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author | H. Peter Anvin <hpa@linux.intel.com> | 2010-07-21 14:23:10 -0700 |
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committer | H. Peter Anvin <hpa@linux.intel.com> | 2010-07-21 15:33:54 -0700 |
commit | 1cff92d8fdb27684308864d9cdb324bee43b40ab (patch) | |
tree | 65a6060dab843f5f2e32a8e0fce0200eeb9d44ef /arch/x86/kernel/xsave.c | |
parent | 4995b9dba908436c1611454f9bd2cb3ddf6babee (diff) | |
download | linux-1cff92d8fdb27684308864d9cdb324bee43b40ab.tar.gz linux-1cff92d8fdb27684308864d9cdb324bee43b40ab.tar.bz2 linux-1cff92d8fdb27684308864d9cdb324bee43b40ab.zip |
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 <hpa@linux.intel.com>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Robert Richter <robert.richter@amd.com>
LKML-Reference: <4C476236.1020302@zytor.com>
Diffstat (limited to 'arch/x86/kernel/xsave.c')
-rw-r--r-- | 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 cfc7901ee94e..b2549c3eb2c3 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(); } |