x86: Remove FAST_FEATURE_TESTS

Since we want to rely on static branches to avoid speculation, remove
any possible fallback code for static_cpu_has.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: torvalds@linux-foundation.org
Link: https://lkml.kernel.org/r/20180319154717.705383007@infradead.org

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 0fa71a78ec99a9ae2e4dcbbadfa74773a5ebc031..cb5b5907dbd6e87e9a53dfc0a524910aef34ebba 100644 (file)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -393,17 +393,6 @@ config X86_FEATURE_NAMES
 
          If in doubt, say Y.
 
-config X86_FAST_FEATURE_TESTS
-       bool "Fast CPU feature tests" if EMBEDDED
-       default y
-       ---help---
-         Some fast-paths in the kernel depend on the capabilities of the CPU.
-         Say Y here for the kernel to patch in the appropriate code at runtime
-         based on the capabilities of the CPU. The infrastructure for patching
-         code at runtime takes up some additional space; space-constrained
-         embedded systems may wish to say N here to produce smaller, slightly
-         slower code.
-
 config X86_X2APIC
        bool "Support x2apic"
        depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)

diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index 736771c9822ef965233b7114fd0b1a025e8c3a46..b27da9602a6dfdf406180214b669a712a126f701 100644 (file)
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -140,7 +140,6 @@ extern void clear_cpu_cap(struct cpuinfo_x86 *c, unsigned int bit);
 
 #define setup_force_cpu_bug(bit) setup_force_cpu_cap(bit)
 
-#if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_X86_FAST_FEATURE_TESTS)
 /*
  * Static testing of CPU features.  Used the same as boot_cpu_has().
  * These will statically patch the target code for additional
@@ -196,13 +195,6 @@ t_no:
                boot_cpu_has(bit) :                             \
                _static_cpu_has(bit)                            \
 )
-#else
-/*
- * Fall back to dynamic for gcc versions which don't support asm goto. Should be
- * a minority now anyway.
- */
-#define static_cpu_has(bit)            boot_cpu_has(bit)
-#endif
 
 #define cpu_has_bug(c, bit)            cpu_has(c, (bit))
 #define set_cpu_bug(c, bit)            set_cpu_cap(c, (bit))