linux-toradex.git/arch/mips/include/asm, branch v4.4.105

MIPS: End asm function prologue macros with .insn

2017-11-21T08:21:22+00:00

[ Upstream commit 08889582b8aa0bbc01a1e5a0033b9f98d2e11caa ]

When building a kernel targeting a microMIPS ISA, recent GNU linkers
will fail the link if they cannot determine that the target of a branch
or jump is microMIPS code, with errors such as the following:

    mips-img-linux-gnu-ld: arch/mips/built-in.o: .text+0x542c:
    Unsupported jump between ISA modes; consider recompiling with
    interlinking enabled.
    mips-img-linux-gnu-ld: final link failed: Bad value

or:

    ./arch/mips/include/asm/uaccess.h:1017: warning: JALX to a
    non-word-aligned address

Placing anything other than an instruction at the start of a function
written in assembly appears to trigger such errors. In order to prepare
for allowing us to follow function prologue macros with an EXPORT_SYMBOL
invocation, end the prologue macros (LEAD, NESTED & FEXPORT) with a
.insn directive. This ensures that the start of the function is marked
as code, which always makes sense for functions & safely prevents us
from hitting the link errors described above.

Signed-off-by: Paul Burton 
Reviewed-by: Maciej W. Rozycki 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14508/
Signed-off-by: Ralf Baechle 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

MIPS: Fix CM region target definitions

2017-11-15T16:13:12+00:00

commit 6a6cba1d945a7511cdfaf338526871195e420762 upstream.

The default CM target field in the GCR_BASE register is encoded with 0
meaning memory & 1 being reserved. However the definitions we use for
those bits effectively get these two values backwards - likely because
they were copied from the definitions for the CM regions where the
target is encoded differently. This results in use setting up GCR_BASE
with the reserved target value by default, rather than targeting memory
as intended. Although we currently seem to get away with this it's not a
great idea to rely upon.

Fix this by changing our macros to match the documentated target values.

The incorrect encoding became used as of commit 9f98f3dd0c51 ("MIPS: Add
generic CM probe & access code") in the Linux v3.15 cycle, and was
likely carried forwards from older but unused code introduced by
commit 39b8d5254246 ("[MIPS] Add support for MIPS CMP platform.") in the
v2.6.26 cycle.

Fixes: 9f98f3dd0c51 ("MIPS: Add generic CM probe & access code")
Signed-off-by: Paul Burton 
Reported-by: Matt Redfearn 
Reviewed-by: James Hogan 
Cc: Matt Redfearn 
Cc: Ralf Baechle 
Cc: linux-mips@linux-mips.org
Cc:  # v3.15+
Patchwork: https://patchwork.linux-mips.org/patch/17562/
Signed-off-by: James Hogan 
[jhogan@kernel.org: Backported 3.15..4.13]
Signed-off-by: Greg Kroah-Hartman

MIPS: Fix minimum alignment requirement of IRQ stack

2017-10-21T15:09:01+00:00

commit 5fdc66e046206306bf61ff2d626bfa52ca087f7b upstream.

Commit db8466c581cc ("MIPS: IRQ Stack: Unwind IRQ stack onto task
stack") erroneously set the initial stack pointer of the IRQ stack to a
value with a 4 byte alignment. The MIPS32 ABI requires that the minimum
stack alignment is 8 byte, and the MIPS64 ABIs(n32/n64) require 16 byte
minimum alignment. Fix IRQ_STACK_START such that it leaves space for the
dummy stack frame (containing interrupted task kernel stack pointer)
while also meeting minimum alignment requirements.

Fixes: db8466c581cc ("MIPS: IRQ Stack: Unwind IRQ stack onto task stack")
Reported-by: Darius Ivanauskas 
Signed-off-by: Matt Redfearn 
Cc: Chris Metcalf 
Cc: Petr Mladek 
Cc: Aaron Tomlin 
Cc: Jason A. Donenfeld 
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/16760/
Signed-off-by: Ralf Baechle 
Signed-off-by: Greg Kroah-Hartman

MIPS: IRQ Stack: Unwind IRQ stack onto task stack

2017-10-08T08:14:19+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

MIPS: Fix unaligned PC interpretation in `compute_return_epc'

2017-07-27T22:06:08+00:00

commit 11a3799dbeb620bf0400b1fda5cc2c6bea55f20a upstream.

Fix a regression introduced with commit fb6883e5809c ("MIPS: microMIPS:
Support handling of delay slots.") and defer to `__compute_return_epc'
if the ISA bit is set in EPC with non-MIPS16, non-microMIPS hardware,
which will then arrange for a SIGBUS due to an unaligned instruction
reference.  Returning EPC here is never correct as the API defines this
function's result to be either a negative error code on failure or one
of 0 and BRANCH_LIKELY_TAKEN on success.

Fixes: fb6883e5809c ("MIPS: microMIPS: Support handling of delay slots.")
Signed-off-by: Maciej W. Rozycki 
Cc: James Hogan 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16395/
Signed-off-by: Ralf Baechle 
Signed-off-by: Greg Kroah-Hartman

MIPS: Only change $28 to thread_info if coming from user mode

2017-04-18T05:14:36+00:00

commit 510d86362a27577f5ee23f46cfb354ad49731e61 upstream.

The SAVE_SOME macro is used to save the execution context on all
exceptions.
If an exception occurs while executing user code, the stack is switched
to the kernel's stack for the current task, and register $28 is switched
to point to the current_thread_info, which is at the bottom of the stack
region.
If the exception occurs while executing kernel code, the stack is left,
and this change ensures that register $28 is not updated. This is the
correct behaviour when the kernel can be executing on the separate irq
stack, because the thread_info will not be at the base of it.

With this change, register $28 is only switched to it's kernel
conventional usage of the currrent thread info pointer at the point at
which execution enters kernel space. Doing it on every exception was
redundant, but OK without an IRQ stack, but will be erroneous once that
is introduced.

Signed-off-by: Matt Redfearn 
Acked-by: Jason A. Donenfeld 
Cc: Thomas Gleixner 
Cc: James Hogan 
Cc: Paul Burton 
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14742/
Signed-off-by: Ralf Baechle 
Signed-off-by: Amit Pundir 
Signed-off-by: Greg Kroah-Hartman

MIPS: Introduce irq_stack

2017-04-18T05:14:35+00:00

commit fe8bd18ffea5327344d4ec2bf11f47951212abd0 upstream.

Allocate a per-cpu irq stack for use within interrupt handlers.

Also add a utility function on_irq_stack to determine if a given stack
pointer is within the irq stack for that cpu.

Signed-off-by: Matt Redfearn 
Acked-by: Jason A. Donenfeld 
Cc: Thomas Gleixner 
Cc: Paolo Bonzini 
Cc: Chris Metcalf 
Cc: Petr Mladek 
Cc: James Hogan 
Cc: Paul Burton 
Cc: Aaron Tomlin 
Cc: Andrew Morton 
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14740/
Signed-off-by: Ralf Baechle 
Signed-off-by: Amit Pundir 
Signed-off-by: Greg Kroah-Hartman

MIPS: End spinlocks with .insn

2017-04-12T10:38:35+00:00

commit 4b5347a24a0f2d3272032c120664b484478455de upstream.

When building for microMIPS we need to ensure that the assembler always
knows that there is code at the target of a branch or jump. Recent
toolchains will fail to link a microMIPS kernel when this isn't the case
due to what it thinks is a branch to non-microMIPS code.

mips-mti-linux-gnu-ld kernel/built-in.o: .spinlock.text+0x2fc: Unsupported branch between ISA modes.
mips-mti-linux-gnu-ld final link failed: Bad value

This is due to inline assembly labels in spinlock.h not being followed
by an instruction mnemonic, either due to a .subsection pseudo-op or the
end of the inline asm block.

Fix this with a .insn direction after such labels.

Signed-off-by: Paul Burton 
Signed-off-by: James Hogan 
Reviewed-by: Maciej W. Rozycki 
Cc: Ralf Baechle 
Cc: Peter Zijlstra 
Cc: Ingo Molnar 
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/15325/
Signed-off-by: James Hogan 
Signed-off-by: Greg Kroah-Hartman

MIPS: Fix special case in 64 bit IP checksumming.

2017-03-12T05:37:23+00:00

commit 66fd848cadaa6be974a8c780fbeb328f0af4d3bd upstream.

For certain arguments such as saddr = 0xc0a8fd60, daddr = 0xc0a8fda1,
len = 80, proto = 17, sum = 0x7eae049d there will be a carry when
folding the intermediate 64 bit checksum to 32 bit but the code doesn't
add the carry back to the one's complement sum, thus an incorrect result
will be generated.

Reported-by: Mark Zhang 
Signed-off-by: Ralf Baechle 
Reviewed-by: James Hogan 
Signed-off-by: James Hogan 
Signed-off-by: Greg Kroah-Hartman

KVM: MIPS: Precalculate MMIO load resume PC

2016-11-18T09:48:36+00:00

commit e1e575f6b026734be3b1f075e780e91ab08ca541 upstream.

The advancing of the PC when completing an MMIO load is done before
re-entering the guest, i.e. before restoring the guest ASID. However if
the load is in a branch delay slot it may need to access guest code to
read the prior branch instruction. This isn't safe in TLB mapped code at
the moment, nor in the future when we'll access unmapped guest segments
using direct user accessors too, as it could read the branch from host
user memory instead.

Therefore calculate the resume PC in advance while we're still in the
right context and save it in the new vcpu->arch.io_pc (replacing the no
longer needed vcpu->arch.pending_load_cause), and restore it on MMIO
completion.

Fixes: e685c689f3a8 ("KVM/MIPS32: Privileged instruction/target branch emulation.")
Signed-off-by: James Hogan 
Cc: Paolo Bonzini 
Cc: "Radim Krčmář" 
Cc: Ralf Baechle 
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Signed-off-by: Paolo Bonzini 
[james.hogan@imgtec.com: Backport to 3.18..4.4]
Signed-off-by: James Hogan 
Signed-off-by: Greg Kroah-Hartman