linux-stable.git/arch/powerpc/kernel, branch v5.4.86

powerpc/rtas: Fix typo of ibm,open-errinjct in RTAS filter

2020-12-30T10:51:38+00:00

commit f10881a46f8914428110d110140a455c66bdf27b upstream.

Commit bd59380c5ba4 ("powerpc/rtas: Restrict RTAS requests from userspace")
introduced the following error when invoking the errinjct userspace
tool:

  [root@ltcalpine2-lp5 librtas]# errinjct open
  [327884.071171] sys_rtas: RTAS call blocked - exploit attempt?
  [327884.071186] sys_rtas: token=0x26, nargs=0 (called by errinjct)
  errinjct: Could not open RTAS error injection facility
  errinjct: librtas: open: Unexpected I/O error

The entry for ibm,open-errinjct in rtas_filter array has a typo where
the "j" is omitted in the rtas call name. After fixing this typo the
errinjct tool functions again as expected.

  [root@ltcalpine2-lp5 linux]# errinjct open
  RTAS error injection facility open, token = 1

Fixes: bd59380c5ba4 ("powerpc/rtas: Restrict RTAS requests from userspace")
Cc: stable@vger.kernel.org
Signed-off-by: Tyrel Datwyler 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20201208195434.8289-1-tyreld@linux.ibm.com
Signed-off-by: Greg Kroah-Hartman

powerpc/64: Fix an EMIT_BUG_ENTRY in head_64.S

2020-12-30T10:51:17+00:00

[ Upstream commit fe18a35e685c9bdabc8b11b3e19deb85a068b75d ]

Commit 63ce271b5e37 ("powerpc/prom: convert PROM_BUG() to standard
trap") added an EMIT_BUG_ENTRY for the trap after the branch to
start_kernel(). The EMIT_BUG_ENTRY was for the address "0b", however the
trap was not labeled with "0". Hence the address used for bug is in
relative_toc() where the previous "0" label is. Label the trap as "0" so
the correct address is used.

Fixes: 63ce271b5e37 ("powerpc/prom: convert PROM_BUG() to standard trap")
Signed-off-by: Jordan Niethe 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20201130004404.30953-1-jniethe5@gmail.com
Signed-off-by: Sasha Levin

powerpc: Avoid broken GCC attribute((optimize))

2020-12-30T10:51:09+00:00

[ Upstream commit a7223f5bfcaeade4a86d35263493bcda6c940891 ]

Commit 7053f80d9696 ("powerpc/64: Prevent stack protection in early
boot") introduced a couple of uses of __attribute__((optimize)) with
function scope, to disable the stack protector in some early boot
code.

Unfortunately, and this is documented in the GCC man pages [0],
overriding function attributes for optimization is broken, and is only
supported for debug scenarios, not for production: the problem appears
to be that setting GCC -f flags using this method will cause it to
forget about some or all other optimization settings that have been
applied.

So the only safe way to disable the stack protector is to disable it
for the entire source file.

[0] https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html

Fixes: 7053f80d9696 ("powerpc/64: Prevent stack protection in early boot")
Signed-off-by: Ard Biesheuvel 
[mpe: Drop one remaining use of __nostackprotector, reported by snowpatch]
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20201028080433.26799-1-ardb@kernel.org
Signed-off-by: Sasha Levin

powerpc/64: Set up a kernel stack for secondaries before cpu_restore()

2020-12-30T10:51:04+00:00

[ Upstream commit 3c0b976bf20d236c57adcefa80f86a0a1d737727 ]

Currently in generic_secondary_smp_init(), cur_cpu_spec->cpu_restore()
is called before a stack has been set up in r1. This was previously fine
as the cpu_restore() functions were implemented in assembly and did not
use a stack. However commit 5a61ef74f269 ("powerpc/64s: Support new
device tree binding for discovering CPU features") used
__restore_cpu_cpufeatures() as the cpu_restore() function for a
device-tree features based cputable entry. This is a C function and
hence uses a stack in r1.

generic_secondary_smp_init() is entered on the secondary cpus via the
primary cpu using the OPAL call opal_start_cpu(). In OPAL, each hardware
thread has its own stack. The OPAL call is ran in the primary's hardware
thread. During the call, a job is scheduled on a secondary cpu that will
start executing at the address of generic_secondary_smp_init().  Hence
the value that will be left in r1 when the secondary cpu enters the
kernel is part of that secondary cpu's individual OPAL stack. This means
that __restore_cpu_cpufeatures() will write to that OPAL stack. This is
not horribly bad as each hardware thread has its own stack and the call
that enters the kernel from OPAL never returns, but it is still wrong
and should be corrected.

Create the temp kernel stack before calling cpu_restore().

As noted by mpe, for a kexec boot, the secondary CPUs are released from
the spin loop at address 0x60 by smp_release_cpus() and then jump to
generic_secondary_smp_init(). The call to smp_release_cpus() is in
setup_arch(), and it comes before the call to emergency_stack_init().
emergency_stack_init() allocates an emergency stack in the PACA for each
CPU.  This address in the PACA is what is used to set up the temp kernel
stack in generic_secondary_smp_init(). Move releasing the secondary CPUs
to after the PACAs have been allocated an emergency stack, otherwise the
PACA stack pointer will contain garbage and hence the temp kernel stack
created from it will be broken.

Fixes: 5a61ef74f269 ("powerpc/64s: Support new device tree binding for discovering CPU features")
Signed-off-by: Jordan Niethe 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20201014072837.24539-1-jniethe5@gmail.com
Signed-off-by: Sasha Levin

powerpc/8xx: Always fault when _PAGE_ACCESSED is not set

2020-11-22T09:14:12+00:00

commit 29daf869cbab69088fe1755d9dd224e99ba78b56 upstream.

The kernel expects pte_young() to work regardless of CONFIG_SWAP.

Make sure a minor fault is taken to set _PAGE_ACCESSED when it
is not already set, regardless of the selection of CONFIG_SWAP.

This adds at least 3 instructions to the TLB miss exception
handlers fast path. Following patch will reduce this overhead.

Also update the rotation instruction to the correct number of bits
to reflect all changes done to _PAGE_ACCESSED over time.

Fixes: d069cb4373fe ("powerpc/8xx: Don't touch ACCESSED when no SWAP.")
Fixes: 5f356497c384 ("powerpc/8xx: remove unused _PAGE_WRITETHRU")
Fixes: e0a8e0d90a9f ("powerpc/8xx: Handle PAGE_USER via APG bits")
Fixes: 5b2753fc3e8a ("powerpc/8xx: Implementation of PAGE_EXEC")
Fixes: a891c43b97d3 ("powerpc/8xx: Prepare handlers for _PAGE_HUGE for 512k pages.")
Cc: stable@vger.kernel.org
Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/af834e8a0f1fa97bfae65664950f0984a70c4750.1602492856.git.christophe.leroy@csgroup.eu
Signed-off-by: Greg Kroah-Hartman

selftests/powerpc: entry flush test

2020-11-22T09:14:11+00:00

commit 89a83a0c69c81a25ce91002b90ca27ed86132a0a upstream.

Add a test modelled on the RFI flush test which counts the number
of L1D misses doing a simple syscall with the entry flush on and off.

For simplicity of backporting, this test duplicates a lot of code from
the upstream rfi_flush. This is cleaned up upstream, but we don't clean
it up here because it would involve bringing in even more commits.

Signed-off-by: Daniel Axtens 
Signed-off-by: Greg Kroah-Hartman

powerpc/64s: flush L1D after user accesses

2020-11-22T09:14:10+00:00

commit 9a32a7e78bd0cd9a9b6332cbdc345ee5ffd0c5de upstream.

IBM Power9 processors can speculatively operate on data in the L1 cache
before it has been completely validated, via a way-prediction mechanism. It
is not possible for an attacker to determine the contents of impermissible
memory using this method, since these systems implement a combination of
hardware and software security measures to prevent scenarios where
protected data could be leaked.

However these measures don't address the scenario where an attacker induces
the operating system to speculatively execute instructions using data that
the attacker controls. This can be used for example to speculatively bypass
"kernel user access prevention" techniques, as discovered by Anthony
Steinhauser of Google's Safeside Project. This is not an attack by itself,
but there is a possibility it could be used in conjunction with
side-channels or other weaknesses in the privileged code to construct an
attack.

This issue can be mitigated by flushing the L1 cache between privilege
boundaries of concern. This patch flushes the L1 cache after user accesses.

This is part of the fix for CVE-2020-4788.

Signed-off-by: Nicholas Piggin 
Signed-off-by: Daniel Axtens 
Signed-off-by: Greg Kroah-Hartman

powerpc/64s: flush L1D on kernel entry

2020-11-22T09:14:10+00:00

commit f79643787e0a0762d2409b7b8334e83f22d85695 upstream.

[backporting note: we need to mark some exception handlers as out-of-line
 because the flushing makes them take too much space -- dja]

IBM Power9 processors can speculatively operate on data in the L1 cache
before it has been completely validated, via a way-prediction mechanism. It
is not possible for an attacker to determine the contents of impermissible
memory using this method, since these systems implement a combination of
hardware and software security measures to prevent scenarios where
protected data could be leaked.

