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

Forwarding to v6.6-rc1.

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

Merge tag 'mm-stable-2023-08-28-18-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:

- Some swap cleanups from Ma Wupeng ("fix WARN_ON in
add_to_a

Merge tag 'mm-stable-2023-08-28-18-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:

- Some swap cleanups from Ma Wupeng ("fix WARN_ON in
add_to_avail_list")

- Peter Xu has a series (mm/gup: Unify hugetlb, speed up thp") which
reduces the special-case code for handling hugetlb pages in GUP. It
also speeds up GUP handling of transparent hugepages.

- Peng Zhang provides some maple tree speedups ("Optimize the fast path
of mas_store()").

- Sergey Senozhatsky has improved te performance of zsmalloc during
compaction (zsmalloc: small compaction improvements").

- Domenico Cerasuolo has developed additional selftest code for zswap
("selftests: cgroup: add zswap test program").

- xu xin has doe some work on KSM's handling of zero pages. These
changes are mainly to enable the user to better understand the
effectiveness of KSM's treatment of zero pages ("ksm: support
tracking KSM-placed zero-pages").

- Jeff Xu has fixes the behaviour of memfd's
MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED sysctl ("mm/memfd: fix sysctl
MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED").

- David Howells has fixed an fscache optimization ("mm, netfs, fscache:
Stop read optimisation when folio removed from pagecache").

- Axel Rasmussen has given userfaultfd the ability to simulate memory
poisoning ("add UFFDIO_POISON to simulate memory poisoning with
UFFD").

- Miaohe Lin has contributed some routine maintenance work on the
memory-failure code ("mm: memory-failure: remove unneeded PageHuge()
check").

- Peng Zhang has contributed some maintenance work on the maple tree
code ("Improve the validation for maple tree and some cleanup").

- Hugh Dickins has optimized the collapsing of shmem or file pages into
THPs ("mm: free retracted page table by RCU").

- Jiaqi Yan has a patch series which permits us to use the healthy
subpages within a hardware poisoned huge page for general purposes
("Improve hugetlbfs read on HWPOISON hugepages").

- Kemeng Shi has done some maintenance work on the pagetable-check code
("Remove unused parameters in page_table_check").

- More folioification work from Matthew Wilcox ("More filesystem folio
conversions for 6.6"), ("Followup folio conversions for zswap"). And
from ZhangPeng ("Convert several functions in page_io.c to use a
folio").

- page_ext cleanups from Kemeng Shi ("minor cleanups for page_ext").

- Baoquan He has converted some architectures to use the
GENERIC_IOREMAP ioremap()/iounmap() code ("mm: ioremap: Convert
architectures to take GENERIC_IOREMAP way").

- Anshuman Khandual has optimized arm64 tlb shootdown ("arm64: support
batched/deferred tlb shootdown during page reclamation/migration").

- Better maple tree lockdep checking from Liam Howlett ("More strict
maple tree lockdep"). Liam also developed some efficiency
improvements ("Reduce preallocations for maple tree").

- Cleanup and optimization to the secondary IOMMU TLB invalidation,
from Alistair Popple ("Invalidate secondary IOMMU TLB on permission
upgrade").

- Ryan Roberts fixes some arm64 MM selftest issues ("selftests/mm fixes
for arm64").

- Kemeng Shi provides some maintenance work on the compaction code
("Two minor cleanups for compaction").

- Some reduction in mmap_lock pressure from Matthew Wilcox ("Handle
most file-backed faults under the VMA lock").

- Aneesh Kumar contributes code to use the vmemmap optimization for DAX
on ppc64, under some circumstances ("Add support for DAX vmemmap
optimization for ppc64").

- page-ext cleanups from Kemeng Shi ("add page_ext_data to get client
data in page_ext"), ("minor cleanups to page_ext header").

- Some zswap cleanups from Johannes Weiner ("mm: zswap: three
cleanups").

- kmsan cleanups from ZhangPeng ("minor cleanups for kmsan").

- VMA handling cleanups from Kefeng Wang ("mm: convert to
vma_is_initial_heap/stack()").

- DAMON feature work from SeongJae Park ("mm/damon/sysfs-schemes:
implement DAMOS tried total bytes file"), ("Extend DAMOS filters for
address ranges and DAMON monitoring targets").

