[Why]
The DP 1.4a Spec requires that training pattern only under certain
specific conditions. Currently driver will re-send
training pattern every time voltage swing value changes,
but that should not be the case.

[How]
Do not re-send training pattern every time VS values
are different. Only send it on the first iteration.
Signed-off-by: Sung Lee <sung.lee@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Abdoulaye Berthe <Abdoulaye.Berthe@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

[why]
On video test pattern request we need to update MSA and VSC so
it will match the requested test pattern dynamic range field.

[how]
Update dynamic range field in MSA and disable VSC as updating VSC
info packet is complicated and not required for test pattern purpose.
Signed-off-by: Wenjing Liu <Wenjing.Liu@amd.com>
Reviewed-by: Nikola Cornij <Nikola.Cornij@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Allocate fences for each entity and remove ctx->fences reference as
fences should be bound to amdgpu_ctx_entity instead amdgpu_ctx.
Signed-off-by: Nirmoy Das <nirmoy.das@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

This reverts commit 9e441478.

The patch will be replaced with a better solution, revert it.
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Tianci.Yin <tianci.yin@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

[why]
In GDDR6 BIST training, a certain mount of bottom VRAM will be encroached by
UMC, that causes problems(like GTT corrupted and page fault observed).

[how]
Saving the content of this bottom VRAM to system memory before training, and
restoring it after training to avoid VRAM corruption.
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Tianci.Yin <tianci.yin@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Better clean that up before some automation starts to complain about it
Signed-off-by: Nirmoy Das <nirmoy.das@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Implement functions to do the RAS error injection and
query EDC counter.
Signed-off-by: Dennis Li <Dennis.Li@amd.com>
Reviewed-by: Guchun Chen <guchun.chen@amd.com>
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

add reg headers to gc includes

v2: remove unused registers and fields in this patch set
Signed-off-by: Dennis Li <Dennis.Li@amd.com>
Reviewed-by: Guchun Chen <guchun.chen@amd.com>
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1. Add IP prefix for the IP related codes.
2. Refactor the code to clear EDC counter.
Signed-off-by: Dennis Li <Dennis.Li@amd.com>
Reviewed-by: Guchun Chen <guchun.chen@amd.com>
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

To avoid calling RAS related functions when RAS feature isn't
supported in hardware. Change to check supported features, instead
of checking asic type.

v2: reuse amdgpu_ras_is_supported function, instead of introducing
a new flag for hardware ras feature.
Signed-off-by: Dennis Li <Dennis.Li@amd.com>
Reviewed-by: Guchun Chen <guchun.chen@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Compared with Vg20, the size of mmhub range is changed from 2 to 8.
Signed-off-by: Dennis Li <Dennis.Li@amd.com>
Reviewed-by: Guchun Chen <guchun.chen@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Add mask & shift definition of MAM_D(0~3)MEM for all mmhub
ranges.
Signed-off-by: Dennis Li <Dennis.Li@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Reading CP_MEM_SLP_CNTL register with RREG32_SOC15 macro will lead to
hang when GPU is in "gfxoff" state.
I do a uniform substitution here.
Signed-off-by: chen gong <curry.gong@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Reading some registers by mmio will result in hang when GPU is in
"gfxoff" state.This problem can be solved by GPU in "ring command
packages" way.
Signed-off-by: chen gong <curry.gong@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Move amdgpu_virt_kiq_rreg/amdgpu_virt_kiq_wreg function to amdgpu_gfx.c,
and rename them to amdgpu_kiq_rreg/amdgpu_kiq_wreg.Make it generic and
flexible.
Signed-off-by: chen gong <curry.gong@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

resolves issue with RAS error injection in mGPU configuration
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: John Clements <john.clements@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

[Why]
PM4 packet size for flush message was oversized.

[How]
Packet size adjusted to allocate flush + fence packets.
Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

+ sc7180 display + DSI support
+ a618 (sc7180) support
+ more UBWC (bandwidth compression) support
+ various cleanups to handle devices that use vs don't
  use zap fw, etc
+ usual random cleanups and fixes
Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Rob Clark <robdclark@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/ <CAF6AEGvv03ifuP0tp7-dmqZtr1iS=s8Vc=az8BNGtEoSMD-dkw@mail.gmail.com

msm needs 5.5-rc4, go to the latest.
Signed-off-by: Dave Airlie <airlied@redhat.com>

Pull RISC-V fixes from Paul Walmsley:
 "Three fixes for RISC-V:

   - Don't free and reuse memory containing the code that CPUs parked at
     boot reside in.

