GitLab

For
	.globl	foo2
	.section	.data.foo,"aR"
	.align 4
	.type	foo2, @object
	.size	foo2, 4
foo2:
	.long	2
	.globl	foo1
	.section	.data.foo
	.align 4
	.type	foo1, @object
	.size	foo1, 4
foo1:
	.long	1

generate a new section if the SHF_GNU_RETAIN bit doesn't match.

	* config/obj-elf.c (SEC_ASSEMBLER_SHF_MASK): New.
	(get_section_by_match): Also check if SEC_ASSEMBLER_SHF_MASK of
	sh_flags matches.  Rename info to sh_info.
	(obj_elf_change_section): Don't check previous SHF_GNU_RETAIN.
	Rename info to sh_info.
	(obj_elf_section): Rename info to sh_info.  Set sh_flags for
	SHF_GNU_RETAIN.
	* config/obj-elf.h (elf_section_match): Rename info to sh_info.
	Add sh_flags.
	* testsuite/gas/elf/elf.exp: Run section27.
	* testsuite/gas/elf/section24b.d: Updated.
	* testsuite/gas/elf/section27.d: New file.
	* testsuite/gas/elf/section27.s: Likewise.

Use the LOCALAPPDATA environment variable to determine the cache dir
when running on Windows with native command line, otherwise nasty
warning "Couldn't determine a path for index cached directory" appears.

Change-Id: I77903f9f0cb4743555866b8aea892cef55132589

Redo fix committed in commit 67748e0f "[gdb/testsuite] Make
gdb.arch/amd64-gs_base.exp unsupported for i386" using is_amd64_regs_target.

Tested on x86_64-linux.

gdb/testsuite/ChangeLog:

2020-12-08  Tom de Vries  <tdevries@suse.de>

	* gdb.arch/amd64-gs_base.exp: Undo commit 67748e0f, reimplement
	using is_amd64_regs_target.

When running test-case gdb.ada/mi_task_arg.exp with target board unix/-m32, I
run into:
...
(gdb) ^M
Expecting: ^(-stack-list-arguments 1[^M
]+)?(\^done,stack-args=\[ \
  frame={level="0",args=\[\]}, \
  frame={level="1",args=\[{name="<_task>",value="0x[0-9A-Fa-f]+"}\]}, \
  frame={level="2",args=\[({name="self_id",value="0x[0-9A-Fa-f]+"})?\]},.*[^M
]+[(]gdb[)] ^M
[ ]*)
-stack-list-arguments 1^M
^done,stack-args=[ \
  frame={level="0",args=[]}, \
  frame={level="1",args=[{name="<_task>",value="0x808abf0"}]}, \
  frame={level="2",args=[{name="self_id",value="<optimized out>"}]}, \
  frame={level="3",args=[]},frame={level="4",args=[]}]^M
(gdb) ^M
FAIL: gdb.ada/mi_task_arg.exp: -stack-list-arguments 1 (unexpected output)
...

The problem is that we're expecting a $hex for the value of self_id, but
instead get <optimized out>.

Looking at the debug info for self_id:
...
 <1><12a1f>: Abbrev Number: 84 (DW_TAG_subprogram)
    <12a20>   DW_AT_name        : system__tasking__stages__task_wrapper
    ...
 <2><12a35>: Abbrev Number: 61 (DW_TAG_formal_parameter)
    <12a36>   DW_AT_name        : self_id
    <12a40>   DW_AT_location    : 0x459e (location list)
...
it refers to location information here:
...
    0000459e 08053060 080531ac (DW_OP_fbreg: 0)
    000045aa 0805327c 080532a5 (DW_OP_fbreg: 0)
    000045b6 08053320 08053324 (DW_OP_fbreg: 0)
...
while the pc used to retrieve the location information is 0x080531c5:
...
 $ gdb -batch outputs/gdb.ada/mi_task_arg/task_switch \
   -ex "break 57" -ex run -ex bt
   ...
 #0  task_switch.break_me () at task_switch.adb:57
 #1  0x0804aaae in task_switch.caller (<_task>=0x808abf0) \
                     at task_switch.adb:51
 #2  0x080531c5 in system.tasking.stages.task_wrapper \
                     (self_id=<optimized out>) at s-tassta.adb:1295
...
which indeed falls outside of the ranges listed in the location info.

Fix this by accepting <optimized out> as valid value of self_id.

Tested on x86_64-linux.

gdb/testsuite/ChangeLog:

2020-12-08  Tom de Vries  <tdevries@suse.de>

	* gdb.ada/mi_task_arg.exp: Accept <optimized out> as valid value of
	self_id.

Commit:

 commit 4d142eaa
 Author:     Jan Kratochvil <jan.kratochvil@redhat.com>
 AuthorDate: Tue Jul 2 20:06:12 2013 +0000

     gdb/testsuite/
	     * gdb.base/break-on-linker-gcd-function.exp: Replace
	     prepare_for_testing by build_executable_from_specs and clean_restart.
 ...

did:

 set additional_flags {-ffunction-sections -Wl,--gc-sections}
 -if {[prepare_for_testing $testfile.exp $testfile $srcfile \
 -        [list debug c++ additional_flags=$additional_flags]]} {
 +if {[build_executable_from_specs $testfile.exp $testfile \
 +       {c++ additional_flags=-Wl,--gc-sections} \
 +       $srcfile {debug c++ additional_flags=-ffunction-sections}]} {

and that left the additional_flags variable behind.  Remove it.

gdb/testsuite/ChangeLog:

	* gdb.base/break-on-linker-gcd-function.exp: Remove unused
	'additional_flags' variable.

binutils	* objcopy.c (is_mergeable_note_section): Remove reference to
	SHF_GNU_BUILD_NOTE.

include	* elf/common.h (SHF_GNU_BUILD_NOTE): Delete.

smart_rename is capable of handling symlinks by copying and it also
tries to preserve ownership and permissions of files when they're
overwritten during the rename.  This is useful in objcopy where the
file properties need to be preserved.

However because smart_rename does this using file names, it leaves a
race window between renames and permission fixes.  This change removes
this race window by using file descriptors from the original BFDs that
were used to manipulate these files wherever possible.

The file that is to be renamed is also passed as a file descriptor so
that we use fchown/fchmod on the file descriptor, thus making sure
that we only modify the file we have opened to write.  Further, in
case the file is to be overwritten (as is the case in ar or objcopy),
the permissions that need to be restored are taken from the file
descriptor that was opened for input so that integrity of the file
status is maintained all the way through to the rename.

binutils/

	* rename.c
	* ar.c
	(write_archive) [!defined (_WIN32) || defined (__CYGWIN32__)]:
	Initialize TARGET_STAT and OFD to pass to SMART_RENAME.
	* arsup.c
	(ar_save) [defined (_WIN32) || defined (__CYGWIN32__)]:
	Likewise.
	* bucomm.h (smart_rename): Add new arguments to declaration.
	* objcopy.c
	(strip_main)[defined (_WIN32) || defined (__CYGWIN32__)]:
	Initialize COPYFD and pass to SMART_RENAME.
	(copy_main) [defined (_WIN32) || defined (__CYGWIN32__)]:
	Likewise.
	* rename.c (try_preserve_permissions): New function.
	(smart_rename): Use it and add new arguments.