However these measures don't address the scenario where an attacker induces
the operating system to speculatively execute instructions using data that
the attacker controls. This can be used for example to speculatively bypass
"kernel user access prevention" techniques, as discovered by Anthony
Steinhauser of Google's Safeside Project. This is not an attack by itself,
but there is a possibility it could be used in conjunction with
side-channels or other weaknesses in the privileged code to construct an
attack.

This issue can be mitigated by flushing the L1 cache between privilege
boundaries of concern. This patch flushes the L1 cache on kernel entry.

This is part of the fix for CVE-2020-4788.

Signed-off-by: Nicholas Piggin 
Signed-off-by: Daniel Axtens 
Signed-off-by: Greg Kroah-Hartman

powerpc/603: Always fault when _PAGE_ACCESSED is not set

2020-11-18T18:20:33+00:00

commit 11522448e641e8f1690c9db06e01985e8e19b401 upstream.

The kernel expects pte_young() to work regardless of CONFIG_SWAP.

Make sure a minor fault is taken to set _PAGE_ACCESSED when it
is not already set, regardless of the selection of CONFIG_SWAP.

Fixes: 84de6ab0e904 ("powerpc/603: don't handle PAGE_ACCESSED in TLB miss handlers.")
Cc: stable@vger.kernel.org
Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/a44367744de54e2315b2f1a8cbbd7f88488072e0.1602342806.git.christophe.leroy@csgroup.eu
Signed-off-by: Greg Kroah-Hartman

powerpc/eeh_cache: Fix a possible debugfs deadlock

2020-11-18T18:20:18+00:00

[ Upstream commit fd552e0542b4532483289cce48fdbd27b692984b ]

Lockdep complains that a possible deadlock below in
eeh_addr_cache_show() because it is acquiring a lock with IRQ enabled,
but eeh_addr_cache_insert_dev() needs to acquire the same lock with IRQ
disabled. Let's just make eeh_addr_cache_show() acquire the lock with
IRQ disabled as well.

        CPU0                    CPU1
        ----                    ----
   lock(&pci_io_addr_cache_root.piar_lock);
                                local_irq_disable();
                                lock(&tp->lock);
                                lock(&pci_io_addr_cache_root.piar_lock);
   
     lock(&tp->lock);

  *** DEADLOCK ***

  lock_acquire+0x140/0x5f0
  _raw_spin_lock_irqsave+0x64/0xb0
  eeh_addr_cache_insert_dev+0x48/0x390
  eeh_probe_device+0xb8/0x1a0
  pnv_pcibios_bus_add_device+0x3c/0x80
  pcibios_bus_add_device+0x118/0x290
  pci_bus_add_device+0x28/0xe0
  pci_bus_add_devices+0x54/0xb0
  pcibios_init+0xc4/0x124
  do_one_initcall+0xac/0x528
  kernel_init_freeable+0x35c/0x3fc
  kernel_init+0x24/0x148
  ret_from_kernel_thread+0x5c/0x80

  lock_acquire+0x140/0x5f0
  _raw_spin_lock+0x4c/0x70
  eeh_addr_cache_show+0x38/0x110
  seq_read+0x1a0/0x660
  vfs_read+0xc8/0x1f0
  ksys_read+0x74/0x130
  system_call_exception+0xf8/0x1d0
  system_call_common+0xe8/0x218

Fixes: 5ca85ae6318d ("powerpc/eeh_cache: Add a way to dump the EEH address cache")
Signed-off-by: Qian Cai 
Reviewed-by: Oliver O'Halloran 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20201028152717.8967-1-cai@redhat.com
Signed-off-by: Sasha Levin

linux-stable.git/arch/powerpc/kernel, branch v5.4.86

powerpc/rtas: Fix typo of ibm,open-errinjct in RTAS filter

powerpc/64: Fix an EMIT_BUG_ENTRY in head_64.S

powerpc: Avoid broken GCC __attribute__((optimize))

powerpc/64: Set up a kernel stack for secondaries before cpu_restore()

powerpc/8xx: Always fault when _PAGE_ACCESSED is not set

selftests/powerpc: entry flush test

powerpc/64s: flush L1D after user accesses

powerpc/64s: flush L1D on kernel entry

powerpc/603: Always fault when _PAGE_ACCESSED is not set

powerpc/eeh_cache: Fix a possible debugfs deadlock

powerpc: Avoid broken GCC attribute((optimize))