   - Fix rv64 build problems for ubsan and some modules by adding
     logical and arithmetic shift helpers for 128-bit values. These are
     from libgcc and are similar to what's present for ARM64.

   - Fix vDSO builds to clean up their own temporary files"

* tag 'riscv/for-v5.5-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  riscv: Less inefficient gcc tishift helpers (and export their symbols)
  riscv: delete temporary files
  riscv: make sure the cores stay looping in .Lsecondary_park

Pull networking fixes from David Miller:

 1) Fix non-blocking connect() in x25, from Martin Schiller.

 2) Fix spurious decryption errors in kTLS, from Jakub Kicinski.

 3) Netfilter use-after-free in mtype_destroy(), from Cong Wang.

 4) Limit size of TSO packets properly in lan78xx driver, from Eric
    Dumazet.

 5) r8152 probe needs an endpoint sanity check, from Johan Hovold.

 6) Prevent looping in tcp_bpf_unhash() during sockmap/tls free, from
    John Fastabend.

 7) hns3 needs short frames padded on transmit, from Yunsheng Lin.

 8) Fix netfilter ICMP header corruption, from Eyal Birger.

 9) Fix soft lockup when low on memory in hns3, from Yonglong Liu.

10) Fix NTUPLE firmware command failures in bnxt_en, from Michael Chan.

11) Fix memory leak in act_ctinfo, from Eric Dumazet.

* git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (91 commits)
  cxgb4: reject overlapped queues in TC-MQPRIO offload
  cxgb4: fix Tx multi channel port rate limit
  net: sched: act_ctinfo: fix memory leak
  bnxt_en: Do not treat DSN (Digital Serial Number) read failure as fatal.
  bnxt_en: Fix ipv6 RFS filter matching logic.
  bnxt_en: Fix NTUPLE firmware command failures.
  net: systemport: Fixed queue mapping in internal ring map
  net: dsa: bcm_sf2: Configure IMP port for 2Gb/sec
  net: dsa: sja1105: Don't error out on disabled ports with no phy-mode
  net: phy: dp83867: Set FORCE_LINK_GOOD to default after reset
  net: hns: fix soft lockup when there is not enough memory
  net: avoid updating qdisc_xmit_lock_key in netdev_update_lockdep_key()
  net/sched: act_ife: initalize ife->metalist earlier
  netfilter: nat: fix ICMP header corruption on ICMP errors
  net: wan: lapbether.c: Use built-in RCU list checking
  netfilter: nf_tables: fix flowtable list del corruption
  netfilter: nf_tables: fix memory leak in nf_tables_parse_netdev_hooks()
  netfilter: nf_tables: remove WARN and add NLA_STRING upper limits
  netfilter: nft_tunnel: ERSPAN_VERSION must not be null
  netfilter: nft_tunnel: fix null-attribute check
  ...

Pull i2c fixes from Wolfram Sang:
 "Two runtime PM fixes and one leak fix"

* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: iop3xx: Fix memory leak in probe error path
  i2c: tegra: Properly disable runtime PM on driver's probe error
  i2c: tegra: Fix suspending in active runtime PM state

A queue can't belong to multiple traffic classes. So, reject
any such configuration that results in overlapped queues for a
traffic class.

Fixes: b1396c2b ("cxgb4: parse and configure TC-MQPRIO offload")
Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

T6 can support 2 egress traffic management channels per port to
double the total number of traffic classes that can be configured.
In this configuration, if the class belongs to the other channel,
then all the queues must be bound again explicitly to the new class,
for the rate limit parameters on the other channel to take effect.

So, always explicitly bind all queues to the port rate limit traffic
class, regardless of the traffic management channel that it belongs
to. Also, only bind queues to port rate limit traffic class, if all
the queues don't already belong to an existing different traffic
class.

Fixes: 4ec4762d ("cxgb4: add TC-MATCHALL classifier egress offload")
Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Implement a cleanup method to properly free ci->params

BUG: memory leak
unreferenced object 0xffff88811746e2c0 (size 64):
  comm "syz-executor617", pid 7106, jiffies 4294943055 (age 14.250s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    c0 34 60 84 ff ff ff ff 00 00 00 00 00 00 00 00  .4`.............
  backtrace:
    [<0000000015aa236f>] kmemleak_alloc_recursive include/linux/kmemleak.h:43 [inline]
    [<0000000015aa236f>] slab_post_alloc_hook mm/slab.h:586 [inline]
    [<0000000015aa236f>] slab_alloc mm/slab.c:3320 [inline]
    [<0000000015aa236f>] kmem_cache_alloc_trace+0x145/0x2c0 mm/slab.c:3549
    [<000000002c946bd1>] kmalloc include/linux/slab.h:556 [inline]
    [<000000002c946bd1>] kzalloc include/linux/slab.h:670 [inline]
    [<000000002c946bd1>] tcf_ctinfo_init+0x21a/0x530 net/sched/act_ctinfo.c:236
    [<0000000086952cca>] tcf_action_init_1+0x400/0x5b0 net/sched/act_api.c:944
    [<000000005ab29bf8>] tcf_action_init+0x135/0x1c0 net/sched/act_api.c:1000
    [<00000000392f56f9>] tcf_action_add+0x9a/0x200 net/sched/act_api.c:1410
    [<0000000088f3c5dd>] tc_ctl_action+0x14d/0x1bb net/sched/act_api.c:1465
    [<000000006b39d986>] rtnetlink_rcv_msg+0x178/0x4b0 net/core/rtnetlink.c:5424
    [<00000000fd6ecace>] netlink_rcv_skb+0x61/0x170 net/netlink/af_netlink.c:2477
    [<0000000047493d02>] rtnetlink_rcv+0x1d/0x30 net/core/rtnetlink.c:5442
    [<00000000bdcf8286>] netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
    [<00000000bdcf8286>] netlink_unicast+0x223/0x310 net/netlink/af_netlink.c:1328
    [<00000000fc5b92d9>] netlink_sendmsg+0x2c0/0x570 net/netlink/af_netlink.c:1917
    [<00000000da84d076>] sock_sendmsg_nosec net/socket.c:639 [inline]
    [<00000000da84d076>] sock_sendmsg+0x54/0x70 net/socket.c:659
    [<0000000042fb2eee>] ____sys_sendmsg+0x2d0/0x300 net/socket.c:2330
    [<000000008f23f67e>] ___sys_sendmsg+0x8a/0xd0 net/socket.c:2384
    [<00000000d838e4f6>] __sys_sendmsg+0x80/0xf0 net/socket.c:2417
    [<00000000289a9cb1>] __do_sys_sendmsg net/socket.c:2426 [inline]
    [<00000000289a9cb1>] __se_sys_sendmsg net/socket.c:2424 [inline]
    [<00000000289a9cb1>] __x64_sys_sendmsg+0x23/0x30 net/socket.c:2424

Fixes: 24ec483c ("net: sched: Introduce act_ctinfo action")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: Kevin 'ldir' Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Kevin 'ldir' Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

The existing __lshrti3 was really inefficient, and the other two helpers
are also needed to compile some modules.

Add the missing versions, and export all of the symbols like arm64
already does.

This code is based on the assembly generated by libgcc builds.

This fixes a build break triggered by ubsan:

riscv64-unknown-linux-gnu-ld: lib/ubsan.o: in function `.L2':
ubsan.c:(.text.unlikely+0x38): undefined reference to `__ashlti3'
riscv64-unknown-linux-gnu-ld: ubsan.c:(.text.unlikely+0x42): undefined reference to `__ashrti3'
Signed-off-by: Olof Johansson <olof@lixom.net>
[paul.walmsley@sifive.com: use SYM_FUNC_{START,END} instead of
 ENTRY/ENDPROC; note libgcc origin]
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>

Pull MTD fixes from Miquel Raynal:
 "Raw NAND:
   - GPMI: Fix the suspend/resume

  SPI-NOR:
   - Fix quad enable on Spansion like flashes
   - Fix selection of 4-byte addressing opcodes on Spansion"

