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>

diff --git a/arch/Kconfig b/arch/Kconfig
index 26b0e2397a5724140bc8683fedd6bbae67706fe5..4b0669cbb3b01d4c0eb66f364859cb6f65654693 100644 (file)
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -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"

diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index 60219bf9419884587ed0c6172a084cd5555bddbf..23f8d8c32886b421a01b4a501dbc5a2cb96ebe08 100644 (file)
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -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,

diff --git a/arch/avr32/Kconfig b/arch/avr32/Kconfig
index e9d689b7c833d2c5218ce3d97876c3023785f4e8..197e96f7040594fa1994f6d7f61edddff6ccd65d 100644 (file)
--- a/arch/avr32/Kconfig
+++ b/arch/avr32/Kconfig
@@ -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

diff --git a/arch/frv/Kconfig b/arch/frv/Kconfig
index cb884e48942560f23eb9de40c24cb62d9b7eb1e9..bad27a6ff407bfcce2aecbac934278eabe9c194f 100644 (file)
--- a/arch/frv/Kconfig
+++ b/arch/frv/Kconfig
@@ -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

diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
index 38280ef4a2af219c8a2aba4fef0a43830acc8515..b1227ddc672ac5ca2a4e3a9ca0ea80a91d41fd60 100644 (file)
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -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

diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index d66e34c718d0927a6eba9daa9a023b7e3bcd228a..effe8f0fa31effc9c1a60863f05774053ff8ff7c 100644 (file)
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -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

diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 65adc86a230e705d64b41b1c69a886268f9a6eb6..e077b0bf56ca51910df1775acd66f319afdae13a 100644 (file)
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -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

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 2729c6663d8a79c42705b9f81828e6ee6d6f5dd0..e55f754dd50d48b05ddae560ff0bba59444f983f 100644 (file)
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -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

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index c03fef7a9c2220c45ca1584ad8f65191bb5c9e76..0f98bbddade57dce3ee1517168b10b03fd6796c4 100644 (file)
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -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

diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index bbdeb48bbf8e40fb80cdf4cd3d4c0b3e132dc6b1..66405eb217669efcb5ded0f3f2e40d3be80dea25 100644 (file)
--- 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

diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 253986bd6bb625a270ae1f27b99d967650b178c4..a63cddfb3a153cbf9eb435c10b0434ea4f6b8965 100644 (file)
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -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

diff --git a/arch/tile/Kconfig b/arch/tile/Kconfig
index 0249b8b4db545bdb26334d05d3e105a387b6f1d0..b30f71ac0d0657f24d6a37f13c7ad802d9f36708 100644 (file)
--- a/arch/tile/Kconfig
+++ b/arch/tile/Kconfig
@@ -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

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index da349723d4115cef7d75aac4680ba2284deaf0d0..a680a60898ded9e9a1afa241e00e6417cf3e8698 100644 (file)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -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)