linux-stable.git/arch/powerpc, branch v4.4.71

powerpc/64e: Fix hang when debugging programs with relocated kernel

2017-05-25T12:30:15+00:00

commit fd615f69a18a9d4aa5ef02a1dc83f319f75da8e7 upstream.

Debug interrupts can be taken during interrupt entry, since interrupt
entry does not automatically turn them off.  The kernel will check
whether the faulting instruction is between [interrupt_base_book3e,
__end_interrupts], and if so clear MSR[DE] and return.

However, when the kernel is built with CONFIG_RELOCATABLE, it can't use
LOAD_REG_IMMEDIATE(r14,interrupt_base_book3e) and
LOAD_REG_IMMEDIATE(r15,__end_interrupts), as they ignore relocation.
Thus, if the kernel is actually running at a different address than it
was built at, the address comparison will fail, and the exception entry
code will hang at kernel_dbg_exc.

r2(toc) is also not usable here, as r2 still holds data from the
interrupted context, so LOAD_REG_ADDR() doesn't work either.  So we use
the *name@got* to get the EV of two labels directly.

Test programs test.c shows as follows:
int main(int argc, char *argv[])
{
	if (access("/proc/sys/kernel/perf_event_paranoid", F_OK) == -1)
		printf("Kernel doesn't have perf_event support\n");
}

Steps to reproduce the bug, for example:
 1) ./gdb ./test
 2) (gdb) b access
 3) (gdb) r
 4) (gdb) s

Signed-off-by: Liu Hailong 
Signed-off-by: Jiang Xuexin 
Reviewed-by: Jiang Biao 
Reviewed-by: Liu Song 
Reviewed-by: Huang Jian 
[scottwood: cleaned up commit message, and specified bad behavior
 as a hang rather than an oops to correspond to mainline kernel behavior]
Fixes: 1cb6e0649248 ("powerpc/book3e: support CONFIG_RELOCATABLE")
Signed-off-by: Scott Wood 
Signed-off-by: Greg Kroah-Hartman

powerpc/pseries: Fix of_node_put() underflow during DLPAR remove

2017-05-25T12:30:15+00:00

commit 68baf692c435339e6295cb470ea5545cbc28160e upstream.

Historically struct device_node references were tracked using a kref embedded as
a struct field. Commit 75b57ecf9d1d ("of: Make device nodes kobjects so they
show up in sysfs") (Mar 2014) refactored device_nodes to be kobjects such that
the device tree could by more simply exposed to userspace using sysfs.

Commit 0829f6d1f69e ("of: device_node kobject lifecycle fixes") (Mar 2014)
followed up these changes to better control the kobject lifecycle and in
particular the referecne counting via of_node_get(), of_node_put(), and
of_node_init().

A result of this second commit was that it introduced an of_node_put() call when
a dynamic node is detached, in of_node_remove(), that removes the initial kobj
reference created by of_node_init().

Traditionally as the original dynamic device node user the pseries code had
assumed responsibilty for releasing this final reference in its platform
specific DLPAR detach code.

This patch fixes a refcount underflow introduced by commit 0829f6d1f6, and
recently exposed by the upstreaming of the recount API.

Messages like the following are no longer seen in the kernel log with this
patch following DLPAR remove operations of cpus and pci devices.

  rpadlpar_io: slot PHB 72 removed
  refcount_t: underflow; use-after-free.
  ------------[ cut here ]------------
  WARNING: CPU: 5 PID: 3335 at lib/refcount.c:128 refcount_sub_and_test+0xf4/0x110

Fixes: 0829f6d1f69e ("of: device_node kobject lifecycle fixes")
Signed-off-by: Tyrel Datwyler 
[mpe: Make change log commit references more verbose]
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/book3s/mce: Move add_taint() later in virtual mode

2017-05-25T12:30:14+00:00

commit d93b0ac01a9ce276ec39644be47001873d3d183c upstream.

machine_check_early() gets called in real mode. The very first time when
add_taint() is called, it prints a warning which ends up calling opal
call (that uses OPAL_CALL wrapper) for writing it to console. If we get a
very first machine check while we are in opal we are doomed. OPAL_CALL
overwrites the PACASAVEDMSR in r13 and in this case when we are done with
MCE handling the original opal call will use this new MSR on it's way
back to opal_return. This usually leads to unexpected behaviour or the
kernel to panic. Instead move the add_taint() call later in the virtual
mode where it is safe to call.

