commit e8cb7a55 ("powerpc: remove superflous inclusions of
asm/fixmap.h") removed inclusion of asm/fixmap.h from files not
including objects from that file.

However, asm/mmu-8xx.h includes  call to __fix_to_virt(). The proper
way would be to include asm/fixmap.h in asm/mmu-8xx.h but it creates
an inclusion loop.

So we have to leave asm/fixmap.h in sysdep/cpm_common.c for
CONFIG_PPC_EARLY_DEBUG_CPM

  CC      arch/powerpc/sysdev/cpm_common.o
In file included from ./arch/powerpc/include/asm/mmu.h:340:0,
                 from ./arch/powerpc/include/asm/reg_8xx.h:8,
                 from ./arch/powerpc/include/asm/reg.h:29,
                 from ./arch/powerpc/include/asm/processor.h:13,
                 from ./arch/powerpc/include/asm/thread_info.h:28,
                 from ./include/linux/thread_info.h:38,
                 from ./arch/powerpc/include/asm/ptrace.h:159,
                 from ./arch/powerpc/include/asm/hw_irq.h:12,
                 from ./arch/powerpc/include/asm/irqflags.h:12,
                 from ./include/linux/irqflags.h:16,
                 from ./include/asm-generic/cmpxchg-local.h:6,
                 from ./arch/powerpc/include/asm/cmpxchg.h:537,
                 from ./arch/powerpc/include/asm/atomic.h:11,
                 from ./include/linux/atomic.h:5,
                 from ./include/linux/mutex.h:18,
                 from ./include/linux/kernfs.h:13,
                 from ./include/linux/sysfs.h:16,
                 from ./include/linux/kobject.h:20,
                 from ./include/linux/device.h:16,
                 from ./include/linux/node.h:18,
                 from ./include/linux/cpu.h:17,
                 from ./include/linux/of_device.h:5,
                 from arch/powerpc/sysdev/cpm_common.c:21:
arch/powerpc/sysdev/cpm_common.c: In function ‘udbg_init_cpm’:
./arch/powerpc/include/asm/mmu-8xx.h:218:25: error: implicit declaration of function ‘__fix_to_virt’ [-Werror=implicit-function-declaration]
 #define VIRT_IMMR_BASE (__fix_to_virt(FIX_IMMR_BASE))
                         ^
arch/powerpc/sysdev/cpm_common.c:75:7: note: in expansion of macro ‘VIRT_IMMR_BASE’
       VIRT_IMMR_BASE);
       ^
./arch/powerpc/include/asm/mmu-8xx.h:218:39: error: ‘FIX_IMMR_BASE’ undeclared (first use in this function)
 #define VIRT_IMMR_BASE (__fix_to_virt(FIX_IMMR_BASE))
                                       ^
arch/powerpc/sysdev/cpm_common.c:75:7: note: in expansion of macro ‘VIRT_IMMR_BASE’
       VIRT_IMMR_BASE);
       ^
./arch/powerpc/include/asm/mmu-8xx.h:218:39: note: each undeclared identifier is reported only once for each function it appears in
 #define VIRT_IMMR_BASE (__fix_to_virt(FIX_IMMR_BASE))
                                       ^
arch/powerpc/sysdev/cpm_common.c:75:7: note: in expansion of macro ‘VIRT_IMMR_BASE’
       VIRT_IMMR_BASE);
       ^
cc1: all warnings being treated as errors
make[1]: *** [arch/powerpc/sysdev/cpm_common.o] Error 1

Fixes: e8cb7a55 ("powerpc: remove superflous inclusions of asm/fixmap.h")
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

The problem is the the calculation should be "end - start + 1" but the
plus one is missing in this calculation.

Fixes: 8626816e ("powerpc: add support for MPIC message register API")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Signed-off-by: Rashmica Gupta <rashmica.g@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

This patch allows the memory removed by memtrace to be readded to the
kernel. So now you don't have to reboot your system to add the memory
back to the kernel or to have a different amount of memory removed.
Signed-off-by: Rashmica Gupta <rashmica.g@gmail.com>
Tested-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

There are some powerpc selftests, as tm/tm-unavailable, that run for a long
period (>120 seconds), and if it is interrupted, as pressing CRTL-C
(SIGINT), the foreground process (harness) dies but the child process and
threads continue to execute (with PPID = 1 now) in background.

In this case, you'd think the whole test exited, but there are remaining
threads and processes being executed in background. Sometimes these
zombies processes are doing annoying things, as consuming the whole CPU or
dumping things to STDOUT.

This patch fixes this problem by attaching an empty signal handler to
SIGINT in the harness process. This handler will interrupt (EINTR) the
parent process waitpid() call, letting the code to follow through the
normal flow, which will kill all the processes in the child process group.

