[PATCH -v7 1/3] Add Kconfig option ARCH_HAVE_NMI_SAFE_CMPXCHG

From: Huang Ying
Date: Thu Dec 02 2010 - 21:47:47 EST


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 to 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@xxxxxxxxx>
Acked-by: Mike Frysinger <vapier@xxxxxxxxxx>
Acked-by: Paul Mundt <lethal@xxxxxxxxxxxx>
Acked-by: Hans-Christian Egtvedt <hans-christian.egtvedt@xxxxxxxxx>
Acked-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Acked-by: Chris Metcalf <cmetcalf@xxxxxxxxxx>
CC: Richard Henderson <rth@xxxxxxxxxxx>
CC: Russell King <linux@xxxxxxxxxxxxxxxx>
CC: Mikael Starvik <starvik@xxxxxxxx>
CC: David Howells <dhowells@xxxxxxxxxx>
CC: Yoshinori Sato <ysato@xxxxxxxxxxxxxxxxxxxx>
CC: Tony Luck <tony.luck@xxxxxxxxx>
CC: Hirokazu Takata <takata@xxxxxxxxxxxxxx>
CC: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
CC: Michal Simek <monstr@xxxxxxxxx>
CC: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
CC: Kyle McMartin <kyle@xxxxxxxxxxx>
CC: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
CC: Chen Liqin <liqin.chen@xxxxxxxxxxxxx>
CC: "David S. Miller" <davem@xxxxxxxxxxxxx>
CC: Ingo Molnar <mingo@xxxxxxxxxx>
CC: Chris Zankel <chris@xxxxxxxxxx>
---
arch/Kconfig | 3 +++
arch/alpha/Kconfig | 1 +
arch/avr32/Kconfig | 1 +
arch/frv/Kconfig | 1 +
arch/ia64/Kconfig | 1 +
arch/m68k/Kconfig | 1 +
arch/parisc/Kconfig | 1 +
arch/powerpc/Kconfig | 1 +
arch/s390/Kconfig | 1 +
arch/sh/Kconfig | 1 +
arch/sparc/Kconfig | 1 +
arch/tile/Kconfig | 1 +
arch/x86/Kconfig | 1 +
13 files changed, 15 insertions(+)

--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -175,4 +175,7 @@ config HAVE_PERF_EVENTS_NMI
config HAVE_ARCH_JUMP_LABEL
bool

+config ARCH_HAVE_NMI_SAFE_CMPXCHG
+ bool
+
source "kernel/gcov/Kconfig"
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -7,6 +7,7 @@ config ALPHA
select HAVE_SYSCALL_WRAPPERS
select HAVE_IRQ_WORK
select HAVE_PERF_EVENTS
+ select ARCH_HAVE_NMI_SAFE_CMPXCHG
select HAVE_DMA_ATTRS
help
The Alpha is a 64-bit general-purpose processor designed and
--- a/arch/avr32/Kconfig
+++ b/arch/avr32/Kconfig
@@ -6,6 +6,7 @@ config AVR32
select HAVE_CLK
select HAVE_OPROFILE
select HAVE_KPROBES
+ 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
--- a/arch/frv/Kconfig
+++ b/arch/frv/Kconfig
@@ -5,6 +5,7 @@ config FRV
select HAVE_ARCH_TRACEHOOK
select HAVE_IRQ_WORK
select HAVE_PERF_EVENTS
+ select ARCH_HAVE_NMI_SAFE_CMPXCHG

config ZONE_DMA
bool
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -22,6 +22,7 @@ config IA64
select HAVE_KVM
select HAVE_ARCH_TRACEHOOK
select HAVE_DMA_API_DEBUG
+ select ARCH_HAVE_NMI_SAFE_CMPXCHG
default y
help
The Itanium Processor Family is Intel's 64-bit successor to
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -4,6 +4,7 @@ config M68K
select HAVE_AOUT
select HAVE_IDE
select GENERIC_ATOMIC64
+ select ARCH_HAVE_NMI_SAFE_CMPXCHG if RMW_INSNS

config MMU
bool
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -11,6 +11,7 @@ config PARISC
select BUG
select HAVE_IRQ_WORK
select HAVE_PERF_EVENTS
+ select ARCH_HAVE_NMI_SAFE_CMPXCHG
select GENERIC_ATOMIC64 if !64BIT
select GENERIC_HARDIRQS_NO__DO_IRQ
help
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -138,6 +138,7 @@ config PPC
select GENERIC_ATOMIC64 if PPC32
select HAVE_IRQ_WORK
select HAVE_PERF_EVENTS
+ select ARCH_HAVE_NMI_SAFE_CMPXCHG
select HAVE_REGS_AND_STACK_ACCESS_API
select HAVE_HW_BREAKPOINT if PERF_EVENTS && PPC_BOOK3S_64

--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -94,6 +94,7 @@ 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
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -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
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -22,6 +22,7 @@ config SPARC
select RTC_CLASS
select RTC_DRV_M48T59
select HAVE_IRQ_WORK
+ select ARCH_HAVE_NMI_SAFE_CMPXCHG
select HAVE_DMA_ATTRS
select HAVE_DMA_API_DEBUG
select HAVE_ARCH_JUMP_LABEL
--- a/arch/tile/Kconfig
+++ b/arch/tile/Kconfig
@@ -104,6 +104,7 @@ config TILE
select GENERIC_FIND_NEXT_BIT
select USE_GENERIC_SMP_HELPERS
select CC_OPTIMIZE_FOR_SIZE
+ select ARCH_HAVE_NMI_SAFE_CMPXCHG

# FIXME: investigate whether we need/want these options.
# select HAVE_IOREMAP_PROT
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -23,6 +23,7 @@ config X86
select HAVE_OPROFILE
select HAVE_PERF_EVENTS
select HAVE_IRQ_WORK
+ select ARCH_HAVE_NMI_SAFE_CMPXCHG if !M386
select HAVE_IOREMAP_PROT
select HAVE_KPROBES
select HAVE_MEMBLOCK
--
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