On amd64, arm64 and i386, we have the possibility to switch between TLS
areas in userspace. The nice thing about this is that it makes it easier
to do light-weight threading, if we ever feel like doing that. On armv6,
let's go into the same direction by making it possible to safely use the
TPIDRURW register, which is intended for this purpose.
Clean up the ARMv6 code to remove md_tp entirely. Simply add a dedicated
field to the PCB to hold the value of TPIDRURW across context switches,
like we do for any other register. As userspace currently uses the
read-only TPIDRURO register, simply ensure that we keep both values in
sync where possible. The system calls for modifying the read-only
register will simply write the intended value into both registers, so
that it lazily ends up in the PCB during the next context switch.
Reviewed by: https://reviews.freebsd.org/D7951
Approved by: andrew
Reviewed by: imp
Differential Revision: https://reviews.freebsd.org/D7951
- Eliminate unused irqframe
- Eliminate unused saframe
- Instead of splitting r4-sp storage between the stack and switchframe,
just put all the registers in switchframe and eliminate the un_32 struct.
Submitted by: Svatopluk Kraus <onwahe@gmail.com>,
Michal Meloun <meloun@miracle.cz>
because an exception may happen at any time. The stack alignment rules on
ARM EABI state the only place the stack must be 8-byte aligned is on a
function boundary.
If an exception happens while a function is setting up or tearing down it's
stack frame it may not be correctly aligned. There is also no requirement
for it to be when the function is a leaf node.
The fix is to align the stack after we have stored a backup of the old stack
pointer, but before we have stored anything in the trapframe. Along with
this we need to adjust the size of the trapframe by 4 bytes to ensure the
stack below it is also correctly aligned.
passing a pointer to an opaque clockframe structure and requiring the
MD code to supply CLKF_FOO() macros to extract needed values out of the
opaque structure, just pass the needed values directly. In practice this
means passing the pair (usermode, pc) to hardclock() and profclock() and
passing the boolean (usermode) to hardclock_cpu() and hardclock_process().
Other details:
- Axe clockframe and CLKF_FOO() macros on all architectures. Basically,
all the archs were taking a trapframe and converting it into a clockframe
one way or another. Now they can just extract the PC and usermode values
directly out of the trapframe and pass it to fooclock().
- Renamed hardclock_process() to hardclock_cpu() as the latter is more
accurate.
- On Alpha, we now run profclock() at hz (profhz == hz) rather than at
the slower stathz.
- On Alpha, for the TurboLaser machines that don't have an 8254
timecounter, call hardclock() directly. This removes an extra
conditional check from every clock interrupt on Alpha on the BSP.
There is probably room for even further pruning here by changing Alpha
to use the simplified timecounter we use on x86 with the lapic timer
since we don't get interrupts from the 8254 on Alpha anyway.
- On x86, clkintr() shouldn't ever be called now unless using_lapic_timer
is false, so add a KASSERT() to that affect and remove a condition
to slightly optimize the non-lapic case.
- Change prototypeof arm_handler_execute() so that it's first arg is a
trapframe pointer rather than a void pointer for clarity.
- Use KCOUNT macro in profclock() to lookup the kernel profiling bucket.
Tested on: alpha, amd64, arm, i386, ia64, sparc64
Reviewed by: bde (mostly)
It only supports sa1110 (on simics) right now, but xscale support should come
soon.
Some of the initial work has been provided by :
Stephane Potvin <sepotvin at videotron.ca>
Most of this comes from NetBSD.
