linux-stable.git/arch/mips/kernel, branch v4.9.76

MIPS: Fix an n32 core file generation regset support regression

2017-11-30T08:39:03+00:00

commit 547da673173de51f73887377eb275304775064ad upstream.

Fix a commit 7aeb753b5353 ("MIPS: Implement task_user_regset_view.")
regression, then activated by commit 6a9c001b7ec3 ("MIPS: Switch ELF
core dumper to use regsets.)", that caused n32 processes to dump o32
core files by failing to set the EF_MIPS_ABI2 flag in the ELF core file
header's `e_flags' member:

$ file tls-core
tls-core: ELF 32-bit MSB executable, MIPS, N32 MIPS64 rel2 version 1 (SYSV), [...]
$ ./tls-core
Aborted (core dumped)
$ file core
core: ELF 32-bit MSB core file MIPS, MIPS-I version 1 (SYSV), SVR4-style
$

Previously the flag was set as the result of a:

statement placed in arch/mips/kernel/binfmt_elfn32.c, however in the
regset case, i.e. when CORE_DUMP_USE_REGSET is set, ELF_CORE_EFLAGS is
no longer used by `fill_note_info' in fs/binfmt_elf.c, and instead the
`->e_flags' member of the regset view chosen is.  We have the views
defined in arch/mips/kernel/ptrace.c, however only an o32 and an n64
one, and the latter is used for n32 as well.  Consequently an o32 core
file is incorrectly dumped from n32 processes (the ELF32 vs ELF64 class
is chosen elsewhere, and the 32-bit one is correctly selected for n32).

Correct the issue then by defining an n32 regset view and using it as
appropriate.  Issue discovered in GDB testing.

Fixes: 7aeb753b5353 ("MIPS: Implement task_user_regset_view.")
Signed-off-by: Maciej W. Rozycki 
Cc: Ralf Baechle 
Cc: Djordje Todorovic 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/17617/
Signed-off-by: James Hogan 
Signed-off-by: Greg Kroah-Hartman

MIPS: traps: Ensure L1 & L2 ECC checking match for CM3 systems

2017-11-21T08:23:28+00:00

[ Upstream commit 35e6de38858f59b6b65dcfeaf700b5d06fc2b93d ]

On systems with CM3, we must ensure that the L1 & L2 ECC enables are set
to the same value. This is presumed by the hardware & cache corruption
can occur when it is not the case. Support enabling & disabling the L2
ECC checking on CM3 systems where this is controlled via a GCR, and
ensure that it matches the state of L1 ECC checking. Remove I6400 from
the switch statement it will no longer hit, and which was incorrect
since the L2 ECC enable bit isn't in the CP0 ErrCtl register.

Signed-off-by: Paul Burton 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14413/
Signed-off-by: Ralf Baechle 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

MIPS: init: Ensure reserved memory regions are not added to bootmem

2017-11-21T08:23:27+00:00

[ Upstream commit e89ef66d7682f031f026eee6bba03c8c2248d2a9 ]

Memories managed through boot_mem_map are generally expected to define
non-crossing areas. However, if part of a larger memory block is marked
as reserved, it would still be added to bootmem allocator as an
available block and could end up being overwritten by the allocator.

Prevent this by explicitly marking the memory as reserved it if exists
in the range used by bootmem allocator.

Signed-off-by: Marcin Nowakowski 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14608/
Signed-off-by: Ralf Baechle 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

MIPS: init: Ensure bootmem does not corrupt reserved memory

2017-11-21T08:23:27+00:00

[ Upstream commit d9b5b658210f28ed9f70c757d553e679d76e2986 ]

Current init code initialises bootmem allocator with all of the low
memory that it assumes is available, but does not check for reserved
memory block, which can lead to corruption of data that may be stored
there.
Move bootmem's allocation map to a location that does not cross any
reserved regions

Signed-off-by: Marcin Nowakowski 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14609/
Signed-off-by: Ralf Baechle 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

MIPS: BMIPS: Fix missing cbr address

2017-11-15T14:53:19+00:00

commit ea4b3afe1eac8f88bb453798a084fba47a1f155a upstream.