* tag 'mtd/fixes-for-5.5-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux:
  mtd: rawnand: gpmi: Restore nfc timing setup after suspend/resume
  mtd: rawnand: gpmi: Fix suspend/resume problem
  mtd: spi-nor: Fix quad enable for Spansion like flashes
  mtd: spi-nor: Fix selection of 4-byte addressing opcodes on Spansion

Pull drm fixes from Dave Airlie:
 "Back from LCA2020, fixes wasn't too busy last week, seems to have
  quieten down appropriately, some amdgpu, i915, then a core mst fix and
  one fix for virtio-gpu and one for rockchip:

  core mst:
   - serialize down messages and clear timeslots are on unplug

  amdgpu:
   - Update golden settings for renoir
   - eDP fix

  i915:
   - uAPI fix: Remove dash and colon from PMU names to comply with
     tools/perf
   - Fix for include file that was indirectly included
   - Two fixes to make sure VMA are marked active for error capture

  virtio:
   - maintain obj reservation lock when submitting cmds

  rockchip:
   - increase link rate var size to accommodate rates"

* tag 'drm-fixes-2020-01-19' of git://anongit.freedesktop.org/drm/drm:
  drm/amd/display: Reorder detect_edp_sink_caps before link settings read.
  drm/amdgpu: update goldensetting for renoir
  drm/dp_mst: Have DP_Tx send one msg at a time
  drm/dp_mst: clear time slots for ports invalid
  drm/i915/pmu: Do not use colons or dashes in PMU names
  drm/rockchip: fix integer type used for storing dp data rate
  drm/i915/gt: Mark ring->vma as active while pinned
  drm/i915/gt: Mark context->state vma as active while pinned
  drm/i915/gt: Skip trying to unbind in restore_ggtt_mappings
  drm/i915: Add missing include file <linux/math64.h>
  drm/virtio: add missing virtio_gpu_array_lock_resv call

Temporary files used in the VDSO build process linger on even after make
mrproper: vdso-dummy.o.tmp, vdso.so.dbg.tmp.

Delete them once they're no longer needed.
Signed-off-by: Ilie Halip <ilie.halip@gmail.com>
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>

Pull x86 fixes from Ingo Molnar:
 "Misc fixes:

   - a resctrl fix for uninitialized objects found by debugobjects

   - a resctrl memory leak fix

   - fix the unintended re-enabling of the of SME and SEV CPU flags if
     memory encryption was disabled at bootup via the MSR space"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/CPU/AMD: Ensure clearing of SME/SEV features is maintained
  x86/resctrl: Fix potential memory leak
  x86/resctrl: Fix an imbalance in domain_remove_cpu()

Pull timer fixes from Ingo Molnar:
 "Three fixes: fix link failure on Alpha, fix a Sparse warning and
  annotate/robustify a lockless access in the NOHZ code"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  tick/sched: Annotate lockless access to last_jiffies_update
  lib/vdso: Make __cvdso_clock_getres() static
  time/posix-stubs: Provide compat itimer supoprt for alpha

Pull cpu/SMT fix from Ingo Molnar:
 "Fix a build bug on CONFIG_HOTPLUG_SMT=y && !CONFIG_SYSFS kernels"

* 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  cpu/SMT: Fix x86 link error without CONFIG_SYSFS

Pull x86 RAS fix from Ingo Molnar:
 "Fix a thermal throttling race that can result in easy to trigger boot
  crashes on certain Ice Lake platforms"

* 'ras-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mce/therm_throt: Do not access uninitialized therm_work

Pull perf fixes from Ingo Molnar:
 "Tooling fixes, three Intel uncore driver fixes, plus an AUX events fix
  uncovered by the perf fuzzer"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86/intel/uncore: Remove PCIe3 unit for SNR
  perf/x86/intel/uncore: Fix missing marker for snr_uncore_imc_freerunning_events
  perf/x86/intel/uncore: Add PCI ID of IMC for Xeon E3 V5 Family
  perf: Correctly handle failed perf_get_aux_event()
  perf hists: Fix variable name's inconsistency in hists__for_each() macro
  perf map: Set kmap->kmaps backpointer for main kernel map chunks
  perf report: Fix incorrectly added dimensions as switch perf data file
  tools lib traceevent: Fix memory leakage in filter_event

