Print a rate limited warning if the TSC timecounter goes backwards from the
viewpoint of any single LWP.

Remove now unused mdlwp fields md_gc_pmap and md_gc_ptp.

branches: 1.46.2;
Rewrite the FPU code on x86. This greatly simplifies the logic and removes
the dependency on IPL_HIGH. NVMM is updated accordingly. Posted on
port-amd64 a week ago.

Bump the kernel version to 9.99.16.

branches: 1.45.14;
Garbage collect unneeded inclusion of <x86/dbregs.h> in <machine/proc.h>

This is left over after introduction of Debug Register accessors.
This interface replaced older watchpoint API.

Sponsored by <The NetBSD Foundation>

Introduce PT_GETDBREGS and PT_SETDBREGS in ptrace(2) on i386 and amd64

This interface is modeled after FreeBSD API with the usage.

This replaced previous watchpoint API. The previous one was introduced
recently in NetBSD-current and remove its spurs without any
backward-compatibility.

Design choices for Debug Register accessors:
- exec() (TRAP_EXEC event) must remove debug registers from LWP
- debug registers are only per-LWP, not per-process globally
- debug registers must not be inherited after (v)forking a process
- debug registers must not be inherited after forking a thread
- a debugger is responsible to set global watchpoints/breakpoints with the
debug registers, to achieve this PTRACE_LWP_CREATE/PTRACE_LWP_EXIT event
monitoring function is designed to be used
- debug register traps must generate SIGTRAP with si_code TRAP_DBREG
- debugger is responsible to retrieve debug register state to distinguish
the exact debug register trap (DR6 is Status Register on x86)
- kernel must not remove debug register traps after triggering a trap event
a debugger is responsible to detach this trap with appropriate PT_SETDBREGS
call (DR7 is Control Register on x86)
- debug registers must not be exposed in mcontext
- userland must not be allowed to set a trap on the kernel

Implementation notes on i386 and amd64:
- the initial state of debug register is retrieved on boot and this value is
stored in a local copy (initdbregs), this value is used to initialize dbreg
context after PT_GETDBREGS
- struct dbregs is stored in pcb as a pointer and by default not initialized
- reserved registers (DR4-DR5, DR9-DR15) are ignored

Further ideas:
- restrict this interface with securelevel

Tested on real hardware i386 (Intel Pentium IV) and amd64 (Intel i7).

This commit enables 390 debug register ATF tests in kernel/arch/x86.
All tests are passing.

This commit does not cover netbsd32 compat code. Currently other interface
PT_GET_SIGINFO/PT_SET_SIGINFO is required in netbsd32 compat code in order to
validate reliably PT_GETDBREGS/PT_SETDBREGS.

This implementation does not cover FreeBSD specific defines in their
<x86/reg.h>: DBREG_DR7_LOCAL_ENABLE, DBREG_DR7_GLOBAL_ENABLE, DBREG_DR7_LEN_1
etc. These values tend to be reinvented by each tracer on its own. GNU
Debugger (GDB) works with NetBSD debug registers after adding this patch:

--- gdb/amd64bsd-nat.c.orig 2016-02-10 03:19:39.000000000 +0000
+++ gdb/amd64bsd-nat.c
@@ -167,6 +167,10 @@ amd64bsd_target (void)

#ifdef HAVE_PT_GETDBREGS

+#ifndef DBREG_DRX
+#define DBREG_DRX(d,x) ((d)->dr[(x)])
+#endif
+
static unsigned long
amd64bsd_dr_get (ptid_t ptid, int regnum)
{


Another reason to stop introducing unpopular defines covering machine
specific register macros is that these value varies across generations of
the same CPU family.

GDB demo:
(gdb) c
Continuing.