Fix NULL pointer access in BMIPS3300 RAC flush.

Fixes: 738a3f79027b ("MIPS: BMIPS: Add early CPU initialization code")
Signed-off-by: Jaedon Shin 
Reviewed-by: Florian Fainelli 
Cc: Kevin Cernekee 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16423/
Signed-off-by: James Hogan 
Signed-off-by: Greg Kroah-Hartman

MIPS: SMP: Fix deadlock & online race

2017-11-15T14:53:19+00:00

commit 9e8c399a88f0b87e41a894911475ed2a8f8dff9e upstream.

Commit 6f542ebeaee0 ("MIPS: Fix race on setting and getting
cpu_online_mask") effectively reverted commit 8f46cca1e6c06 ("MIPS: SMP:
Fix possibility of deadlock when bringing CPUs online") and thus has
reinstated the possibility of deadlock.

The commit was based on testing of kernel v4.4, where the CPU hotplug
core code issued a BUG() if the starting CPU is not marked online when
the boot CPU returns from __cpu_up. The commit fixes this race (in
v4.4), but re-introduces the deadlock situation.

As noted in the commit message, upstream differs in this area. Commit
8df3e07e7f21f ("cpu/hotplug: Let upcoming cpu bring itself fully up")
adds a completion event in the CPU hotplug core code, making this race
impossible. However, people were unhappy with relying on the core code
to do the right thing.

To address the issues both commits were trying to fix, add a second
completion event in the MIPS smp hotplug path. It removes the
possibility of a race, since the MIPS smp hotplug code now synchronises
both the boot and secondary CPUs before they return to the hotplug core
code. It also addresses the deadlock by ensuring that the secondary CPU
is not marked online before it's counters are synchronised.

This fix should also be backported to fix the race condition introduced
by the backport of commit 8f46cca1e6c06 ("MIPS: SMP: Fix possibility of
deadlock when bringing CPUs online"), through really that race only
existed before commit 8df3e07e7f21f ("cpu/hotplug: Let upcoming cpu
bring itself fully up").

Signed-off-by: Matt Redfearn 
Fixes: 6f542ebeaee0 ("MIPS: Fix race on setting and getting cpu_online_mask")
CC: Matija Glavinic Pecotic 
Patchwork: https://patchwork.linux-mips.org/patch/17376/
Signed-off-by: James Hogan 
[jhogan@kernel.org: Backported 4.1..4.9]
Signed-off-by: Greg Kroah-Hartman

MIPS: Fix race on setting and getting cpu_online_mask

2017-11-15T14:53:19+00:00

commit 6f542ebeaee0ee552a902ce3892220fc22c7ec8e upstream.

While testing cpu hoptlug (cpu down and up in loops) on kernel 4.4, it was
observed that occasionally check for cpu online will fail in kernel/cpu.c,
_cpu_up:

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/tree/kernel/cpu.c?h=v4.4.79#n485
 518        /* Arch-specific enabling code. */
 519        ret = __cpu_up(cpu, idle);
 520
 521        if (ret != 0)
 522                goto out_notify;
 523        BUG_ON(!cpu_online(cpu));

Reason is race between start_secondary and _cpu_up. cpu_callin_map is set
before cpu_online_mask. In __cpu_up, cpu_callin_map is waited for, but cpu
online mask is not, resulting in race in which secondary processor started
and set cpu_callin_map, but not yet set the online mask,resulting in above
BUG being hit.

Upstream differs in the area. cpu_online check is in bringup_wait_for_ap,
which is after cpu reached AP_ONLINE_IDLE,where secondary passed its start
function. Nonetheless, fix makes start_secondary safe and not depending on
other locks throughout the code. It protects as well against cpu_online
checks put in between sometimes in the future.

Fix this by moving completion after all flags are set.

Signed-off-by: Matija Glavinic Pecotic 
Cc: Alexander Sverdlin 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16925/
Signed-off-by: Ralf Baechle 
Signed-off-by: Greg Kroah-Hartman

MIPS: SMP: Use a completion event to signal CPU up

2017-11-15T14:53:19+00:00

commit a00eeede507c975087b7b8df8cf2c9f88ba285de upstream.

If a secondary CPU failed to start, for any reason, the CPU requesting
the secondary to start would get stuck in the loop waiting for the
secondary to be present in the cpu_callin_map.

Rather than that, use a completion event to signal that the secondary
CPU has started and is waiting to synchronise counters.

Since the CPU presence will no longer be marked in cpu_callin_map,
remove the redundant test from arch_cpu_idle_dead().

Signed-off-by: Matt Redfearn 
Cc: Maciej W. Rozycki 
Cc: Jiri Slaby 
Cc: Paul Gortmaker 
Cc: Chris Metcalf 
Cc: Thomas Gleixner 
Cc: Qais Yousef 
Cc: James Hogan 
Cc: Paul Burton 
Cc: Marcin Nowakowski 
Cc: Andrew Morton 
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14502/
Signed-off-by: Ralf Baechle 
Signed-off-by: Greg Kroah-Hartman

MIPS: smp-cps: Fix retrieval of VPE mask on big endian CPUs

2017-10-08T08:26:09+00:00

[ Upstream commit fb2155e3c30dc2043b52020e26965067a3e7779c ]

The vpe_mask member of struct core_boot_config is of type atomic_t,
which is a 32bit type. In cps-vec.S this member was being retrieved by a
PTR_L macro, which on 64bit systems is a 64bit load. On little endian
systems this is OK, since the double word that is retrieved will have
the required less significant word in the correct position. However, on
big endian systems the less significant word of the load is retrieved
from address+4, and the more significant from address+0. The destination
register therefore ends up with the required word in the more
significant word
e.g. when starting the second VP of a big endian 64bit system, the load

PTR_L    ta2, COREBOOTCFG_VPEMASK(a0)

ends up setting register ta2 to 0x0000000300000000

When this value is written to the CPC it is ignored, since it is
invalid to write anything larger than 4 bits. This results in any VP
other than VP0 in a core failing to start in 64bit big endian systems.

Change the load to a 32bit load word instruction to fix the bug.

Fixes: f12401d7219f ("MIPS: smp-cps: Pull boot config retrieval out of mips_cps_boot_vpes")
Signed-off-by: Matt Redfearn 
Cc: Paul Burton 
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/15787/
Signed-off-by: Ralf Baechle 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

MIPS: IRQ Stack: Unwind IRQ stack onto task stack

2017-10-08T08:26:09+00:00

[ Upstream commit db8466c581cca1a08b505f1319c3ecd246f16fa8 ]

When the separate IRQ stack was introduced, stack unwinding only
proceeded as far as the top of the IRQ stack, leading to kernel
backtraces being less useful, lacking the trace of what was interrupted.

Fix this by providing a means for the kernel to unwind the IRQ stack
onto the interrupted task stack. The processor state is saved to the
kernel task stack on interrupt. The IRQ_STACK_START macro reserves an
unsigned long at the top of the IRQ stack where the interrupted task
stack pointer can be saved. After the active stack is switched to the
IRQ stack, save the interrupted tasks stack pointer to the reserved
location.

Fix the stack unwinding code to look for the frame being the top of the
IRQ stack and if so get the next frame from the saved location. The
existing test does not work with the separate stack since the ra is no
longer pointed at ret_from_{irq,exception}.

The test to stop unwinding the stack 32 bytes from the top of a stack
must be modified to allow unwinding to continue up to the location of
the saved task stack pointer when on the IRQ stack. The low / high marks
of the stack are set depending on whether the sp is on an irq stack or
not.

Signed-off-by: Matt Redfearn 
Cc: Paolo Bonzini 
Cc: Marcin Nowakowski 
Cc: Masanari Iida 
Cc: Chris Metcalf 
Cc: James Hogan 
Cc: Paul Burton 
Cc: Ingo Molnar 
Cc: Jason A. Donenfeld 
Cc: Andrew Morton 
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/15788/
Signed-off-by: Ralf Baechle 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman