[PATCH 075/208] x86/fpu: Remove xsave_init() __init obfuscation

Ingo Molnar
2015-05-05T16:29:57Z

So this code surprised me - and being surprised when reading FPU code
does not help maintainability of an already overly complex subsystem.

Remove the obfuscation and just don't use __init annotation for now.
Anyone who wants to free these ~600 bytes of xstate_enable_boot_cpu()
should implement it cleanly.

Reviewed-by: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/fpu/xsave.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kernel/fpu/xsave.c b/arch/x86/kernel/fpu/xsave.c
index 4ff726e4e29b..6c1cbb2487fe 100644
--- a/arch/x86/kernel/fpu/xsave.c
+++ b/arch/x86/kernel/fpu/xsave.c
@@ -606,8 +606,11 @@ static void __init init_xstate_size(void)

/*
* Enable and initialize the xsave feature.
+ *
+ * ( Not marked __init because of false positive section warnings
+ * generated by xsave_init(). )
*/
-static void __init xstate_enable_boot_cpu(void)
+static void /* __init */ xstate_enable_boot_cpu(void)
{
unsigned int eax, ebx, ecx, edx;

@@ -663,21 +666,20 @@ static void __init xstate_enable_boot_cpu(void)
/*
* For the very first instance, this calls xstate_enable_boot_cpu();
* for all subsequent instances, this calls xstate_enable().
- *
- * This is somewhat obfuscated due to the lack of powerful enough
- * overrides for the section checks.
*/
void xsave_init(void)
{
- static __refdata void (*next_func)(void) = xstate_enable_boot_cpu;
- void (*this_func)(void);
+ static char on_boot_cpu = 1;

if (!cpu_has_xsave)
return;

- this_func = next_func;
- next_func = xstate_enable;
- this_func();
+ if (on_boot_cpu) {
+ on_boot_cpu = 0;
+ xstate_enable_boot_cpu();
+ } else {
+ xstate_enable();
+ }
}

/*
--
2.1.0