Watchpoint 2: traceme

Old value = 0
New value = 16
main (argc=1, argv=0x7f7fff79fe30) at test.c:8
8 printf("traceme=%d\n", traceme);

(Currently the GDB interface is not reliable due to NetBSD support bugs)

Sponsored by <The NetBSD Foundation>

branches: 1.43.2;
Add support for hardware assisted watchpoints/breakpoints API in ptrace(2)

Add new ptrace(2) calls:
- PT_COUNT_WATCHPOINTS - count the number of available hardware watchpoints
- PT_READ_WATCHPOINT - read struct ptrace_watchpoint from the kernel state
- PT_WRITE_WATCHPOINT - write new struct ptrace_watchpoint state, this
includes enabling and disabling watchpoints

The ptrace_watchpoint structure contains MI and MD parts:

typedef struct ptrace_watchpoint {
int pw_index; /* HW Watchpoint ID (count from 0) */
lwpid_t pw_lwpid; /* LWP described */
struct mdpw pw_md; /* MD fields */
} ptrace_watchpoint_t;

For example amd64 defines MD as follows:
struct mdpw {
void *md_address;
int md_condition;
int md_length;
};

These calls are protected with the __HAVE_PTRACE_WATCHPOINTS guard.

Tested on amd64, initial support added for i386 and XEN.

Sponsored by <The NetBSD Foundation>

branches: 1.42.6; 1.42.10;
Move the amd64 and i386 pcb to the bottom of the uarea, and move the
kernel stack to the top.
Change the pcb layouts so that fpu save area is at the end and is
64byte aligned ready for xsave (saving the ymm registers).
Welcome to 6.99.32

Remove all references to MDL_USEDFPU and deferred fpu initialisation.
The cost of zeroing the save area on exec is minimal.
This stops the FP registers of a random process being used the first
time an lwp uses the fpu.
sendsig_siginfo() and get_mcontext() now unconditionally copy the FP
registers.
I'll remove the double-copy for signal handlers soon.
get_mcontext() might have been leaking kernel memory to userspace - and
may still do so if i386_use_fxsave is false (short copies).

revert fpu/pcu changes until we figure out what's wrong; they cause random
freezes

Use the MI "pcu" framework for bookkeeping of npx/fpu states on x86.
This reduces the amount of MD code enormously, and makes it easier
to implement support for newer CPU features which require more fpu
state, or for fpu usage by the kernel.
For access to FPU state across CPUs, an xcall kthread is used now
rather than a dedicated IPI.
No user visible changes intended.

branches: 1.38.8; 1.38.18; 1.38.22;
Retire struct user, remove sys/user.h inclusions. Note sys/user.h header
as obsolete. Remove USER_TO_UAREA/UAREA_TO_USER macros.

Various #include fixes and review by matt@.

branches: 1.37.2; 1.37.6;
Remove stray opt_redzone.h

branches: 1.36.6; 1.36.8;
pmap_remove_all() for x86. Also, always defer freeing ptps to pmap_update().
There may be a better way to do this, but for now this is simple and avoids
potential bugs.

Proposed on tech-kern and discussed with chs@.

branches: 1.35.6; 1.35.8; 1.35.10; 1.35.12;
i386:
- make tss per-cpu. this considerably speeds up context switch for,
at least, pentium4, where ltr instruction seems very slow.
i386, xen:
- kill cpu_maxproc.
kvm86:
- adapt to per-cpu tss.
- cleanup and simplify.
- move kvm86_mp_lock to more meaningful place.
- disable preemption during a call.

branches: 1.34.6;
s/proc/lwp/ in comment

fsbase/gsbase:

- Fix a few bugs with it, in particular fork/exec handling.
- Store the descriptors in the PCB, not in the LWP.

