powerpc/watchpoints: Disable preemption in thread_change_pc()

thread_change_pc() uses CPU local data, so must be protected from
swapping CPUs while it is reading the breakpoint struct.

The error is

powerpc/watchpoints: Disable preemption in thread_change_pc()

thread_change_pc() uses CPU local data, so must be protected from
swapping CPUs while it is reading the breakpoint struct.

The error is more noticeable after 1e60f3564bad ("powerpc/watchpoints:
Track perf single step directly on the breakpoint"), which added an
unconditional __this_cpu_read() call in thread_change_pc(). However the
existing __this_cpu_read() that runs if a breakpoint does need to be
re-inserted has the same issue.

Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230829063457.54157-2-bgray@linux.ibm.com

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Merge drm/drm-next into drm-intel-next

Sync to v6.6-rc1.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>

Merge drm/drm-fixes into drm-misc-fixes

Forwarding to v6.6-rc1.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>

Merge tag 'powerpc-6.6-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc updates from Michael Ellerman:

- Add HOTPLUG_SMT support (/sys/devices/system/cpu/smt) and hon

Merge tag 'powerpc-6.6-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc updates from Michael Ellerman:

- Add HOTPLUG_SMT support (/sys/devices/system/cpu/smt) and honour the
configured SMT state when hotplugging CPUs into the system

- Combine final TLB flush and lazy TLB mm shootdown IPIs when using the
Radix MMU to avoid a broadcast TLBIE flush on exit

- Drop the exclusion between ptrace/perf watchpoints, and drop the now
unused associated arch hooks

- Add support for the "nohlt" command line option to disable CPU idle

- Add support for -fpatchable-function-entry for ftrace, with GCC >=
13.1

- Rework memory block size determination, and support 256MB size on
systems with GPUs that have hotpluggable memory

- Various other small features and fixes

Thanks to Andrew Donnellan, Aneesh Kumar K.V, Arnd Bergmann, Athira
Rajeev, Benjamin Gray, Christophe Leroy, Frederic Barrat, Gautam
Menghani, Geoff Levand, Hari Bathini, Immad Mir, Jialin Zhang, Joel
Stanley, Jordan Niethe, Justin Stitt, Kajol Jain, Kees Cook, Krzysztof
Kozlowski, Laurent Dufour, Liang He, Linus Walleij, Mahesh Salgaonkar,
Masahiro Yamada, Michal Suchanek, Nageswara R Sastry, Nathan Chancellor,
Nathan Lynch, Naveen N Rao, Nicholas Piggin, Nick Desaulniers, Omar
Sandoval, Randy Dunlap, Reza Arbab, Rob Herring, Russell Currey, Sourabh
Jain, Thomas Gleixner, Trevor Woerner, Uwe Kleine-König, Vaibhav Jain,
Xiongfeng Wang, Yuan Tan, Zhang Rui, and Zheng Zengkai.

* tag 'powerpc-6.6-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (135 commits)
macintosh/ams: linux/platform_device.h is needed
powerpc/xmon: Reapply "Relax frame size for clang"
powerpc/mm/book3s64: Use 256M as the upper limit with coherent device memory attached
powerpc/mm/book3s64: Fix build error with SPARSEMEM disabled
powerpc/iommu: Fix notifiers being shared by PCI and VIO buses
powerpc/mpc5xxx: Add missing fwnode_handle_put()
powerpc/config: Disable SLAB_DEBUG_ON in skiroot
powerpc/pseries: Remove unused hcall tracing instruction
powerpc/pseries: Fix hcall tracepoints with JUMP_LABEL=n
powerpc: dts: add missing space before {
powerpc/eeh: Use pci_dev_id() to simplify the code
powerpc/64s: Move CPU -mtune options into Kconfig
powerpc/powermac: Fix unused function warning
powerpc/pseries: Rework lppaca_shared_proc() to avoid DEBUG_PREEMPT
powerpc: Don't include lppaca.h in paca.h
powerpc/pseries: Move hcall_vphn() prototype into vphn.h
powerpc/pseries: Move VPHN constants into vphn.h
cxl: Drop unused detach_spa()
powerpc: Drop zalloc_maybe_bootmem()
powerpc/powernv: Use struct opal_prd_msg in more places
...