Get file state from the descriptor opened by copy_file for the input
BFD.  This ensures continuity in the view of the input file through
the descriptor.  At the moment it is only to preserve timestamps
recorded at the point that we opened the file for input but in the
next patch this state will also be used to preserve ownership and
permissions wherever applicable.

binutils/

	* objcopy.c (copy_file): New argument IN_STAT.  Return stat of
	ibfd through it.
	(strip_main): Remove redundant stat calls.  adjust copy_file
	calls.
	(copy_main): Likewise.

The purpose of creating a temporary file securely using mkstemp is
defeated if it is closed in make_tempname and reopened later for use;
it is as good as using mktemp.  Get the file descriptor instead and
then use it to create the BFD object.

bfd/

	* opncls.c (bfd_fdopenw): New function.
	* bfd-in2.h: Regenerate.

binutils/

	* bucomm.c (make_tempname): Add argument to return file
	descriptor.
	* bucomm.h (make_tempname): Likewise.
	* ar.c: Include libbfd.h.
	(write_archive): Adjust for change in make_tempname.  Call
	bfd_fdopenw instead of bfd_openw.
	* objcopy.c: Include libbfd.h.
	(copy_file): New argument OFD.  Use bfd_fdopenw instead of
	bfd_openw.
	(strip_main): Adjust for change in make_tempname and
	copy_file.
	(copy_main): Likewise.

I happened to notice that expression completion did not work correctly
for "maint print type".  This patch adds the appropriate completer
there.

gdb/ChangeLog
2020-12-07  Tom Tromey  <tromey@adacore.com>

	* maint.c (_initialize_maint_cmds): Use expression command
	completer for "maint print type".

I'm unsure why this is deserving of a warning.  Not writing the most
efficient code surely can't be a real problem, but that is what
https://gcc.gnu.org/bugzilla//show_bug.cgi?id=88059#c1 seems to say.

plugin.cc:528:10: error: 'char* strncpy(char*, const char*, size_t)' specified bound depends on the length of the source argument [-Werror=stringop-overflow=]
  528 |   strncpy(tempdir, dir_template, len);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
plugin.cc:526:22: note: length computed here
  526 |   size_t len = strlen(dir_template) + 1;
      |                ~~~~~~^~~~~~~~~~~~~~

	* plugin.cc (Plugin_recorder::init): Replace strncpy with memcpy.

It looks like csky missed out on an edit for 706704c8.  Not that it
matters very much.  There doesn't appear to be any csky reloc howto
that sets the negate bit.

Similarly for ns32k and nds32.

	* elf32-csky.c (csky_relocate_contents): Correct negate test.
	* cpu-ns32k.c (_bfd_do_ns32k_reloc_contents): Likewise.
	* elf32-nds32.c (nds32_relocate_contents): Likewise.

README-how-to-make-a-release (point releases): Add a note to update the milestone list on sourceware's bugzilla.

The commit

  commit 733d554a
  Author: Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>
  Date:   Tue Oct 27 10:56:03 2020 +0100

  gdb/breakpoint: add flags to 'condition' and 'break' commands to force condition

introduced the '-force-condition' flag to the 'break' command.  This
flag was defined as a keyword like 'thread', 'task', and 'if'.
However, it starts with '-'.  This difference caused an uncovered case
when tab-completing a seemingly complete linespec.

Below, we see "-force-condition" in the completion list, where both
the options and the keywords are listed:

  (gdb) break -function main <TAB>
  -force-condition  -function  -label  -line  -qualified
  -source           if         task    thread

But tab-completing '-' lists only options:

  (gdb) break -function main -<TAB>
  -function   -label      -line       -qualified  -source

This patch fixes the problem by adding keywords to the completion
list, so that we see:

  (gdb) break -function main -<TAB>
  -force-condition  -function  -label  -line  -qualified  -source

gdb/ChangeLog:
2020-12-07  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>

	* completer.c (complete_explicit_location): Also add keywords
	that start with '-' to the completion list.

gdb/testsuite/ChangeLog:
2020-12-07  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>

	* gdb.linespec/explicit.exp: Extend with a test to check completing
	'-' after seemingly complete options.

The break command's "-force-condition" flag is currently required to
be followed by the "if" keyword.  This prevents flexibility when using
other keywords, e.g. "thread":

  (gdb) break main -force-condition thread 1 if foo
  Function "main -force-condition" not defined.
  Make breakpoint pending on future shared library load? (y or [n]) n

Remove the requirement that "-force-condition" is always followed by
an "if", so that more flexibility is obtained when positioning
keywords.

gdb/ChangeLog:
2020-12-07  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>

	* linespec.c (linespec_lexer_lex_keyword): The "-force-condition"
	keyword may be followed by any keyword.
	* breakpoint.c (find_condition_and_thread): Advance 'tok' by
	'toklen' in the case for "-force-condition".

gdb/testsuite/ChangeLog:
2020-12-07  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>

	* gdb.linespec/keywords.exp: Add tests to check positional
	flexibility of "-force-condition".

Suppose we have the script file below:

  break main
  commands
    print 123
  end
  run

If started with this script file, GDB executes the breakpoint command:

  $ gdb -q -x myscript --args ./test
  Reading symbols from ./test...
  Breakpoint 1 at 0x114e: file test.c, line 2.

  Breakpoint 1, main () at test.c:2
  2         return 0;
  $1 = 123
  (gdb)

However, if we remove the "run" line from the script and pass it with
the '-ex' option instead, the command is not executed:

  $ gdb -q -x myscript_no_run --args ./test
  Reading symbols from ./test...
  Breakpoint 1 at 0x114e: file test.c, line 2.
  Starting program: /path/to/test

  Breakpoint 1, main () at test.c:2
  2         return 0;
  (gdb)

If the user enters a command at this point, the breakpoint command
is executed, yielding weird output:

  $ gdb -q -x myscript_no_run --args ./test
  Reading symbols from ./test...
  Breakpoint 1 at 0x114e: file test.c, line 2.
  Starting program: /path/to/test

  Breakpoint 1, main () at test.c:2
  2         return 0;
  (gdb) print "a"
  $1 = "a"
  $2 = 123

When consuming script files, GDB runs bp actions after executing a
command.  See `command_handler` in event-top.c:

  if (c[0] != '#')
    {
      execute_command (command, ui->instream == ui->stdin_stream);

      /* Do any commands attached to breakpoint we stopped at.  */
      bpstat_do_actions ();
    }

However, for '-ex' commands, `bpstat_do_actions` is not invoked.
Hence, the misaligned output explained above occurs.  To fix the
problem, add a call to `bpstat_do_actions` after executing a command.

gdb/ChangeLog:
2020-12-07  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>

	* main.c (catch_command_errors): Add a flag parameter; invoke
	`bpstat_do_actions` if the flag is set.
	(execute_cmdargs): Update a call to `catch_command_errors`.

gdb/testsuite/ChangeLog:
2020-12-07  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>

	* gdb.base/bp-cmds-run-with-ex.c: New file.
	* gdb.base/bp-cmds-run-with-ex.exp: New file.
	* gdb.base/bp-cmds-run-with-ex.gdb: New file.
	* gdb.gdb/python-interrupts.exp: Update the call to
	'catch_command_errors' with the new argument.
	* gdb.gdb/python-selftest.exp: Ditto.

