sys: Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

elfnote: place note in a PT_NOTE program header

Some tools (firecraker loader) only check for notes in PT_NOTE program
headers, so make sure the notes added using the ELFNOTE macro end up
in such he

elfnote: place note in a PT_NOTE program header

Some tools (firecraker loader) only check for notes in PT_NOTE program
headers, so make sure the notes added using the ELFNOTE macro end up
in such header.

Output from readelf -Wl for and amd64 kernel after the change:

Elf file type is EXEC (Executable file)
Entry point 0xffffffff8038a000
There are 11 program headers, starting at offset 64

Program Headers:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
PHDR 0x000040 0xffffffff80200040 0x0000000000200040 0x000268 0x000268 R 0x8
INTERP 0x0002a8 0xffffffff802002a8 0x00000000002002a8 0x00000d 0x00000d R 0x1
[Requesting program interpreter: /red/herring]
LOAD 0x000000 0xffffffff80200000 0x0000000000200000 0x189e28 0x189e28 R 0x200000
LOAD 0x18a000 0xffffffff8038a000 0x000000000038a000 0xe447e8 0xe447e8 R E 0x200000
LOAD 0xfce7f0 0xffffffff811ce7f0 0x00000000011ce7f0 0x6b955c 0x6b955c R 0x200000
LOAD 0x1800000 0xffffffff81a00000 0x0000000001a00000 0x000140 0x000140 RW 0x200000
LOAD 0x1801000 0xffffffff81a01000 0x0000000001a01000 0x1c8480 0x5ff000 RW 0x200000
DYNAMIC 0x1800000 0xffffffff81a00000 0x0000000001a00000 0x000140 0x000140 RW 0x8
GNU_RELRO 0x1800000 0xffffffff81a00000 0x0000000001a00000 0x000140 0x000140 R 0x1
GNU_STACK 0x000000 0x0000000000000000 0x0000000000000000 0x000000 0x000000 RW 0
NOTE 0x1687ae0 0xffffffff81887ae0 0x0000000001887ae0 0x0001c0 0x0001c0 R 0x4

Section to Segment mapping:
Segment Sections...
[...]
10 .note.gnu.build-id .note.Xen

Reported by: cperciva
Fixes: 1a9cdd373a6a ('xen: add PV/PVH kernel entry point')
Fixes: 93ee134a24fa ('Integrate support for xen in to i386 common code.')
Sponsored by: Citrix Systems R&D
Reviewed by: emaste
Differential revision: https://reviews.freebsd.org/D35611

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x86: remove gcov kernel support

Reviewed by: jhb
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D29529

i386: clean up empty lines in .c and .h files

i386: stop guessing the address of the trap frame in ddb backtrace.

Save the address of the trap frame in %ebp on kernel entry. This
automatically provides it in struct i386_frame.f_frame to unwind

i386: stop guessing the address of the trap frame in ddb backtrace.

Save the address of the trap frame in %ebp on kernel entry. This
automatically provides it in struct i386_frame.f_frame to unwinder.

While there, more accurately handle the terminating frames,

Reviewed by: avg, markj
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D22321

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Fix recent breakages of kernel profiling, mostly on i386 (high resolution
kernel profiling remains broken).

memmove() was broken using ALTENTRY(). ALTENTRY() is only different from
ENTRY() in the p

Fix recent breakages of kernel profiling, mostly on i386 (high resolution
kernel profiling remains broken).

memmove() was broken using ALTENTRY(). ALTENTRY() is only different from
ENTRY() in the profiling case, and its use in that case was sort of
backwards. The backwardness magically turned memmove() into memcpy()
instead of completely breaking it. Only the high resolution parts of
profiling itself were broken. Use ordinary ENTRY() for memmove().
Turn bcopy() into a tail call to memmove() to reduce complications.
This gives slightly different pessimizations and profiling lossage.
The pessimizations are minimized by not using a frame pointer() for
bcopy().

Calls to profiling functions from exception trampolines were not
relocated. This caused crashes on the first exception. Fix this using
function pointers.

Addresses of exception handlers in trampolines were not relocated. This
caused unknown offsets in the profiling data. Relocate by abusing
setidt_disp as for pmc although this is slower than necessary and
requires namespace pollution. pmc seems to be missing some relocations.
Stack traces and lots of other things in debuggers need similar relocations.

Most user addresses were misclassified as unknown kernel addresses and
then ignored. Treat all unknown addresses as user. Now only user
addresses in the kernel text range are significantly misclassified (as
known kernel addresses).

The ibrs functions didn't preserve enough registers. This is the only
recent breakage on amd64. Although these functions are written in
asm, in the profiling case they call profiling functions which are
mostly for the C ABI, so they only have to save call-used registers.
They also have to save arg and return registers in some cases and
actually save them in all cases to reduce complications. They end up
saving all registers except %ecx on i386 and %r10 and %r11 on amd64.
Saving these is only needed for 1 caller on each of amd64 and i386.
Save them there. This is slightly simpler.