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powerpc/watchpoints: Remove ptrace/perf exclusion tracking

ptrace and perf watchpoints were considered incompatible in
commit 29da4f91c0c1 ("powerpc/watchpoint: Don't allow concurrent perf
and ptrac

powerpc/watchpoints: Remove ptrace/perf exclusion tracking

ptrace and perf watchpoints were considered incompatible in
commit 29da4f91c0c1 ("powerpc/watchpoint: Don't allow concurrent perf
and ptrace events"), but the logic in that commit doesn't really apply.

Ptrace doesn't automatically single step; the ptracer must request this
explicitly. And the ptracer can do so regardless of whether a
ptrace/perf watchpoint triggered or not: it could single step every
instruction if it wanted to. Whatever stopped the ptracee before
executing the instruction that would trigger the perf watchpoint is no
longer relevant by this point.

To get correct behaviour when perf and ptrace are watching the same
data we must ignore the perf watchpoint. After all, ptrace has
before-execute semantics, and perf is after-execute, so perf doesn't
actually care about the watchpoint trigger at this point in time.
Pausing before execution does not mean we will actually end up executing
the instruction.

Importantly though, we don't remove the perf watchpoint yet. This is
key.

The ptracer is free to do whatever it likes right now. E.g., it can
continue the process, single step. or even set the child PC somewhere
completely different.

If it does try to execute the instruction though, without reinserting
the watchpoint (in which case we go back to the start of this example),
the perf watchpoint would immediately trigger. This time there is no
ptrace watchpoint, so we can safely perform a single step and increment
the perf counter. Upon receiving the single step exception, the existing
code already handles propagating or consuming it based on whether
another subsystem (e.g. ptrace) requested a single step. Again, this is
needed with or without perf/ptrace exclusion, because ptrace could be
single stepping this instruction regardless of if a watchpoint is
involved.

Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230801011744.153973-6-bgray@linux.ibm.com

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powerpc/watchpoints: Simplify watchpoint reinsertion

We only remove watchpoints when they have the perf_single_step flag set,
so we can reinsert them during the first iteration.

Signed-off-by: Benj

powerpc/watchpoints: Simplify watchpoint reinsertion

We only remove watchpoints when they have the perf_single_step flag set,
so we can reinsert them during the first iteration.

Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230801011744.153973-5-bgray@linux.ibm.com

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powerpc/watchpoints: Track perf single step directly on the breakpoint

There is a bug in the current watchpoint tracking logic, where the
teardown in arch_unregister_hw_breakpoint() uses bp->ctx->ta

powerpc/watchpoints: Track perf single step directly on the breakpoint

There is a bug in the current watchpoint tracking logic, where the
teardown in arch_unregister_hw_breakpoint() uses bp->ctx->task, which it
does not have a reference of and parallel threads may be in the process
of destroying. This was partially addressed in commit fb822e6076d9
("powerpc/hw_breakpoint: Fix oops when destroying hw_breakpoint event"),
but the underlying issue of accessing a struct member in an unknown
state still remained. Syzkaller managed to trigger a null pointer
derefernce due to the race between the task destructor and checking the
pointer and dereferencing it in the loop.

While this null pointer dereference could be fixed by using READ_ONCE
to access the task up front, that just changes the error to manipulating
possbily freed memory.

Instead, the breakpoint logic needs to be reworked to remove any
dependency on a context or task struct during breakpoint removal.

The reason we have this currently is to clear thread.last_hit_ubp. This
member is used to differentiate the perf DAWR single-step sequence from
other causes of single-step, such as userspace just calling
ptrace(PTRACE_SINGLESTEP, ...). We need to differentiate them because,
when the single step interrupt is received, we need to know whether to
re-insert the DAWR breakpoint (perf) or not (ptrace / other).

arch_unregister_hw_breakpoint() needs to clear this information to
prevent dangling pointers to possibly freed memory. These pointers are
dereferenced in single_step_dabr_instruction() without a way to check
their validity.