In replace_operator_with_call, we resize the elts array like this:
...
  exp->nelts = exp->nelts + 7 - oplen;
  exp->resize (exp->nelts);
...

Although all the current callers ensure that the new size is bigger, it could
also be smaller, in which case the following memmove possibly reads out of
bounds:
...
   memmove (exp->elts + pc + 7, exp->elts + pc + oplen,
           EXP_ELEM_TO_BYTES (save_nelts - pc - oplen));
...

Fix this by doing the resize after the memmove in case the new size is
smaller.

Tested on x86_64-linux.

gdb/ChangeLog:

2020-12-07  Tom de Vries  <tdevries@suse.de>

	* ada-lang.c (replace_operator_with_call): Handle shrink resize.

The patch to change struct expression to use new introduced a
regression -- there is a spot that reallocates expressions that I
failed to update.

This patch rewrites this code to follow the new approach.  Now the
rewriting is done in place.

gdb/ChangeLog
2020-12-06  Tom Tromey  <tom@tromey.com>

	PR ada/26999
	* ada-lang.c (replace_operator_with_call): Rewrite.

This fixes a long-lived bug in the s390 port.

When trying to step over a breakpoint set on a BC (branch on condition)
instruction with displaced stepping on IBM Z, gdb would incorrectly
adjust the pc regardless of whether or not the branch was taken. Since
the branch target is an absolute address, this would cause the inferior
to jump around wildly whenever the branch was taken, either crashing it
or causing it to behave unpredictably.

It turns out that the logic to handle BC instructions correctly was in
the code, but that the enum value representing its opcode has always
been incorrect.

This patch corrects the enum value to the actual opcode, fixing the
stepping problem. The enum value is also used in the prologue analysis
code, so this also fixes a minor bug where more of the prologue would
be read than was necessary.

gdb/ChangeLog:

        PR breakpoints/27009
        * s390-tdep.h (op_bc): Correct BC opcode value.

The gdb_mpz class currently provides a couple of methods which
essentially export an mpz_t value into either a buffer, or an integral
type. The export is based on using the mpz_export function which
we discovered can be a bit treacherous if used without caution.

In particular, the initial motivation for this patch was to catch
situations where the mpz_t value was so large that it would not fit
in the destination area. mpz_export does not know the size of
the buffer, and therefore can happily write past the end of our buffer.

While designing a solution to the above problem, I also discovered
that we also needed to be careful when exporting signed numbers.
In particular, numbers which are larger than the maximum value
for a given signed type size, but no so large as to fit in the
*unsigned* version with the same size, would end up being exported
incorrectly. This is related to the fact that mpz_export ignores
the sign of the value being exportd, and assumes an unsigned export.
Thus, for such large values, the appears as if mpz_export is able
to fit our value into our buffer, but in fact, it does not.

Also, I noticed that gdb_mpz::write wasn't taking its unsigned_p
parameter, which was a hole.

For all these reasons, a new low-level private method called
"safe_export" has been added to class gdb_mpz, whose goal is
to perform all necessary checks and manipulations for a safe
and correct export. As a bonus, this method allows us to factorize
the handling of negative value exports.

The gdb_mpz::as_integer and gdb_mpz::write methods are then simplified
to take advantage of this new safe_export method.

gdb/ChangeLog:

        * gmp-utils.h (gdb_mpz::safe_export): New private method.
        (gdb_mpz::as_integer): Reimplement using gdb_mpz::safe_export.
        * gmp-utils.c (gdb_mpz::write): Rewrite using gdb_mpz::safe_export.
        (gdb_mpz::safe_export): New method.
        * unittests/gmp-utils-selftests .c (gdb_mpz_as_integer):
        Update function description.
        (check_as_integer_raises_out_of_range_error): New function.
        (gdb_mpz_as_integer_out_of_range): New function.
        (_initialize_gmp_utils_selftests): Register
        gdb_mpz_as_integer_out_of_range as a selftest.

Match the condition used in `elf_vax_instantiate_got_entries' for the
creation of GOT entries in the processing of R_VAX_GOT32 relocations in
`elf_vax_check_relocs', removing incorrect warnings about a GOT addend
mismatch like:

./ld-new: tmpdir/got-local-ref-off-r.o: warning: GOT addend of 1 to `bar_hidden' does not match previous GOT addend of 0
./ld-new: tmpdir/got-local-ref-off-r.o: warning: GOT addend of 2 to `bar_hidden' does not match previous GOT addend of 0

and corresponding failures with the test cases newly added here:

FAIL: GOT test (executable hidden reference with offset)
FAIL: GOT test (executable visible reference with offset)

for symbols that are considered local for reasons other than having been
forced local with a version script, which is usually the ELF visibility.
Correct code is produced regardless, but the warning breaks `-Werror'
compilation and may upset people regardless.

Interestingly this shows with executable links only, because in shared
library links code from `elf_link_add_object_symbols' triggers:

	    /* If the symbol already has a dynamic index, but
	       visibility says it should not be visible, turn it into
	       a local symbol.  */
	    switch (ELF_ST_VISIBILITY (h->other))
	      {
	      case STV_INTERNAL:
	      case STV_HIDDEN:
		(*bed->elf_backend_hide_symbol) (info, h, TRUE);
		dynsym = FALSE;
		break;
	      }

that sets `h->forced_local' like with a version script.

Add suitable test cases including disassembly to verify correct code has
been produced where no warnings have been issued, and that warnings do
get issued where necessary.  Do not verify (broken) code produced in the
latter case; we should probably make the warning an error, or preferably
actually start supporting GOT references with different addends as they
appear feasible with explicitly relocated GOT that we use.

	bfd/
	* elf32-vax.c (elf_vax_check_relocs) <R_VAX_GOT32>: Use
	SYMBOL_REFERENCES_LOCAL rather than `h->forced_local' to check
	whether the symbol referred is local or not.

	ld/
	* testsuite/ld-vax-elf/got-local-exe-off-hidden.dd: New test
	dump.
	* testsuite/ld-vax-elf/got-local-exe-off-visible.dd: New test
	dump.
	* testsuite/ld-vax-elf/got-local-lib-off-hidden.dd: New test
	dump.
	* testsuite/ld-vax-elf/got-local-lib-off-visible.ed: New test
	dump.
	* testsuite/ld-vax-elf/got-local-off-external.ed: New test dump.
	* testsuite/ld-vax-elf/got-local-exe-off.xd: New test dump.
	* testsuite/ld-vax-elf/got-local-lib-off.xd: New test dump.
	* testsuite/ld-vax-elf/got-local.ld: New test linker script.
	* testsuite/ld-vax-elf/got-local-aux-off.s: New test source.
	* testsuite/ld-vax-elf/got-local-def-off.s: New test source.
	* testsuite/ld-vax-elf/got-local-ref-off-external.s: New test
	source.
	* testsuite/ld-vax-elf/got-local-ref-off-hidden.s: New test
	source.
	* testsuite/ld-vax-elf/got-local-ref-off-visible.s: New test
	source.
	* testsuite/ld-vax-elf/vax-elf.exp: Run the new tests.