- Compaction work from Kemeng Shi ("Fixes and cleanups to compaction").

- Liam Howlett has improved the maple tree node replacement code
("maple_tree: Change replacement strategy").

- ZhangPeng has a general code cleanup - use the K() macro more widely
("cleanup with helper macro K()").

- Aneesh Kumar brings memmap-on-memory to ppc64 ("Add support for
memmap on memory feature on ppc64").

- pagealloc cleanups from Kemeng Shi ("Two minor cleanups for pcp list
in page_alloc"), ("Two minor cleanups for get pageblock
migratetype").

- Vishal Moola introduces a memory descriptor for page table tracking,
"struct ptdesc" ("Split ptdesc from struct page").

- memfd selftest maintenance work from Aleksa Sarai ("memfd: cleanups
for vm.memfd_noexec").

- MM include file rationalization from Hugh Dickins ("arch: include
asm/cacheflush.h in asm/hugetlb.h").

- THP debug output fixes from Hugh Dickins ("mm,thp: fix sloppy text
output").

- kmemleak improvements from Xiaolei Wang ("mm/kmemleak: use
object_cache instead of kmemleak_initialized").

- More folio-related cleanups from Matthew Wilcox ("Remove _folio_dtor
and _folio_order").

- A VMA locking scalability improvement from Suren Baghdasaryan
("Per-VMA lock support for swap and userfaults").

- pagetable handling cleanups from Matthew Wilcox ("New page table
range API").

- A batch of swap/thp cleanups from David Hildenbrand ("mm/swap: stop
using page->private on tail pages for THP_SWAP + cleanups").

- Cleanups and speedups to the hugetlb fault handling from Matthew
Wilcox ("Change calling convention for ->huge_fault").

- Matthew Wilcox has also done some maintenance work on the MM
subsystem documentation ("Improve mm documentation").

* tag 'mm-stable-2023-08-28-18-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (489 commits)
maple_tree: shrink struct maple_tree
maple_tree: clean up mas_wr_append()
secretmem: convert page_is_secretmem() to folio_is_secretmem()
nios2: fix flush_dcache_page() for usage from irq context
hugetlb: add documentation for vma_kernel_pagesize()
mm: add orphaned kernel-doc to the rst files.
mm: fix clean_record_shared_mapping_range kernel-doc
mm: fix get_mctgt_type() kernel-doc
mm: fix kernel-doc warning from tlb_flush_rmaps()
mm: remove enum page_entry_size
mm: allow ->huge_fault() to be called without the mmap_lock held
mm: move PMD_ORDER to pgtable.h
mm: remove checks for pte_index
memcg: remove duplication detection for mem_cgroup_uncharge_swap
mm/huge_memory: work on folio->swap instead of page->private when splitting folio
mm/swap: inline folio_set_swap_entry() and folio_swap_entry()
mm/swap: use dedicated entry for swap in folio
mm/swap: stop using page->private on tail pages for THP_SWAP
selftests/mm: fix WARNING comparing pointer to 0
selftests: cgroup: fix test_kmem_memcg_deletion kernel mem check
...

show more ...

minmax: add in_range() macro

Patch series "New page table range API", v6.

This patchset changes the API used by the MM to set up page table entries.
The four APIs are:

set_ptes(mm, addr, ptep,

minmax: add in_range() macro

Patch series "New page table range API", v6.

This patchset changes the API used by the MM to set up page table entries.
The four APIs are:

set_ptes(mm, addr, ptep, pte, nr)
update_mmu_cache_range(vma, addr, ptep, nr)
flush_dcache_folio(folio)
flush_icache_pages(vma, page, nr)

flush_dcache_folio() isn't technically new, but no architecture
implemented it, so I've done that for them. The old APIs remain around
but are mostly implemented by calling the new interfaces.

The new APIs are based around setting up N page table entries at once.
The N entries belong to the same PMD, the same folio and the same VMA, so
ptep++ is a legitimate operation, and locking is taken care of for you.
Some architectures can do a better job of it than just a loop, but I have
hesitated to make too deep a change to architectures I don't understand
well.