This is broken with current FW level. We got lucky so far for not getting
very first MCE hit while in OPAL. But easily reproducible on Mambo.

Fixes: 27ea2c420cad ("powerpc: Set the correct kernel taint on machine check errors.")
Signed-off-by: Mahesh Salgaonkar 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/powernv: Fix opal_exit tracepoint opcode

2017-05-14T11:32:54+00:00

commit a7e0fb6c2029a780444d09560f739e020d54fe4d upstream.

Currently the opal_exit tracepoint usually shows the opcode as 0:

  -0     [047] d.h.   635.654292: opal_entry: opcode=63
  -0     [047] d.h.   635.654296: opal_exit: opcode=0 retval=0
  kopald-1209  [019] d...   636.420943: opal_entry: opcode=10
  kopald-1209  [019] d...   636.420959: opal_exit: opcode=0 retval=0

This is because we incorrectly load the opcode into r0 before calling
__trace_opal_exit(), whereas it expects the opcode in r3 (first function
parameter). In fact we are leaving the retval in r3, so opcode and
retval will always show the same value.

Instead load the opcode into r3, resulting in:

  -0     [040] d.h.   636.618625: opal_entry: opcode=63
  -0     [040] d.h.   636.618627: opal_exit: opcode=63 retval=0

Fixes: c49f63530bb6 ("powernv: Add OPAL tracepoints")
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/kprobe: Fix oops when kprobed on 'stdu' instruction

2017-04-27T07:09:33+00:00

commit 9e1ba4f27f018742a1aa95d11e35106feba08ec1 upstream.

If we set a kprobe on a 'stdu' instruction on powerpc64, we see a kernel
OOPS:

  Bad kernel stack pointer cd93c840 at c000000000009868
  Oops: Bad kernel stack pointer, sig: 6 [#1]
  ...
  GPR00: c000001fcd93cb30 00000000cd93c840 c0000000015c5e00 00000000cd93c840
  ...
  NIP [c000000000009868] resume_kernel+0x2c/0x58
  LR [c000000000006208] program_check_common+0x108/0x180

On a 64-bit system when the user probes on a 'stdu' instruction, the kernel does
not emulate actual store in emulate_step() because it may corrupt the exception
frame. So the kernel does the actual store operation in exception return code
i.e. resume_kernel().

resume_kernel() loads the saved stack pointer from memory using lwz, which only
loads the low 32-bits of the address, causing the kernel crash.

Fix this by loading the 64-bit value instead.

Fixes: be96f63375a1 ("powerpc: Split out instruction analysis part of emulate_step()")
Signed-off-by: Ravi Bangoria 
Reviewed-by: Naveen N. Rao 
Reviewed-by: Ananth N Mavinakayanahalli 
[mpe: Change log massage, add stable tag]
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc: Disable HFSCR[TM] if TM is not supported

2017-04-21T07:30:06+00:00

commit 7ed23e1bae8bf7e37fd555066550a00b95a3a98b upstream.

On Power8 & Power9 the early CPU inititialisation in __init_HFSCR()
turns on HFSCR[TM] (Hypervisor Facility Status and Control Register
[Transactional Memory]), but that doesn't take into account that TM
might be disabled by CPU features, or disabled by the kernel being built
with CONFIG_PPC_TRANSACTIONAL_MEM=n.

So later in boot, when we have setup the CPU features, clear HSCR[TM] if
the TM CPU feature has been disabled. We use CPU_FTR_TM_COMP to account
for the CONFIG_PPC_TRANSACTIONAL_MEM=n case.

Without this a KVM guest might try use TM, even if told not to, and
cause an oops in the host kernel. Typically the oops is seen in
__kvmppc_vcore_entry() and may or may not be fatal to the host, but is
always bad news.

In practice all shipping CPU revisions do support TM, and all host
kernels we are aware of build with TM support enabled, so no one should
actually be able to hit this in the wild.

