[PATCH] x86: Make cpu_tss available to external modules

[PATCH] x86: Make cpu_tss available to external modules

[Marc Dionne]

Commit 75182b1632 ("x86/asm/entry: Switch all C consumers of
kernel_stack to this_cpu_sp0()") changed current_thread_info
to use this_cpu_sp0, and indirectly made it rely on init_tss
which was exported with EXPORT_PER_CPU_SYMBOL_GPL.
As a result some macros and inline functions such as set/get_fs,
test_thread_flag and variants have been made unusable for
external modules.

Make cpu_tss exported with EXPORT_PER_CPU_SYMBOL so that these
functions are accessible again, as they were previously.

Signed-off-by: Marc Dionne <marc.dionne@your-file-system.com>
---
 arch/x86/kernel/process.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 8213da6..bfc99b3 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -57,7 +57,7 @@ __visible DEFINE_PER_CPU_SHARED_ALIGNED(struct tss_struct, cpu_tss) = {
 	.io_bitmap		= { [0 ... IO_BITMAP_LONGS] = ~0 },
 #endif
 };
-EXPORT_PER_CPU_SYMBOL_GPL(cpu_tss);
+EXPORT_PER_CPU_SYMBOL(cpu_tss);
 
 #ifdef CONFIG_X86_64
 static DEFINE_PER_CPU(unsigned char, is_idle);
-- 
2.1.0

Re: [PATCH] x86: Make cpu_tss available to external modules

[Andy Lutomirski]

On May 4, 2015 11:46 PM, "Marc Dionne" <marc.c.dionne@gmail.com> wrote:
>
> Commit 75182b1632 ("x86/asm/entry: Switch all C consumers of
> kernel_stack to this_cpu_sp0()") changed current_thread_info
> to use this_cpu_sp0, and indirectly made it rely on init_tss
> which was exported with EXPORT_PER_CPU_SYMBOL_GPL.
> As a result some macros and inline functions such as set/get_fs,
> test_thread_flag and variants have been made unusable for
> external modules.

This is okay with me.  I have my doubts as to whether set_fs/get_fs is
a sane interface at all, let alone in non-GPL modules, but both it and
cond_resched (my best guess as to the test_thread_flag offender) have
plenty of historical precedent for non-GPL use, and I didn't intend to
break that.

Acked-by: Andy Lutomirski <luto@kernel.org>

[tip:x86/urgent] x86: Make cpu_tss available to external modules

[tip-bot for Marc Dionne]

Commit-ID:  de71ad2c97862eae1516aa36528cc3b317c17b2f
Gitweb:     http://git.kernel.org/tip/de71ad2c97862eae1516aa36528cc3b317c17b2f
Author:     Marc Dionne <marc.c.dionne@gmail.com>
AuthorDate: Mon, 4 May 2015 15:16:44 -0300
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Tue, 5 May 2015 20:40:31 +0200

x86: Make cpu_tss available to external modules

Commit 75182b1632 ("x86/asm/entry: Switch all C consumers of
kernel_stack to this_cpu_sp0()") changed current_thread_info
to use this_cpu_sp0, and indirectly made it rely on init_tss
which was exported with EXPORT_PER_CPU_SYMBOL_GPL.
As a result some macros and inline functions such as set/get_fs,
test_thread_flag and variants have been made unusable for
external modules.

Make cpu_tss exported with EXPORT_PER_CPU_SYMBOL so that these
functions are accessible again, as they were previously.

Signed-off-by: Marc Dionne <marc.dionne@your-file-system.com>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/1430763404-21221-1-git-send-email-marc.dionne@your-file-system.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/kernel/process.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 8213da6..bfc99b3 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -57,7 +57,7 @@ __visible DEFINE_PER_CPU_SHARED_ALIGNED(struct tss_struct, cpu_tss) = {
 	.io_bitmap		= { [0 ... IO_BITMAP_LONGS] = ~0 },
 #endif
 };
-EXPORT_PER_CPU_SYMBOL_GPL(cpu_tss);
+EXPORT_PER_CPU_SYMBOL(cpu_tss);
 
 #ifdef CONFIG_X86_64
 static DEFINE_PER_CPU(unsigned char, is_idle);