In a couple of gdb_mpz methods, we are computing the number of
bits in a gdb::array_view of gdb_byte. Since gdb_byte is defined
using a host-side type (see common-types.h), the number of bits
in a gdb_byte should be HOST_CHAR_BIT, not TARGET_CHAR_BIT.

gdb/ChangeLog:

        * gmp-utils.c (gdb_mpz::read): Use HOST_CHAR_BIT instead of
        TARGET_CHAR_BIT.
        (gdb_mpz::write): Likewise.

Since converting load to mov needs to rewrite the REX byte and we don't
know if there is a REX byte with GOTPCREL relocation, do it only for
GOTPCRELX relocations.

bfd/

	PR ld/27016
	* elf64-x86-64.c (elf_x86_64_convert_load_reloc): Convert load
	to mov only for GOTPCRELX relocations.

ld/

	PR ld/27016
	* testsuite/ld-x86-64/x86-64.exp: Run pr27016a and pr27016b.
	* testsuite/ld-x86-64/pr27016a.d: New file.
	* testsuite/ld-x86-64/pr27016a.s: Likewise.
	* testsuite/ld-x86-64/pr27016b.d: Likewise.
	* testsuite/ld-x86-64/pr27016b.s: Likewise.

As observed on a binary compiled on AMD64 Ubuntu 20.04, against glibc
2.31 (I think it's the libc that provides this startup code, right?),
there are enough bytes at the executable's entry point to hold more than
one displaced step buffer.  gdbarch_max_insn_length is 16, and the
code at _start looks like:

0000000000001040 <_start>:
    1040:       f3 0f 1e fa             endbr64
    1044:       31 ed                   xor    %ebp,%ebp
    1046:       49 89 d1                mov    %rdx,%r9
    1049:       5e                      pop    %rsi
    104a:       48 89 e2                mov    %rsp,%rdx
    104d:       48 83 e4 f0             and    $0xfffffffffffffff0,%rsp
    1051:       50                      push   %rax
    1052:       54                      push   %rsp
    1053:       4c 8d 05 56 01 00 00    lea    0x156(%rip),%r8        # 11b0 <__libc_csu_fini>
    105a:       48 8d 0d df 00 00 00    lea    0xdf(%rip),%rcx        # 1140 <__libc_csu_init>
    1061:       48 8d 3d c1 00 00 00    lea    0xc1(%rip),%rdi        # 1129 <main>
    1068:       ff 15 72 2f 00 00       callq  *0x2f72(%rip)        # 3fe0 <__libc_start_main@GLIBC_2.2.5>
    106e:       f4                      hlt
    106f:       90                      nop

The two buffers would occupy [0x1040, 0x1060).

I checked on Alpine, which uses the musl C library, the startup code
looks like:

0000000000001048 <_start>:
    1048:       48 31 ed                xor    %rbp,%rbp
    104b:       48 89 e7                mov    %rsp,%rdi
    104e:       48 8d 35 e3 2d 00 00    lea    0x2de3(%rip),%rsi        # 3e38 <_DYNAMIC>
    1055:       48 83 e4 f0             and    $0xfffffffffffffff0,%rsp
    1059:       e8 00 00 00 00          callq  105e <_start_c>

000000000000105e <_start_c>:
    105e:       48 8b 37                mov    (%rdi),%rsi
    1061:       48 8d 57 08             lea    0x8(%rdi),%rdx
    1065:       45 31 c9                xor    %r9d,%r9d
    1068:       4c 8d 05 47 01 00 00    lea    0x147(%rip),%r8        # 11b6 <_fini>
    106f:       48 8d 0d 8a ff ff ff    lea    -0x76(%rip),%rcx        # 1000 <_init>
    1076:       48 8d 3d 0c 01 00 00    lea    0x10c(%rip),%rdi        # 1189 <main>
    107d:       e9 9e ff ff ff          jmpq   1020 <__libc_start_main@plt>

Even though there's a _start_c symbol, it all appears to be code that
runs once at the very beginning of the program, so it looks fine if the
two buffers occupy [0x1048, 0x1068).

One important thing I discovered while doing this is that when debugging
a dynamically-linked executable, breakpoints in the shared library
loader are hit before executing the _start code, and these breakpoints
may be displaced-stepped.  So it's very important that the buffer bytes
are restored properly after doing the displaced steps, otherwise the
_start code will be corrupted once we try to execute it.

Another thing that made me think about is that library constructors (as
in `__attribute__((constructor))`) run before _start.  And they are free
to spawn threads.  What if one of these threads executes a displaced
step, therefore changing the bytes at _start, while the main thread
executes _start?  That doesn't sound good and I don't know how we could
prevent it.  But this is a problem that predates the current patch.

Even when stress-testing the implementation, by making many threads do
displaced steps over and over, I didn't see a significant performance (I
confirmed that the two buffers were used by checking the "set debug
displaced" logs though).  However, this patch mostly helps make the
feature testable by anybody with an AMD64/Linux machine, so I think it's
useful.

gdb/ChangeLog:

	* amd64-linux-tdep.c (amd64_linux_init_abi): Pass 2 as the
	number of displaced step buffers.

Change-Id: Ia0c96ea0fcda893f4726df6fdac7be5214620112

The displaced_step_buffer class, introduced in the previous patch,
manages access to a single displaced step buffer.  Change it into
displaced_step_buffers (note the plural), which manages access to
multiple displaced step buffers.

When preparing a displaced step for a thread, it looks for an unused
buffer.