Fixes: 2a3563b023e5 ("powerpc: Setup in HFSCR for POWER8")
Cc: stable@vger.kernel.org # v3.10+
Signed-off-by: Benjamin Herrenschmidt 
Tested-by: Sam Bobroff 
[mpe: Rewrite change log with input from Sam, add Fixes/stable]
Signed-off-by: Michael Ellerman 
[sb: Backported to linux-4.4.y: adjusted context]
Signed-off-by: Sam Bobroff 
Signed-off-by: Greg Kroah-Hartman

powerpc: Don't try to fix up misaligned load-with-reservation instructions

2017-04-12T10:38:34+00:00

commit 48fe9e9488743eec9b7c1addd3c93f12f2123d54 upstream.

In the past, there was only one load-with-reservation instruction,
lwarx, and if a program attempted a lwarx on a misaligned address, it
would take an alignment interrupt and the kernel handler would emulate
it as though it was lwzx, which was not really correct, but benign since
it is loading the right amount of data, and the lwarx should be paired
with a stwcx. to the same address, which would also cause an alignment
interrupt which would result in a SIGBUS being delivered to the process.

We now have 5 different sizes of load-with-reservation instruction. Of
those, lharx and ldarx cause an immediate SIGBUS by luck since their
entries in aligninfo[] overlap instructions which were not fixed up, but
lqarx overlaps with lhz and will be emulated as such. lbarx can never
generate an alignment interrupt since it only operates on 1 byte.

To straighten this out and fix the lqarx case, this adds code to detect
the l[hwdq]arx instructions and return without fixing them up, resulting
in a SIGBUS being delivered to the process.

Signed-off-by: Paul Mackerras 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/mm: Add missing global TLB invalidate if cxl is active

2017-04-12T10:38:34+00:00

commit 88b1bf7268f56887ca88eb09c6fb0f4fc970121a upstream.

Commit 4c6d9acce1f4 ("powerpc/mm: Add hooks for cxl") converted local
TLB invalidates to global if the cxl driver is active. This is necessary
because the CAPP snoops invalidations to forward them to the PSL on the
cxl adapter. However one path was forgotten. native_flush_hash_range()
still does local TLB invalidates, as found out the hard way recently.

This patch fixes it by following the same logic as previously: if the
cxl driver is active, the local TLB invalidates are 'upgraded' to
global.

Fixes: 4c6d9acce1f4 ("powerpc/mm: Add hooks for cxl")
Signed-off-by: Frederic Barrat 
Reviewed-by: Aneesh Kumar K.V 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

powerpc/boot: Fix zImage TOC alignment

2017-03-26T10:13:19+00:00

commit 97ee351b50a49717543533cfb85b4bf9d88c9680 upstream.

Recent toolchains force the TOC to be 256 byte aligned. We need to
enforce this alignment in the zImage linker script, otherwise pointers
to our TOC variables (__toc_start) could be incorrect. If the actual
start of the TOC and __toc_start don't have the same value we crash
early in the zImage wrapper.

Suggested-by: Alan Modra 
Signed-off-by: Michael Ellerman 
Signed-off-by: Greg Kroah-Hartman

KVM: PPC: Book3S PR: Fix illegal opcode emulation

2017-03-26T10:13:18+00:00

commit 708e75a3ee750dce1072134e630d66c4e6eaf63c upstream.

If kvmppc_handle_exit_pr() calls kvmppc_emulate_instruction() to emulate
one instruction (in the BOOK3S_INTERRUPT_H_EMUL_ASSIST case), it calls
kvmppc_core_queue_program() afterwards if kvmppc_emulate_instruction()
returned EMULATE_FAIL, so the guest gets an program interrupt for the
illegal opcode.
However, the kvmppc_emulate_instruction() also tried to inject a
program exception for this already, so the program interrupt gets
injected twice and the return address in srr0 gets destroyed.
All other callers of kvmppc_emulate_instruction() are also injecting
a program interrupt, and since the callers have the right knowledge
about the srr1 flags that should be used, it is the function
kvmppc_emulate_instruction() that should _not_ inject program
interrupts, so remove the kvmppc_core_queue_program() here.

This fixes the issue discovered by Laurent Vivier with kvm-unit-tests
where the logs are filled with these messages when the test tries
to execute an illegal instruction:

     Couldn't emulate instruction 0x00000000 (op 0 xop 0)
     kvmppc_handle_exit_pr: emulation at 700 failed (00000000)

Signed-off-by: Thomas Huth 
Reviewed-by: Alexander Graf 
Tested-by: Laurent Vivier 
Signed-off-by: Paul Mackerras 
Cc: Sumit Semwal 
Signed-off-by: Greg Kroah-Hartman