linux.git/arch/powerpc/kernel/paca.c, branch v5.4.211

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/pseries/svm: Fix incorrect check for shared_lppaca_size

2020-07-22T07:33:14+00:00

commit b710d27bf72068b15b2f0305d825988183e2ff28 upstream.

Early secure guest boot hits the below crash while booting with
vcpus numbers aligned with page boundary for PAGE size of 64k
and LPPACA size of 1k i.e 64, 128 etc.

  Partition configured for 64 cpus.
  CPU maps initialized for 1 thread per core
  ------------[ cut here ]------------
  kernel BUG at arch/powerpc/kernel/paca.c:89!
  Oops: Exception in kernel mode, sig: 5 [#1]
  LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA pSeries

This is due to the BUG_ON() for shared_lppaca_total_size equal to
shared_lppaca_size. Instead the code should only BUG_ON() if we have
exceeded the total_size, which indicates we've overflowed the array.

Fixes: bd104e6db6f0 ("powerpc/pseries/svm: Use shared memory for LPPACA structures")
Cc: stable@vger.kernel.org # v5.4+
Signed-off-by: Satheesh Rajendran 
Reviewed-by: Laurent Dufour 
Reviewed-by: Thiago Jung Bauermann 
[mpe: Reword change log to clarify we're fixing not removing the check]
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20200619070113.16696-1-sathnaga@linux.vnet.ibm.com
Signed-off-by: Greg Kroah-Hartman

powerpc/64: Prevent stack protection in early boot

2020-04-17T08:50:23+00:00

commit 7053f80d96967d8e72e9f2a724bbfc3906ce2b07 upstream.

The previous commit reduced the amount of code that is run before we
setup a paca. However there are still a few remaining functions that
run with no paca, or worse, with an arbitrary value in r13 that will
be used as a paca pointer.

In particular the stack protector canary is stored in the paca, so if
stack protector is activated for any of these functions we will read
the stack canary from wherever r13 points. If r13 happens to point
outside of memory we will get a machine check / checkstop.

For example if we modify initialise_paca() to trigger stack
protection, and then boot in the mambo simulator with r13 poisoned in
skiboot before calling the kernel:

  DEBUG: 19952232: (19952232): INSTRUCTION: PC=0xC0000000191FC1E8: [0x3C4C006D]: addis   r2,r12,0x6D [fetch]
  DEBUG: 19952236: (19952236): INSTRUCTION: PC=0xC00000001807EAD8: [0x7D8802A6]: mflr    r12 [fetch]
  FATAL ERROR: 19952276: (19952276): Check Stop for 0:0: Machine Check with ME bit of MSR off
  DEBUG: 19952276: (19952276): INSTRUCTION: PC=0xC0000000191FCA7C: [0xE90D0CF8]: ld      r8,0xCF8(r13) [Instruction Failed]
  INFO: 19952276: (19952277): ** Execution stopped: Mambo Error, Machine Check Stop,  **
  systemsim % bt
  pc:                             0xC0000000191FCA7C      initialise_paca+0x54
  lr:                             0xC0000000191FC22C      early_setup+0x44
  stack:0x00000000198CBED0        0x0     +0x0
  stack:0x00000000198CBF00        0xC0000000191FC22C      early_setup+0x44
  stack:0x00000000198CBF90        0x1801C968      +0x1801C968

So annotate the relevant functions to ensure stack protection is never
enabled for them.

Fixes: 06ec27aea9fc ("powerpc/64: add stack protector support")
Cc: stable@vger.kernel.org # v4.20+
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20200320032116.1024773-2-mpe@ellerman.id.au
Signed-off-by: Greg Kroah-Hartman

powerpc/64: Setup a paca before parsing device tree etc.

2020-04-17T08:50:23+00:00

commit d4a8e98621543d5798421eed177978bf2b3cdd11 upstream.

Currently we set up the paca after parsing the device tree for CPU
features. Prior to that, r13 contains random data, which means there
is random data in r13 while we're running the generic dt parsing code.

This random data varies depending on whether we boot through a vmlinux
or a zImage: for the vmlinux case it's usually around zero, but for
zImages we see random values like 912a72603d420015.

This is poor practice, and can also lead to difficult-to-debug
crashes. For example, when kcov is enabled, the kcov instrumentation
attempts to read preempt_count out of the current task, which goes via
the paca. This then crashes in the zImage case.

Similarly stack protector can cause crashes if r13 is bogus, by
reading from the stack canary in the paca.

To resolve this:

 - move the paca setup to before the CPU feature parsing.

 - because we no longer have access to CPU feature flags in paca
 setup, change the HV feature test in the paca setup path to consider
 the actual value of the MSR rather than the CPU feature.

Translations get switched on once we leave early_setup, so I think
we'd already catch any other cases where the paca or task aren't set
up.

Boot tested on a P9 guest and host.

Fixes: fb0b0a73b223 ("powerpc: Enable kcov")
Fixes: 06ec27aea9fc ("powerpc/64: add stack protector support")
Cc: stable@vger.kernel.org # v4.20+
Reviewed-by: Andrew Donnellan 
Suggested-by: Michael Ellerman 
Signed-off-by: Daniel Axtens 
[mpe: Reword comments & change log a bit to mention stack protector]
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20200320032116.1024773-1-mpe@ellerman.id.au
Signed-off-by: Greg Kroah-Hartman

powerpc/pseries/svm: Use shared memory for LPPACA structures

2019-08-29T23:55:40+00:00

LPPACA structures need to be shared with the host. Hence they need to be in
shared memory. Instead of allocating individual chunks of memory for a
given structure from memblock, a contiguous chunk of memory is allocated
and then converted into shared memory. Subsequent allocation requests will
come from the contiguous chunk which will be always shared memory for all
structures.

