Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Use our nitems() macro when param.h is available.

Replacements specific to arm, mips, pc98, powerpc and sparc64.

Discussed in: freebsd-current

Remove unneeded includes of <sys/linker_set.h>. Other headers that use
it internally contain nested includes.

Reviewed by: bde

- In GCC 4.2 __builtin_frame_address() was fixed to include the
V9 stack bias so we no longer need to add it in db_backtrace()
and stack_capture() respectively. This also reverts r182018,
which kludged around the resulting unaligned access.
- Sync the sun4v versions of db_trace.c and stack_machdep.c with
the sparc64 ones and fix some style bugs.

MFC after: 3 days

Break out stack(9) from ddb(4):

- Introduce per-architecture stack_machdep.c to hold stack_save(9).
- Introduce per-architecture machine/stack.h to capture any common
definitions required between db_trace.c and stack_machdep.c.
- Add new kernel option "options STACK"; we will build in stack(9) if it is
defined, or also if "options DDB" is defined to provide compatibility
with existing users of stack(9).

Add new stack_save_td(9) function, which allows the capture of a stacktrace
of another thread rather than the current thread, which the existing
stack_save(9) was limited to. It requires that the thread be neither
swapped out nor running, which is the responsibility of the consumer to
enforce.

Update stack(9) man page.

Build tested: amd64, arm, i386, ia64, powerpc, sparc64, sun4v
Runtime tested: amd64 (rwatson), arm (cognet), i386 (rwatson)

Simplify the pager support in DDB. Allowing different db commands to
install custom pager functions didn't actually happen in practice (they
all just used the simple pager and passed in a local quit pointer). So,
just hardcode the simple pager as the only pager and make it set a global
db_pager_quit flag that db commands can check when the user hits 'q' (or a
suitable variant) at the pager prompt. Also, now that it's easy to do so,
enable paging by default for all ddb commands. Any command that wishes to
honor the quit flag can do so by checking db_pager_quit. Note that the
pager can also be effectively disabled by setting $lines to 0.

Other fixes:
- 'show idt' on i386 and pc98 now actually checks the quit flag and
terminates early.
- 'show intr' now actually checks the quit flag and terminates early.

- Don't bother traversing trap frames in stack_save(). This fixes panics
when option DEBUG_LOCKS is used. Trap frames are determined by checking
whether the caller was one of the tl0_*() or tl1_*() asm functions via
a newly added pair of dummy symbols in exception.S which mark the begin
and end of these functions. The tl_trap_* pair marks those in the special
.trap section and the tl_text_* in the regular .text section. Because
of their performance penalty db_search_symbol()/db_symbol_values() and
linker_ddb_search_symbol()/linker_ddb_symbol_values() aren't used here
for determining the caller, with db_search_symbol()/db_symbol_values()
additionally not being reentrant.
- For consistency, change db_backtrace() to also use the new markers for
determining the tl0_*() and tl1_*() asm functions instead of bcmp()'ing
the symbol name.
- Use FBSDID in db_trace.c.

PR: 93226
Based on a patch by: Antoine Brodin <antoine.brodin@laposte.net>
Ok'ed by: jhb

- Add support for saving stack traces and displaying them via printf(9)
and KTR.

Contributed by: Antoine Brodin <antoine.brodin@laposte.net>
Concept code from: Neal Fachan <neal@isilon.com>

Don't include sys/user.h merely for its side-effect of recursively
including other headers.

- Change the ddb paging "support" to use a variable (db_lines_per_page) to
control the number of lines per page rather than a constant. The variable
can be examined and changed in ddb as '$lines'. Setting the variable to
0 will effectively turn off paging.
- Change db_putchar() to force out pending whitespace before outputting
newlines and carriage returns so that one can rub out content on the
current line via '\r \r' type strings.
- Change the simple pager to rub out the --More-- prompt explicitly when
the routine exits.
- Add some aliases to the simple pager to make it more compatible with
more(1): 'e' and 'j' do a single line. 'd' does half a page, and
'f' does a full page.

MFC after: 1 month
Inspired by: kris

- Add support for "paging" in stack trace output. That is, when you do
a stack trace from ddb, the output will pause with a '--More--' prompt
every 18 lines. If you hit Enter, it will print another line and prompt
again. If you hit space it will output another page and then prompt.
If you hit 'q' or 'x' it will abort the rest of the stack trace.
- Fix the sparc64 userland stack trace to honor the total count of lines
to print. This is useful if your trace happens to walk back onto
0xdeadc0de and gets stuck in an endless loop.

