1. 19 Oct, 2020 5 commits
    • Michael Neuling's avatar
      powerpc: Fix undetected data corruption with P9N DD2.1 VSX CI load emulation · 1da4a027
      Michael Neuling authored
      __get_user_atomic_128_aligned() stores to kaddr using stvx which is a
      VMX store instruction, hence kaddr must be 16 byte aligned otherwise
      the store won't occur as expected.
      
      Unfortunately when we call __get_user_atomic_128_aligned() in
      p9_hmi_special_emu(), the buffer we pass as kaddr (ie. vbuf) isn't
      guaranteed to be 16B aligned. This means that the write to vbuf in
      __get_user_atomic_128_aligned() has the bottom bits of the address
      truncated. This results in other local variables being
      overwritten. Also vbuf will not contain the correct data which results
      in the userspace emulation being wrong and hence undetected user data
      corruption.
      
      In the past we've been mostly lucky as vbuf has ended up aligned but
      this is fragile and isn't always true. CONFIG_STACKPROTECTOR in
      particular can change the stack arrangement enough that our luck runs
      out.
      
      This issue only occurs on POWER9 Nimbus <= DD2.1 bare metal.
      
      The fix is to align vbuf to a 16 byte boundary.
      
      Fixes: 5080332c ("powerpc/64s: Add workaround for P9 vector CI load issue")
      Cc: stable@vger.kernel.org # v4.15+
      Signed-off-by: default avatarMichael Neuling <mikey@neuling.org>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      Link: https://lore.kernel.org/r/20201013043741.743413-1-mikey@neuling.org
      1da4a027
    • Vasant Hegde's avatar
      powerpc/powernv/dump: Handle multiple writes to ack attribute · 358ab796
      Vasant Hegde authored
      Even though we use self removing sysfs helper, we still need
      to make sure we do the final kobject delete conditionally.
      sysfs_remove_file_self() will handle parallel calls to remove
      the sysfs attribute file and returns true only in the caller
      that removed the attribute file. The other parallel callers
      are returned false. Do the final kobject delete checking
      the return value of sysfs_remove_file_self().
      Signed-off-by: default avatarVasant Hegde <hegdevasant@linux.vnet.ibm.com>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      Link: https://lore.kernel.org/r/20201017164236.264713-1-hegdevasant@linux.vnet.ibm.com
      358ab796
    • Vasant Hegde's avatar
      powerpc/powernv/dump: Fix race while processing OPAL dump · 0a43ae3e
      Vasant Hegde authored
      Every dump reported by OPAL is exported to userspace through a sysfs
      interface and notified using kobject_uevent(). The userspace daemon
      (opal_errd) then reads the dump and acknowledges that the dump is
      saved safely to disk. Once acknowledged the kernel removes the
      respective sysfs file entry causing respective resources to be
      released including kobject.
      
      However it's possible the userspace daemon may already be scanning
      dump entries when a new sysfs dump entry is created by the kernel.
      User daemon may read this new entry and ack it even before kernel can
      notify userspace about it through kobject_uevent() call. If that
      happens then we have a potential race between
      dump_ack_store->kobject_put() and kobject_uevent which can lead to
      use-after-free of a kernfs object resulting in a kernel crash.
      
      This patch fixes this race by protecting the sysfs file
      creation/notification by holding a reference count on kobject until we
      safely send kobject_uevent().
      
      The function create_dump_obj() returns the dump object which if used
      by caller function will end up in use-after-free problem again.
      However, the return value of create_dump_obj() function isn't being
      used today and there is no need as well. Hence change it to return
      void to make this fix complete.
      
      Fixes: c7e64b9c ("powerpc/powernv Platform dump interface")
      Signed-off-by: default avatarVasant Hegde <hegdevasant@linux.vnet.ibm.com>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      Link: https://lore.kernel.org/r/20201017164210.264619-1-hegdevasant@linux.vnet.ibm.com
      0a43ae3e
    • Srikar Dronamraju's avatar
      powerpc/smp: Use GFP_ATOMIC while allocating tmp mask · 84dbf66c
      Srikar Dronamraju authored
      Qian Cai reported a regression where CPU Hotplug fails with the latest
      powerpc/next
      
