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Add Kconfig option ARCH_HAVE_NMI_SAFE_CMPXCHG

cmpxchg() is widely used by lockless code, including NMI-safe lockless
code.  But on some architectures, the cmpxchg() implementation is not
NMI-safe, on these architectures the lockless code may need a
spin_trylock_irqsave() based implementation.

This patch adds a Kconfig option: ARCH_HAVE_NMI_SAFE_CMPXCHG, so that
NMI-safe lockless code can depend on it or provide different
implementation according to it.

On many architectures, cmpxchg is only NMI-safe for several specific
operand sizes. So, ARCH_HAVE_NMI_SAFE_CMPXCHG define in this patch
only guarantees cmpxchg is NMI-safe for sizeof(unsigned long).

Signed-off-by: Huang Ying <ying.huang@intel.com>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Acked-by: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Acked-by: Richard Henderson <rth@twiddle.net>
CC: Mikael Starvik <starvik@axis.com>
Acked-by: David Howells <dhowells@redhat.com>
CC: Yoshinori Sato <ysato@users.sourceforge.jp>
CC: Tony Luck <tony.luck@intel.com>
CC: Hirokazu Takata <takata@linux-m32r.org>
CC: Geert Uytterhoeven <geert@linux-m68k.org>
CC: Michal Simek <monstr@monstr.eu>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
CC: Kyle McMartin <kyle@mcmartin.ca>
CC: Martin Schwidefsky <schwidefsky@de.ibm.com>
CC: Chen Liqin <liqin.chen@sunplusct.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: Ingo Molnar <mingo@redhat.com>
CC: Chris Zankel <chris@zankel.net>
Signed-off-by: Len Brown <len.brown@intel.com>
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commit df013ffb8119c89f062ab05b7f544704315db47b 1 parent 9fb0bfe
Huang Ying authored lenb committed
3  arch/Kconfig
View
@@ -178,4 +178,7 @@ config HAVE_ARCH_MUTEX_CPU_RELAX
config HAVE_RCU_TABLE_FREE
bool
+config ARCH_HAVE_NMI_SAFE_CMPXCHG
+ bool
+
source "kernel/gcov/Kconfig"
1  arch/alpha/Kconfig
View
@@ -13,6 +13,7 @@ config ALPHA
select AUTO_IRQ_AFFINITY if SMP
select GENERIC_IRQ_SHOW
select ARCH_WANT_OPTIONAL_GPIOLIB
+ select ARCH_HAVE_NMI_SAFE_CMPXCHG
help
The Alpha is a 64-bit general-purpose processor designed and
marketed by the Digital Equipment Corporation of blessed memory,
1  arch/avr32/Kconfig
View
@@ -10,6 +10,7 @@ config AVR32
select GENERIC_IRQ_PROBE
select HARDIRQS_SW_RESEND
select GENERIC_IRQ_SHOW
+ select ARCH_HAVE_NMI_SAFE_CMPXCHG
help
AVR32 is a high-performance 32-bit RISC microprocessor core,
designed for cost-sensitive embedded applications, with particular
1  arch/frv/Kconfig
View
@@ -7,6 +7,7 @@ config FRV
select HAVE_PERF_EVENTS
select HAVE_GENERIC_HARDIRQS
select GENERIC_IRQ_SHOW
+ select ARCH_HAVE_NMI_SAFE_CMPXCHG
config ZONE_DMA
bool
1  arch/ia64/Kconfig
View
@@ -27,6 +27,7 @@ config IA64
select GENERIC_PENDING_IRQ if SMP
select IRQ_PER_CPU
select GENERIC_IRQ_SHOW
+ select ARCH_HAVE_NMI_SAFE_CMPXCHG
default y
help
The Itanium Processor Family is Intel's 64-bit successor to
1  arch/m68k/Kconfig
View
@@ -6,6 +6,7 @@ config M68K
select GENERIC_ATOMIC64 if MMU
select HAVE_GENERIC_HARDIRQS if !MMU
select GENERIC_IRQ_SHOW if !MMU
+ select ARCH_HAVE_NMI_SAFE_CMPXCHG if RMW_INSNS
config RWSEM_GENERIC_SPINLOCK
bool
1  arch/parisc/Kconfig
View
@@ -15,6 +15,7 @@ config PARISC
select HAVE_GENERIC_HARDIRQS
select GENERIC_IRQ_PROBE
select IRQ_PER_CPU
+ select ARCH_HAVE_NMI_SAFE_CMPXCHG
help
The PA-RISC microprocessor is designed by Hewlett-Packard and used
1  arch/powerpc/Kconfig
View
@@ -134,6 +134,7 @@ config PPC
select GENERIC_IRQ_SHOW_LEVEL
select HAVE_RCU_TABLE_FREE if SMP
select HAVE_SYSCALL_TRACEPOINTS
+ select ARCH_HAVE_NMI_SAFE_CMPXCHG
config EARLY_PRINTK
bool
1  arch/s390/Kconfig
View
@@ -81,6 +81,7 @@ config S390
select INIT_ALL_POSSIBLE
select HAVE_IRQ_WORK
select HAVE_PERF_EVENTS
+ select ARCH_HAVE_NMI_SAFE_CMPXCHG
select HAVE_KERNEL_GZIP
select HAVE_KERNEL_BZIP2
select HAVE_KERNEL_LZMA
1  arch/sh/Kconfig
View
@@ -11,6 +11,7 @@ config SUPERH
select HAVE_DMA_ATTRS
select HAVE_IRQ_WORK
select HAVE_PERF_EVENTS
+ select ARCH_HAVE_NMI_SAFE_CMPXCHG if (GUSA_RB || CPU_SH4A)
select PERF_USE_VMALLOC
select HAVE_KERNEL_GZIP
select HAVE_KERNEL_BZIP2
1  arch/sparc/Kconfig
View
@@ -53,6 +53,7 @@ config SPARC64
select HAVE_PERF_EVENTS
select PERF_USE_VMALLOC
select IRQ_PREFLOW_FASTEOI
+ select ARCH_HAVE_NMI_SAFE_CMPXCHG
config ARCH_DEFCONFIG
string
1  arch/tile/Kconfig
View
@@ -12,6 +12,7 @@ config TILE
select GENERIC_PENDING_IRQ if SMP
select GENERIC_IRQ_SHOW
select SYS_HYPERVISOR
+ select ARCH_HAVE_NMI_SAFE_CMPXCHG if !M386
# FIXME: investigate whether we need/want these options.
# select HAVE_IOREMAP_PROT
1  arch/x86/Kconfig
View
@@ -70,6 +70,7 @@ config X86
select IRQ_FORCED_THREADING
select USE_GENERIC_SMP_HELPERS if SMP
select HAVE_BPF_JIT if (X86_64 && NET)
+ select ARCH_HAVE_NMI_SAFE_CMPXCHG
config INSTRUCTION_DECODER
def_bool (KPROBES || PERF_EVENTS)
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