linux-stable.git/arch/mips/kernel/cps-vec.S, branch linux-4.4.y

MIPS: smp-cps: Stop printing EJTAG exceptions to UART

2020-05-10T08:25:40+00:00

commit 6609ccdc852f7bfbfa54300dd5b3cd89eb4ced6f upstream.

When CONFIG_MIPS_CPS_NS16550 is enabled, some register state is dumped
to the UART when an exception is taken via the BEV on secondary cores.
EJTAG exceptions are architecturally expected to be handled by the BEV
even when Status.BEV is 0. This effectively means that if userland
executes an sdbbp instruction on a secondary core then the kernel dumps
register state to the UART even though the exception is perfectly normal
& expected. Prevent this by simply not dumping information to the UART
for EJTAG exceptions.

Fixes: 609cf6f2291a ("MIPS: CPS: Early debug using an ns16550-compatible UART")
Signed-off-by: Paul Burton 
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/12341/
Signed-off-by: Ralf Baechle 
Signed-off-by: Greg Kroah-Hartman

MIPS: CPS: drop .set mips64r2 directives

2015-12-22T11:16:32+00:00

Commit 977e043d5ea1 ("MIPS: kernel: cps-vec: Replace mips32r2 ISA level
with mips64r2") leads to .set mips64r2 directives being present in 32
bit (ie. CONFIG_32BIT=y) kernels. This is incorrect & leads to MIPS64
instructions being emitted by the assembler when expanding
pseudo-instructions. For example the "move" instruction can legitimately
be expanded to a "daddu". This causes problems when the kernel is run on
a MIPS32 CPU, as CONFIG_32BIT kernels of course often are...

Fix this by dropping the .set  directives entirely now that Kconfig
should be ensuring that kernels including this code are built with a
suitable -march= compiler flag.

Signed-off-by: Paul Burton 
Cc: Markos Chandras 
Cc: James Hogan 
Cc:  # 3.16+
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/10869/
Signed-off-by: Ralf Baechle

MIPS: CPS: Skip Config1 presence check

2015-11-11T07:35:05+00:00

The Config1 register is architecturally defined as required, and is thus
present in all systems which may make use of cps-vec.S. Skip the check
for its presence via the Config.M bit.

Signed-off-by: Paul Burton 
Cc: linux-mips@linux-mips.org
Cc: Markos Chandras 
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/11204/
Signed-off-by: Ralf Baechle

MIPS: CPS: Read CM GCR base from cop0

2015-11-11T07:35:01+00:00

Rather than patching the start of mips_cps_core_entry to provide the
base address of the CM GCRs, simply read that base address from the cop0
CMGCRBase register, converting from the physical address to an uncached
virtual address.

Signed-off-by: Paul Burton 
Cc: linux-mips@linux-mips.org
Cc: Rusty Russell 
Cc: Andrew Bresticker 
Cc: linux-kernel@vger.kernel.org
Cc: Niklas Cassel 
Cc: Ezequiel Garcia 
Cc: Markos Chandras 
Patchwork: https://patchwork.linux-mips.org/patch/11203/
Signed-off-by: Ralf Baechle

MIPS: CPS: Early debug using an ns16550-compatible UART

2015-11-11T07:34:25+00:00

Provide support for outputting early debug information, in the form of
various register values should an exception occur, during the early
bringup of secondary cores. This code requires an ns16550-compatible
UART accessible from the secondary core, and is written in assembly due
to the environment in which such early exceptions occur where way may
not have a stack, be coherent or even have initialised caches.

[ralf@linux-mips.org: Fix merge conflict.]

Signed-off-by: Paul Burton 
Cc: linux-mips@linux-mips.org
Cc: Steven J. Hill 
Cc: Andrew Bresticker 
Cc: Leonid Yegoshin 
Cc: Maciej W. Rozycki 
Cc: Jason Cooper 
Cc: linux-kernel@vger.kernel.org
Cc: James Hogan 
Cc: Markos Chandras 
Patchwork: https://patchwork.linux-mips.org/patch/11202/
Signed-off-by: Ralf Baechle

MIPS: CPS: Set Status.KX on entry for MIPS64 kernels

2015-10-26T08:49:47+00:00

If the kernel may make use of 64 bit addresses outside of the
compatibility address space then we need to set KX such that those
accesses can succeed. Do so for MIPS64 kernels.

Signed-off-by: Paul Burton 
Cc: linux-mips@linux-mips.org
Cc: Markos Chandras 
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/11201/
Signed-off-by: Ralf Baechle

MIPS: CPS: Set Status.BEV bit during early boot

2015-10-26T08:49:47+00:00

Set the Status.BEV bit throughout the early startup of a secondary core
such that if an exception occurs the core branches to one of the
exception vector entries from cps-vec.S, rather than branching to
whatever is set in EBase.

Signed-off-by: Paul Burton 
Cc: linux-mips@linux-mips.org
Cc: Markos Chandras 
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/11200/
Signed-off-by: Ralf Baechle

MIPS: CPS: #ifdef on CONFIG_MIPS_MT_SMP rather than CONFIG_MIPS_MT

2015-09-30T16:16:02+00:00

The CONFIG_MIPS_MT symbol can be selected by CONFIG_MIPS_VPE_LOADER in
addition to CONFIG_MIPS_MT_SMP. We only want MT code in the CPS SMP boot
vector if we're using MT for SMP. Thus switch the config symbol we ifdef
against to CONFIG_MIPS_MT_SMP.

Signed-off-by: Paul Burton 
Cc: Markos Chandras 
Cc: James Hogan 
Cc:  # 3.16+
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/10867/
Signed-off-by: Ralf Baechle

MIPS: CPS: Don't include MT code in non-MT kernels.

2015-09-30T16:15:51+00:00

The MT-specific code in mips_cps_boot_vpes can safely be omitted from
kernels which don't support MT, with the default VPE==0 case being used
as it would be after the has_mt (Config3.MT) check failed at runtime.
Discarding the code entirely will save us a few bytes & allow cleaner
handling of MT ASE instructions by later patches.

Signed-off-by: Paul Burton 
Cc: Markos Chandras 
Cc: James Hogan 
Cc:  # 3.16+
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/10866/
Signed-off-by: Ralf Baechle

MIPS: CPS: Stop dangling delay slot from has_mt.

2015-09-30T16:15:29+00:00

The has_mt macro ended with a branch, leaving its callers with a delay
slot that would be executed if Config3.MT is not set. However it would
not be executed if Config3 (or earlier Config registers) don't exist
which makes it somewhat inconsistent at best. Fill the delay slot in the
macro & fix the mips_cps_boot_vpes caller appropriately.

Signed-off-by: Paul Burton 
Cc: Markos Chandras 
Cc: James Hogan 
Cc:  # 3.16+
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/10865/
Signed-off-by: Ralf Baechle