MFC after: 1 month
Tested on: i386, alpha, sparc64

Unify db_stack_trace_cmd(). All it did was look up the thread given
the thread ID and call db_trace_thread().
Since arm has all the logic in db_stack_trace_cmd(), rename the
new DB_COMMAND function to db_stack_trace to avoid conflicts on
arm.
While here, have db_stack_trace parse its own arguments so that
we can use a more natural radix for IDs. If the ID is not a thread
ID, or more precisely when no thread exists with the ID, try if
there's a process with that ID and return the first thread in it.
This makes it easier to print stack traces from the ps output.

requested by: rwatson@
tested on: amd64, i386, ia64

Mega update for the KDB framework: turn DDB into a KDB backend.
Most of the changes are a direct result of adding thread awareness.
Typically, DDB_REGS is gone. All registers are taken from the
trapframe and backtraces use the PCB based contexts. DDB_REGS was
defined to be a trapframe on all platforms anyway.
Thread awareness introduces the following new commands:
thread X switch to thread X (where X is the TID),
show threads list all threads.

The backtrace code has been made more flexible so that one can
create backtraces for any thread by giving the thread ID as an
argument to trace.

With this change, ia64 has support for breakpoints.

Don't confuse NULL with 0.

Prefer new location of pci include files (which have only been in the
tree for two or more years now), except in a few places where there's
code to be compatible with older versions of FreeBSD.

Rename pcb_fp to pcb_sp, so as to not be confused with floating point
state.

Implement db_print_backtrace. This may need to flush out the windows
as well.

Use correct function name in previous commit.

Submitted by: jake
Pointy hat to: jhb

Implement db_print_backtrace() if DDB is compiled into the kernel. This
MD function is just a wrapper around db_stack_trace_cmd() that prints out
a backtrace of curthread. Currently, this function is only implemented
on i386 and alpha (and the alpha version isn't quite tested yet, will do
that in a bit). Other changes:

- For i386, fix a bug in the raw frame address case. The eip we extract
from the passed in frame address does not match the frame we received.
Thus, instead of printing a bogus frame with the wrong eip, go ahead
and advance frame down to the same frame as the eip we are using.
- For alpha, attempt to add a way of doing a raw trace for alpha. Instead
of passing a frame address in 'addr', pass in a pointer to a structure
containing PC and KSP and use those to start the backtrace. The alpha
db_print_backtrace() uses asm to read in the current PC and KSP values
into such a request.

Tested on: i386
Requested by: many

Forgot these files in previous commit to frame.h. Also add needed include
of machine/emul.h.

Oops. Should have said

Submitted by: tmm

Cleanup the trace back routine slightly. Print the leaf return value so
that traps inside of leaf functions are less confusing. Add a function
to print a non-symbolic trace of the user stack.

Pre-KSE/M3 commit.
this is a low-functionality change that changes the kernel to access the main
thread of a process via the linked list of threads rather than
assuming that it is embedded in the process. It IS still embeded there
but remove all teh code that assumes that in preparation for the next commit
which will actually move it out.

Reviewed by: peter@freebsd.org, gallatin@cs.duke.edu, benno rice,

Be paranoid about the sizeof passed to db_get_value, not all trapframe
fields are u_long.
Print useful information about traps in backtraces.
GC some dead code.

1. Remove kdbframe. Bad idea.
2. Add a TF_DONE macro, which fiddles a trapframe to make the retry on
return from traps act like a done (advance past the trapping
instruction instead of re-executing).
3. Flush the windows before entering the debugger, since it is no
longer done in the breakpoint trap vector.
4. Print a warning if trace <pid> is attempted, it is not yet implemented.
5. Print traps better and decode system calls in traces.

Submitted by: rwatson (4)

Catch up to changing entry point names so traces through traps
mostly work right. This catches recursive traps too early, but
generally such traps are fatal and we won't get this far anyway.

Change tf_arg to uintptr_t from void * to reflect the fact that
non-pointer values may be passed in it. Add appropriate casts.

The interrupt type is now passed in tf_arg instead tf_type.

Catch up with new trap entry point names.

Add code to handle stack traces that go all the way back to userland.
Use a better algorithm for finding out if an address is in the kernel.

Submitted by: tmm

The author isn't a [UC] Regents. Correct the copyright language.

Flesh out the sparc64 port considerably. This contains:
- mostly complete kernel pmap support, and tested but currently turned
off userland pmap support
- low level assembly language trap, context switching and support code
- fully implemented atomic.h and supporting cpufunc.h
- some support for kernel debugging with ddb
- various header tweaks and filling out of machine dependent structures