- When computing the TSC frequency, call i8254_delay() and not DELAY().
- Use atomics to adjust the pmap reference count, instead of taking locks.
- Implement I386_{SET,GET}_{FS,GS}BASE, allowing %fs and %gs to be used
as per-thread registers. This is compatible with FreeBSD.
- Run patches after we have attached CPUs, since we then know if the
system is uniprocessor or not. Eliminates a lot of #ifdef MULTIPROCESSOR
and makes running MP kernels on UP systems cheaper.
- Patch out many of the 'lock' prefixes to nops if uniprocessor.
- Do a wbinvd after patching to ensure that the trace/instruction cache
is up to date.

branches: 1.31.2; 1.31.18; 1.31.20; 1.31.24; 1.31.26;
Kill caddr_t; there will be some MI fallout, but it will be fixed shortly.

branches: 1.30.2;
Merge newlock2 to head.

fix a typo in 1.28. (ccaddr_t -> caddr_t)

branches: 1.28.6; 1.28.8;
i386 and xen: move struct user to the highest address in uarea
and reduce UPAGES from 4 to 3 in the case of !NOREDZONE.

branches: 1.27.4; 1.27.6; 1.27.8; 1.27.12; 1.27.14;
Remove leading __ from __(const|inline|signed|volatile) -- it is obsolete.

branches: 1.26.16;
- Locate comment in right place.
- Fix wrt protection against multiple inclusion.

rename i386 mdlwp flags from MDP_ to MDL_
to avoid confusion with mdproc flags which also have MDP_ prefixes.

remove a duplicated definition of MDP_USEDFPU.

Nuke __P().

Pass pointers to frames from assembly, do not use the 'frame on stack
as argument passed by value' trick, as gcc 3.3.x makes (valid) assumptions
about the stack that will not be true. Costs 2 instructions per trap/syscall
on i386, 4 per interrupt for MP. One instruction per trap/syscall on amd64,
2 per interrupt for MP. I expect gcc 3.3.1 to make up for this by better
optimization (it'd better..)

While here, make amd64 compile again by using subr_mbr_disk.c

Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22364, verified by myself.

branches: 1.20.2;
Protect kernel opt_*.h include by #ifdef _KERNEL_OPT

Make sure to include opt_foo.h if a defflag option FOO is used.

Use PAGE_SIZE rather than NBPG.

Merge the nathanw_sa branch.

re-do my previous commit correctly

override KSTACK_LOWEST_ADDR and KSTACK_SIZE for redzone.

branches: 1.14.2;
Add flag to indicate that a process set some mtrrs that need to be
cleaned up automatically on exit.

branches: 1.13.4; 1.13.6; 1.13.8;
Include "machine/frame.h" to avoid lint errors while building "libc".

Introduce 2 new flags in types.h:
* __HAVE_SYSCALL_INTERN. If this is defined, e_syscall is replaced by
e_syscall_intern, which is called at key places in the kernel. This can be
used to set a MD syscall handler pointer. This obsoletes and replaces the
*_HAS_SEPARATED_SYSCALL flags.
* __HAVE_MINIMAL_EMUL. If this is defined, certain (deprecated) elements in
struct emul are omitted.

Move the TSS selector out of the PCB and put it into mdproc. We
need to access this when we have the proclist locked for reading,
and thus cannot store it in the PCB (which may be swapped out).

As part of this, call pmap_activate() from cpu_switch() to switch
to the new address space, and refresh the PCB's copy of the LDT
selector from the pmap structure (see above paragraph). We need
to do this for MP support anyhow.

Fixes a "panic: spinlock_switchcheck: CPU 0 has 1 spin locks" via
gdt_compact() reported by Nathan Williams.

branches: 1.10.32; 1.10.44;
Move the `used fpu' flag into mdproc, so it can be referenced when a process
is swapped out. Implement process_{read,write}_fpregs.

Make md_regs a pointer to a trapframe.

Rename ibcs2_sigflags to __spare, but leave the space for now.

new RCS ID format.

Add flags for iBCS2 compat.

branches: 1.5.2;
lots of changes: prototype migration, move lots of variables, definitions,
and structure elements around. kill some unnecessary type and macro
definitions. standardize clock handling. More changes than you'd want.

branches: 1.4.2;
Remove two unused fields.

Cleanup and garbage collection; nothing significant. From magnum branch.

branches: 1.2.4;
add rcsids to everything and clean up headers

branches: 1.1.1;
Initial revision