Remove saving %ecx in handle_ibrs_exit on i386. Both handle_ibrs_entry
and handle_ibrs_exit use %ecx, but only the latter needed to or did
save it. But saving it there doesn't work for the profiling case.

amd64 has more automatic saving of the most common scratch registers
%rax, %rcx and %rdx (its complications for %r10 are from unusual use
of %r10 by SYSCALL). Thus profiling of handle_ibrs_exit_rs() was not
broken, and I didn't simplify the saving by moving the saving of these
registers from it to the caller.

show more ...

Support IBRS for i386.

Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D15522

Use local unique labels inside most often used macros.

Discussed with: bde
Sponsored by: The FreeBSD Foundation
MFC after: 1 week

Fix double-load of %cr3 and double-copy of the stack frame for the
kernel entry from userspace vm86.

Sponsored by: The FreeBSD Foundation
MFC after: 1 week

Kernel entry from vm86 mode, where PCB_VM86CALL pcb flag is not set,
is executed on the right stack already. No copy from the entry stack
to the kstack must be performed for vm86 bios call code to f

Kernel entry from vm86 mode, where PCB_VM86CALL pcb flag is not set,
is executed on the right stack already. No copy from the entry stack
to the kstack must be performed for vm86 bios call code to function.

To access the pcb flags on kernel entry, unconditionally switch to
kernel address space if vm86 mode is detected.

This fixes very early vm86 bios calls, typically done when boot is
performed by boot2 without loader, and kernel falls back to BIOS calls
to get SMAP.

Reported by: bde
Sponsored by: The FreeBSD Foundation

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Create a macro for PIC code which loads %cr3 from tramp_idleptd.

Sponsored by: The FreeBSD Foundation

Fix move of the frame to the normal stack for interrupts occuring from
the vm86 mode.

Submitted by: jhb

Use symbolic constant, explaining the operation.

Sponsored by: The FreeBSD Foundation

i386 4/4G split.

The change makes the user and kernel address spaces on i386
independent, giving each almost the full 4G of usable virtual addresses
except for one PDE at top used for trampoline and

i386 4/4G split.

The change makes the user and kernel address spaces on i386
independent, giving each almost the full 4G of usable virtual addresses
except for one PDE at top used for trampoline and per-CPU trampoline
stacks, and system structures that must be always mapped, namely IDT,
GDT, common TSS and LDT, and process-private TSS and LDT if allocated.

By using 1:1 mapping for the kernel text and data, it appeared
possible to eliminate assembler part of the locore.S which bootstraps
initial page table and KPTmap. The code is rewritten in C and moved
into the pmap_cold(). The comment in vmparam.h explains the KVA
layout.

There is no PCID mechanism available in protected mode, so each
kernel/user switch forth and back completely flushes the TLB, except
for the trampoline PTD region. The TLB invalidations for userspace
becomes trivial, because IPI handlers switch page tables. On the other
hand, context switches no longer need to reload %cr3.

copyout(9) was rewritten to use vm_fault_quick_hold(). An issue for
new copyout(9) is compatibility with wiring user buffers around sysctl
handlers. This explains two kind of locks for copyout ptes and
accounting of the vslock() calls. The vm_fault_quick_hold() AKA slow
path, is only tried after the 'fast path' failed, which temporary
changes mapping to the userspace and copies the data to/from small
per-cpu buffer in the trampoline. If a page fault occurs during the
copy, it is short-circuit by exception.s to not even reach C code.

The change was motivated by the need to implement the Meltdown
mitigation, but instead of KPTI the full split is done. The i386
architecture already shows the sizing problems, in particular, it is
impossible to link clang and lld with debugging. I expect that the
issues due to the virtual address space limits would only exaggerate
and the split gives more liveness to the platform.

Tested by: pho
Discussed with: bde
Sponsored by: The FreeBSD Foundation
MFC after: 1 month
Differential revision: https://reviews.freebsd.org/D14633

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Merge ^/head r325999 through r326131.

sys: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 3-Clause license.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for

sys: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 3-Clause license.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.

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Merge ^/head r323559 through r325504.

MFhead@r324095

Restore a part of r323722.

Do not return from interrupt using the POP_FRAME;iret instruction
sequence, always jump to doreti.

The user segments selectors saved on the stack might become invalid
bec

Restore a part of r323722.

Do not return from interrupt using the POP_FRAME;iret instruction
sequence, always jump to doreti.

The user segments selectors saved on the stack might become invalid
because userspace manipulated LDT in a parallel thread. trap() is
aware of such issue, but it is only prepared to handle it at iret and
segment registers load operations in doreti path.

Also remove POP_FRAME macro because it is no longer used.

Reviewed by: bde, jhb (as part of r323722)
Sponsored by: The FreeBSD Foundation
MFC after: 1 week

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Merge ^/head r314420 through r314481.

Renumber copyright clause 4

Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is

Renumber copyright clause 4

Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is too pedantic, so give up on that point.

Submitted by: Jan Schaumann <jschauma@stevens.edu>
Pull Request: https://github.com/freebsd/freebsd/pull/96

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MFH r289384-r293170

Sponsored by: The FreeBSD Foundation

Catch up with head (r291075).

Merge from head

Use movw instead of movl (or plain mov) when moving segment registers
into memory. This is a nop on clang's assembler, but some assemblers
complain if the size suffix is incorrect.

Submitted by: bde