linux-toradex.git/arch/mips/kernel/cevt-r4k.c, branch v6.10

MIPS: cevt-r4k: Offset the value used to clear compare interrupt

2023-02-27T22:45:17+00:00

In c0_compare_int_usable we clear compare interrupt by write value
just read out from counter to compare register.

However sometimes if those all instructions are graduated together
then it's possible that at the time compare register is written, the
counter haven't progressed, thus the interrupt is triggered again.

It also applies to QEMU that instructions is executed significantly
faster then counter.

Offset the value used to clear interrupt by one to prevent that happen.

Signed-off-by: Jiaxun Yang 
Signed-off-by: Thomas Bogendoerfer

MIPS: Remove KVM_GUEST support

2021-03-10T14:18:40+00:00

KVM_GUEST is broken and unmaintained, so let's remove it.

Reviewed-by: Huacai Chen 
Reviewed-by: Jiaxun Yang 
Signed-off-by: Thomas Bogendoerfer

mips: cevt-r4k: Update the r4k-clockevent frequency in sync with CPU

2020-05-22T07:14:32+00:00

Due to being embedded into the CPU cores MIPS count/compare timer
frequency is changed together with the CPU clocks alteration.
In case if frequency really changes the kernel clockevent framework
must be notified, otherwise the kernel timers won't work correctly.
Fix this by calling clockevents_update_freq() for each r4k clockevent
handlers registered per available CPUs.

Traditionally MIPS r4k-clock are clocked with CPU frequency divided by 2.
But this isn't true for some of the platforms. Due to this we have to save
the basic CPU frequency, so then use it to scale the initial timer
frequency (mips_hpt_frequency) and pass the updated value further to the
clockevent framework.

Signed-off-by: Serge Semin 
Cc: Alexey Malahov 
Cc: Thomas Bogendoerfer 
Cc: Paul Burton 
Cc: Ralf Baechle 
Cc: Greg Kroah-Hartman 
Cc: Arnd Bergmann 
Cc: Rob Herring 
Cc: devicetree@vger.kernel.org
Signed-off-by: Thomas Bogendoerfer

MIPS: pass non-NULL dev_id on shared request_irq()

2020-03-16T15:04:49+00:00

Recently all usages of setup_irq() was replaced by request_irq().
request_irq() does a few sanity checks that were not done in
setup_irq(), if they fail irq registration will fail. One of the check
is to ensure that non-NULL dev_id is passed in the case of shared irq.
This caused malta on qemu to hang.

Fix it by passing handler as dev_id to all request_irq()'s that are
shared. For sni, instead of passing non-NULL dev_id, remove shared irq
flags.

Fixes: ac8fd122e070 ("MIPS: Replace setup_irq() by request_irq()")
Reported-by: Nathan Chancellor 
Suggested-by: Thomas Bogendoerfer 
Signed-off-by: afzal mohammed 
Tested-by: Guenter Roeck 
Tested-by: Nathan Chancellor 
Signed-off-by: Thomas Bogendoerfer

MIPS: Replace setup_irq() by request_irq()

2020-03-05T15:47:35+00:00

request_irq() is preferred over setup_irq(). Invocations of setup_irq()
occur after memory allocators are ready.

Per tglx[1], setup_irq() existed in olden days when allocators were not
ready by the time early interrupts were initialized.

Hence replace setup_irq() by request_irq().

remove_irq() has been replaced by free_irq() as well.

There were build error's during previous version, couple of which was
reported by kbuild test robot  of which one was reported
by Thomas Bogendoerfer  as well. There were a
few more issues including build errors, those also have been fixed.

[1] https://lkml.kernel.org/r/alpine.DEB.2.20.1710191609480.1971@nanos

Signed-off-by: afzal mohammed 
Signed-off-by: Thomas Bogendoerfer

MIPS: cevt-r4k: Fix out-of-bounds array access

2017-04-10T11:31:12+00:00

calculate_min_delta() may incorrectly access a 4th element of buf2[]
which only has 3 elements. This may trigger undefined behaviour and has
been reported to cause strange crashes in start_kernel() sometime after
timer initialization when built with GCC 5.3, possibly due to
register/stack corruption:

sched_clock: 32 bits at 200MHz, resolution 5ns, wraps every 10737418237ns
CPU 0 Unable to handle kernel paging request at virtual address ffffb0aa, epc == 8067daa8, ra == 8067da84
Oops[#1]:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.9.18 #51
task: 8065e3e0 task.stack: 80644000
$ 0   : 00000000 00000001 00000000 00000000
$ 4   : 8065b4d0 00000000 805d0000 00000010
$ 8   : 00000010 80321400 fffff000 812de408
$12   : 00000000 00000000 00000000 ffffffff
$16   : 00000002 ffffffff 80660000 806a666c
$20   : 806c0000 00000000 00000000 00000000
$24   : 00000000 00000010
$28   : 80644000 80645ed0 00000000 8067da84
Hi    : 00000000
Lo    : 00000000
epc   : 8067daa8 start_kernel+0x33c/0x500
ra    : 8067da84 start_kernel+0x318/0x500
Status: 11000402 KERNEL EXL
Cause : 4080040c (ExcCode 03)
BadVA : ffffb0aa
PrId  : 0501992c (MIPS 1004Kc)
Modules linked in:
Process swapper/0 (pid: 0, threadinfo=80644000, task=8065e3e0, tls=00000000)
Call Trace:
[<8067daa8>] start_kernel+0x33c/0x500
Code: 24050240  0c0131f9  24849c64  41606020  000000c0  0c1a45e6 00000000  0c1a5f44

