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SherrySun5 and others added 22 commits July 22, 2022 14:31
…t on v3 hw

v3.x Synopsys EDAC DDR doesn't have the QOS Interrupt register. Use the
ECC Clear Register to disable the error interrupts instead.

Fixes: f7824de ("EDAC/synopsys: Add support for version 3 of the Synopsys EDAC DDR")
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Shubhrajyoti Datta <Shubhrajyoti.datta@xilinx.com>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220427015137.8406-2-sherry.sun@nxp.com
zynqmp_get_error_info() writes 0 to the ECC_CLR_OFST register after
an interrupt for a {un-,}correctable error is raised, which disables
the error interrupts. Then the interrupt handler will be called only
once. Therefore, re-enable the error interrupt line at the end of
intr_handler() for v3.x Synopsys EDAC DDR.

Fixes: f7824de ("EDAC/synopsys: Add support for version 3 of the Synopsys EDAC DDR")
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Shubhrajyoti Datta <Shubhrajyoti.datta@xilinx.com>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220427015137.8406-3-sherry.sun@nxp.com
This adds a quirk for the Crucial P2.

Signed-off-by: Tobias Gruetzmacher <tobias-git@23.gs>
Signed-off-by: Christoph Hellwig <hch@lst.de>
The commit

  cb51a37 ("EDAC/ghes: Setup DIMM label from DMI and use it in error reports")

enforced that both the bank and device strings passed to
dimm_setup_label() are not NULL.

However, there are BIOSes, for example on a

  HPE ProLiant DL360 Gen10/ProLiant DL360 Gen10, BIOS U32 03/15/2019

which don't populate both strings:

  Handle 0x0020, DMI type 17, 84 bytes
  Memory Device
          Array Handle: 0x0013
          Error Information Handle: Not Provided
          Total Width: 72 bits
          Data Width: 64 bits
          Size: 32 GB
          Form Factor: DIMM
          Set: None
          Locator: PROC 1 DIMM 1        <===== device
          Bank Locator: Not Specified   <===== bank

This results in a buffer overflow because ghes_edac_register() calls
strlen() on an uninitialized label, which had non-zero values left over
from krealloc_array():

  detected buffer overflow in __fortify_strlen
   ------------[ cut here ]------------
   kernel BUG at lib/string_helpers.c:983!
   invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
   CPU: 1 PID: 1 Comm: swapper/0 Tainted: G          I       5.18.6-200.fc36.x86_64 #1
   Hardware name: HPE ProLiant DL360 Gen10/ProLiant DL360 Gen10, BIOS U32 03/15/2019
   RIP: 0010:fortify_panic
   ...
   Call Trace:
    <TASK>
    ghes_edac_register.cold
    ghes_probe
    platform_probe
    really_probe
    __driver_probe_device
    driver_probe_device
    __driver_attach
    ? __device_attach_driver
    bus_for_each_dev
    bus_add_driver
    driver_register
    acpi_ghes_init
    acpi_init
    ? acpi_sleep_proc_init
    do_one_initcall

The label contains garbage because the commit in Fixes reallocs the
DIMMs array while scanning the system but doesn't clear the newly
allocated memory.

Change dimm_setup_label() to always initialize the label to fix the
issue. Set it to the empty string in case BIOS does not provide both
bank and device so that ghes_edac_register() can keep the default label
given by edac_mc_alloc_dimms().

  [ bp: Rewrite commit message. ]

Fixes: b9cae27 ("EDAC/ghes: Scan the system once on driver init")
Co-developed-by: Robert Richter <rric@kernel.org>
Signed-off-by: Robert Richter <rric@kernel.org>
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Robert Elliott <elliott@hpe.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220719220124.760359-1-toshi.kani@hpe.com
… block-5.19

Pull NVMe fix from Christoph:

"nvme fix for Linux 5.19

 - yet another duplicate ID quirk (Tobias Gruetzmacher)"

* tag 'nvme-5.19-2022-07-27' of git://git.infradead.org/nvme:
  nvme-pci: Crucial P2 has bogus namespace ids
Commit

  4675ff0 ("kmemcheck: rip it out")

removed kmemcheck and its corresponding build config KMEMCHECK.