This patch moves the tracking of this information to the breakpoint
itself. This means we no longer have to do anything special to clean up.

Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230801011744.153973-4-bgray@linux.ibm.com

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powerpc/watchpoints: Don't track info persistently

info is cheap to retrieve, and is likely optimised by the compiler
anyway. On the other hand, propagating it across the functions makes it
possible

powerpc/watchpoints: Don't track info persistently

info is cheap to retrieve, and is likely optimised by the compiler
anyway. On the other hand, propagating it across the functions makes it
possible to be inconsistent and adds needless complexity.

Remove it, and invoke counter_arch_bp() when we need to work with it.

As we don't persist it, we just use the local bp array to track whether
we are ignoring a breakpoint.

Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230801011744.153973-3-bgray@linux.ibm.com

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powerpc/watchpoints: Explain thread_change_pc() more

The behaviour of the thread_change_pc() function is a bit cryptic
without being more familiar with how the watchpoint logic handles
perf's after-

powerpc/watchpoints: Explain thread_change_pc() more

The behaviour of the thread_change_pc() function is a bit cryptic
without being more familiar with how the watchpoint logic handles
perf's after-execute semantics.

Expand the comment to explain why we can re-insert the breakpoint and
unset the perf_single_step flag.

Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230801011744.153973-2-bgray@linux.ibm.com

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Merge branch 'next' into for-linus

Prepare input updates for 6.3 merge window.

Merge drm/drm-next into drm-misc-next

Backmerging into drm-misc-next to get DRM accelerator infrastructure,
which is required by ipuv driver.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>

Merge tag 'v6.2-rc3' into next

Merge with mainline to bring in timer_shutdown_sync() API.

Merge drm/drm-next into drm-intel-next

Sync up with v6.2-rc1.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>

Merge drm/drm-next into drm-intel-gt-next

Sync after v6.2-rc1 landed in drm-next.

We need to get some dependencies in place before we can merge
the fixes series from Gwan-gyeong and Chris.

Referen

Merge drm/drm-next into drm-intel-gt-next

Sync after v6.2-rc1 landed in drm-next.

We need to get some dependencies in place before we can merge
the fixes series from Gwan-gyeong and Chris.

References: https://lore.kernel.org/all/Y6x5JCDnh2rvh4lA@intel.com/
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

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Merge tag 'v6.2-rc1' into media_tree

Linux 6.2-rc1

* tag 'v6.2-rc1': (14398 commits)
Linux 6.2-rc1
treewide: Convert del_timer*() to timer_shutdown*()
pstore: Properly assign mem_type propert

Merge tag 'v6.2-rc1' into media_tree

Linux 6.2-rc1

* tag 'v6.2-rc1': (14398 commits)
Linux 6.2-rc1
treewide: Convert del_timer*() to timer_shutdown*()
pstore: Properly assign mem_type property
pstore: Make sure CONFIG_PSTORE_PMSG selects CONFIG_RT_MUTEXES
cfi: Fix CFI failure with KASAN
perf python: Fix splitting CC into compiler and options
afs: Stop implementing ->writepage()
afs: remove afs_cache_netfs and afs_zap_permits() declarations
afs: remove variable nr_servers
afs: Fix lost servers_outstanding count
ALSA: usb-audio: Add new quirk FIXED_RATE for JBL Quantum810 Wireless
ALSA: azt3328: Remove the unused function snd_azf3328_codec_outl()
gcov: add support for checksum field
test_maple_tree: add test for mas_spanning_rebalance() on insufficient data
maple_tree: fix mas_spanning_rebalance() on insufficient data
hugetlb: really allocate vma lock for all sharable vmas
kmsan: export kmsan_handle_urb
kmsan: include linux/vmalloc.h
mm/mempolicy: fix memory leak in set_mempolicy_home_node system call
mm, mremap: fix mremap() expanding vma with addr inside vma
...

