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.