For now, all users still pass a single displaced step buffer, so no real
behavior change is expected here.  The following patch makes a user pass
more than one buffer, so the functionality introduced by this patch is
going to be useful in the next one.

gdb/ChangeLog:

	* displaced-stepping.h (struct displaced_step_buffer): Rename
	to...
	(struct displaced_step_buffers): ... this.
	<m_addr, m_current_thread, m_copy_insn_closure>: Remove.
	<struct displaced_step_buffer>: New inner class.
	<m_buffers>: New.
	* displaced-stepping.c (displaced_step_buffer::prepare): Rename
	to...
	(displaced_step_buffers::prepare): ... this, adjust for multiple
	buffers.
	(displaced_step_buffer::finish):  Rename to...
	(displaced_step_buffers::finish): ... this, adjust for multiple
	buffers.
	(displaced_step_buffer::copy_insn_closure_by_addr): Rename to...
	(displaced_step_buffers::copy_insn_closure_by_addr): ... this,
	adjust for multiple buffers.
	(displaced_step_buffer::restore_in_ptid): Rename to...
	(displaced_step_buffers::restore_in_ptid): ... this, adjust for
	multiple buffers.
	* linux-tdep.h (linux_init_abi): Change supports_displaced_step
	for num_disp_step_buffers.
	* linux-tdep.c (struct linux_gdbarch_data)
	<num_disp_step_buffers>: New field.
	(struct linux_info) <disp_step_buf>: Rename to...
	<disp_step_bufs>: ... this, change type to
	displaced_step_buffers.
	(linux_displaced_step_prepare): Use
	linux_gdbarch_data::num_disp_step_buffers to create that number
	of buffers.
	(linux_displaced_step_finish): Adjust.
	(linux_displaced_step_copy_insn_closure_by_addr): Adjust.
	(linux_displaced_step_restore_all_in_ptid): Adjust.
	(linux_init_abi): Change supports_displaced_step parameter for
	num_disp_step_buffers, save it in linux_gdbarch_data.
	* aarch64-linux-tdep.c (aarch64_linux_init_abi): Adjust.
	* alpha-linux-tdep.c (alpha_linux_init_abi): Adjust.
	* amd64-linux-tdep.c (amd64_linux_init_abi_common): Change
	supports_displaced_step parameter for num_disp_step_buffers.
	(amd64_linux_init_abi): Adjust.
	(amd64_x32_linux_init_abi): Adjust.
	* arc-linux-tdep.c (arc_linux_init_osabi): Adjust.
	* arm-linux-tdep.c (arm_linux_init_abi): Adjust.
	* bfin-linux-tdep.c (bfin_linux_init_abi): Adjust.
	* cris-linux-tdep.c (cris_linux_init_abi): Adjust.
	* csky-linux-tdep.c (csky_linux_init_abi): Adjust.
	* frv-linux-tdep.c (frv_linux_init_abi): Adjust.
	* hppa-linux-tdep.c (hppa_linux_init_abi): Adjust.
	* i386-linux-tdep.c (i386_linux_init_abi): Adjust.
	* ia64-linux-tdep.c (ia64_linux_init_abi): Adjust.
	* m32r-linux-tdep.c (m32r_linux_init_abi): Adjust.
	* m68k-linux-tdep.c (m68k_linux_init_abi):
	* microblaze-linux-tdep.c (microblaze_linux_init_abi):
	* mips-linux-tdep.c (mips_linux_init_abi): Adjust.
	* mn10300-linux-tdep.c (am33_linux_init_osabi): Adjust.
	* nios2-linux-tdep.c (nios2_linux_init_abi): Adjust.
	* or1k-linux-tdep.c (or1k_linux_init_abi): Adjust.
	* ppc-linux-tdep.c (ppc_linux_init_abi): Adjust.
	* riscv-linux-tdep.c (riscv_linux_init_abi): Adjust.
	* rs6000-tdep.c (struct ppc_inferior_data) <disp_step_buf>:
	Change type to displaced_step_buffers.
	* s390-linux-tdep.c (s390_linux_init_abi_any): Adjust.
	* sh-linux-tdep.c (sh_linux_init_abi): Adjust.
	* sparc-linux-tdep.c (sparc32_linux_init_abi): Adjust.
	* sparc64-linux-tdep.c (sparc64_linux_init_abi): Adjust.
	* tic6x-linux-tdep.c (tic6x_uclinux_init_abi): Adjust.
	* tilegx-linux-tdep.c (tilegx_linux_init_abi): Adjust.
	* xtensa-linux-tdep.c (xtensa_linux_init_abi): Adjust.

Change-Id: Ia9c02f207da2c9e1d9188020139619122392bb70

The following patch will need to fill a field in linux_gdbarch_data
while the gdbarch is being built.  linux_gdbarch_data is currently
allocated as a post-init gdbarch data, meaning it's not possible to fill
it before the gdbarch is completely initialized.  Change it to a
pre-init gdbarch data to allow this.

The init_linux_gdbarch_data function doesn't use the created gdbarch,
it only allocates the linux_gdbarch_data structure on the gdbarch's
obstack, so the change is trivial.

gdb/ChangeLog:

	* linux-tdep.c (init_linux_gdbarch_data): Change parameter to
	obkstack.
	(_initialize_linux_tdep): Register pre-init gdb data instead of
	post-init.

Change-Id: If35ce91b6bb5435680d43b9268d811d95661644f

Today, GDB only allows a single displaced stepping operation to happen
per inferior at a time.  There is a single displaced stepping buffer per
inferior, whose address is fixed (obtained with
gdbarch_displaced_step_location), managed by infrun.c.

In the case of the AMD ROCm target [1] (in the context of which this
work has been done), it is typical to have thousands of threads (or
waves, in SMT terminology) executing the same code, hitting the same
breakpoint (possibly conditional) and needing to to displaced step it at
the same time.  The limitation of only one displaced step executing at a
any given time becomes a real bottleneck.

To fix this bottleneck, we want to make it possible for threads of a
same inferior to execute multiple displaced steps in parallel.  This
patch builds the foundation for that.

In essence, this patch moves the task of preparing a displaced step and
cleaning up after to gdbarch functions.  This allows using different
schemes for allocating and managing displaced stepping buffers for
different platforms.  The gdbarch decides how to assign a buffer to a
thread that needs to execute a displaced step.

On the ROCm target, we are able to allocate one displaced stepping
buffer per thread, so a thread will never have to wait to execute a
displaced step.

On Linux, the entry point of the executable if used as the displaced
stepping buffer, since we assume that this code won't get used after
startup.  From what I saw (I checked with a binary generated against
glibc and musl), on AMD64 we have enough space there to fit two
displaced stepping buffers.  A subsequent patch makes AMD64/Linux use
two buffers.

In addition to having multiple displaced stepping buffers, there is also
the idea of sharing displaced stepping buffers between threads.  Two
threads doing displaced steps for the same PC could use the same buffer
at the same time.  Two threads stepping over the same instruction (same
opcode) at two different PCs may also be able to share a displaced
stepping buffer.  This is an idea for future patches, but the
architecture built by this patch is made to allow this.

Now, the implementation details.  The main part of this patch is moving
the responsibility of preparing and finishing a displaced step to the
gdbarch.  Before this patch, preparing a displaced step is driven by the
displaced_step_prepare_throw function.  It does some calls to the
gdbarch to do some low-level operations, but the high-level logic is
there.  The steps are roughly:

- Ask the gdbarch for the displaced step buffer location
- Save the existing bytes in the displaced step buffer
- Ask the gdbarch to copy the instruction into the displaced step buffer
- Set the pc of the thread to the beginning of the displaced step buffer

Similarly, the "fixup" phase, executed after the instruction was
successfully single-stepped, is driven by the infrun code (function
displaced_step_finish).  The steps are roughly:

- Restore the original bytes in the displaced stepping buffer
- Ask the gdbarch to fixup the instruction result (adjust the target's
  registers or memory to do as if the instruction had been executed in
  its original location)

The displaced_step_inferior_state::step_thread field indicates which
thread (if any) is currently using the displaced stepping buffer, so it
is used by displaced_step_prepare_throw to check if the displaced
stepping buffer is free to use or not.

This patch defers the whole task of preparing and cleaning up after a
displaced step to the gdbarch.  Two new main gdbarch methods are added,
with the following semantics:

  - gdbarch_displaced_step_prepare: Prepare for the given thread to
    execute a displaced step of the instruction located at its current PC.
    Upon return, everything should be ready for GDB to resume the thread
    (with either a single step or continue, as indicated by
    gdbarch_displaced_step_hw_singlestep) to make it displaced step the
    instruction.

  - gdbarch_displaced_step_finish: Called when the thread stopped after
    having started a displaced step.  Verify if the instruction was
    executed, if so apply any fixup required to compensate for the fact
    that the instruction was executed at a different place than its
    original pc.  Release any resources that were allocated for this
    displaced step.  Upon return, everything should be ready for GDB to
    resume the thread in its "normal" code path.

The displaced_step_prepare_throw function now pretty much just offloads
to gdbarch_displaced_step_prepare and the displaced_step_finish function
offloads to gdbarch_displaced_step_finish.

The gdbarch_displaced_step_location method is now unnecessary, so is
removed.  Indeed, the core of GDB doesn't know how many displaced step
buffers there are nor where they are.

To keep the existing behavior for existing architectures, the logic that
was previously implemented in infrun.c for preparing and finishing a
displaced step is moved to displaced-stepping.c, to the
displaced_step_buffer class.  Architectures are modified to implement
the new gdbarch methods using this class.  The behavior is not expected
to change.

The other important change (which arises from the above) is that the
core of GDB no longer prevents concurrent displaced steps.  Before this
patch, start_step_over walks the global step over chain and tries to
initiate a step over (whether it is in-line or displaced).  It follows
these rules:

  - if an in-line step is in progress (in any inferior), don't start any
    other step over
  - if a displaced step is in progress for an inferior, don't start
    another displaced step for that inferior

After starting a displaced step for a given inferior, it won't start
another displaced step for that inferior.

In the new code, start_step_over simply tries to initiate step overs for
all the threads in the list.  But because threads may be added back to
the global list as it iterates the global list, trying to initiate step
overs, start_step_over now starts by stealing the global queue into a
local queue and iterates on the local queue.  In the typical case, each
thread will either:

  - have initiated a displaced step and be resumed
  - have been added back by the global step over queue by
    displaced_step_prepare_throw, because the gdbarch will have returned
    that there aren't enough resources (i.e. buffers) to initiate a
    displaced step for that thread

Lastly, if start_step_over initiates an in-line step, it stops
iterating, and moves back whatever remaining threads it had in its local
step over queue to the global step over queue.

Two other gdbarch methods are added, to handle some slightly annoying
corner cases.  They feel awkwardly specific to these cases, but I don't
see any way around them:

  - gdbarch_displaced_step_copy_insn_closure_by_addr: in
    arm_pc_is_thumb, arm-tdep.c wants to get the closure for a given
    buffer address.

  - gdbarch_displaced_step_restore_all_in_ptid: when a process forks
    (at least on Linux), the address space is copied.  If some displaced
    step buffers were in use at the time of the fork, we need to restore
    the original bytes in the child's address space.

These two adjustments are also made in infrun.c:

  - prepare_for_detach: there may be multiple threads doing displaced
    steps when we detach, so wait until all of them are done

  - handle_inferior_event: when we handle a fork event for a given
    thread, it's possible that other threads are doing a displaced step at
    the same time.  Make sure to restore the displaced step buffer
    contents in the child for them.

[1] https://github.com/ROCm-Developer-Tools/ROCgdb

gdb/ChangeLog:

	* displaced-stepping.h (struct
	displaced_step_copy_insn_closure): Adjust comments.
	(struct displaced_step_inferior_state) <step_thread,
	step_gdbarch, step_closure, step_original, step_copy,
	step_saved_copy>: Remove fields.
	(struct displaced_step_thread_state): New.
	(struct displaced_step_buffer): New.
	* displaced-stepping.c (displaced_step_buffer::prepare): New.
	(write_memory_ptid): Move from infrun.c.
	(displaced_step_instruction_executed_successfully): New,
	factored out of displaced_step_finish.
	(displaced_step_buffer::finish): New.
	(displaced_step_buffer::copy_insn_closure_by_addr): New.
	(displaced_step_buffer::restore_in_ptid): New.
	* gdbarch.sh (displaced_step_location): Remove.
	(displaced_step_prepare, displaced_step_finish,
	displaced_step_copy_insn_closure_by_addr,
	displaced_step_restore_all_in_ptid): New.
	* gdbarch.c: Re-generate.
	* gdbarch.h: Re-generate.
	* gdbthread.h (class thread_info) <displaced_step_state>: New
	field.
	(thread_step_over_chain_remove): New declaration.
	(thread_step_over_chain_next): New declaration.
	(thread_step_over_chain_length): New declaration.
	* thread.c (thread_step_over_chain_remove): Make non-static.
	(thread_step_over_chain_next): New.
	(global_thread_step_over_chain_next): Use
	thread_step_over_chain_next.
	(thread_step_over_chain_length): New.
	(global_thread_step_over_chain_enqueue): Add debug print.
	(global_thread_step_over_chain_remove): Add debug print.
	* infrun.h (get_displaced_step_copy_insn_closure_by_addr):
	Remove.
	* infrun.c (get_displaced_stepping_state): New.
	(displaced_step_in_progress_any_inferior): Remove.
	(displaced_step_in_progress_thread): Adjust.
	(displaced_step_in_progress): Adjust.
	(displaced_step_in_progress_any_thread): New.
	(get_displaced_step_copy_insn_closure_by_addr): Remove.
	(gdbarch_supports_displaced_stepping): Use
	gdbarch_displaced_step_prepare_p.
	(displaced_step_reset): Change parameter from inferior to
	thread.
	(displaced_step_prepare_throw): Implement using
	gdbarch_displaced_step_prepare.
	(write_memory_ptid): Move to displaced-step.c.
	(displaced_step_restore): Remove.
	(displaced_step_finish): Implement using
	gdbarch_displaced_step_finish.
	(start_step_over): Allow starting more than one displaced step.
	(prepare_for_detach): Handle possibly multiple threads doing
	displaced steps.
	(handle_inferior_event): Handle possibility that fork event
	happens while another thread displaced steps.
	* linux-tdep.h (linux_displaced_step_prepare): New.
	(linux_displaced_step_finish): New.
	(linux_displaced_step_copy_insn_closure_by_addr): New.
	(linux_displaced_step_restore_all_in_ptid): New.
	(linux_init_abi): Add supports_displaced_step parameter.
	* linux-tdep.c (struct linux_info) <disp_step_buf>: New field.
	(linux_displaced_step_prepare): New.
	(linux_displaced_step_finish): New.
	(linux_displaced_step_copy_insn_closure_by_addr): New.
	(linux_displaced_step_restore_all_in_ptid): New.
	(linux_init_abi): Add supports_displaced_step parameter,
	register displaced step methods if true.
	(_initialize_linux_tdep): Register inferior_execd observer.
	* amd64-linux-tdep.c (amd64_linux_init_abi_common): Add
	supports_displaced_step parameter, adjust call to
	linux_init_abi.  Remove call to
	set_gdbarch_displaced_step_location.
	(amd64_linux_init_abi): Adjust call to
	amd64_linux_init_abi_common.
	(amd64_x32_linux_init_abi): Likewise.
	* aarch64-linux-tdep.c (aarch64_linux_init_abi): Adjust call to
	linux_init_abi.  Remove call to
	set_gdbarch_displaced_step_location.
	* arm-linux-tdep.c (arm_linux_init_abi): Likewise.
	* i386-linux-tdep.c (i386_linux_init_abi): Likewise.
	* alpha-linux-tdep.c (alpha_linux_init_abi): Adjust call to
	linux_init_abi.
	* arc-linux-tdep.c (arc_linux_init_osabi): Likewise.
	* bfin-linux-tdep.c (bfin_linux_init_abi): Likewise.
	* cris-linux-tdep.c (cris_linux_init_abi): Likewise.
	* csky-linux-tdep.c (csky_linux_init_abi): Likewise.
	* frv-linux-tdep.c (frv_linux_init_abi): Likewise.
	* hppa-linux-tdep.c (hppa_linux_init_abi): Likewise.
	* ia64-linux-tdep.c (ia64_linux_init_abi): Likewise.
	* m32r-linux-tdep.c (m32r_linux_init_abi): Likewise.
	* m68k-linux-tdep.c (m68k_linux_init_abi): Likewise.
	* microblaze-linux-tdep.c (microblaze_linux_init_abi): Likewise.
	* mips-linux-tdep.c (mips_linux_init_abi): Likewise.
	* mn10300-linux-tdep.c (am33_linux_init_osabi): Likewise.
	* nios2-linux-tdep.c (nios2_linux_init_abi): Likewise.
	* or1k-linux-tdep.c (or1k_linux_init_abi): Likewise.
	* riscv-linux-tdep.c (riscv_linux_init_abi): Likewise.
	* s390-linux-tdep.c (s390_linux_init_abi_any): Likewise.
	* sh-linux-tdep.c (sh_linux_init_abi): Likewise.
	* sparc-linux-tdep.c (sparc32_linux_init_abi): Likewise.
	* sparc64-linux-tdep.c (sparc64_linux_init_abi): Likewise.
	* tic6x-linux-tdep.c (tic6x_uclinux_init_abi): Likewise.
	* tilegx-linux-tdep.c (tilegx_linux_init_abi): Likewise.
	* xtensa-linux-tdep.c (xtensa_linux_init_abi): Likewise.
	* ppc-linux-tdep.c (ppc_linux_init_abi): Adjust call to
	linux_init_abi.  Remove call to
	set_gdbarch_displaced_step_location.
	* arm-tdep.c (arm_pc_is_thumb): Call
	gdbarch_displaced_step_copy_insn_closure_by_addr instead of
	get_displaced_step_copy_insn_closure_by_addr.
	* rs6000-aix-tdep.c (rs6000_aix_init_osabi): Adjust calls to
	clear gdbarch methods.
	* rs6000-tdep.c (struct ppc_inferior_data): New structure.
	(get_ppc_per_inferior): New function.
	(ppc_displaced_step_prepare): New function.
	(ppc_displaced_step_finish): New function.
	(ppc_displaced_step_restore_all_in_ptid): New function.
	(rs6000_gdbarch_init): Register new gdbarch methods.
	* s390-tdep.c (s390_gdbarch_init): Don't call
	set_gdbarch_displaced_step_location, set new gdbarch methods.

gdb/testsuite/ChangeLog:

	* gdb.arch/amd64-disp-step-avx.exp: Adjust pattern.
	* gdb.threads/forking-threads-plus-breakpoint.exp: Likewise.
	* gdb.threads/non-stop-fair-events.exp: Likewise.

Change-Id: I387cd235a442d0620ec43608fd3dc0097fcbf8c8

Move displaced-stepping related stuff unchanged to displaced-stepping.h
and displaced-stepping.c.  This helps make the following patch a bit
smaller and easier to read.

gdb/ChangeLog:

	* Makefile.in (COMMON_SFILES): Add displaced-stepping.c.
	* aarch64-tdep.h: Include displaced-stepping.h.
	* displaced-stepping.h (struct displaced_step_copy_insn_closure):
	Move here.
	(displaced_step_copy_insn_closure_up): Move here.
	(struct buf_displaced_step_copy_insn_closure): Move here.
	(struct displaced_step_inferior_state): Move here.
	(debug_displaced): Move here.
	(displaced_debug_printf_1): Move here.
	(displaced_debug_printf): Move here.
	* displaced-stepping.c: New file.
	* gdbarch.sh: Include displaced-stepping.h in gdbarch.h.
	* gdbarch.h: Re-generate.
	* inferior.h: Include displaced-stepping.h.
	* infrun.h (debug_displaced): Move to displaced-stepping.h.
	(displaced_debug_printf_1): Likewise.
	(displaced_debug_printf): Likewise.
	(struct displaced_step_copy_insn_closure): Likewise.
	(displaced_step_copy_insn_closure_up): Likewise.
	(struct buf_displaced_step_copy_insn_closure): Likewise.
	(struct displaced_step_inferior_state): Likewise.
	* infrun.c (show_debug_displaced): Move to displaced-stepping.c.
	(displaced_debug_printf_1): Likewise.
	(displaced_step_copy_insn_closure::~displaced_step_copy_insn_closure):
	Likewise.
	(_initialize_infrun): Don't register "set/show debug displaced".

Change-Id: I29935f5959b80425370630a45148fc06cd4227ca

Pass to get_linux_inferior_data the inferior for which we want to obtain
the linux-specific data, rather than assuming the current inferior.
This helps slightly reduce the diff in the upcoming main patch.

Update the sole caller to pass the current inferior.

gdb/ChangeLog:

	* linux-tdep.c (get_linux_inferior_data): Add inferior
	parameter.
	(linux_vsyscall_range): Pass current inferior.

Change-Id: Ie4b61190e4a2e89b5b55a140cfecd4de66d92393

This is a preparatory patch to reduce the size of the diff of the
upcoming main patch.  It introduces enum types for the return values of
displaced step "prepare" and "finish" operations.  I find that this
expresses better the intention of the code, rather than returning
arbitrary integer values (-1, 0 and 1) which are difficult to remember.
That makes the code easier to read.