One thing I have changed in every architecture is that PG_arch_1 is now a
per-folio bit instead of a per-page bit when used for dcache clean/dirty
tracking. This was something that would have to happen eventually, and it
makes sense to do it now rather than iterate over every page involved in a
cache flush and figure out if it needs to happen.

The point of all this is better performance, and Fengwei Yin has measured
improvement on x86. I suspect you'll see improvement on your architecture
too. Try the new will-it-scale test mentioned here:
https://lore.kernel.org/linux-mm/20230206140639.538867-5-fengwei.yin@intel.com/
You'll need to run it on an XFS filesystem and have
CONFIG_TRANSPARENT_HUGEPAGE set.

This patchset is the basis for much of the anonymous large folio work
being done by Ryan, so it's received quite a lot of testing over the last
few months.


This patch (of 38):

Determine if a value lies within a range more efficiently (subtraction +
comparison vs two comparisons and an AND). It also has useful (under some
circumstances) behaviour if the range exceeds the maximum value of the
type. Convert all the conflicting definitions of in_range() within the
kernel; some can use the generic definition while others need their own
definition.

Link: https://lkml.kernel.org/r/20230802151406.3735276-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20230802151406.3735276-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

show more ...

Merge tag 'v5.18'

Linux 5.18

Merge tag 'v5.17-rc4' into for-linus

Merge with mainline to get the Intel ASoC generic helpers header and
other changes.

Merge tag 'v5.16' into next

Sync up with mainline to bring in the latest API changes.

Merge branch 'for-next' into for-linus

Pull 5.17 materials.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

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

Backmerging to bring drm-misc-next-fixes up to the latest state for
the current release cycle.

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

Merge branch 'reset/of-get-optional-exclusive' of git://git.pengutronix.de/pza/linux into timers/drivers/next

"Add optional variant of of_reset_control_get_exclusive(). If the
requested reset is not

Merge branch 'reset/of-get-optional-exclusive' of git://git.pengutronix.de/pza/linux into timers/drivers/next

"Add optional variant of of_reset_control_get_exclusive(). If the
requested reset is not specified in the device tree, this function
returns NULL instead of an error."

This dependency is needed for the Generic Timer Module (a.k.a OSTM)
support for RZ/G2L.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

show more ...

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

Sync up with drm-next to get v5.16-rc2.

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

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

Thomas needs the dma_resv_for_each_fence API for i915/ttm async migration
work.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

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

Backmerging from drm/drm-next for v5.16-rc1.

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

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

We need -rc1 to address a breakage in drm/scheduler affecting panfrost.

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

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

To pick up some tools/perf/ patches that went via tip/perf/core, such
as:

tools/perf: Add mem_hops field in perf_mem_data_src structu

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

To pick up some tools/perf/ patches that went via tip/perf/core, such
as:

tools/perf: Add mem_hops field in perf_mem_data_src structure

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

show more ...

Merge tag 'net-next-for-5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next

Pull networking updates from Jakub Kicinski:
"Core:

- Remove socket skb caches

- Add a SO_RESE

Merge tag 'net-next-for-5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next

Pull networking updates from Jakub Kicinski:
"Core:

- Remove socket skb caches

- Add a SO_RESERVE_MEM socket op to forward allocate buffer space and
avoid memory accounting overhead on each message sent

- Introduce managed neighbor entries - added by control plane and
resolved by the kernel for use in acceleration paths (BPF / XDP
right now, HW offload users will benefit as well)

- Make neighbor eviction on link down controllable by userspace to
work around WiFi networks with bad roaming implementations

- vrf: Rework interaction with netfilter/conntrack

- fq_codel: implement L4S style ce_threshold_ect1 marking

- sch: Eliminate unnecessary RCU waits in mini_qdisc_pair_swap()

BPF:

- Add support for new btf kind BTF_KIND_TAG, arbitrary type tagging
as implemented in LLVM14

- Introduce bpf_get_branch_snapshot() to capture Last Branch Records

- Implement variadic trace_printk helper

- Add a new Bloomfilter map type

- Track <8-byte scalar spill and refill

- Access hw timestamp through BPF's __sk_buff

- Disallow unprivileged BPF by default

- Document BPF licensing

Netfilter:

- Introduce egress hook for looking at raw outgoing packets

- Allow matching on and modifying inner headers / payload data

- Add NFT_META_IFTYPE to match on the interface type either from
ingress or egress