Commit

  0f620ce ("objtool: Rename "VMLINUX_VALIDATION" -> "NOINSTR_VALIDATION"")

renamed the debug config option.

Adjust x86_debug.config to those changes in debug configs.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220722121815.27535-1-lukas.bulwahn@gmail.com
This reverts commit 007faec.

Now that hyperv does its own protocol negotiation:

  49d6a3c ("x86/Hyper-V: Add SEV negotiate protocol support in Isolation VM")

revert this exposure of the sev_es_ghcb_hv_call() helper.

Cc: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by:Tianyu Lan <tiala@microsoft.com>
Link: https://lore.kernel.org/r/20220614014553.1915929-1-ltykernel@gmail.com
Commit 26f09e9 ("mm/memblock: add memblock memory allocation apis")
added a check to determine whether arm_dma_zone_size is exceeding the
amount of kernel virtual address space available between the upper 4GB
virtual address limit and PAGE_OFFSET in order to provide a suitable
definition of MAX_DMA_ADDRESS that should fit within the 32-bit virtual
address space. The quantity used for comparison was off by a missing
trailing 0, leading to MAX_DMA_ADDRESS to be overflowing a 32-bit
quantity.

This was caught thanks to CONFIG_DEBUG_VIRTUAL on the bcm2711 platform
where we define a dma_zone_size of 1GB and we have a PAGE_OFFSET value
of 0xc000_0000 (CONFIG_VMSPLIT_3G) leading to MAX_DMA_ADDRESS being
0x1_0000_0000 which overflows the unsigned long type used throughout
__pa() and then __virt_addr_valid(). Because the virtual address passed
to __virt_addr_valid() would now be 0, the function would loudly warn
and flood the kernel log, thus making the platform unable to boot
properly.

Fixes: 26f09e9 ("mm/memblock: add memblock memory allocation apis")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
While RTC clock was added in H616 ccu_common list, it was not in H6
list. That caused invalid pointer dereference like this:

Unable to handle kernel NULL pointer dereference at virtual address 000000000000020c
Mem abort info:
  ESR = 0x96000004
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x04: level 0 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000004
  CM = 0, WnR = 0
user pgtable: 4k pages, 48-bit VAs, pgdp=000000004d574000
[000000000000020c] pgd=0000000000000000, p4d=0000000000000000
Internal error: Oops: 96000004 [#1] PREEMPT SMP
CPU: 3 PID: 339 Comm: cat Tainted: G    B             5.18.0-rc1+ #1352
Hardware name: Tanix TX6 (DT)
pstate: 00000005 (nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : ccu_gate_is_enabled+0x48/0x74
lr : ccu_gate_is_enabled+0x40/0x74
sp : ffff80000c0b76d0
x29: ffff80000c0b76d0 x28: 00000000016e3600 x27: 0000000000000000
x26: 0000000000000000 x25: 0000000000000002 x24: ffff00000952fe08
x23: ffff800009611400 x22: ffff00000952fe79 x21: 0000000000000000
x20: 0000000000000001 x19: ffff80000aad6f08 x18: 0000000000000000
x17: 2d2d2d2d2d2d2d2d x16: 2d2d2d2d2d2d2d2d x15: 2d2d2d2d2d2d2d2d
x14: 0000000000000000 x13: 00000000f2f2f2f2 x12: ffff700001816e89
x11: 1ffff00001816e88 x10: ffff700001816e88 x9 : dfff800000000000
x8 : ffff80000c0b7447 x7 : 0000000000000001 x6 : ffff700001816e88
x5 : ffff80000c0b7440 x4 : 0000000000000001 x3 : ffff800008935c50
x2 : dfff800000000000 x1 : 0000000000000000 x0 : 000000000000020c
Call trace:
 ccu_gate_is_enabled+0x48/0x74
 clk_core_is_enabled+0x7c/0x1c0
 clk_summary_show_subtree+0x1dc/0x334
 clk_summary_show_subtree+0x250/0x334
 clk_summary_show_subtree+0x250/0x334
 clk_summary_show_subtree+0x250/0x334
 clk_summary_show_subtree+0x250/0x334
 clk_summary_show+0x90/0xdc
 seq_read_iter+0x248/0x6d4
 seq_read+0x17c/0x1fc
 full_proxy_read+0x90/0xf0
 vfs_read+0xdc/0x28c
 ksys_read+0xc8/0x174
 __arm64_sys_read+0x44/0x5c
 invoke_syscall+0x60/0x190
 el0_svc_common.constprop.0+0x7c/0x160
 do_el0_svc+0x38/0xa0
 el0_svc+0x68/0x160
 el0t_64_sync_handler+0x10c/0x140
 el0t_64_sync+0x18c/0x190
Code: d1006260 97e5c98 785e8260 8b0002a0 (b9400000)
---[ end trace 0000000000000000 ]---

