Isolate the logic of printing unhandled signals out of _exception_pkey().
No functional change, only code rearrangement.
Signed-off-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

The alignment_handler is documented to only work on Power8/Power9, but
we can make it run on older CPUs by guarding more of the tests with
feature checks.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>

Currently the alignment_handler test prints "Can't open /dev/fb0"
about 80 times per run, which is a little annoying.

Refactor it to check earlier if it can open /dev/fb0 and skip if not,
this results in each test printing something like:

  test: test_alignment_handler_vsx_206
  tags: git_version:v4.18-rc3-134-gfb21a48904aa
  [SKIP] Test skipped on line 291
  skip: test_alignment_handler_vsx_206
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>

Because rfi_flush_fallback runs immediately before the return to
userspace it currently runs with the user r1 (stack pointer). This
means if we oops in there we will report a bad kernel stack pointer in
the exception entry path, eg:

  Bad kernel stack pointer 7ffff7150e40 at c0000000000023b4
  Oops: Bad kernel stack pointer, sig: 6 [#1]
  LE SMP NR_CPUS=32 NUMA PowerNV
  Modules linked in:
  CPU: 0 PID: 1246 Comm: klogd Not tainted 4.18.0-rc2-gcc-7.3.1-00175-g0443f8a69ba3 #7
  NIP:  c0000000000023b4 LR: 0000000010053e00 CTR: 0000000000000040
  REGS: c0000000fffe7d40 TRAP: 4100   Not tainted  (4.18.0-rc2-gcc-7.3.1-00175-g0443f8a69ba3)
  MSR:  9000000002803031 <SF,HV,VEC,VSX,FP,ME,IR,DR,LE>  CR: 44000442  XER: 20000000
  CFAR: c00000000000bac8 IRQMASK: c0000000f1e66a80
  GPR00: 0000000002000000 00007ffff7150e40 00007fff93a99900 0000000000000020
  ...
  NIP [c0000000000023b4] rfi_flush_fallback+0x34/0x80
  LR [0000000010053e00] 0x10053e00

Although the NIP tells us where we were, and the TRAP number tells us
what happened, it would still be nicer if we could report the actual
exception rather than barfing about the stack pointer.

We an do that fairly simply by loading the kernel stack pointer on
entry and restoring the user value before returning. That way we see a
regular oops such as:

  Unrecoverable exception 4100 at c00000000000239c
  Oops: Unrecoverable exception, sig: 6 [#1]
  LE SMP NR_CPUS=32 NUMA PowerNV
  Modules linked in:
  CPU: 0 PID: 1251 Comm: klogd Not tainted 4.18.0-rc3-gcc-7.3.1-00097-g4ebfcac65acd-dirty #40
  NIP:  c00000000000239c LR: 0000000010053e00 CTR: 0000000000000040
  REGS: c0000000f1e17bb0 TRAP: 4100   Not tainted  (4.18.0-rc3-gcc-7.3.1-00097-g4ebfcac65acd-dirty)
  MSR:  9000000002803031 <SF,HV,VEC,VSX,FP,ME,IR,DR,LE>  CR: 44000442  XER: 20000000
  CFAR: c00000000000bac8 IRQMASK: 0
  ...
  NIP [c00000000000239c] rfi_flush_fallback+0x3c/0x80
  LR [0000000010053e00] 0x10053e00
  Call Trace:
  [c0000000f1e17e30] [c00000000000b9e4] system_call+0x5c/0x70 (unreliable)

Note this shouldn't make the kernel stack pointer vulnerable to a
meltdown attack, because it should be flushed from the cache before we
return to userspace. The user r1 value will be in the cache, because
we load it in the return path, but that is harmless.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>

Look for fw-features properties to determine the appropriate settings
for the count cache flush, and then call the generic powerpc code to
set it up based on the security feature flags.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Use the existing hypercall to determine the appropriate settings for
the count cache flush, and then call the generic powerpc code to set
it up based on the security feature flags.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Some CPU revisions support a mode where the count cache needs to be
flushed by software on context switch. Additionally some revisions may
have a hardware accelerated flush, in which case the software flush
sequence can be shortened.

If we detect the appropriate flag from firmware we patch a branch
into _switch() which takes us to a count cache flush sequence.

That sequence in turn may be patched to return early if we detect that
the CPU supports accelerating the flush sequence in hardware.

Add debugfs support for reporting the state of the flush, as well as
runtime disabling it.

And modify the spectre_v2 sysfs file to report the state of the
software flush.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Add security feature flags to indicate the need for software to flush
the count cache on context switch, and for the presence of a hardware
assisted count cache flush.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Add a macro and some helper C functions for patching single asm
instructions.

The gas macro means we can do something like:

  1:	nop
  	patch_site 1b, patch__foo

Which is less visually distracting than defining a GLOBAL symbol at 1,
and also doesn't pollute the symbol table which can confuse eg. perf.

These are obviously similar to our existing feature sections, but are
not automatically patched based on CPU/MMU features, rather they are
designed to be manually patched by C code at some arbitrary point.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Currently only supported on powerpc.
Signed-off-by: Diana Craciun <diana.craciun@nxp.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Used barrier_nospec to sanitize the syscall table.
Signed-off-by: Diana Craciun <diana.craciun@nxp.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Implement the barrier_nospec as a isync;sync instruction sequence.
The implementation uses the infrastructure built for BOOK3S 64.
Signed-off-by: Diana Craciun <diana.craciun@nxp.com>
[mpe: Split out of larger patch]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

In a subsequent patch we will enable building security.c for Book3E.
However the NXP platforms are not vulnerable to Meltdown, so make the
Meltdown vulnerability reporting PPC_BOOK3S_64 specific.
Signed-off-by: Diana Craciun <diana.craciun@nxp.com>
[mpe: Split out of larger patch]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Currently we require platform code to call setup_barrier_nospec(). But
if we add an empty definition for the !CONFIG_PPC_BARRIER_NOSPEC case
then we can call it in setup_arch().
Signed-off-by: Diana Craciun <diana.craciun@nxp.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Add a config symbol to encode which platforms support the
barrier_nospec speculation barrier. Currently this is just Book3S 64
but we will add Book3E in a future patch.
Signed-off-by: Diana Craciun <diana.craciun@nxp.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

NXP Book3E platforms are not vulnerable to speculative store
bypass, so make the mitigations PPC_BOOK3S_64 specific.
Signed-off-by: Diana Craciun <diana.craciun@nxp.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

The speculation barrier can be disabled from the command line
with the parameter: "nospectre_v1".
Signed-off-by: Diana Craciun <diana.craciun@nxp.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

We only need to use __MASKABLE_EXCEPTION in one of the four cases for
hardware interrupt, so use the helper macros in the other cases.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

We pass the "loc" (location) parameter to MASKABLE_EXCEPTION and
friends, but it's not used, so drop it.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

_MASKABLE_RELON_EXCEPTION_PSERIES() does nothing useful, update all
callers to use __MASKABLE_RELON_EXCEPTION_PSERIES() directly.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

_MASKABLE_EXCEPTION_PSERIES() does nothing useful, update all callers
to use __MASKABLE_EXCEPTION_PSERIES() directly.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

To just EXCEPTION_RELON_PROLOG().
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

The EXCEPTION_RELON_PROLOG_PSERIES_1() macro does the same job as
EXCEPTION_PROLOG_2 (which we just recently created), except for
"RELON" (relocation on) exceptions.

So rename it as such.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

As with the other patches in this series, we are removing the
"PSERIES" from the name as it's no longer meaningful.

In this case it's not simply a case of removing the "PSERIES" as that
would result in a clash with the existing EXCEPTION_PROLOG_1.

Instead we name this one EXCEPTION_PROLOG_2, as it's usually used in
sequence after 0 and 1.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

The "PSERIES" in STD_EXCEPTION_PSERIES is to differentiate the macros
from the legacy iSeries versions, which are called
STD_EXCEPTION_ISERIES. It is not anything to do with pseries vs
powernv or powermac etc.

We removed the legacy iSeries code in 2012, in commit 8ee3e0d6x
("powerpc: Remove the main legacy iSerie platform code").

