linux/arch/avr32/Kconfig
Petr Mladek 42a0bb3f71 printk/nmi: generic solution for safe printk in NMI
printk() takes some locks and could not be used a safe way in NMI
context.

The chance of a deadlock is real especially when printing stacks from
all CPUs.  This particular problem has been addressed on x86 by the
commit a9edc88093 ("x86/nmi: Perform a safe NMI stack trace on all
CPUs").

The patchset brings two big advantages.  First, it makes the NMI
backtraces safe on all architectures for free.  Second, it makes all NMI
messages almost safe on all architectures (the temporary buffer is
limited.  We still should keep the number of messages in NMI context at
minimum).

Note that there already are several messages printed in NMI context:
WARN_ON(in_nmi()), BUG_ON(in_nmi()), anything being printed out from MCE
handlers.  These are not easy to avoid.

This patch reuses most of the code and makes it generic.  It is useful
for all messages and architectures that support NMI.

The alternative printk_func is set when entering and is reseted when
leaving NMI context.  It queues IRQ work to copy the messages into the
main ring buffer in a safe context.

__printk_nmi_flush() copies all available messages and reset the buffer.
Then we could use a simple cmpxchg operations to get synchronized with
writers.  There is also used a spinlock to get synchronized with other
flushers.

We do not longer use seq_buf because it depends on external lock.  It
would be hard to make all supported operations safe for a lockless use.
It would be confusing and error prone to make only some operations safe.

The code is put into separate printk/nmi.c as suggested by Steven
Rostedt.  It needs a per-CPU buffer and is compiled only on
architectures that call nmi_enter().  This is achieved by the new
HAVE_NMI Kconfig flag.

The are MN10300 and Xtensa architectures.  We need to clean up NMI
handling there first.  Let's do it separately.

The patch is heavily based on the draft from Peter Zijlstra, see

  https://lkml.org/lkml/2015/6/10/327

[arnd@arndb.de: printk-nmi: use %zu format string for size_t]
[akpm@linux-foundation.org: min_t->min - all types are size_t here]
Signed-off-by: Petr Mladek <pmladek@suse.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Jan Kara <jack@suse.cz>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>	[arm part]
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jiri Kosina <jkosina@suse.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: David Miller <davem@davemloft.net>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-20 17:58:30 -07:00