Protocols:

- Multi-Path TCP:
- increase default max additional subflows to 2
- rework forward memory allocation
- add getsockopts: MPTCP_INFO, MPTCP_TCPINFO, MPTCP_SUBFLOW_ADDRS

- MCTP flow support allowing lower layer drivers to configure msg
muxing as needed

- Automatic Multicast Tunneling (AMT) driver based on RFC7450

- HSR support the redbox supervision frames (IEC-62439-3:2018)

- Support for the ip6ip6 encapsulation of IOAM

- Netlink interface for CAN-FD's Transmitter Delay Compensation

- Support SMC-Rv2 eliminating the current same-subnet restriction, by
exploiting the UDP encapsulation feature of RoCE adapters

- TLS: add SM4 GCM/CCM crypto support

- Bluetooth: initial support for link quality and audio/codec offload

Driver APIs:

- Add a batched interface for RX buffer allocation in AF_XDP buffer
pool

- ethtool: Add ability to control transceiver modules' power mode

- phy: Introduce supported interfaces bitmap to express MAC
capabilities and simplify PHY code

- Drop rtnl_lock from DSA .port_fdb_{add,del} callbacks

New drivers:

- WiFi driver for Realtek 8852AE 802.11ax devices (rtw89)

- Ethernet driver for ASIX AX88796C SPI device (x88796c)

Drivers:

- Broadcom PHYs
- support 72165, 7712 16nm PHYs
- support IDDQ-SR for additional power savings

- PHY support for QCA8081, QCA9561 PHYs

- NXP DPAA2: support for IRQ coalescing

- NXP Ethernet (enetc): support for software TCP segmentation

- Renesas Ethernet (ravb) - support DMAC and EMAC blocks of
Gigabit-capable IP found on RZ/G2L SoC

- Intel 100G Ethernet
- support for eswitch offload of TC/OvS flow API, including
offload of GRE, VxLAN, Geneve tunneling
- support application device queues - ability to assign Rx and Tx
queues to application threads
- PTP and PPS (pulse-per-second) extensions

- Broadcom Ethernet (bnxt)
- devlink health reporting and device reload extensions

- Mellanox Ethernet (mlx5)
- offload macvlan interfaces
- support HW offload of TC rules involving OVS internal ports
- support HW-GRO and header/data split
- support application device queues

- Marvell OcteonTx2:
- add XDP support for PF
- add PTP support for VF

- Qualcomm Ethernet switch (qca8k): support for QCA8328

- Realtek Ethernet DSA switch (rtl8366rb)
- support bridge offload
- support STP, fast aging, disabling address learning
- support for Realtek RTL8365MB-VC, a 4+1 port 10M/100M/1GE switch

- Mellanox Ethernet/IB switch (mlxsw)
- multi-level qdisc hierarchy offload (e.g. RED, prio and shaping)
- offload root TBF qdisc as port shaper
- support multiple routing interface MAC address prefixes
- support for IP-in-IP with IPv6 underlay

- MediaTek WiFi (mt76)
- mt7921 - ASPM, 6GHz, SDIO and testmode support
- mt7915 - LED and TWT support

- Qualcomm WiFi (ath11k)
- include channel rx and tx time in survey dump statistics
- support for 80P80 and 160 MHz bandwidths
- support channel 2 in 6 GHz band
- spectral scan support for QCN9074
- support for rx decapsulation offload (data frames in 802.3
format)

- Qualcomm phone SoC WiFi (wcn36xx)
- enable Idle Mode Power Save (IMPS) to reduce power consumption
during idle

- Bluetooth driver support for MediaTek MT7922 and MT7921

- Enable support for AOSP Bluetooth extension in Qualcomm WCN399x and
Realtek 8822C/8852A

- Microsoft vNIC driver (mana)
- support hibernation and kexec

- Google vNIC driver (gve)
- support for jumbo frames
- implement Rx page reuse

Refactor:

- Make all writes to netdev->dev_addr go thru helpers, so that we can
add this address to the address rbtree and handle the updates

- Various TCP cleanups and optimizations including improvements to
CPU cache use

- Simplify the gnet_stats, Qdisc stats' handling and remove
qdisc->running sequence counter