This patch also fixes a typo.
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Gustavo Romero <gromero@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

For (bad) historical reasons, OPAL used to create a non-standard pair
of properties "opal-interrupts" and "opal-interrupts-names" for
representing the list of interrupts it wants Linux to request on its
behalf.

Among other issues, the opal-interrupts doesn't have a way to carry
the type of interrupts, and they were assumed to be all level
sensitive.

This is wrong on some recent systems where some of them are edge
sensitive causing warnings in the XIVE code and possible misbehaviours
if they need to be retriggered (typically the NPU2 TCE error
interrupts).

This makes Linux switch to using the standard "interrupts" and
"interrupt-names" properties instead when they are available, using
standard of_irq helpers, which can carry all the desired type
information.

Newer versions of OPAL will generate those properties in addition to
the legacy ones.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[mpe: Fixup prefix logic to check strlen(r->name). Reinstate setting
 of start = 0 in opal_event_shutdown() to avoid double free warnings]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

GCC supports -mcpu=e300c2 and -mcpu=e300c3

This patch gives the opportunity to tune kernel to one of
those two types.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

This patch extends to PPC32 the capability to select the exact
CPU type.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

At the time being, when adding a new CPU for selection, both
Kconfig.cputype and Makefile have to be modified.

This patch moves into Kconfig.cputype the name of the CPU to me
passed to the -mcpu= argument.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Rename the option to TARGET_CPU to echo the gcc documentation]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

In Makefiles if we're testing a CONFIG_FOO symbol for equality with 'y'
we can instead just use ifdef. The latter reads easily, so convert to
it where possible.
Signed-off-by: Rodrigo R. Galvao <rosattig@linux.vnet.ibm.com>
Reviewed-by: Mauro S. M. Rodrigues <maurosr@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

In __copy_tofrom_user, if we encounter an exception on a store, we
stop copying and return the number of bytes not copied.  However,
if the store is wider than one byte and is to an unaligned address,
it is possible that the store operand overlaps a page boundary
and the exception occurred on the latter part of the store operand,
meaning that it would be possible to copy a few more bytes.  Since
copy_to_user is generally expected to copy as much as possible,
it would be better to copy those extra few bytes.  This adds code
to do that.  Since this edge case is not performance-critical,
the code has been written to be compact rather than as fast as
possible.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

This adds a set of test cases to test the behaviour of
copy_tofrom_user when exceptions are encountered accessing the
source or destination.  Currently, copy_tofrom_user does not always
copy as many bytes as possible when an exception occurs on a store
to the destination, and that is reflected in failures in these tests.

Based on a test program from Anton Blanchard.

[paulus@ozlabs.org - test all three paths, wrote commit description,
 made EX_TABLE create an exception table.]
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

The hand-coded assembler 64-bit copy routines include feature sections
that select one code path or another depending on which CPU we are
executing on.  The self-tests for these copy routines end up testing
just one path.  This adds a mechanism for selecting any desired code
path at compile time, and makes 2 or 3 versions of each test, each
using a different code path, so as to cover all the possible paths.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
[mpe: Add -mcpu=power4 to CFLAGS for older compilers]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

This aims to make the generation of exception table entries for the
loads and stores in __copy_tofrom_user_base clearer and easier to
verify.  Instead of having a series of local labels on the loads and
stores, with a series of corresponding labels later for the exception
handlers, we now use macros to generate exception table entries at the
point of each load and store that could potentially trap.  We do this
with the macros lex (load exception) and stex (store exception).
These macros are used right before the load or store to which they
apply.

Some complexity is introduced by the fact that we have some more work
to do after hitting an exception, because we need to calculate and
return the number of bytes not copied.  The code uses r3 as the
current pointer into the destination buffer, that is, the address of
the first byte of the destination that has not been modified.
However, at various points in the copy loops, r3 can be 4, 8, 16 or 24
bytes behind that point.

To express this offset in an understandable way, we define a symbol
r3_offset which is updated at various points so that it equal to the
difference between the address of the first unmodified byte of the
destination and the value in r3.  (In fact it only needs to be
accurate at the point of each lex or stex macro invocation.)

The rules for updating r3_offset are as follows:

* It starts out at 0
* An addi r3,r3,N instruction decreases r3_offset by N
* A store instruction (stb, sth, stw, std) to N(r3)
  increases r3_offset by the width of the store (1, 2, 4, 8)
* A store with update instruction (stbu, sthu, stwu, stdu) to N(r3)
  sets r3_offset to the width of the store.