Fix that by adding rtc clock to H6 ccu_common list too.

Fixes: 38d321b ("clk: sunxi-ng: h6-r: Add RTC gate clock")
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/20220719183725.2605141-1-jernej.skrabec@gmail.com
Reviewed-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
…able

Some cloud hypervisors do not provide IBPB on very recent CPU processors,
including AMD processors affected by Retbleed.

Using IBPB before firmware calls on such systems would cause a GPF at boot
like the one below. Do not enable such calls when IBPB support is not
present.

  EFI Variables Facility v0.08 2004-May-17
  general protection fault, maybe for address 0x1: 0000 [#1] PREEMPT SMP NOPTI
  CPU: 0 PID: 24 Comm: kworker/u2:1 Not tainted 5.19.0-rc8+ #7
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015
  Workqueue: efi_rts_wq efi_call_rts
  RIP: 0010:efi_call_rts
  Code: e8 37 33 58 ff 41 bf 48 00 00 00 49 89 c0 44 89 f9 48 83 c8 01 4c 89 c2 48 c1 ea 20 66 90 b9 49 00 00 00 b8 01 00 00 00 31 d2 <0f> 30 e8 7b 9f 5d ff e8 f6 f8 ff ff 4c 89 f1 4c 89 ea 4c 89 e6 48
  RSP: 0018:ffffb373800d7e38 EFLAGS: 00010246
  RAX: 0000000000000001 RBX: 0000000000000006 RCX: 0000000000000049
  RDX: 0000000000000000 RSI: ffff94fbc19d8fe0 RDI: ffff94fbc1b2b300
  RBP: ffffb373800d7e70 R08: 0000000000000000 R09: 0000000000000000
  R10: 000000000000000b R11: 000000000000000b R12: ffffb3738001fd78
  R13: ffff94fbc2fcfc00 R14: ffffb3738001fd80 R15: 0000000000000048
  FS:  0000000000000000(0000) GS:ffff94fc3da00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: ffff94fc30201000 CR3: 000000006f610000 CR4: 00000000000406f0
  Call Trace:
   <TASK>
   ? __wake_up
   process_one_work
   worker_thread
   ? rescuer_thread
   kthread
   ? kthread_complete_and_exit
   ret_from_fork
   </TASK>
  Modules linked in:

Fixes: 28a99e9 ("x86/amd: Use IBPB for firmware calls")
Reported-by: Dimitri John Ledkov <dimitri.ledkov@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220728122602.2500509-1-cascardo@canonical.com
When offset is larger than the size of the bit array, we should not
attempt to access the array as we can perform an access beyond the
end of the array. Fix this by changing the pre-condition.

Using "cmp r2, r1; bhs ..." covers us for the size == 0 case, since
this will always take the branch when r1 is zero, irrespective of
the value of r2. This means we can fix this bug without adding any
additional code!

Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
There was a report that a task is waiting at the
throttle_direct_reclaim. The pgscan_direct_throttle in vmstat was
increasing.

This is a bug where zone_watermark_fast returns true even when the free
is very low. The commit f27ce0e ("page_alloc: consider highatomic
reserve in watermark fast") changed the watermark fast to consider
highatomic reserve. But it did not handle a negative value case which
can be happened when reserved_highatomic pageblock is bigger than the
actual free.

If watermark is considered as ok for the negative value, allocating
contexts for order-0 will consume all free pages without direct reclaim,
and finally free page may become depleted except highatomic free.