Pull locking fixes from Ingo Molnar:
 "Three fixes:

    - Fix an rwsem spin-on-owner crash, introduced in v5.4

    - Fix a lockdep bug when running out of stack_trace entries,
      introduced in v5.4

    - Docbook fix"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/rwsem: Fix kernel crash when spinning on RWSEM_OWNER_UNKNOWN
  futex: Fix kernel-doc notation warning
  locking/lockdep: Fix buffer overrun problem in stack_trace[]

Pull irq fix from Ingo Molnar:
 "Fix a recent regression in the Ingenic SoCs irqchip driver that floods
  the syslog"

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip/ingenic: Get rid of the legacy IRQ domain

Pull EFI fixes from Ingo Molnar:
 "Three EFI fixes:

   - Fix a slow-boot-scrolling regression but making sure we use WC for
     EFI earlycon framebuffer mappings on x86

   - Fix a mixed EFI mode boot crash

   - Disable paging explicitly before entering startup_32() in mixed
     mode bootup"

* 'efi-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/efistub: Disable paging at mixed mode entry
  efi/libstub/random: Initialize pointer variables to zero for mixed mode
  efi/earlycon: Fix write-combine mapping on x86

Pull rseq fixes from Ingo Molnar:
 "Two rseq bugfixes:

   - CLONE_VM !CLONE_THREAD didn't work properly, the kernel would end
     up corrupting the TLS of the parent. Technically a change in the
     ABI but the previous behavior couldn't resonably have been relied
     on by applications so this looks like a valid exception to the ABI
     rule.

   - Make the RSEQ_FLAG_UNREGISTER ABI behavior consistent with the
     handling of other flags. This is not thought to impact any
     applications either"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  rseq: Unregister rseq for clone CLONE_VM
  rseq: Reject unknown flags on rseq unregister

Pull thread fixes from Christian Brauner:
 "Here is an urgent fix for ptrace_may_access() permission checking.

  Commit 69f594a3 ("ptrace: do not audit capability check when
  outputing /proc/pid/stat") introduced the ability to opt out of audit
  messages for accesses to various proc files since they are not
  violations of policy.

  While doing so it switched the check from ns_capable() to
  has_ns_capability{_noaudit}(). That means it switched from checking
  the subjective credentials (ktask->cred) of the task to using the
  objective credentials (ktask->real_cred). This is appears to be wrong.
  ptrace_has_cap() is currently only used in ptrace_may_access() And is
  used to check whether the calling task (subject) has the
  CAP_SYS_PTRACE capability in the provided user namespace to operate on
  the target task (object). According to the cred.h comments this means
  the subjective credentials of the calling task need to be used.

  With this fix we switch ptrace_has_cap() to use security_capable() and
  thus back to using the subjective credentials.

  As one example where this might be particularly problematic, Jann
  pointed out that in combination with the upcoming IORING_OP_OPENAT{2}
  feature, this bug might allow unprivileged users to bypass the
  capability checks while asynchronously opening files like /proc/*/mem,
  because the capability checks for this would be performed against
  kernel credentials.

  To illustrate on the former point about this being exploitable: When
  io_uring creates a new context it records the subjective credentials
  of the caller. Later on, when it starts to do work it creates a kernel
  thread and registers a callback. The callback runs with kernel creds
  for ktask->real_cred and ktask->cred.

  To prevent this from becoming a full-blown 0-day io_uring will call
  override_cred() and override ktask->cred with the subjective
  credentials of the creator of the io_uring instance. With
  ptrace_has_cap() currently looking at ktask->real_cred this override
  will be ineffective and the caller will be able to open arbitray proc
  files as mentioned above.

  Luckily, this is currently not exploitable but would be so once
  IORING_OP_OPENAT{2} land in v5.6. Let's fix it now.

  To minimize potential regressions I successfully ran the criu
  testsuite. criu makes heavy use of ptrace() and extensively hits
  ptrace_may_access() codepaths and has a good change of detecting any
  regressions.

  Additionally, I succesfully ran the ptrace and seccomp kernel tests"

* tag 'for-linus-2020-01-18' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
  ptrace: reintroduce usage of subjective credentials in ptrace_has_cap()