While we are able to use a kmem_cache constructor for the Debug Trace Log,
LPPACAs are allocated very early in the boot process (before SLUB is
available) so we need to use a simpler scheme here.

Introduce helper is_svm_platform() which uses the S bit of the MSR to tell
whether we're running as a secure guest.

Signed-off-by: Anshuman Khandual 
Signed-off-by: Thiago Jung Bauermann 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20190820021326.6884-9-bauerman@linux.ibm.com

powerpc/pseries: Add and use LPPACA_SIZE constant

2019-08-29T23:55:40+00:00

Helps document what the hard-coded number means.

Also take the opportunity to fix an #endif comment.

Suggested-by: Alexey Kardashevskiy 
Signed-off-by: Thiago Jung Bauermann 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20190820021326.6884-8-bauerman@linux.ibm.com

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

2019-05-30T18:26:32+00:00

Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman

powerpc/mm: Add helpers for accessing hash translation related variables

2019-04-21T13:12:38+00:00

We want to switch to allocating them runtime only when hash translation is
enabled. Add helpers so that both book3s and nohash can be adapted to
upcoming change easily.

Signed-off-by: Aneesh Kumar K.V 
Signed-off-by: Michael Ellerman

powerpc: use memblock functions returning virtual address

2019-03-12T17:04:01+00:00

Since only the virtual address of allocated blocks is used, lets use
functions returning directly virtual address.

Those functions have the advantage of also zeroing the block.

[rppt@linux.ibm.com: powerpc: remove duplicated alloc_stack() function]
  Link: http://lkml.kernel.org/r/20190226064032.GA5873@rapoport-lnx
[rppt@linux.ibm.com: updated error message in alloc_stack() to be more verbose]
[rppt@linux.ibm.com: convereted several additional call sites ]
Link: http://lkml.kernel.org/r/1548057848-15136-3-git-send-email-rppt@linux.ibm.com
Signed-off-by: Christophe Leroy 
Signed-off-by: Mike Rapoport 
Acked-by: Michael Ellerman 
Cc: Catalin Marinas 
Cc: Christoph Hellwig 
Cc: "David S. Miller" 
Cc: Dennis Zhou 
Cc: Geert Uytterhoeven 
Cc: Greentime Hu 
Cc: Greg Kroah-Hartman 
Cc: Guan Xuetao 
Cc: Guo Ren 
Cc: Guo Ren 				[c-sky]
Cc: Heiko Carstens 
Cc: Juergen Gross 			[Xen]
Cc: Mark Salter 
Cc: Matt Turner 
Cc: Max Filippov 
Cc: Michal Simek 
Cc: Paul Burton 
Cc: Petr Mladek 
Cc: Richard Weinberger 
Cc: Rich Felker 
Cc: Rob Herring 
Cc: Rob Herring 
Cc: Russell King 
Cc: Stafford Horne 
Cc: Tony Luck 
Cc: Vineet Gupta 
Cc: Yoshinori Sato 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

powerpc: prefer memblock APIs returning virtual address

2019-03-08T02:32:03+00:00

Patch series "memblock: simplify several early memory allocation", v4.

These patches simplify some of the early memory allocations by replacing
usage of older memblock APIs with newer and shinier ones.

Quite a few places in the arch/ code allocated memory using a memblock
API that returns a physical address of the allocated area, then
converted this physical address to a virtual one and then used memset(0)
to clear the allocated range.

More recent memblock APIs do all the three steps in one call and their
usage simplifies the code.

It's important to note that regardless of API used, the core allocation
is nearly identical for any set of memblock allocators: first it tries
to find a free memory with all the constraints specified by the caller
and then falls back to the allocation with some or all constraints
disabled.

The first three patches perform the conversion of call sites that have
exact requirements for the node and the possible memory range.

The fourth patch is a bit one-off as it simplifies openrisc's
implementation of pte_alloc_one_kernel(), and not only the memblock
usage.

The fifth patch takes care of simpler cases when the allocation can be
satisfied with a simple call to memblock_alloc().

The sixth patch removes one-liner wrappers for memblock_alloc on arm and
unicore32, as suggested by Christoph.

This patch (of 6):

There are a several places that allocate memory using memblock APIs that
return a physical address, convert the returned address to the virtual
address and frequently also memset(0) the allocated range.

Update these places to use memblock allocators already returning a
virtual address.  Use memblock functions that clear the allocated memory
instead of calling memset(0) where appropriate.

The calls to memblock_alloc_base() that were not followed by memset(0)
are replaced with memblock_alloc_try_nid_raw().  Since the latter does
not panic() when the allocation fails, the appropriate panic() calls are
added to the call sites.

Link: http://lkml.kernel.org/r/1546248566-14910-2-git-send-email-rppt@linux.ibm.com
Signed-off-by: Mike Rapoport 
Cc: Arnd Bergmann 
Cc: Benjamin Herrenschmidt 
Cc: "David S. Miller" 
Cc: Guan Xuetao 
Cc: Greentime Hu 
Cc: Heiko Carstens 
Cc: Jonas Bonn 
Cc: Martin Schwidefsky 
Cc: Michael Ellerman 
Cc: Michal Hocko 
Cc: Michal Simek 
Cc: Mark Salter 
Cc: Paul Mackerras 
Cc: Rich Felker 
Cc: Russell King 
Cc: Stefan Kristiansson 
Cc: Stafford Horne 
Cc: Vincent Chen 
Cc: Yoshinori Sato 
Cc: Christoph Hellwig 
Cc: Michal Simek 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds