instruction set. Thumb-2 requires an if-then instruction to implement
conditional codes.
When building for ARM mode the it-then instructions do not generate any
assembled instruction as per the ARMv7-A Architecture Reference Manual, and
are safe to use.
While this allows the atomic instructions to be built, it doesn't mean we
fully support Thumb code. It works in small tests, but is still known to
fail in a large number of places.
While here add a check for the armv6t2 architecture.
- We should check is_d32 to see howmany registers we have
- In vfp_restore mark vfpscr as an output register
Without the second part it appears we can return the incorrect value from
vfp_bounce if the VFP condition flags are set as it may override the
register holding the return value.
This follows section 18.4.2.2 SD Soft Reset Flow in the TI AM335x Technical
Reference Manual and seems to fix the "ti_mmchs0: Error: current cmd NULL,
already done?" messages.
Gcc outputs pre-UAL asm and expects the ldcl instruction with a condition
in the form ldc<c>l, where the code produces the instruction in the UAL
form ldcl<c>. Work around this by checking if we are using clang or gcc and
adjusting the instruction.
While here correct the cmp instruction's value to include the # before the
immediate value.
ePWM is controlled by sysctl nodes dev.am335x_pwm.N.period,
dev.am335x_pwm.N.dutyA and dev.am335x_pwm.N.dutyB that controls
PWM period and duty cycles for channels A and B respectively.
Period and duty cycle are measured in clock ticks. Default
clock frequency for AM335x PWM subsystem is 100MHz
pmap_remove_all()
This flag should already be cleared by pmap_nuke_pv()
Submitted by: Zbigniew Bodek <zbb@semihalf.com>
Sponsored by: The FreeBSD Foundation, Semihalf
When doing pmap_enter_locked(), enable write permission only when access
type indicates attempt to write. Otherwise, leave the page read only but
mark it writable in pv_flags.
This will result in:
1. Marking page writable during pmap_enter() but only when ensured that it
will be written right away so that we will not get redundant permissions
fault on write attempt.
2. Keeping page read only when it is permitted to be written but there was
no actual write attempt. Hence, we will get permissions fault on write
access and mark page writable in pmap_fault_fixup() what will indicate
modification status.
Submitted by: Zbigniew Bodek <zbb@semihalf.com>
Sponsored by: The FreeBSD Foundation, Semihalf
Force UMA zone to allocate service structures like slabs using own
allocator. uma_debug code performs atomic ops on uma_slab_t fields
and safety of this operation is not guaranteed for write-back caches
Issues were noted by Bruce Evans and are present on all architectures.
On i386, a counter fetch should use atomic read of 64bit value,
otherwise carry from the increment on other CPU could be lost for the
given fetch, making error of 2^32. If 64bit read (cmpxchg8b) is not
available on the machine, it cannot be SMP and it is enough to disable
preemption around read to avoid the split read.
On x86 the counter increment is not atomic on purpose, which makes it
possible for the store of the incremented result to override just
zeroed per-cpu slot. The effect would be a counter going off by
arbitrary value after zeroing. Perform the counter zeroing on the
same processor which does the increments, making the operations
mutually exclusive. On i386, same as for the fetching, if the
cmpxchg8b is not available, machine is not SMP and we disable
preemption for zeroing.
PowerPC64 is treated the same as amd64.
For other architectures, the changes made to allow the compilation to
succeed, without fixing the issues with zeroing or fetching. It
should be possible to handle them by using the 64bit loads and stores
atomic WRT preemption (assuming the architectures also converted from
using critical sections to proper asm). If architecture does not
provide the facility, using global (spin) mutex would be non-optimal
but working solution.
Noted by: bde
Sponsored by: The FreeBSD Foundation
- Initialize SMAPx registers too although they're unused in QEMU
- Do not pass IO/MEM resources to upper bus for activation, handle them locally.
Previously ACTIVATE method of upper bus was no-op so nothing bad
happened. But now FDT maps physaddr to vaddr and it causes
troubles: fdtbus_activate_resource resource assumes that
bustag/bushandle are already set which in this case is wrong.
past a trapframe.
Use this macro in exception_exit as it is the function the unwinder enters
as the functions that store the frame setting lr to point to it.
Provide both __sync_*-style and __atomic_*-style functions that perform
the atomic operations on ARMv5 by using Restartable Atomic Sequences.
While there, clean up some pieces of code where it's sufficient to use
regular uint32_t to store register contents and don't need full reg_t's.
Also sync this back to the MIPS code.
