Commit ccb7735a authored by Eric Biggers's avatar Eric Biggers Committed by Dave Hansen
Browse files

x86/fpu: Fully optimize out WARN_ON_FPU() 



Currently WARN_ON_FPU evaluates its argument even if
CONFIG_X86_DEBUG_FPU is disabled, which adds unnecessary instructions to
several functions, for example kernel_fpu_begin().  Fix this by using
BUILD_BUG_ON_INVALID(x) in the no-debug case rather than (void)(x).

Fixes: 83242c51 ("x86/fpu: Make WARN_ON_FPU() more robust in the !CONFIG_X86_DEBUG_FPU case")
Suggested-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/all/20250127224523.94300-1-ebiggers%40kernel.org
parent a64dcfb4

arch/x86/kernel/fpu/internal.h

+1 −1
Original line number Diff line number Diff line
@@ -18,7 +18,7 @@ static __always_inline __pure bool use_fxsr(void) 
#ifdef CONFIG_X86_DEBUG_FPU

# define WARN_ON_FPU(x) WARN_ON_ONCE(x)

#else

# define WARN_ON_FPU(x) ({ (void)(x); 0; })

# define WARN_ON_FPU(x) ({ BUILD_BUG_ON_INVALID(x); 0; })

#endif



/* Used in init.c */