freebsd with flexible iflib nic queues
d7f827116f
to userland with interrupts disabled until we restore PSR. However, it has been observed that interrupts do actually happen before they are enabled again. This is a bit surprising and I don't know yet what's going on exactly. Nevertheless, the code was not crafted carefully enough to allow interrupts to happen and we could clobber the kernel stack of another thread when interrupts did happen. This is what happens: we restore the (memory) stack pointer (sp) and the register stack base prior to restoring ar.k6 and ar.k7. This is not a problem if interrupts don't happen between setting sp/ar.bspstore and ar.k6/ar.k7. Alas, interrupts can happen. Since sp/ar.bspstore already point to the userland stacks, we need to switch to the kernel stack in interrupt. However, ar.k6 and ar.k7 have not been set, which means that we were switching to some unrelated kstack and happily clobbered the trapframe present there if the thread to which the kstack belonged was in kernel mode or otherwise we could have our trapframe clobbered if that other thread enters the kernel. Nasty either way. We now carefully restore ar.k6 prior to restoring ar.bspstore and likewise for ar.k7 and sp. All we need is the guarantee that an interrupt does not clobber ar.k6 or ar.k7 before we're back in userland. That has been achieved by restoring ar.k6/ar.k7 unconditionally (see exception.s) While here, remove the disabling of interrupts on EPC entry. It was added as a way to "resolve" the crashes until it was understood what was going on. I think I achieved the latter, so we can remove the patch. Note that setting up a trapframe with interrupts enabled has it's own share of corner cases, but it's better to properly fixed those than to keep a mostly wrong patch around because we're afraid to remove it... Approved by: re@ (blanket) |
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| contrib | ||
| crypto | ||
| etc | ||
| games | ||
| gnu | ||
| include | ||
| kerberos5 | ||
| lib | ||
| libexec | ||
| release | ||
| sbin | ||
| secure | ||
| share | ||
| sys | ||
| tools | ||
| usr.bin | ||
| usr.sbin | ||
| COPYRIGHT | ||
| MAINTAINERS | ||
| Makefile | ||
| Makefile.inc1 | ||
| README | ||
| UPDATING | ||
This is the top level of the FreeBSD source directory. This file was last revised on: $FreeBSD$ For copyright information, please see the file COPYRIGHT in this directory (additional copyright information also exists for some sources in this tree - please see the specific source directories for more information). The Makefile in this directory supports a number of targets for building components (or all) of the FreeBSD source tree, the most commonly used one being ``world'', which rebuilds and installs everything in the FreeBSD system from the source tree except the kernel, the kernel-modules and the contents of /etc. The ``buildkernel'' and ``installkernel'' targets build and install the kernel and the modules (see below). Please see the top of the Makefile in this directory for more information on the standard build targets and compile-time flags. Building a kernel is a somewhat more involved process, documentation for which can be found at: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html And in the config(8) man page. Note: If you want to build and install the kernel with the ``buildkernel'' and ``installkernel'' targets, you might need to build world before. More information is available in the handbook. The sample kernel configuration files reside in the sys/<arch>/conf sub-directory (assuming that you've installed the kernel sources), the file named GENERIC being the one used to build your initial installation kernel. The file NOTES contains entries and documentation for all possible devices, not just those commonly used. It is the successor of the ancient LINT file, but in contrast to LINT, it is not buildable as a kernel but a pure reference and documentation file. Source Roadmap: --------------- bin System/user commands. contrib Packages contributed by 3rd parties. crypto Cryptography stuff (see crypto/README). etc Template files for /etc. games Amusements. gnu Various commands and libraries under the GNU Public License. Please see gnu/COPYING* for more information. include System include files. kerberos5 Kerberos5 (Heimdal) package. lib System libraries. libexec System daemons. release Release building Makefile & associated tools. sbin System commands. secure Cryptographic libraries and commands. share Shared resources. sys Kernel sources. tools Utilities for regression testing and miscellaneous tasks. usr.bin User commands. usr.sbin System administration commands. For information on synchronizing your source tree with one or more of the FreeBSD Project's development branches, please see: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/synching.html