There is some trickiness to the way that the lex and stex macros and
the associated exception handlers work.  I would have liked to use
the current value of r3_offset in the name of the symbol used as
the exception handler, as in ".Lld_exc_$(r3_offset)" and then
have symbols .Lld_exc_0, .Lld_exc_8, .Lld_exc_16 etc. corresponding
to the offsets that needed to be added to r3.  However, I couldn't
see a way to do that with gas.

Instead, the exception handler address is .Lld_exc - r3_offset or
.Lst_exc - r3_offset, that is, the distance ahead of .Lld_exc/.Lst_exc
that we start executing is equal to the amount that we need to add to
r3.  This works because r3_offset is always a small multiple of 4,
and our instructions are 4 bytes long.  This means that before
.Lld_exc and .Lst_exc, we have a sequence of instructions that
increments r3 by 4, 8, 16 or 24 depending on where we start.  The
sequence increments r3 by 4 per instruction (on average).

We also replace the exception table for the 4k copy loop by a
macro per load or store.  These loads and stores all use exactly
the same exception handler, which simply resets the argument registers
r3, r4 and r5 to there original values and re-does the whole copy
using the slower loop.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

for_each_node_by_name() iterators only exit normally when the loop
cursor is NULL, So there is no need to call of_node_put().
Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Reviewed-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

NX increments readOffset by FIFO size in receive FIFO control register
when CRB is read. But the index in RxFIFO has to match with the
corresponding entry in FIFO maintained by VAS in kernel. Otherwise NX
may be processing incorrect CRBs and can cause CRB timeout.

VAS FIFO offset is 0 when the receive window is opened during
initialization. When the module is reloaded or in kexec boot, readOffset
in FIFO control register may not match with VAS entry. This patch adds
nx_coproc_init OPAL call to reset readOffset and queued entries in FIFO
control register for both high and normal FIFOs.
Signed-off-by: Haren Myneni <haren@us.ibm.com>
[mpe: Fixup uninitialized variable warning]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Export opal_check_token symbol for modules to check the availability
of OPAL calls before using them.
Signed-off-by: Haren Myneni <haren@us.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Fix build errors and warnings in t1042rdb_diu.c by adding header files
and MODULE_LICENSE().

../arch/powerpc/platforms/85xx/t1042rdb_diu.c:152:1: warning: data definition has no type or storage class
 early_initcall(t1042rdb_diu_init);
../arch/powerpc/platforms/85xx/t1042rdb_diu.c:152:1: error: type defaults to 'int' in declaration of 'early_initcall' [-Werror=implicit-int]
../arch/powerpc/platforms/85xx/t1042rdb_diu.c:152:1: warning: parameter names (without types) in function declaration

and
WARNING: modpost: missing MODULE_LICENSE() in arch/powerpc/platforms/85xx/t1042rdb_diu.o
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Scott Wood <oss@buserror.net>
Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Call trace observed while running perf-fuzzer:

  CPU: 43 PID: 9088 Comm: perf_fuzzer Not tainted 4.13.0-32-generic #35~lp1746225
  task: c000003f776ac900 task.stack: c000003f77728000
  NIP: c000000000299b70 LR: c0000000002a4534 CTR: c00000000029bb80
  REGS: c000003f7772b760 TRAP: 0700   Not tainted  (4.13.0-32-generic)
  MSR: 900000000282b033 <SF,HV,VEC,VSX,EE,FP,ME,IR,DR,RI,LE>
    CR: 24008822  XER: 00000000
  CFAR: c000000000299a70 SOFTE: 0
  GPR00: c0000000002a4534 c000003f7772b9e0 c000000001606200 c000003fef858908
  GPR04: c000003f776ac900 0000000000000001 ffffffffffffffff 0000003fee730000
  GPR08: 0000000000000000 0000000000000000 c0000000011220d8 0000000000000002
  GPR12: c00000000029bb80 c000000007a3d900 0000000000000000 0000000000000000
  GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
  GPR20: 0000000000000000 0000000000000000 c000003f776ad090 c000000000c71354
  GPR24: c000003fef716780 0000003fee730000 c000003fe69d4200 c000003f776ad330
  GPR28: c0000000011220d8 0000000000000001 c0000000014c6108 c000003fef858900
  NIP [c000000000299b70] perf_pmu_sched_task+0x170/0x180
  LR [c0000000002a4534] __perf_event_task_sched_in+0xc4/0x230
  Call Trace:
    perf_iterate_sb+0x158/0x2a0 (unreliable)
    __perf_event_task_sched_in+0xc4/0x230
    finish_task_switch+0x21c/0x310
    __schedule+0x304/0xb80
    schedule+0x40/0xc0
    do_wait+0x254/0x2e0
    kernel_wait4+0xa0/0x1a0
    SyS_wait4+0x64/0xc0
    system_call+0x58/0x6c
  Instruction dump:
  3beafea0 7faa4800 409eff18 e8010060 eb610028 ebc10040 7c0803a6 38210050
  eb81ffe0 eba1ffe8 ebe1fff8 4e800020 <0fe00000> 4bffffbc 60000000 60420000
  ---[ end trace 8c46856d314c1811 ]---

The context switch call-backs for thread-imc are defined in sched_task function.
So when thread-imc events are grouped with software pmu events,
perf_pmu_sched_task hits the WARN_ON_ONCE condition, since software PMUs are
assumed not to have a sched_task defined.