Then allocating contexts may fall into throttle_direct_reclaim. This
symptom may easily happen in a system where wmark min is low and other
reclaimers like kswapd does not make free pages quickly.

Handle the negative case by using MIN.

Link: https://lkml.kernel.org/r/20220725095212.25388-1-jaewon31.kim@samsung.com
Fixes: f27ce0e ("page_alloc: consider highatomic reserve in watermark fast")
Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com>
Reported-by: GyeongHwan Hong <gh21.hong@samsung.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Yong-Taek Lee <ytk.lee@samsung.com>
Cc: <stable@vger.kerenl.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
If hmm_range_fault() is called with the HMM_PFN_REQ_FAULT flag and a
device private PTE is found, the hmm_range::dev_private_owner page is used
to determine if the device private page should not be faulted in. 
However, if the device private page is not owned by the caller,
hmm_range_fault() returns an error instead of calling migrate_to_ram() to
fault in the page.

For example, if a page is migrated to GPU private memory and a RDMA fault
capable NIC tries to read the migrated page, without this patch it will
get an error.  With this patch, the page will be migrated back to system
memory and the NIC will be able to read the data.

Link: https://lkml.kernel.org/r/20220727000837.4128709-2-rcampbell@nvidia.com
Link: https://lkml.kernel.org/r/20220725183615.4118795-2-rcampbell@nvidia.com
Fixes: 08ddddd ("mm/hmm: check the device private page owner in hmm_range_fault()")
Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
Reported-by: Felix Kuehling <felix.kuehling@amd.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Cc: Philip Yang <Philip.Yang@amd.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
…with retbleed

Updates descriptions for "mitigations=off" and "mitigations=auto,nosmt"
with the respective retbleed= settings.

Signed-off-by: Eiichi Tsukata <eiichi.tsukata@nutanix.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: corbet@lwn.net
Link: https://lore.kernel.org/r/20220728043907.165688-1-eiichi.tsukata@nutanix.com
Pull block fix from Jens Axboe:
 "Just a single fix for NVMe, yet another quirk addition"

* tag 'block-5.19-2022-07-29' of git://git.kernel.dk/linux-block:
  nvme-pci: Crucial P2 has bogus namespace ids
…/scm/linux/kernel/git/akpm/mm

Pull misc fixes from Andrew Morton:
 "Two hotfixes, both cc:stable"

* tag 'mm-hotfixes-stable-2022-07-29' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
  mm/hmm: fault non-owner device private entries
  page_alloc: fix invalid watermark check on a negative value
… by first waiter

With commit d257cc8 ("locking/rwsem: Make handoff bit handling more
consistent"), the writer that sets the handoff bit can be interrupted
out without clearing the bit if the wait queue isn't empty. This disables
reader and writer optimistic lock spinning and stealing.

Now if a non-first writer in the queue is somehow woken up or a new
waiter enters the slowpath, it can't acquire the lock.  This is not the
case before commit d257cc8 as the writer that set the handoff bit
will clear it when exiting out via the out_nolock path. This is less
efficient as the busy rwsem stays in an unlock state for a longer time.

In some cases, this new behavior may cause lockups as shown in [1] and
[2].

This patch allows a non-first writer to ignore the handoff bit if it
is not originally set or initiated by the first waiter. This patch is
shown to be effective in fixing the lockup problem reported in [1].

[1] https://lore.kernel.org/lkml/20220617134325.GC30825@techsingularity.net/
[2] https://lore.kernel.org/lkml/3f02975c-1a9d-be20-32cf-f1d8e3dfafcc@oracle.com/

Fixes: d257cc8 ("locking/rwsem: Make handoff bit handling more consistent")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: John Donnelly <john.p.donnelly@oracle.com>
Tested-by: Mel Gorman <mgorman@techsingularity.net>
Link: https://lore.kernel.org/r/20220622200419.778799-1-longman@redhat.com
Pull ARM fixes from Russell King:
 "Last set of ARM fixes for 5.19:

   - fix for MAX_DMA_ADDRESS overflow

   - fix for find_*_bit performing an out of bounds memory access"

* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm:
  ARM: findbit: fix overflowing offset
  ARM: 9216/1: Fix MAX_DMA_ADDRESS overflow
…ux/kernel/git/ras/ras

Pull EDAC fixes from Borislav Petkov:

 - Relax the condition under which the DIMM label in ghes_edac is set in
   order to accomodate an HPE BIOS which sets only the device but not
   the bank

 - Two forgotten fixes to synopsys_edac when handling error interrupts

* tag 'edac_urgent_for_v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/ras/ras:
  EDAC/ghes: Set the DIMM label unconditionally
  EDAC/synopsys: Re-enable the error interrupts on v3 hw
  EDAC/synopsys: Use the correct register to disable the error interrupt on v3 hw
…linux/kernel/git/tip/tip

Pull locking fix from Borislav Petkov:

 - Avoid rwsem lockups in certain situations when handling the handoff
   bit

* tag 'locking_urgent_for_v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/rwsem: Allow slowpath writer to ignore handoff bit if not set by first waiter
…x/kernel/git/tip/tip

Pull x86 fixes from Borislav Petkov:

 - Update the 'mitigations=' kernel param documentation

 - Check the IBPB feature flag before enabling IBPB in firmware calls
   because cloud vendors' fantasy when it comes to creating guest
   configurations is unlimited

 - Unexport sev_es_ghcb_hv_call() before 5.19 releases now that HyperV
   doesn't need it anymore

 - Remove dead CONFIG_* items

* tag 'x86_urgent_for_v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  docs/kernel-parameters: Update descriptions for "mitigations=" param with retbleed
  x86/bugs: Do not enable IBPB at firmware entry when IBPB is not available
  Revert "x86/sev: Expose sev_es_ghcb_hv_call() for use by HyperV"
  x86/configs: Update configs in x86_debug.config
…/kernel/git/clk/linux

Pull clk fix from Stephen Boyd:
 "One-liner fix of a NULL pointer deref in the Allwinner clk driver"

* tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux:
  clk: sunxi-ng: Fix H6 RTC clock definition
@pull pull bot added the ⤵️ pull label Jul 31, 2022
@pull pull bot merged commit 334c0ef into Kadantte:master Jul 31, 2022
pull bot pushed a commit that referenced this pull request Jan 14, 2023
The inline assembly for arm64's cmpxchg_double*() implementations use a
+Q constraint to hazard against other accesses to the memory location
being exchanged. However, the pointer passed to the constraint is a
pointer to unsigned long, and thus the hazard only applies to the first
8 bytes of the location.

GCC can take advantage of this, assuming that other portions of the
location are unchanged, leading to a number of potential problems.

This is similar to what we fixed back in commit:

  fee960b ("arm64: xchg: hazard against entire exchange variable")

... but we forgot to adjust cmpxchg_double*() similarly at the same
time.

The same problem applies, as demonstrated with the following test:

| struct big {
|         u64 lo, hi;
| } __aligned(128);
|
| unsigned long foo(struct big *b)
| {
|         u64 hi_old, hi_new;
|
|         hi_old = b->hi;
|         cmpxchg_double_local(&b->lo, &b->hi, 0x12, 0x34, 0x56, 0x78);
|         hi_new = b->hi;
|
|         return hi_old ^ hi_new;
| }

... which GCC 12.1.0 compiles as:

| 0000000000000000 <foo>:
|    0:   d503233f        paciasp
|    4:   aa0003e4        mov     x4, x0
|    8:   1400000e        b       40 <foo+0x40>
|    c:   d2800240        mov     x0, #0x12                       // #18
|   10:   d2800681        mov     x1, #0x34                       // #52
|   14:   aa0003e5        mov     x5, x0
|   18:   aa0103e6        mov     x6, x1
|   1c:   d2800ac2        mov     x2, #0x56                       // #86
|   20:   d2800f03        mov     x3, #0x78                       // #120
|   24:   48207c82        casp    x0, x1, x2, x3, [x4]
|   28:   ca05000        eor     x0, x0, x5
|   2c:   ca060021        eor     x1, x1, x6
|   30:   aa010000        orr     x0, x0, x1
|   34:   d2800000        mov     x0, #0x0                        // #0    <--- BANG
|   38:   d50323bf        autiasp
|   3c:   d65f03c0        ret
|   40:   d2800240        mov     x0, #0x12                       // #18
|   44:   d2800681        mov     x1, #0x34                       // #52
|   48:   d2800ac2        mov     x2, #0x56                       // #86
|   4c:   d2800f03        mov     x3, #0x78                       // #120
|   50:   f9800091        prfm    pstl1strm, [x4]
|   54:   c87f1885        ldxp    x5, x6, [x4]
|   58:   ca0000a5        eor     x5, x5, x0
|   5c:   ca0100c6        eor     x6, x6, x1
|   60:   aa0600a6        orr     x6, x5, x6
|   64:   b5000066        cbnz    x6, 70 <foo+0x70>
|   68:   c8250c82        stxp    w5, x2, x3, [x4]
|   6c:   35ffff45        cbnz    w5, 54 <foo+0x54>
|   70:   d2800000        mov     x0, #0x0                        // #0     <--- BANG
|   74:   d50323bf        autiasp
|   78:   d65f03c0        ret

Notice that at the lines with "BANG" comments, GCC has assumed that the
higher 8 bytes are unchanged by the cmpxchg_double() call, and that
`hi_old ^ hi_new` can be reduced to a constant zero, for both LSE and
LL/SC versions of cmpxchg_double().

This patch fixes the issue by passing a pointer to __uint128_t into the
+Q constraint, ensuring that the compiler hazards against the entire 16
bytes being modified.

With this change, GCC 12.1.0 compiles the above test as:

| 0000000000000000 <foo>:
|    0:   f9400407        ldr     x7, [x0, #8]
|    4:   d503233f        paciasp
|    8:   aa0003e4        mov     x4, x0
|    c:   1400000f        b       48 <foo+0x48>
|   10:   d2800240        mov     x0, #0x12                       // #18
|   14:   d2800681        mov     x1, #0x34                       // #52
|   18:   aa0003e5        mov     x5, x0
|   1c:   aa0103e6        mov     x6, x1
|   20:   d2800ac2        mov     x2, #0x56                       // #86
|   24:   d2800f03        mov     x3, #0x78                       // #120
|   28:   48207c82        casp    x0, x1, x2, x3, [x4]
|   2c:   ca05000        eor     x0, x0, x5
|   30:   ca060021        eor     x1, x1, x6
|   34:   aa010000        orr     x0, x0, x1
|   38:   f9400480        ldr     x0, [x4, #8]
|   3c:   d50323bf        autiasp
|   40:   ca0000e0        eor     x0, x7, x0
|   44:   d65f03c0        ret
|   48:   d2800240        mov     x0, #0x12                       // #18
|   4c:   d2800681        mov     x1, #0x34                       // #52
|   50:   d2800ac2        mov     x2, #0x56                       // #86
|   54:   d2800f03        mov     x3, #0x78                       // #120
|   58:   f9800091        prfm    pstl1strm, [x4]
|   5c:   c87f1885        ldxp    x5, x6, [x4]
|   60:   ca0000a5        eor     x5, x5, x0
|   64:   ca0100c6        eor     x6, x6, x1
|   68:   aa0600a6        orr     x6, x5, x6
|   6c:   b5000066        cbnz    x6, 78 <foo+0x78>
|   70:   c8250c82        stxp    w5, x2, x3, [x4]
|   74:   35ffff45        cbnz    w5, 5c <foo+0x5c>
|   78:   f9400480        ldr     x0, [x4, #8]
|   7c:   d50323bf        autiasp
|   80:   ca0000e0        eor     x0, x7, x0
|   84:   d65f03c0        ret

... sampling the high 8 bytes before and after the cmpxchg, and
performing an EOR, as we'd expect.

For backporting, I've tested this atop linux-4.9.y with GCC 5.5.0. Note
that linux-4.9.y is oldest currently supported stable release, and
mandates GCC 5.1+. Unfortunately I couldn't get a GCC 5.1 binary to run
on my machines due to library incompatibilities.

I've also used a standalone test to check that we can use a __uint128_t
pointer in a +Q constraint at least as far back as GCC 4.8.5 and LLVM
3.9.1.

Fixes: 5284e1b ("arm64: xchg: Implement cmpxchg_double")
Fixes: e9a4b79 ("arm64: cmpxchg_dbl: patch in lse instructions when supported by the CPU")
Reported-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/lkml/Y6DEfQXymYVgL3oJ@boqun-archlinux/
Reported-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/lkml/Y6GXoO4qmH9OIZ5Q@hirez.programming.kicks-ass.net/
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: stable@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20230104151626.3262137-1-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
pull bot pushed a commit that referenced this pull request Jan 20, 2024
Like commit 1cf3bfc ("bpf: Support 64-bit pointers to kfuncs")
for s390x, add support for 64-bit pointers to kfuncs for LoongArch.
Since the infrastructure is already implemented in BPF core, the only
thing need to be done is to override bpf_jit_supports_far_kfunc_call().

Before this change, several test_verifier tests failed:

  # ./test_verifier | grep # | grep FAIL
  #119/p calls: invalid kfunc call: ptr_to_mem to struct with non-scalar FAIL
  #120/p calls: invalid kfunc call: ptr_to_mem to struct with nesting depth > 4 FAIL
  #121/p calls: invalid kfunc call: ptr_to_mem to struct with FAM FAIL
  #122/p calls: invalid kfunc call: reg->type != PTR_TO_CTX FAIL
  #123/p calls: invalid kfunc call: void * not allowed in func proto without mem size arg FAIL
  #124/p calls: trigger reg2btf_ids[reg->type] for reg->type > __BPF_REG_TYPE_MAX FAIL
  #125/p calls: invalid kfunc call: reg->off must be zero when passed to release kfunc FAIL
  #126/p calls: invalid kfunc call: don't match first member type when passed to release kfunc FAIL
  #127/p calls: invalid kfunc call: PTR_TO_BTF_ID with negative offset FAIL
  #128/p calls: invalid kfunc call: PTR_TO_BTF_ID with variable offset FAIL
  #129/p calls: invalid kfunc call: referenced arg needs refcounted PTR_TO_BTF_ID FAIL
  #130/p calls: valid kfunc call: referenced arg needs refcounted PTR_TO_BTF_ID FAIL
  #486/p map_kptr: ref: reference state created and released on xchg FAIL

This is because the kfuncs in the loaded module are far away from
__bpf_call_base:

  ffff800002009440 t bpf_kfunc_call_test_fail1    [bpf_testmod]
  9000000002e128d8 T __bpf_call_base

The offset relative to __bpf_call_base does NOT fit in s32, which breaks
the assumption in BPF core. Enable bpf_jit_supports_far_kfunc_call() lifts
this limit.

Note that to reproduce the above result, tools/testing/selftests/bpf/config
should be applied, and run the test with JIT enabled, unpriv BPF enabled.

With this change, the test_verifier tests now all passed:

  # ./test_verifier
  ...
  Summary: 777 PASSED, 0 SKIPPED, 0 FAILED

Tested-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
pull bot pushed a commit that referenced this pull request Oct 5, 2025
…nter dereference

There is a critical race condition in kprobe initialization that can lead to
NULL pointer dereference and kernel crash.

[1135630.084782] Unable to handle kernel paging request at virtual address 0000710a04630000
...
[1135630.260314] pstate: 404003c9 (nZcv DAIF +PAN -UAO)
[1135630.269239] pc : kprobe_perf_func+0x30/0x260
[1135630.277643] lr : kprobe_dispatcher+0x44/0x60
[1135630.286041] sp : ffffaeff4977fa40
[1135630.293441] x29: ffffaeff4977fa40 x28: ffffaf015340e400
[1135630.302837] x27: 0000000000000000 x26: 0000000000000000
[1135630.312257] x25: ffffaf029ed108a8 x24: ffffaf015340e528
[1135630.321705] x23: ffffaeff4977fc50 x22: ffffaeff4977fc50
[1135630.331154] x21: 0000000000000000 x20: ffffaeff4977fc50
[1135630.340586] x19: ffffaf015340e400 x18: 0000000000000000
[1135630.349985] x17: 0000000000000000 x16: 0000000000000000
[1135630.359285] x15: 0000000000000000 x14: 0000000000000000
[1135630.368445] x13: 0000000000000000 x12: 0000000000000000
[1135630.377473] x11: 0000000000000000 x10: 0000000000000000
[1135630.386411] x9 : 0000000000000000 x8 : 0000000000000000
[1135630.395252] x7 : 0000000000000000 x6 : 0000000000000000
[1135630.403963] x5 : 0000000000000000 x4 : 0000000000000000
[1135630.412545] x3 : 0000710a04630000 x2 : 0000000000000006
[1135630.421021] x1 : ffffaeff4977fc50 x0 : 0000710a04630000
[1135630.429410] Call trace:
[1135630.434828]  kprobe_perf_func+0x30/0x260
[1135630.441661]  kprobe_dispatcher+0x44/0x60
[1135630.448396]  aggr_pre_handler+0x70/0xc8
[1135630.454959]  kprobe_breakpoint_handler+0x140/0x1e0
[1135630.462435]  brk_handler+0xbc/0xd8
[1135630.468437]  do_debug_exception+0x84/0x138
[1135630.475074]  el1_dbg+0x18/0x8c
[1135630.480582]  security_file_permission+0x0/0xd0
[1135630.487426]  vfs_write+0x70/0x1c0
[1135630.493059]  ksys_write+0x5c/0xc8
[1135630.498638]  __arm64_sys_write+0x24/0x30
[1135630.504821]  el0_svc_common+0x78/0x130
[1135630.510838]  el0_svc_handler+0x38/0x78
[1135630.516834]  el0_svc+0x8/0x1b0

kernel/trace/trace_kprobe.c: 1308
0xffff3df8995039ec <kprobe_perf_func+0x2c>:     ldr     x21, [x24,#120]
include/linux/compiler.h: 294
0xffff3df8995039f0 <kprobe_perf_func+0x30>:     ldr     x1, [x21,x0]

kernel/trace/trace_kprobe.c
1308: head = this_cpu_ptr(call->perf_events);
1309: if (hlist_empty(head))
1310: 	return 0;

crash> struct trace_event_call -o
struct trace_event_call {
  ...
  [120] struct hlist_head *perf_events;  //(call->perf_event)
  ...
}

crash> struct trace_event_call ffffaf015340e528
struct trace_event_call {
  ...
  perf_events = 0xffff0ad5fa89f088, //this value is correct, but x21 = 0
  ...
}

Race Condition Analysis:

The race occurs between kprobe activation and perf_events initialization:

  CPU0                                    CPU1
  ====                                    ====
  perf_kprobe_init
    perf_trace_event_init
      tp_event->perf_events = list;(1)
      tp_event->class->reg (2)← KPROBE ACTIVE
                                          Debug exception triggers
                                          ...
                                          kprobe_dispatcher
                                            kprobe_perf_func (tk->tp.flags & TP_FLAG_PROFILE)
                                              head = this_cpu_ptr(call->perf_events)(3)
                                              (perf_events is still NULL)

Problem:
1. CPU0 executes (1) assigning tp_event->perf_events = list
2. CPU0 executes (2) enabling kprobe functionality via class->reg()
3. CPU1 triggers and reaches kprobe_dispatcher
4. CPU1 checks TP_FLAG_PROFILE - condition passes (step 2 completed)
5. CPU1 calls kprobe_perf_func() and crashes at (3) because
   call->perf_events is still NULL

CPU1 sees that kprobe functionality is enabled but does not see that
perf_events has been assigned.

Add pairing read and write memory barriers to guarantee that if CPU1
sees that kprobe functionality is enabled, it must also see that
perf_events has been assigned.

Link: https://lore.kernel.org/all/20251001022025.44626-1-chenyuan_fl@163.com/

Fixes: 50d7805 ("tracing/kprobes: Add probe handler dispatcher to support perf and ftrace concurrent use")
Cc: stable@vger.kernel.org
Signed-off-by: Yuan Chen <chenyuan@kylinos.cn>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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