>From 55b936c7a359a14d72bcba6c3fceba4cfbe3fedf Mon Sep 17 00:00:00 2001 From: H. Peter Anvin Date: Wed, 21 Jul 2010 14:23:10 -0700 Subject: [PATCH] x86, xsave: Make xstate_enable_boot_cpu() __init, protect on CPU 0 xstate_enable_boot_cpu() is, as the name implies, only used on the boot CPU; furthermore, it invokes alloc_bootmem(), which is __init; hence it needs to be tagged __init rather than __cpuinit. Furthermore, it is *not* safe in the long run to rely on CPU 0 only coming online during the early boot -- at some point we're going to support offlining (and re-onlining) the boot CPU, and at that point we must not call xstate_enable_boot_cpu() again. The code is a fair bit more obscure than one would like, because the __ref overrides aren't quite powerful enough. Signed-off-by: H. Peter Anvin Acked-by: Suresh Siddha Cc: Robert Richter LKML-Reference: <4C476236.1020302@zytor.com> --- arch/x86/kernel/xsave.c | 28 +++++++++++++++++----------- 1 files changed, 17 insertions(+), 11 deletions(-) diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c index cfc7901..b2549c3 100644 --- a/arch/x86/kernel/xsave.c +++ b/arch/x86/kernel/xsave.c @@ -360,10 +360,10 @@ unsigned int sig_xstate_size = sizeof(struct _fpstate); /* * Enable the extended processor state save/restore feature */ -static inline void xstate_enable(u64 mask) +static inline void xstate_enable(void) { set_in_cr4(X86_CR4_OSXSAVE); - xsetbv(XCR_XFEATURE_ENABLED_MASK, mask); + xsetbv(XCR_XFEATURE_ENABLED_MASK, pcntxt_mask); } /* @@ -421,7 +421,7 @@ static void __init setup_xstate_init(void) /* * Enable and initialize the xsave feature. */ -static void __cpuinit xstate_enable_boot_cpu(void) +static void __init xstate_enable_boot_cpu(void) { unsigned int eax, ebx, ecx, edx; @@ -444,7 +444,7 @@ static void __cpuinit xstate_enable_boot_cpu(void) */ pcntxt_mask = pcntxt_mask & XCNTXT_MASK; - xstate_enable(pcntxt_mask); + xstate_enable(); /* * Recompute the context size for enabled features @@ -462,16 +462,22 @@ static void __cpuinit xstate_enable_boot_cpu(void) pcntxt_mask, xstate_size); } +/* + * 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 __cpuinit xsave_init(void) { + static __refdata void (*next_func)(void) = xstate_enable_boot_cpu; + void (*this_func)(void); + if (!cpu_has_xsave) return; - /* - * Boot processor to setup the FP and extended state context info. - */ - if (!smp_processor_id()) - xstate_enable_boot_cpu(); - else - xstate_enable(pcntxt_mask); + this_func = next_func; + next_func = xstate_enable; + this_func(); } -- 1.7.0.1