Patch to move the thread_imc enable/disable opal call back from sched_task to
event_[add/del] function

Fixes: f74c89bd ("powerpc/perf: Add thread IMC PMU support")
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Reviewed-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Tested-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

The page table fragment allocator uses the main page refcount racily
with respect to speculative references. A customer observed a BUG due
to page table page refcount underflow in the fragment allocator. This
can be caused by the fragment allocator set_page_count stomping on a
speculative reference, and then the speculative failure handler
decrements the new reference, and the underflow eventually pops when
the page tables are freed.

Fix this by using a dedicated field in the struct page for the page
table fragment allocator.

Fixes: 5c1f6ee9 ("powerpc: Reduce PTE table memory wastage")
Cc: stable@vger.kernel.org # v3.10+
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Resolved <"foo* bar" should be "foo *bar"> error
Signed-off-by: Parth Y Shah <sparth1292@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Pasemi code still uses printk(KERN_ERR/KERN_WARN ... change these to
pr_err(, pr_warn(... to match other powerpc arch code.

No functional changes.
Signed-off-by: Darren Stevens <darren@stevens-zone.net>
[mpe: Unsplit some strings while we're at it]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Call show_user_instructions() in arch/powerpc/kernel/traps.c to dump
instructions at faulty location, useful to debugging.

Before this patch, an unhandled signal message looked like:

  pandafault[10524]: segfault (11) at 100007d0 nip 1000061c lr 7fffbd295100 code 2 in pandafault[10000000+10000]

After this patch, it looks like:

  pandafault[10524]: segfault (11) at 100007d0 nip 1000061c lr 7fffbd295100 code 2 in pandafault[10000000+10000]
  pandafault[10524]: code: 4bfffeec 4bfffee8 3c401002 38427f00 fbe1fff8 f821ffc1 7c3f0b78 3d22fffe
  pandafault[10524]: code: 392988d0 f93f0020 e93f0020 39400048 <99490000> 39200000 7d234b78 383f0040
Signed-off-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

show_user_instructions() is a slightly modified version of
show_instructions() that allows userspace instruction dump.

This will be useful within show_signal_msg() to dump userspace
instructions of the faulty location.

Here is a sample of what show_user_instructions() outputs:

  pandafault[10850]: code: 4bfffeec 4bfffee8 3c401002 38427f00 fbe1fff8 f821ffc1 7c3f0b78 3d22fffe
  pandafault[10850]: code: 392988d0 f93f0020 e93f0020 39400048 <99490000> 39200000 7d234b78 383f0040

The current->comm and current->pid printed can serve as a glue that
links the instructions dump to its originator, allowing messages to be
interleaved in the logs.
Signed-off-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

This adds VMA address in the message printed for unhandled signals,
similarly to what other architectures, like x86, print.

Before this patch, a page fault looked like:

  pandafault[61470]: unhandled signal 11 at 100007d0 nip 1000061c lr 7fff8d185100 code 2

After this patch, a page fault looks like:

  pandafault[6303]: segfault 11 at 100007d0 nip 1000061c lr 7fff93c55100 code 2 in pandafault[10000000+10000]
Signed-off-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Use %lx format to print registers.  This avoids having two different
formats and avoids checking for MSR_64BIT, improving readability of the
function.

Even though we could have used %px, which is functionally equivalent to %lx
as per Documentation/core-api/printk-formats.rst, it is not semantically
correct because the data printed are not pointers.  And using %px requires
casting data to (void *).

Besides that, %lx matches the format used in show_regs().

Before this patch:

  pandafault[4808]: unhandled signal 11 at 0000000010000718 nip 0000000010000574 lr 00007fff935e7a6c code 2

After this patch:

  pandafault[4732]: unhandled signal 11 at 10000718 nip 10000574 lr 7fff86697a6c code 2
Signed-off-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Replace printk_ratelimited() by printk() and a default rate limit
burst to limit displaying unhandled signals messages.

This will allow us to call print_vma_addr() in a future patch, which
does not work with printk_ratelimited().
Signed-off-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

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>