- Driver changes and API updates to address devlink locking
deficiencies"

* tag 'net-next-for-5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2122 commits)
Revert "net: avoid double accounting for pure zerocopy skbs"
selftests: net: add arp_ndisc_evict_nocarrier
net: ndisc: introduce ndisc_evict_nocarrier sysctl parameter
net: arp: introduce arp_evict_nocarrier sysctl parameter
libbpf: Deprecate AF_XDP support
kbuild: Unify options for BTF generation for vmlinux and modules
selftests/bpf: Add a testcase for 64-bit bounds propagation issue.
bpf: Fix propagation of signed bounds from 64-bit min/max into 32-bit.
bpf: Fix propagation of bounds from 64-bit min/max into 32-bit and var_off.
net: vmxnet3: remove multiple false checks in vmxnet3_ethtool.c
net: avoid double accounting for pure zerocopy skbs
tcp: rename sk_wmem_free_skb
netdevsim: fix uninit value in nsim_drv_configure_vfs()
selftests/bpf: Fix also no-alu32 strobemeta selftest
bpf: Add missing map_delete_elem method to bloom filter map
selftests/bpf: Add bloom map success test for userspace calls
bpf: Add alignment padding for "map_extra" + consolidate holes
bpf: Bloom filter map naming fixups
selftests/bpf: Add test cases for struct_ops prog
bpf: Add dummy BPF STRUCT_OPS for test purpose
...

show more ...

Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

Alexei Starovoitov says:

====================
pull-request: bpf-next 2021-09-17

We've added 63 non-merge commits during the last

Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

Alexei Starovoitov says:

====================
pull-request: bpf-next 2021-09-17

We've added 63 non-merge commits during the last 12 day(s) which contain
a total of 65 files changed, 2653 insertions(+), 751 deletions(-).

The main changes are:

1) Streamline internal BPF program sections handling and
bpf_program__set_attach_target() in libbpf, from Andrii.

2) Add support for new btf kind BTF_KIND_TAG, from Yonghong.

3) Introduce bpf_get_branch_snapshot() to capture LBR, from Song.

4) IMUL optimization for x86-64 JIT, from Jie.

5) xsk selftest improvements, from Magnus.

6) Introduce legacy kprobe events support in libbpf, from Rafael.

7) Access hw timestamp through BPF's __sk_buff, from Vadim.

* https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (63 commits)
selftests/bpf: Fix a few compiler warnings
libbpf: Constify all high-level program attach APIs
libbpf: Schedule open_opts.attach_prog_fd deprecation since v0.7
selftests/bpf: Switch fexit_bpf2bpf selftest to set_attach_target() API
libbpf: Allow skipping attach_func_name in bpf_program__set_attach_target()
libbpf: Deprecated bpf_object_open_opts.relaxed_core_relocs
selftests/bpf: Stop using relaxed_core_relocs which has no effect
libbpf: Use pre-setup sec_def in libbpf_find_attach_btf_id()
bpf: Update bpf_get_smp_processor_id() documentation
libbpf: Add sphinx code documentation comments
selftests/bpf: Skip btf_tag test if btf_tag attribute not supported
docs/bpf: Add documentation for BTF_KIND_TAG
selftests/bpf: Add a test with a bpf program with btf_tag attributes
selftests/bpf: Test BTF_KIND_TAG for deduplication
selftests/bpf: Add BTF_KIND_TAG unit tests
selftests/bpf: Change NAME_NTH/IS_NAME_NTH for BTF_KIND_TAG format
selftests/bpf: Test libbpf API function btf__add_tag()
bpftool: Add support for BTF_KIND_TAG
libbpf: Add support for BTF_KIND_TAG
libbpf: Rename btf_{hash,equal}_int to btf_{hash,equal}_int_tag
...
====================

Link: https://lore.kernel.org/r/20210917173738.3397064-1-ast@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

show more ...

Merge branch 'bpf: introduce bpf_get_branch_snapshot'

Song Liu says:

====================

Changes v6 => v7:
1. Improve/fix intel_pmu_snapshot_branch_stack() logic. (Peter).

Changes v5 => v6:
1. A

Merge branch 'bpf: introduce bpf_get_branch_snapshot'

Song Liu says:

====================

Changes v6 => v7:
1. Improve/fix intel_pmu_snapshot_branch_stack() logic. (Peter).

