sysctl: Enable IA64 "ignore-unaligned-usertrap" to be used cross-arch

IA64 defines /proc/sys/kernel/ignore-unaligned-usertrap to control
verbose warnings on unaligned access emulation.

Although the exact mechanics of what to do with sysctl (ignore/shout)
are arch specific, this change enables the sysctl to be usable cross-arch.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

3 files changed, 15 insertions, 2 deletions

diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
index 3279646120e3..5fb10644d9ed 100644
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -40,6 +40,7 @@ config IA64
         select ARCH_THREAD_INFO_ALLOCATOR
         select ARCH_CLOCKSOURCE_DATA
         select GENERIC_TIME_VSYSCALL_OLD
+        select SYSCTL_ARCH_UNALIGN_NO_WARN
         select HAVE_MOD_ARCH_SPECIFIC
         select MODULES_USE_ELF_RELA
         default y
diff --git a/init/Kconfig b/init/Kconfig
index 7d30240e5bfe..523bee15fb44 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1232,6 +1232,13 @@ config SYSCTL_EXCEPTION_TRACE
         help
           Enable support for /proc/sys/debug/exception-trace.
 
+config SYSCTL_ARCH_UNALIGN_NO_WARN
+        bool
+        help
+          Enable support for /proc/sys/kernel/ignore-unaligned-usertrap
+          Allows arch to define/use @no_unaligned_warning to possibly warn
+          about unaligned access emulation going on under the hood.
+
 config KALLSYMS
          bool "Load all symbols for debugging/ksymoops" if EXPERT
          default y
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index c88878db491e..840fd5eb2309 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -161,10 +161,13 @@ extern int unaligned_enabled;
 #endif
 
 #ifdef CONFIG_IA64
-extern int no_unaligned_warning;
 extern int unaligned_dump_stack;
 #endif
 
+#ifdef CONFIG_SYSCTL_ARCH_UNALIGN_NO_WARN
+extern int no_unaligned_warning;
+#endif
+
 #ifdef CONFIG_PROC_SYSCTL
 static int proc_do_cad_pid(struct ctl_table *table, int write,
                   void __user *buffer, size_t *lenp, loff_t *ppos);
@@ -911,7 +914,7 @@ static struct ctl_table kern_table[] = {
                 .proc_handler   = proc_doulongvec_minmax,
         },
 #endif
-#ifdef CONFIG_IA64
+#ifdef CONFIG_SYSCTL_ARCH_UNALIGN_NO_WARN
         {
                 .procname       = "ignore-unaligned-usertrap",
                 .data           = &no_unaligned_warning,
@@ -919,6 +922,8 @@ static struct ctl_table kern_table[] = {
                 .mode           = 0644,
                 .proc_handler   = proc_dointvec,
         },
+#endif
+#ifdef CONFIG_IA64
         {
                 .procname       = "unaligned-dump-stack",
                 .data           = &unaligned_dump_stack,