mirrors
/
linux-stable
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
1
0
Fork 0
Code Issues Releases Wiki Activity
1,075,772 Commits 104 Branches 5,031 Tags 5.4 GiB
C 97.6%
Assembly 1%
Shell 0.5%
Python 0.3%
Makefile 0.3%
Go to file
Nicholas Piggin 1455294939 powerpc/64s/hash: Make hash faults work in NMI context 
[ Upstream commit 8b91cee5ea ]

Hash faults are not resoved in NMI context, instead causing the access
to fail. This is done because perf interrupts can get backtraces
including walking the user stack, and taking a hash fault on those could
deadlock on the HPTE lock if the perf interrupt hits while the same HPTE
lock is being held by the hash fault code. The user-access for the stack
walking will notice the access failed and deal with that in the perf
code.

The reason to allow perf interrupts in is to better profile hash faults.

The problem with this is any hash fault on a kernel access that happens
in NMI context will crash, because kernel accesses must not fail.

Hard lockups, system reset, machine checks that access vmalloc space
including modules and including stack backtracing and symbol lookup in
modules, per-cpu data, etc could all run into this problem.

Fix this by disallowing perf interrupts in the hash fault code (the
direct hash fault is covered by MSR[EE]=0 so the PMI disable just needs
to extend to the preload case). This simplifies the tricky logic in hash
faults and perf, at the cost of reduced profiling of hash faults.

perf can still latch addresses when interrupts are disabled, it just
won't get the stack trace at that point, so it would still find hot
spots, just sometimes with confusing stack chains.

An alternative could be to allow perf interrupts here but always do the
slowpath stack walk if we are in nmi context, but that slows down all
perf interrupt stack walking on hash though and it does not remove as
much tricky code.

Reported-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Tested-by: Laurent Dufour <ldufour@linux.ibm.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220204035348.545435-1-npiggin@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
 		2022-04-13 19:27:18 +02:00
Documentation KVM: arm64: Do not change the PMU event filter after a VCPU has run 2022-04-13 19:27:13 +02:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
arch powerpc/64s/hash: Make hash faults work in NMI context 2022-04-13 19:27:18 +02:00
block block: restore the old set_task_ioprio() behaviour wrt PF_EXITING 2022-04-08 13:58:57 +02:00
certs certs: Fix build error when CONFIG_MODULE_SIG_KEY is empty 2022-01-23 00:08:44 +09:00
crypto crypto: xts - Add softdep on ecb 2022-04-08 13:58:36 +02:00
drivers mt76: mt7915: fix injected MPDU transmission to not use HW A-MSDU 2022-04-13 19:27:18 +02:00
fs coredump: Use the vma snapshot in fill_files_note 2022-04-08 13:59:04 +02:00
include vfio/pci: Stub vfio_pci_vga_rw when !CONFIG_VFIO_PCI_VGA 2022-04-13 19:27:17 +02:00
init net: initialize init_net earlier 2022-04-13 19:27:12 +02:00
ipc ipc/sem: do not sleep with a spin lock held 2022-02-04 09:25:05 -08:00
kernel bpf: Adjust BPF stack helper functions to accommodate skip > 0 2022-04-08 13:59:00 +02:00
lib ref_tracker: implement use-after-free detection 2022-04-13 19:27:12 +02:00
mm mm: kfence: fix objcgs vector allocation 2022-04-13 19:27:07 +02:00
net mctp: make __mctp_dev_get() take a refcount hold 2022-04-13 19:27:18 +02:00
samples samples/bpf, xdpsock: Fix race when running for fix duration of time 2022-04-08 13:58:18 +02:00
scripts modpost: restore the warning message for missing symbol versions 2022-04-08 13:58:54 +02:00
security Fix incorrect type in assignment of ipv6 port for audit 2022-04-08 13:58:37 +02:00
sound ASoC: topology: Allow TLV control to be either read or write 2022-04-08 13:59:02 +02:00
tools libbpf: Fix accessing the first syscall argument on s390 2022-04-13 19:27:14 +02:00
usr kbuild: remove include/linux/cyclades.h from header file check 2022-01-27 08:51:08 +01:00
virt KVM: avoid double put_page with gfn-to-pfn cache 2022-04-08 13:58:52 +02:00
.clang-format genirq/msi: Make interrupt allocation less convoluted 2021-12-16 22:22:20 +01:00
.cocciconfig
…
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap MAINTAINERS: Update Jisheng's email address 2022-03-08 17:30:32 +01:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: replace a Microchip AT91 maintainer 2022-02-09 11:30:01 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS net: dsa: realtek-smi: move to subdirectory 2022-04-08 13:58:12 +02:00
Makefile Linux 5.17.2 2022-04-08 13:59:05 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.