Changes v5 => v6:
1. Add local_irq_save/restore to intel_pmu_snapshot_branch_stack. (Peter)
2. Remove buf and size check in bpf_get_branch_snapshot, move flags check
to later fo the function. (Peter, Andrii)
3. Revise comments for bpf_get_branch_snapshot in bpf.h (Andrii)

Changes v4 => v5:
1. Modify perf_snapshot_branch_stack_t to save some memcpy. (Andrii)
2. Minor fixes in selftests. (Andrii)

Changes v3 => v4:
1. Do not reshuffle intel_pmu_disable_all(). Use some inline to save LBR
entries. (Peter)
2. Move static_call(perf_snapshot_branch_stack) to the helper. (Alexei)
3. Add argument flags to bpf_get_branch_snapshot. (Andrii)
4. Make MAX_BRANCH_SNAPSHOT an enum (Andrii). And rename it as
PERF_MAX_BRANCH_SNAPSHOT
5. Make bpf_get_branch_snapshot similar to bpf_read_branch_records.
(Andrii)
6. Move the test target function to bpf_testmod. Updated kallsyms_find_next
to work properly with modules. (Andrii)

Changes v2 => v3:
1. Fix the use of static_call. (Peter)
2. Limit the use to perfmon version >= 2. (Peter)
3. Modify intel_pmu_snapshot_branch_stack() to use intel_pmu_disable_all
and intel_pmu_enable_all().

Changes v1 => v2:
1. Rename the helper as bpf_get_branch_snapshot;
2. Fix/simplify the use of static_call;
3. Instead of percpu variables, let intel_pmu_snapshot_branch_stack output
branch records to an output argument of type perf_branch_snapshot.

Branch stack can be very useful in understanding software events. For
example, when a long function, e.g. sys_perf_event_open, returns an errno,
it is not obvious why the function failed. Branch stack could provide very
helpful information in this type of scenarios.

This set adds support to read branch stack with a new BPF helper
bpf_get_branch_trace(). Currently, this is only supported in Intel systems.
It is also possible to support the same feaure for PowerPC.

The hardware that records the branch stace is not stopped automatically on
software events. Therefore, it is necessary to stop it in software soon.
Otherwise, the hardware buffers/registers will be flushed. One of the key
design consideration in this set is to minimize the number of branch record
entries between the event triggers and the hardware recorder is stopped.
Based on this goal, current design is different from the discussions in
original RFC [1]:
1) Static call is used when supported, to save function pointer
dereference;
2) intel_pmu_lbr_disable_all is used instead of perf_pmu_disable(),
because the latter uses about 10 entries before stopping LBR.

With current code, on Intel CPU, LBR is stopped after 7 branch entries
after fexit triggers:

ID: 0 from bpf_get_branch_snapshot+18 to intel_pmu_snapshot_branch_stack+0
ID: 1 from __brk_limit+477143934 to bpf_get_branch_snapshot+0
ID: 2 from __brk_limit+477192263 to __brk_limit+477143880 # trampoline
ID: 3 from __bpf_prog_enter+34 to __brk_limit+477192251
ID: 4 from migrate_disable+60 to __bpf_prog_enter+9
ID: 5 from __bpf_prog_enter+4 to migrate_disable+0
ID: 6 from bpf_testmod_loop_test+20 to __bpf_prog_enter+0
ID: 7 from bpf_testmod_loop_test+20 to bpf_testmod_loop_test+13
ID: 8 from bpf_testmod_loop_test+20 to bpf_testmod_loop_test+13
...

[1] https://lore.kernel.org/bpf/20210818012937.2522409-1-songliubraving@fb.com/
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

show more ...

selftests/bpf: Add test for bpf_get_branch_snapshot

This test uses bpf_get_branch_snapshot from a fexit program. The test uses
a target function (bpf_testmod_loop_test) and compares the record again

selftests/bpf: Add test for bpf_get_branch_snapshot

This test uses bpf_get_branch_snapshot from a fexit program. The test uses
a target function (bpf_testmod_loop_test) and compares the record against
kallsyms. If there isn't enough record matching kallsyms, the test fails.

Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210910183352.3151445-4-songliubraving@fb.com

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