linux.git/arch/powerpc/kernel/paca.c, branch v5.9

Merge branch 'fixes' into next

2020-07-18T12:43:55+00:00

Merge our fixes branch, primarily to bring in the ebb selftests build
fix and the pkey fix, which is a dependency for some future work.

powerpc/pseries/svm: Fix incorrect check for shared_lppaca_size

2020-07-14T11:57:26+00:00

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

powerpc/pseries/svm: Drop unused align argument in alloc_shared_lppaca() function

2020-06-22T00:37:59+00:00

Argument "align" in alloc_shared_lppaca() was unused inside the
function. Let's drop it and update code comment for page alignment.

Signed-off-by: Satheesh Rajendran 
Reviewed-by: Thiago Jung Bauermann 
Reviewed-by: Laurent Dufour 
[mpe: Massage comment wording/formatting]
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20200612142953.135408-1-sathnaga@linux.vnet.ibm.com

mm: reorder includes after introduction of linux/pgtable.h

2020-06-09T16:39:13+00:00

The replacement of  with  made the include
of the latter in the middle of asm includes.  Fix this up with the aid of
the below script and manual adjustments here and there.

	import sys
	import re

	if len(sys.argv) is not 3:
	    print "USAGE: %s  " % (sys.argv[0])
	    sys.exit(1)

	hdr_to_move="#include " % sys.argv[2]
	moved = False
	in_hdrs = False

	with open(sys.argv[1], "r") as f:
	    lines = f.readlines()
	    for _line in lines:
		line = _line.rstrip('
')
		if line == hdr_to_move:
		    continue
		if line.startswith("#include 
Signed-off-by: Andrew Morton 
Cc: Arnd Bergmann 
Cc: Borislav Petkov 
Cc: Brian Cain 
Cc: Catalin Marinas 
Cc: Chris Zankel 
Cc: "David S. Miller" 
Cc: Geert Uytterhoeven 
Cc: Greentime Hu 
Cc: Greg Ungerer 
Cc: Guan Xuetao 
Cc: Guo Ren 
Cc: Heiko Carstens 
Cc: Helge Deller 
Cc: Ingo Molnar 
Cc: Ley Foon Tan 
Cc: Mark Salter 
Cc: Matthew Wilcox 
Cc: Matt Turner 
Cc: Max Filippov 
Cc: Michael Ellerman 
Cc: Michal Simek 
Cc: Nick Hu 
Cc: Paul Walmsley 
Cc: Richard Weinberger 
Cc: Rich Felker 
Cc: Russell King 
Cc: Stafford Horne 
Cc: Thomas Bogendoerfer 
Cc: Thomas Gleixner 
Cc: Tony Luck 
Cc: Vincent Chen 
Cc: Vineet Gupta 
Cc: Will Deacon 
Cc: Yoshinori Sato 
Link: http://lkml.kernel.org/r/20200514170327.31389-4-rppt@kernel.org
Signed-off-by: Linus Torvalds

mm: introduce include/linux/pgtable.h

2020-06-09T16:39:13+00:00

The include/linux/pgtable.h is going to be the home of generic page table
manipulation functions.

Start with moving asm-generic/pgtable.h to include/linux/pgtable.h and
make the latter include asm/pgtable.h.

Signed-off-by: Mike Rapoport 
Signed-off-by: Andrew Morton 
Cc: Arnd Bergmann 
Cc: Borislav Petkov 
Cc: Brian Cain 
Cc: Catalin Marinas 
Cc: Chris Zankel 
Cc: "David S. Miller" 
Cc: Geert Uytterhoeven 
Cc: Greentime Hu 
Cc: Greg Ungerer 
Cc: Guan Xuetao 
Cc: Guo Ren 
Cc: Heiko Carstens 
Cc: Helge Deller 
Cc: Ingo Molnar 
Cc: Ley Foon Tan 
Cc: Mark Salter 
Cc: Matthew Wilcox 
Cc: Matt Turner 
Cc: Max Filippov 
Cc: Michael Ellerman 
Cc: Michal Simek 
Cc: Nick Hu 
Cc: Paul Walmsley 
Cc: Richard Weinberger 
Cc: Rich Felker 
Cc: Russell King 
Cc: Stafford Horne 
Cc: Thomas Bogendoerfer 
Cc: Thomas Gleixner 
Cc: Tony Luck 
Cc: Vincent Chen 
Cc: Vineet Gupta 
Cc: Will Deacon 
Cc: Yoshinori Sato 
Link: http://lkml.kernel.org/r/20200514170327.31389-3-rppt@kernel.org
Signed-off-by: Linus Torvalds

powerpc/rtas: Implement reentrant rtas call

2020-06-02T10:59:08+00:00

Implement rtas_call_reentrant() for reentrant rtas-calls:
"ibm,int-on", "ibm,int-off",ibm,get-xive" and  "ibm,set-xive".

On LoPAPR Version 1.1 (March 24, 2016), from 7.3.10.1 to 7.3.10.4,
items 2 and 3 say:

2 - For the PowerPC External Interrupt option: The * call must be
reentrant to the number of processors on the platform.
3 - For the PowerPC External Interrupt option: The * argument call
buffer for each simultaneous call must be physically unique.

So, these rtas-calls can be called in a lockless way, if using
a different buffer for each cpu doing such rtas call.

For this, it was suggested to add the buffer (struct rtas_args)
in the PACA struct, so each cpu can have it's own buffer.
The PACA struct received a pointer to rtas buffer, which is
allocated in the memory range available to rtas 32-bit.

Reentrant rtas calls are useful to avoid deadlocks in crashing,
where rtas-calls are needed, but some other thread crashed holding
the rtas.lock.

This is a backtrace of a deadlock from a kdump testing environment:

  #0 arch_spin_lock
  #1  lock_rtas ()
  #2  rtas_call (token=8204, nargs=1, nret=1, outputs=0x0)
  #3  ics_rtas_mask_real_irq (hw_irq=4100)
  #4  machine_kexec_mask_interrupts
  #5  default_machine_crash_shutdown
  #6  machine_crash_shutdown
  #7  __crash_kexec
  #8  crash_kexec
  #9  oops_end

Signed-off-by: Leonardo Bras 
[mpe: Move under #ifdef PSERIES to avoid build breakage]
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20200518234245.200672-3-leobras.c@gmail.com

powerpc/64: Prevent stack protection in early boot

2020-03-25T01:09:38+00:00

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

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

2020-03-25T01:09:37+00:00

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

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