UBSAN also detects the same issue:

================================================================
UBSAN: Undefined behaviour in arch/mips/kernel/cevt-r4k.c:85:41
load of address 80647e4c with insufficient space
for an object of type 'unsigned int'
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.9.18 #47
Call Trace:
[<80028f70>] show_stack+0x88/0xa4
[<80312654>] dump_stack+0x84/0xc0
[<8034163c>] ubsan_epilogue+0x14/0x50
[<803417d8>] __ubsan_handle_type_mismatch+0x160/0x168
[<8002dab0>] r4k_clockevent_init+0x544/0x764
[<80684d34>] time_init+0x18/0x90
[<8067fa5c>] start_kernel+0x2f0/0x500
=================================================================

buf2[] is intentionally only 3 elements so that the last element is the
median once 5 samples have been inserted, so explicitly prevent the
possibility of comparing against the 4th element rather than extending
the array.

Fixes: 1fa405552e33f2 ("MIPS: cevt-r4k: Dynamically calculate min_delta_ns")
Reported-by: Rabin Vincent 
Signed-off-by: James Hogan 
Tested-by: Rabin Vincent 
Cc: linux-mips@linux-mips.org
Cc:  # 4.7.x-
Patchwork: https://patchwork.linux-mips.org/patch/15892/
Signed-off-by: Ralf Baechle

MIPS: Fix r4k clockevents registration

2016-07-24T09:59:48+00:00

CPUFreq need min_delta_ticks/max_delta_ticks to be initialized, and
this can be done by clockevents_config_and_register().

Cc: stable@vger.kernel.org
Signed-off-by: Heiher 
Signed-off-by: Huacai Chen 
Cc: John Crispin 
Cc: Steven J . Hill 
Cc: Fuxin Zhang 
Cc: Zhangjin Wu 
Cc: stable@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13817/
Signed-off-by: Ralf Baechle

MIPS: cevt-r4k: Dynamically calculate min_delta_ns

2016-05-13T13:30:25+00:00

Calculate the MIPS clockevent device's min_delta_ns dynamically based on
the time it takes to perform the mips_next_event() sequence.

Virtualisation in particular makes the current fixed min_delta of 0x300
inappropriate under some circumstances, as the CP0_Count and CP0_Compare
registers may be being emulated by the hypervisor, and the frequency may
not correspond directly to the CPU frequency.

We actually use twice the median of multiple 75th percentiles of
multiple measurements of how long the mips_next_event() sequence takes,
in order to fairly efficiently eliminate outliers due to unexpected
hypervisor latency (which would need handling with retries when it
occurs during normal operation anyway).

Signed-off-by: James Hogan 
Cc: Daniel Lezcano 
Cc: Thomas Gleixner 
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/13176/
Signed-off-by: Ralf Baechle

MIPS: cevt-r4k: Migrate to new 'set-state' interface

2015-09-03T10:07:52+00:00

Migrate cevt-4k driver to the new 'set-state' interface provided by
clockevents core, the earlier 'set-mode' interface is marked obsolete
now.

This also enables us to implement callbacks for new states of clockevent
devices, for example: ONESHOT_STOPPED.

We weren't doing anything in the ->set_mode() callback. So, this patch
doesn't provide any set-state callbacks.

Signed-off-by: Viresh Kumar 
Cc: James Hogan 
Cc: Andrew Bresticker 
Cc: Qais Yousef 
Cc: Jason Cooper 
Cc: Leonid Yegoshin 
Cc: Daniel Lezcano 
Cc: linux-mips@linux-mips.org
Cc: linaro-kernel@lists.linaro.org
Cc: Thomas Gleixner 
Patchwork: https://patchwork.linux-mips.org/patch/10605/
Signed-off-by: Ralf Baechle

MIPS: Remove "weak" from get_c0_compare_int() declaration

2015-09-03T10:07:38+00:00

Weak header file declarations are error-prone because they make every
definition weak, and the linker chooses one based on link order (see
10629d711ed7 ("PCI: Remove __weak annotation from pcibios_get_phb_of_node
decl")).

get_c0_compare_int() is defined in several files.  Each definition is weak,
so I assume Kconfig prevents two or more from being included.  The caller
contains default code used when get_c0_compare_int() isn't defined at all.

Add a weak get_c0_compare_int() definition with the default code and remove
the weak annotation from the declaration.

Then the platform implementations will be strong and will override the weak
default.  If multiple platforms are ever configured in, we'll get a link
error instead of calling a random platform's implementation.

Signed-off-by: Bjorn Helgaas 
Reviewed-by: James Hogan 
Cc: Andrew Bresticker 
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/10686/
Signed-off-by: Ralf Baechle