      BUG: sleeping function called from invalid context at mm/slab.h:494
      in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 0, name: swapper/88
      no locks held by swapper/88/0.
      irq event stamp: 18074448
      hardirqs last  enabled at (18074447): [<c0000000001a2a7c>] tick_nohz_idle_enter+0x9c/0x110
      hardirqs last disabled at (18074448): [<c000000000106798>] do_idle+0x138/0x3b0
      do_idle at kernel/sched/idle.c:253 (discriminator 1)
      softirqs last  enabled at (18074440): [<c0000000000bbec4>] irq_enter_rcu+0x94/0xa0
      softirqs last disabled at (18074439): [<c0000000000bbea0>] irq_enter_rcu+0x70/0xa0
      CPU: 88 PID: 0 Comm: swapper/88 Tainted: G        W         5.9.0-rc8-next-20201007 #1
      Call Trace:
      [c00020000a4bfcf0] [c000000000649e98] dump_stack+0xec/0x144 (unreliable)
      [c00020000a4bfd30] [c0000000000f6c34] ___might_sleep+0x2f4/0x310
      [c00020000a4bfdb0] [c000000000354f94] slab_pre_alloc_hook.constprop.82+0x124/0x190
      [c00020000a4bfe00] [c00000000035e9e8] __kmalloc_node+0x88/0x3a0
      slab_alloc_node at mm/slub.c:2817
      (inlined by) __kmalloc_node at mm/slub.c:4013
      [c00020000a4bfe80] [c0000000006494d8] alloc_cpumask_var_node+0x38/0x80
      kmalloc_node at include/linux/slab.h:577
      (inlined by) alloc_cpumask_var_node at lib/cpumask.c:116
      [c00020000a4bfef0] [c00000000003eedc] start_secondary+0x27c/0x800
      update_mask_by_l2 at arch/powerpc/kernel/smp.c:1267
      (inlined by) add_cpu_to_masks at arch/powerpc/kernel/smp.c:1387
      (inlined by) start_secondary at arch/powerpc/kernel/smp.c:1420
      [c00020000a4bff90] [c00000000000c468] start_secondary_resume+0x10/0x14
      
      Allocating a temporary mask while performing a CPU Hotplug operation
      with CONFIG_CPUMASK_OFFSTACK enabled, leads to calling a sleepable
      function from a atomic context. Fix this by allocating the temporary
      mask with GFP_ATOMIC flag. Also instead of having to allocate twice,
      allocate the mask in the caller so that we only have to allocate once.
      If the allocation fails, assume the mask to be same as sibling mask, which
      will make the scheduler to drop this domain for this CPU.
      
      Fixes: 70a94089 ("powerpc/smp: Optimize update_coregroup_mask")
      Fixes: 3ab33d6d ("powerpc/smp: Optimize update_mask_by_l2")
      Reported-by: default avatarQian Cai <cai@redhat.com>
      Signed-off-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      Link: https://lore.kernel.org/r/20201019042716.106234-3-srikar@linux.vnet.ibm.com
      84dbf66c
    • Srikar Dronamraju's avatar
      powerpc/smp: Remove unnecessary variable · 966730a6
      Srikar Dronamraju authored
      Commit 3ab33d6d ("powerpc/smp: Optimize update_mask_by_l2")
      introduced submask_fn in update_mask_by_l2 to track the right submask.
      However commit f6606cfd ("powerpc/smp: Dont assume l2-cache to be
      superset of sibling") introduced sibling_mask in update_mask_by_l2 to
      track the same submask. Remove sibling_mask in favour of submask_fn.
      Signed-off-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      Link: https://lore.kernel.org/r/20201019042716.106234-2-srikar@linux.vnet.ibm.com
      966730a6
  2. 16 Oct, 2020 2 commits
  3. 15 Oct, 2020 1 commit
    • Qian Cai's avatar
      Revert "powerpc/pci: unmap legacy INTx interrupts when a PHB is removed" · ffd0b25c
      Qian Cai authored
      This reverts commit 3a3181e1 which
      causes memory corruptions on POWER9 powernv. eg:
      
        pci_bus 0035:08: busn_res: [bus 08-0c] is released
        =============================================================================
        BUG kmalloc-16 (Tainted: G        W  O     ): Object already free
        -----------------------------------------------------------------------------
        Disabling lock debugging due to kernel taint
        INFO: Allocated in pcibios_scan_phb+0x104/0x3e0 age=1960714 cpu=4 pid=1
        	__slab_alloc+0xa4/0xf0
        	__kmalloc+0x294/0x330
        	pcibios_scan_phb+0x104/0x3e0
        	pcibios_init+0x84/0x124
        	do_one_initcall+0xac/0x528
        	kernel_init_freeable+0x35c/0x3fc
        	kernel_init+0x24/0x148
        	ret_from_kernel_thread+0x5c/0x80
        INFO: Freed in pcibios_remove_bus+0x70/0x90 age=0 cpu=16 pid=1717146
        	kfree+0x49c/0x510
        	pcibios_remove_bus+0x70/0x90
        	pci_remove_bus+0xe4/0x110
        	pci_remove_bus_device+0x74/0x170
        	pci_remove_bus_device+0x4c/0x170
        	pci_stop_and_remove_bus_device_locked+0x34/0x50
        	remove_store+0xc0/0xe0
        	dev_attr_store+0x30/0x50
        	sysfs_kf_write+0x68/0xb0
        	kernfs_fop_write+0x114/0x260
        	vfs_write+0xe4/0x260
        	ksys_write+0x74/0x130
        	system_call_exception+0xf8/0x1d0
        	system_call_common+0xe8/0x218
        INFO: Slab 0x0000000099caaf22 objects=178 used=174 fp=0x00000000006a64b0 flags=0x7fff8000000201
        INFO: Object 0x00000000f360132d @offset=30192 fp=0x0000000000000000
      Signed-off-by: default avatarQian Cai <cai@lca.pw>
      Acked-by: default avatarOliver O'Halloran <oohall@gmail.com>
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      Link: https://lore.kernel.org/r/20201014182811.12027-1-cai@lca.pw
      ffd0b25c
  4. 14 Oct, 2020 1 commit
  5. 08 Oct, 2020 25 commits
  6. 07 Oct, 2020 6 commits