Make most AST handlers dynamically registered. This allows to have
subsystem-specific handler source located in the subsystem files,
instead of making subr_trap.c aware of it. For instance, signal
delivery code on return to userspace is now moved to kern_sig.c.
Also, it allows to have some handlers designated as the cleanup (kclear)
type, which are called both at AST and on thread/process exit. For
instance, ast(), exit1(), and NFS server no longer need to be aware
about UFS softdep processing.
The dynamic registration also allows third-party modules to register AST
handlers if needed. There is one caveat with loadable modules: the
code does not make any effort to ensure that the module is not unloaded
before all threads processed through AST handler in it. In fact, this
is already present behavior for hwpmc.ko and ufs.ko. I do not think it
is worth the efforts and the runtime overhead to try to fix it.
Reviewed by: markj
Tested by: emaste (arm64), pho
Discussed with: jhb
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D35888
In r361544, the pmap drivers were converted to ifuncs. When doing so,
this changed the call type of pmap functions to be called via the
secure-plt stubs.
These stubs depend on the TOC base being loaded to r30 to run properly.
On SMP AIM (i.e. a dual processor G4 or running 32-bit on G5), since the
APs were being started up from the reset vector instead of going
through __start, they had never had r30 initialized properly, so when the
cpu_reset code in trap_subr32.S attempted to branch to
pmap_cpu_bootstrap(), it was loading the target from the wrong location.
Ensure r30 is set up directly in the cpu_reset trap code, so we can make
PLT calls as normal.
Fixes boot on my SMP G4.
Reviewed by: jhibbits
MFC after: 3 days
Sponsored by: Tag1 Consulting, Inc.
In this context, 0 actually means 0 (i.e. this is a li instruction).
While most assemblers will ignore this, I did have a compile failure at one
point when using an external toolchain.
In the future, we should use the li syntax to make this clearer.
Sponsored by: Tag1 Consulting, Inc.
In rS354701, I replaced text relocations with offsets from &generictrap.
Unfortunately, the magic variable I was using doesn't actually mean the
address of &generictrap, in bridge mode it actually means &generictrap64.
So, for bridge mode to work, it is necessary to differentiate between
"where do we need to branch to to handle a trap" and "where is &generictrap
for purposes of doing relative math".
Introduce a new TRAP_ENTRY and use it instead of TRAP_GENTRAP for doing
actual calls to the generic trap handler.
Reported by: Mark Millard <marklmi@yahoo.com>
Reviewed by: jhibbits
Sponsored by: Tag1 Consulting, Inc.
Differential Revision: https://reviews.freebsd.org/D23057
Fix wrong section ordering that was causing a ".got is not contiguous with
other relro sections" lld error. This also brings ldscript.powerpc and
ldscript.powerpcspe closer to ldscript.powerpc64.
Also, remove unnecessary text relocs from the ppc32 AIM trap code.
Approved by: jhibbits (mentor)
Differential Revision: https://reviews.freebsd.org/D22349
mtmsr and mtsr require context synchronizing instructions to follow. Without
a CSI, there's a chance for a machine check exception. This reportedly does
occur on a MPC750 (PowerMac G3).
Reported by: Mark Millard
Currently, the trap code switches to the the temporary stack in the dbtrap
section. It works in most cases, but in the beginning of the execution, the
temp stack is being used, as starting in the powerpc_init() code.
In this current scenario, the stack is being overwritten, which causes the
return of breakpoint() to take abnormal execution.
This current patchset create a small stack to use by the dbtrap: codepath
avoiding the corruption of the temporary stack.
PR: 224872
Submitted by: breno.leitao_gmail.com
Reviewed by: jhibbits
Differential Revision: https://reviews.freebsd.org/D14484
Clang apparently requires the explicit form of this instruction, and rejects
uses which ignore the optional cmpD register. This was the only use of the
shorthand form of the instruction, so just fix it up to match the others.
PR: kern/215681
Submitted by: Mark Millard
Reported by: Mark Millard <markmi _AT_ dsl-only.net>
MFC after: 2 weeks
executables. The goal here, not yet accomplished, is to let the e500 kernel
run under QEMU by setting KERNBASE to something that fits in low memory and
then having the kernel relocate itself at runtime.
A "size" symbol with its address set to the length of handler would be
shifted forward with all other addresses when relocations are processed.
Instead, just note the end and do the subtraction at runtime.
Summary:
Revert the initial FBT-with-KDB changes for trap_subr*.S, and instead use the
db_trap filter function to handle dtrace trap filtering. With this, the MMU is
enabled by the support code, simplifying the codepath altogether.
Test Plan: Tested on my G4 PowerBook
Reviewers: #powerpc, nwhitehorn
Reviewed By: nwhitehorn
Differential Revision: https://reviews.freebsd.org/D1207
MFC after: 3 weeks
containing the trap instruction encoding (0x7c810808), and restoring it back
with the frame on return. This caused it to panic on my ppc32 machine, but
somehow my ppc64 machine overlooked it, because I was using such a simple
dtrace probe.
X-MFC-with: r259245
MFC after: 2 weeks
much of which is not necessary for PowerPC.
The FBT module can likely be factored into 3 separate files: common,
intel, and powerpc, rather than duplicating most of the code between
the x86 and PowerPC flavors.
All DTrace modules for PowerPC will be MFC'd together once Fasttrap is
completed.
There is one known issue: Some probes will display an error message along the
lines of: "Invalid address (0)"
I tested this with both a simple dtrace probe and dtruss on a few different
binaries on 32-bit. I only compiled 64-bit, did not run it, but I don't expect
problems without the modules loaded. Volunteers are welcome.
MFC after: 1 month
Luckily, it mostly wasn't important, so this didn't cause major problems.
Also improve register reuse when setting up trap frames very slightly.
Submitted by: Justin Hibbits <chmeeedalf at gmail dot com>
MFC after: 5 days
instead of a PCPU field for curthread. This averts a race on SMP systems
with a high interrupt rate where the thread looking up the value of
curthread could be preempted and migrated between obtaining the PCPU
pointer and reading the value of pc_curthread, resulting in curthread being
observed to be the current thread on the thread's original CPU. This played
merry havoc with the system, in particular with mutexes. Many thanks to
jhb for helping me work this one out.
Note that Book-E is in principle susceptible to the same problem, but has
not been modified yet due to lack of Book-E hardware.
MFC after: 2 weeks
some interesting bugs (mostly on SMP systems) with atomic operations
silently failing in interrupt heavy situations, especially when using
overflow pages.
concurrency bug. Since all SLB/SR entries were invalidated during an
exception, a decrementer exception could cause the user segment to be
invalidated during a copyin()/copyout() without a thread switch that
would cause it to be restored from the PCB, potentially causing the
operation to continue on invalid memory. This is now handled by explicit
restoration of segment 12 from the PCB on 32-bit systems and a check in
the Data Segment Exception handler on 64-bit.
While here, cause copyin()/copyout() to check whether the requested
user segment is already installed, saving some pipeline flushes, and
fix the synchronization primitives around the mtsr and slbmte
instructions to prevent accessing stale segments.
MFC after: 2 weeks
Kernel sources for 64-bit PowerPC, along with build-system changes to keep
32-bit kernels compiling (build system changes for 64-bit kernels are
coming later). Existing 32-bit PowerPC kernel configurations must be
updated after this change to specify their architecture.
