Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 asm updates from Ingo Molnar:
 "Most of the changes relate to Peter Zijlstra's cleanup of ptregs
  handling, in particular the i386 part is now much simplified and
  standardized - no more partial ptregs stack frames via the esp/ss
  oddity. This simplifies ftrace, kprobes, the unwinder, ptrace, kdump
  and kgdb.

  There's also a CR4 hardening enhancements by Kees Cook, to make the
  generic platform functions such as native_write_cr4() less useful as
  ROP gadgets that disable SMEP/SMAP. Also protect the WP bit of CR0
  against similar attacks.

  The rest is smaller cleanups/fixes"

* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/alternatives: Add int3_emulate_call() selftest
  x86/stackframe/32: Allow int3_emulate_push()
  x86/stackframe/32: Provide consistent pt_regs
  x86/stackframe, x86/ftrace: Add pt_regs frame annotations
  x86/stackframe, x86/kprobes: Fix frame pointer annotations
  x86/stackframe: Move ENCODE_FRAME_POINTER to asm/frame.h
  x86/entry/32: Clean up return from interrupt preemption path
  x86/asm: Pin sensitive CR0 bits
  x86/asm: Pin sensitive CR4 bits
  Documentation/x86: Fix path to entry_32.S
  x86/asm: Remove unused TASK_TI_flags from asm-offsets.c

1 files changed, 20 insertions, 0 deletions

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index dad20bc891d5..8febe90470f4 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -366,6 +366,25 @@ out:
 	cr4_clear_bits(X86_CR4_UMIP);
 }
 
+DEFINE_STATIC_KEY_FALSE_RO(cr_pinning);
+EXPORT_SYMBOL(cr_pinning);
+unsigned long cr4_pinned_bits __ro_after_init;
+EXPORT_SYMBOL(cr4_pinned_bits);
+
+/*
+ * Once CPU feature detection is finished (and boot params have been
+ * parsed), record any of the sensitive CR bits that are set, and
+ * enable CR pinning.
+ */
+static void __init setup_cr_pinning(void)
+{
+	unsigned long mask;
+
+	mask = (X86_CR4_SMEP | X86_CR4_SMAP | X86_CR4_UMIP);
+	cr4_pinned_bits = this_cpu_read(cpu_tlbstate.cr4) & mask;
+	static_key_enable(&cr_pinning.key);
+}
+
 /*
  * Protection Keys are not available in 32-bit mode.
  */
@@ -1468,6 +1487,7 @@ void __init identify_boot_cpu(void)
 	enable_sep_cpu();
 #endif
 	cpu_detect_tlb(&boot_cpu_data);
+	setup_cr_pinning();
 }
 
 void identify_secondary_cpu(struct cpuinfo_x86 *c)