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Merge branch 'master' into mm-nonmm-stable

Merge branch 'master' into mm-stable

Merge wireless into wireless-next

Due to the two cherry picked commits from wireless to wireless-next we have
several conflicts in mt76. To avoid any bugs with conflicts merge wireless into
wireless

Merge wireless into wireless-next

Due to the two cherry picked commits from wireless to wireless-next we have
several conflicts in mt76. To avoid any bugs with conflicts merge wireless into
wireless-next.

96f134dc1964 wifi: mt76: handle possible mt76_rx_token_consume failures
fe13dad8992b wifi: mt76: dma: do not increment queue head if mt76_dma_add_buf fails

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Merge drm/drm-fixes into drm-misc-fixes

Let's start the fixes cycle.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

No conflicts.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Merge branch 'linus'

Merge remote-tracking branch 'torvalds/master' into perf/core

To pick up fixes.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Merge tag 'powerpc-6.2-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc updates from Michael Ellerman:

- Add powerpc qspinlock implementation optimised for large syst

Merge tag 'powerpc-6.2-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc updates from Michael Ellerman:

- Add powerpc qspinlock implementation optimised for large system
scalability and paravirt. See the merge message for more details

- Enable objtool to be built on powerpc to generate mcount locations

- Use a temporary mm for code patching with the Radix MMU, so the
writable mapping is restricted to the patching CPU

- Add an option to build the 64-bit big-endian kernel with the ELFv2
ABI

- Sanitise user registers on interrupt entry on 64-bit Book3S

- Many other small features and fixes

Thanks to Aboorva Devarajan, Angel Iglesias, Benjamin Gray, Bjorn
Helgaas, Bo Liu, Chen Lifu, Christoph Hellwig, Christophe JAILLET,
Christophe Leroy, Christopher M. Riedl, Colin Ian King, Deming Wang,
Disha Goel, Dmitry Torokhov, Finn Thain, Geert Uytterhoeven, Gustavo A.
R. Silva, Haowen Bai, Joel Stanley, Jordan Niethe, Julia Lawall, Kajol
Jain, Laurent Dufour, Li zeming, Miaoqian Lin, Michael Jeanson, Nathan
Lynch, Naveen N. Rao, Nayna Jain, Nicholas Miehlbradt, Nicholas Piggin,
Pali Rohár, Randy Dunlap, Rohan McLure, Russell Currey, Sathvika
Vasireddy, Shaomin Deng, Stephen Kitt, Stephen Rothwell, Thomas
Weißschuh, Tiezhu Yang, Uwe Kleine-König, Xie Shaowen, Xiu Jianfeng,
XueBing Chen, Yang Yingliang, Zhang Jiaming, ruanjinjie, Jessica Yu,
and Wolfram Sang.

* tag 'powerpc-6.2-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (181 commits)
powerpc/code-patching: Fix oops with DEBUG_VM enabled
powerpc/qspinlock: Fix 32-bit build
powerpc/prom: Fix 32-bit build
powerpc/rtas: mandate RTAS syscall filtering
powerpc/rtas: define pr_fmt and convert printk call sites
powerpc/rtas: clean up includes
powerpc/rtas: clean up rtas_error_log_max initialization
powerpc/pseries/eeh: use correct API for error log size
powerpc/rtas: avoid scheduling in rtas_os_term()
powerpc/rtas: avoid device tree lookups in rtas_os_term()
powerpc/rtasd: use correct OF API for event scan rate
powerpc/rtas: document rtas_call()
powerpc/pseries: unregister VPA when hot unplugging a CPU
powerpc/pseries: reset the RCU watchdogs after a LPM
powerpc: Take in account addition CPU node when building kexec FDT
powerpc: export the CPU node count
powerpc/cpuidle: Set CPUIDLE_FLAG_POLLING for snooze state
powerpc/dts/fsl: Fix pca954x i2c-mux node names
cxl: Remove unnecessary cxl_pci_window_alignment()
selftests/powerpc: Fix resource leaks
...

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Merge branch 'main' into zstd-linus

Merge branch 'for-6.2/apple' into for-linus

- new quirks for select Apple keyboards (Kerem Karabay, Aditya Garg)