address is zero.  GDB
thinks address zero is a function's address rather than this function
is GC'ed.

In this patch, we choose 'lowpc' got in read_file_scope to check
whether 'lowpc' is greater than zero.  If it isn't, address zero really
means the function is GC'ed.  In this patch, we pass 'lowpc' in
read_file_scope through handle_DW_AT_stmt_list and dwarf_decode_lines,
and to dwarf_decode_lines_1 finally.

This patch fixes the fail above. This patch also covers the path that
partial symbol isn't used, which is tested by starting gdb with
--readnow option.

It is regression tested on x86-linux with
target_board=dwarf4-gdb-index, and arm-none-eabi.  OK to apply?

gdb:

2014-09-19  Yao Qi  <yao@codesourcery.com>

	* dwarf2read.c (dwarf_decode_lines): Update declaration.
	(handle_DW_AT_stmt_list): Add argument 'lowpc'.  Update
	comments.  Callers update.
	(dwarf_decode_lines): Likewise.
	(dwarf_decode_lines_1): Add argument 'lowpc'.  Update
	comments.  Skip the line table if  'lowpc' is greater than
	'address'.  Don't check
	dwarf2_per_objfile->has_section_at_zero.

gdb/testsuite:

2014-09-19  Yao Qi  <yao@codesourcery.com>

	* gdb.base/break-on-linker-gcd-function.exp: Move test into new
	proc set_breakpoint_on_gcd_function.  Invoke
	set_breakpoint_on_gcd_function.  Restart GDB with --readnow and
	invoke set_breakpoint_on_gcd_function again.
Run dw2-var-zero-addr.exp with --readnow

This patch is to extend dw2-var-zero-add.exp to cover the case that
partial symtabl is not used while full symtab is used, in order to
cover the changes in patch 2/3.  This patch restarts GDB with
--readnow and does the same test again.

gdb/testsuite:

2014-09-19  Yao Qi  <yao@codesourcery.com>

	* gdb.dwarf2/dw2-var-zero-addr.exp: Move test into new proc test.
	Invoke test.  Restart GDB with --readnow and invoke test again.
S/390: Don't replace R_390_TLS_LE32/64 with R_390_TLS_TPOFF for PIE.

bfd:

2014-09-19  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* elf32-s390.c: Don't replace R_390_TLS_LE32 with R_390_TLS_TPOFF
	for PIE.
	* elf64-s390.c: Don't replace R_390_TLS_LE64 with R_390_TLS_TPOFF
	for PIE.
Refactor ptrace extended event status.

This commit implements functions for identifying and extracting extended
ptrace event information from a Linux wait status.  These are just
convenience functions intended to hide the ">> 16" used to extract the
event from the wait status word, replacing the hard-coded shift with a more
descriptive function call.  This is preparatory work for implementation of
follow-fork and detach-on-fork for extended-remote linux targets.

gdb/ChangeLog:

	* linux-nat.c (linux_handle_extended_wait): Call
	linux_ptrace_get_extended_event.
	(wait_lwp): Call linux_is_extended_waitstatus.
	(linux_nat_filter_event): Call linux_ptrace_get_extended_event
	and linux_is_extended_waitstatus.
	* nat/linux-ptrace.c (linux_test_for_tracefork): Call
	linux_ptrace_get_extended_event.
	(linux_ptrace_get_extended_event): New function.
	(linux_is_extended_waitstatus): New function.
	* nat/linux-ptrace.h (linux_ptrace_get_extended_event)
	(linux_is_extended_waitstatus): New declarations.

gdb/gdbserver/ChangeLog:

	* linux-low.c (handle_extended_wait): Call
	linux_ptrace_get_extended_event.
	(get_stop_pc, get_detach_signal, linux_low_filter_event): Call
	linux_is_extended_waitstatus.

---
Add Sergio Durigan Junior as maintainer of SystemTap support in GDB.

gdb/ChangeLog:

	* MAINTAINERS: Add Sergio Durigan Junior as maintainer of
	SystemTap support in GDB.
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