I put the new enum types in a new displaced-stepping.h file, because I
introduce that file in a later patch anyway.  Putting it there avoids
having to move it later.

There is one change in behavior for displaced_step_finish: it currently
returns 0 if the thread wasn't doing a displaced step and 1 if the
thread was doing a displaced step which was executed successfully.  It
turns out that this distinction is not needed by any caller, so I've
merged these two cases into "_OK", rather than adding an extra
enumerator.

gdb/ChangeLog:

	* infrun.c (displaced_step_prepare_throw): Change return type to
	displaced_step_prepare_status.
	(displaced_step_prepare): Likewise.
	(displaced_step_finish): Change return type to
	displaced_step_finish_status.
	(resume_1): Adjust.
	(stop_all_threads): Adjust.
	* displaced-stepping.h: New file.

Change-Id: I5c8fe07212cd398d5b486b5936d9d0807acd3788

This is a preparatory patch to reduce a little bit the diff size of the
main patch later in this series.  It renames the displaced_step_fixup
function in infrun.c to displaced_step_finish.

The rationale is to better differentiate the low and high level
operations.

We first have the low level operation of writing an instruction to a
displaced buffer, called "copy_insn".  The mirror low level operation to
fix up the state after having executed the instruction is "fixup".  The
high level operation of preparing a thread for a displaced step (which
includes doing the "copy_insn" and some more bookkeeping) is called
"prepare" (as in displaced_step_prepare).  The mirror high level
operation to cleaning up after a displaced step (which includes doing
the "fixup" and some more bookkeeping) is currently also called "fixup"
(as in displaced_step_fixup), just like the low level operation.

I think that choosing a different name for the low and high level
cleanup operation makes it clearer, hence "finish".

gdb/ChangeLog:

	* infrun.c (displaced_step_fixup): Rename to...
	(displaced_step_finish): ... this, update all callers.

Change-Id: Id32f48c1e2091d09854c77fcedcc14d2519957a2

Since we're going to introduce other "displaced step" functions and
another kind of displaced step closure, make it clear that this is the
return type of the gdbarch_displaced_step_copy_insn function.

gdb/ChangeLog:

	* infrun.h (get_displaced_step_closure_by_addr): Rename to...
	(get_displaced_step_copy_insn_closure_by_addr): ... this.
	Update all users.
	(displaced_step_closure): Rename to...
	(displaced_step_copy_insn_closure): ... this.  Update all users.
	(displaced_step_closure_up): Rename to...
	(displaced_step_copy_insn_closure_up). ... this.  Update all
	users.
	(buf_displaced_step_closure): Rename to...
	(buf_displaced_step_copy_insn_closure): ... this.  Update all
	users.
	* infrun.c (get_displaced_step_closure_by_addr): Rename to...
	(get_displaced_step_copy_insn_closure_by_addr): ... this.
	Update all users.
	* aarch64-tdep.c (aarch64_displaced_step_closure): Rename to...
	(aarch64_displaced_step_copy_insn_closure): ... this.  Update
	all users.
	* amd64-tdep.c (amd64_displaced_step_closure): Rename to...
	(amd64_displaced_step_copy_insn_closure): ... this.  Update all
	users.
	* arm-tdep.h (arm_displaced_step_closure): Rename to...
	(arm_displaced_step_copy_insn_closure): ... this.  Update all
	users.
	* i386-tdep.h (i386_displaced_step_closure): Rename to...
	(i386_displaced_step_copy_insn_closure): ... this.  Update all
	users.
	* rs6000-tdep.c (ppc_displaced_step_closure): Rename to...
	(ppc_displaced_step_copy_insn_closure): ... this.  Update all
	users.
	* s390-tdep.c (s390_displaced_step_closure): Rename to...
	(s390_displaced_step_copy_insn_closure): ... this.  Update all
	users.
	* gdbarch.h: Re-generate.
	* gdbarch.c: Re-generate.

Change-Id: I11f56dbcd4c3532fb195a08ba93bccf1d12a03c8

Rename step_over_queue_head to global_thread_step_over_chain_head, to
make it more obvious when reading code that we are touching the global
queue.  Rename all functions that operate on it to have "global" in
their name, to make it clear on which chain they operate on.  Also, in a
subsequent patch, we'll need both global and non-global versions of
these functions, so it will be easier to do the distinction if they are
named properly.

Normalize the naming to use "chain" everywhere instead of sometimes
"queue", sometimes "chain".

I also reworded a few comments in gdbthread.h.  They implied that the
step over chain is per-inferior, when in reality there is only one
global chain, not one per inferior, as far as I understand.

gdb/ChangeLog:

	* gdbthread.h (thread_step_over_chain_enqueue): Rename to...
	(global_thread_step_over_chain_enqueue): ... this.  Update all
	users.
	(thread_step_over_chain_remove): Rename to...
	(global_thread_step_over_chain_remove): ... this.  Update all
	users.
	(thread_step_over_chain_next): Rename to...
	(global_thread_step_over_chain_next): ... this.  Update all
	users.
	* infrun.h (step_over_queue_head): Rename to...
	(global_thread_step_over_chain_head): ... this.  Update all
	users.
	* infrun.c (step_over_queue_head): Rename to...
	(global_thread_step_over_chain_head): ... this.  Update all
	users.
	* thread.c (step_over_chain_remove): Rename to...
	(thread_step_over_chain_remove): ... this.  Update all users.
	(thread_step_over_chain_next): Rename to...
	(global_thread_step_over_chain_next): ... this.  Update all
	users.
	(thread_step_over_chain_enqueue): Rename to...
	(global_thread_step_over_chain_enqueue): ... this.  Update all
	users.
	(thread_step_over_chain_remove): Rename to...
	(global_thread_step_over_chain_remove): ... this.  Update all
	users.

Change-Id: Iabbf57d83c01321ca199d83fadb57f5b04e4d6d9

Remove function get_displaced_stepping_state.  When it was introduced,
inferiors' displaced stepping state was kept in a linked list in
infrun.c, so it was handy.  Nowadays, the state is kept inside struct
inferior directly, so we can just access it directly instead.

gdb/ChangeLog:

	* infrun.c (get_displaced_stepping_state): Remove, change
	callers to access the field directly.

Change-Id: I9a733e32e29c7ebf856ab0befe1076bbb8c7af69

In handle_inferior_event, where we handle forks, we make sure to restore
the bytes of the displaced stepping buffer in the child's address
space.  However, we only do it when the forking thread was the one
doing a displaced step.  It could happen that a thread forks while
another one is doing a displaced step.  In this case, we also need to
restore the bytes in the child.

Move the byte-restoring code outside of the condition that checks
whether the event thread was displaced stepping.

gdb/ChangeLog:

	* infrun.c (handle_inferior_event): Restore displaced step
	buffer bytes in child process when handling fork, even if fork
	happened in another thread than the displaced-stepping one.

Change-Id: Ibb0daaeb123aba03f4fb4b4d820754eb2436bc69