So remove "PSERIES" from the macros.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

EXCEPTION_RELON_PROLOG_PSERIES() only has two users,
STD_RELON_EXCEPTION_PSERIES() and STD_RELON_EXCEPTION_HV() both of
which "call" SET_SCRATCH0(), so just move SET_SCRATCH0() into
EXCEPTION_RELON_PROLOG_PSERIES().
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

EXCEPTION_PROLOG_PSERIES() only has two users, STD_EXCEPTION_PSERIES()
and STD_EXCEPTION_HV() both of which "call" SET_SCRATCH0(), so just
move SET_SCRATCH0() into EXCEPTION_PROLOG_PSERIES().
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Pasemi arch code finds the root of the PCI-e bus by searching the
device-tree for a node called 'pxp'. But the root bus has a compatible
property of 'pasemi,rootbus' so search for that instead.
Signed-off-by: Darren Stevens <darren@stevens-zone.net>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

This patch adds a test for testing the new assembly strlen() for PPC32
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[mpe: Fix 64-bit build]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

The generic implementation of strlen() reads strings byte per byte.

This patch implements strlen() in assembly based on a read of entire
words, in the same spirit as what some other arches and glibc do.

On a 8xx the time spent in strlen is reduced by 3/4 for long strings.

strlen() selftest on an 8xx provides the following values:

Before the patch (ie with the generic strlen() in lib/string.c):

  len 256 : time = 1.195055
  len 016 : time = 0.083745
  len 008 : time = 0.046828
  len 004 : time = 0.028390

After the patch:

  len 256 : time = 0.272185 ==> 78% improvment
  len 016 : time = 0.040632 ==> 51% improvment
  len 008 : time = 0.033060 ==> 29% improvment
  len 004 : time = 0.029149 ==> 2% degradation

On a 832x:

Before the patch:

  len 256 : time = 0.236125
  len 016 : time = 0.018136
  len 008 : time = 0.011000
  len 004 : time = 0.007229

After the patch:

  len 256 : time = 0.094950 ==> 60% improvment
  len 016 : time = 0.013357 ==> 26% improvment
  len 008 : time = 0.010586 ==> 4% improvment
  len 004 : time = 0.008784
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

This patch adds a test for strlen()

string.c contains a copy of strlen() from lib/string.c

The test first tests the correctness of strlen() by comparing
the result with libc strlen(). It tests all cases of alignment.

It them tests the duration of an aligned strlen() on a 4 bytes string,
on a 16 bytes string and on a 256 bytes string.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[mpe: Drop change log from copy of string.c]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

This patch renames memcmp test to memcmp_64 and adds a memcmp_32 test
for testing the 32 bits version of memcmp()
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[mpe: Fix 64-bit build by adding build_32bit test]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

rtas_log_buf is a buffer to hold RTAS event data that are communicated
to kernel by hypervisor. This buffer is then used to pass RTAS event
data to user through proc fs. This buffer is allocated from
vmalloc (non-linear mapping) area.

On Machine check interrupt, register r3 points to RTAS extended event
log passed by hypervisor that contains the MCE event. The pseries
machine check handler then logs this error into rtas_log_buf. The
rtas_log_buf is a vmalloc-ed (non-linear) buffer we end up taking up a
page fault (vector 0x300) while accessing it. Since machine check
interrupt handler runs in NMI context we can not afford to take any
page fault. Page faults are not honored in NMI context and causes
kernel panic. Apart from that, as Nick pointed out,
pSeries_log_error() also takes a spin_lock while logging error which
is not safe in NMI context. It may endup in deadlock if we get another
MCE before releasing the lock. Fix this by deferring the logging of
rtas error to irq work queue.

Current implementation uses two different buffers to hold rtas error
log depending on whether extended log is provided or not. This makes
bit difficult to identify which buffer has valid data that needs to
logged later in irq work. Simplify this using single buffer, one per
paca, and copy rtas log to it irrespective of whether extended log is
provided or not. Allocate this buffer below RMA region so that it can
be accessed in real mode mce handler.

Fixes: b96672dd ("powerpc: Machine check interrupt is a non-maskable interrupt")
Cc: stable@vger.kernel.org # v4.14+
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

The global mce data buffer that used to copy rtas error log is of 2048
(RTAS_ERROR_LOG_MAX) bytes in size. Before the copy we read
extended_log_length from rtas error log header, then use max of
extended_log_length and RTAS_ERROR_LOG_MAX as a size of data to be copied.
Ideally the platform (phyp) will never send extended error log with
size > 2048. But if that happens, then we have a risk of buffer overrun
and corruption. Fix this by using min_t instead.

Fixes: d368514c ("powerpc: Fix corruption when grabbing FWNMI data")
Reported-by: Michal Suchanek <msuchanek@suse.com>
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>