From 5e907bb0459399b0d1cc8d4c7e9f363a995b748a Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Thu, 30 Apr 2015 09:09:26 +0200 Subject: [PATCH] x86/alternatives, x86/fpu: Add 'alternatives_patched' debug flag and use it in xsave_state() We'd like to use xsave_state() earlier, but its SYSTEM_BOOTING check is too imprecise. The real condition that xsave_state() would like to check is whether alternative XSAVE instructions were patched into the kernel image already. Add such a (read-mostly) debug flag and use it in xsave_state(). Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Dave Hansen Cc: Fenghua Yu Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Thomas Gleixner Signed-off-by: Ingo Molnar --- arch/x86/include/asm/alternative.h | 6 ++++++ arch/x86/include/asm/fpu/xstate.h | 2 +- arch/x86/kernel/alternative.c | 5 +++++ 3 files changed, 12 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h index ba32af062f61..7bfc85bbb8ff 100644 --- a/arch/x86/include/asm/alternative.h +++ b/arch/x86/include/asm/alternative.h @@ -52,6 +52,12 @@ struct alt_instr { u8 padlen; /* length of build-time padding */ } __packed; +/* + * Debug flag that can be tested to see whether alternative + * instructions were patched in already: + */ +extern int alternatives_patched; + extern void alternative_instructions(void); extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end); diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h index 31a002ad5aeb..ab2c507b58b6 100644 --- a/arch/x86/include/asm/fpu/xstate.h +++ b/arch/x86/include/asm/fpu/xstate.h @@ -119,7 +119,7 @@ static inline int xsave_state(struct xsave_struct *fx) u32 hmask = mask >> 32; int err = 0; - WARN_ON(system_state == SYSTEM_BOOTING); + WARN_ON(!alternatives_patched); /* * If xsaves is enabled, xsaves replaces xsaveopt because diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index aef653193160..7fe097235376 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -21,6 +21,10 @@ #include #include +int __read_mostly alternatives_patched; + +EXPORT_SYMBOL_GPL(alternatives_patched); + #define MAX_PATCH_LEN (255-1) static int __initdata_or_module debug_alternative; @@ -627,6 +631,7 @@ void __init alternative_instructions(void) apply_paravirt(__parainstructions, __parainstructions_end); restart_nmi(); + alternatives_patched = 1; } /**