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config AVR32
def_bool y
# With EXPERT=n, we get lots of stuff automatically selected
# that we usually don't need on AVR32.
select EXPERT
select HAVE_CLK
select HAVE_EXIT_THREAD
select HAVE_OPROFILE
select HAVE_KPROBES
select VIRT_TO_BUS
select GENERIC_IRQ_PROBE
select GENERIC_ATOMIC64
select HARDIRQS_SW_RESEND
select GENERIC_IRQ_SHOW
select ARCH_HAVE_CUSTOM_GPIO_H
select ARCH_WANT_IPC_PARSE_VERSION
select ARCH_HAVE_NMI_SAFE_CMPXCHG
select GENERIC_CLOCKEVENTS
select HAVE_MOD_ARCH_SPECIFIC
select MODULES_USE_ELF_RELA
select HAVE_NMI
help
AVR32 is a high-performance 32-bit RISC microprocessor core,
designed for cost-sensitive embedded applications, with particular
emphasis on low power consumption and high code density.
There is an AVR32 Linux project with a web page at
http://avr32linux.org/.
config STACKTRACE_SUPPORT
def_bool y
config LOCKDEP_SUPPORT
def_bool y
config TRACE_IRQFLAGS_SUPPORT
def_bool y
config RWSEM_GENERIC_SPINLOCK
def_bool y
config RWSEM_XCHGADD_ALGORITHM
def_bool n
config ARCH_HAS_ILOG2_U32
def_bool n
config ARCH_HAS_ILOG2_U64
def_bool n
config GENERIC_HWEIGHT
def_bool y
config GENERIC_CALIBRATE_DELAY
def_bool y
config GENERIC_BUG
def_bool y
depends on BUG
source "init/Kconfig"
source "kernel/Kconfig.freezer"
menu "System Type and features"
config SUBARCH_AVR32B
bool
config MMU
bool
config PERFORMANCE_COUNTERS
bool
config PLATFORM_AT32AP
bool
select SUBARCH_AVR32B
select MMU
select PERFORMANCE_COUNTERS
select GPIOLIB
select GENERIC_ALLOCATOR
select HAVE_FB_ATMEL
#
# CPU types
#
# AP7000 derivatives
config CPU_AT32AP700X
bool
select PLATFORM_AT32AP
config CPU_AT32AP7000
bool
select CPU_AT32AP700X
config CPU_AT32AP7001
bool
select CPU_AT32AP700X
config CPU_AT32AP7002
bool
select CPU_AT32AP700X
# AP700X boards
config BOARD_ATNGW100_COMMON
bool
select CPU_AT32AP7000
choice
prompt "AVR32 board type"
default BOARD_ATSTK1000
config BOARD_ATSTK1000
bool "ATSTK1000 evaluation board"
config BOARD_ATNGW100_MKI
bool "ATNGW100 Network Gateway"
select BOARD_ATNGW100_COMMON
config BOARD_ATNGW100_MKII
bool "ATNGW100 mkII Network Gateway"
select BOARD_ATNGW100_COMMON
config BOARD_HAMMERHEAD
bool "Hammerhead board"
select CPU_AT32AP7000
select USB_ARCH_HAS_HCD
help
The Hammerhead platform is built around an AVR32 32-bit microcontroller from Atmel.
It offers versatile peripherals, such as ethernet, usb device, usb host etc.
The board also incorporates a power supply and is a Power over Ethernet (PoE) Powered
Device (PD).
Additionally, a Cyclone III FPGA from Altera is integrated on the board. The FPGA is
mapped into the 32-bit AVR memory bus. The FPGA offers two DDR2 SDRAM interfaces, which
will cover even the most exceptional need of memory bandwidth. Together with the onboard
video decoder the board is ready for video processing.
For more information see: http://www.miromico.ch/index.php/hammerhead.html
config BOARD_FAVR_32
bool "Favr-32 LCD-board"
select CPU_AT32AP7000
config BOARD_MERISC
bool "Merisc board"
select CPU_AT32AP7000
help
Merisc is the family name for a range of AVR32-based boards.
The boards are designed to be used in a man-machine
interfacing environment, utilizing a touch-based graphical
user interface. They host a vast range of I/O peripherals as
well as a large SDRAM & Flash memory bank.
For more information see: http://www.martinsson.se/merisc
config BOARD_MIMC200
bool "MIMC200 CPU board"
select CPU_AT32AP7000
endchoice
source "arch/avr32/boards/atstk1000/Kconfig"
source "arch/avr32/boards/atngw100/Kconfig"
source "arch/avr32/boards/hammerhead/Kconfig"
source "arch/avr32/boards/favr-32/Kconfig"
source "arch/avr32/boards/merisc/Kconfig"
choice
prompt "Boot loader type"
default LOADER_U_BOOT
config LOADER_U_BOOT
bool "U-Boot (or similar) bootloader"
endchoice
source "arch/avr32/mach-at32ap/Kconfig"
config LOAD_ADDRESS
hex
default 0x10000000 if LOADER_U_BOOT=y && CPU_AT32AP700X=y
config ENTRY_ADDRESS
hex
default 0x90000000 if LOADER_U_BOOT=y && CPU_AT32AP700X=y
config PHYS_OFFSET
hex
default 0x10000000 if CPU_AT32AP700X=y
source "kernel/Kconfig.preempt"
config QUICKLIST
def_bool y
config ARCH_HAVE_MEMORY_PRESENT
def_bool n
config NEED_NODE_MEMMAP_SIZE
def_bool n
config ARCH_FLATMEM_ENABLE
def_bool y
config ARCH_DISCONTIGMEM_ENABLE
def_bool n
config ARCH_SPARSEMEM_ENABLE
def_bool n
config NODES_SHIFT
int
default "2"
depends on NEED_MULTIPLE_NODES
source "mm/Kconfig"
config OWNERSHIP_TRACE
bool "Ownership trace support"
default y
help
Say Y to generate an Ownership Trace message on every context switch,
enabling Nexus-compliant debuggers to keep track of the PID of the
currently executing task.
config NMI_DEBUGGING
bool "NMI Debugging"
default n
help
Say Y here and pass the nmi_debug command-line parameter to
the kernel to turn on NMI debugging. Depending on the value
of the nmi_debug option, various pieces of information will
be dumped to the console when a Non-Maskable Interrupt
happens.
# FPU emulation goes here
source "kernel/Kconfig.hz"
config CMDLINE
string "Default kernel command line"
default ""
help
If you don't have a boot loader capable of passing a command line string
to the kernel, you may specify one here. As a minimum, you should specify
the memory size and the root device (e.g., mem=8M, root=/dev/nfs).
endmenu
menu "Power management options"
source "kernel/power/Kconfig"
config ARCH_SUSPEND_POSSIBLE
def_bool y
menu "CPU Frequency scaling"
source "drivers/cpufreq/Kconfig"
endmenu
endmenu
menu "Bus options"
config PCI
bool
source "drivers/pci/Kconfig"
source "drivers/pcmcia/Kconfig"
endmenu
menu "Executable file formats"
source "fs/Kconfig.binfmt"
endmenu
source "net/Kconfig"
source "drivers/Kconfig"
source "fs/Kconfig"
source "arch/avr32/Kconfig.debug"
source "security/Kconfig"
source "crypto/Kconfig"
source "lib/Kconfig"