1 files changed, 77 insertions, 0 deletions
diff --git a/arch/x86/entry/entry.S b/arch/x86/entry/entry.S
new file mode 100644
index 000000000000..6ba2b3adcef0
--- /dev/null
+++ b/arch/x86/entry/entry.S
@@ -0,0 +1,77 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Common place for both 32- and 64-bit entry routines.
+ */
+
+#include <linux/export.h>
+#include <linux/kvm_types.h>
+#include <linux/linkage.h>
+#include <linux/objtool.h>
+#include <asm/msr-index.h>
+#include <asm/unwind_hints.h>
+#include <asm/segment.h>
+#include <asm/cache.h>
+#include <asm/cpufeatures.h>
+#include <asm/nospec-branch.h>
+
+#include "calling.h"
+
+.pushsection .noinstr.text, "ax"
+
+/* Clobbers AX, CX, DX */
+SYM_FUNC_START(write_ibpb)
+	ANNOTATE_NOENDBR
+	movl	$MSR_IA32_PRED_CMD, %ecx
+	movl	_ASM_RIP(x86_pred_cmd), %eax
+	xorl	%edx, %edx
+	wrmsr
+
+	/* Make sure IBPB clears return stack preductions too. */
+	FILL_RETURN_BUFFER %rax, RSB_CLEAR_LOOPS, X86_BUG_IBPB_NO_RET
+	RET
+SYM_FUNC_END(write_ibpb)
+EXPORT_SYMBOL_FOR_KVM(write_ibpb);
+
+SYM_FUNC_START(__WARN_trap)
+	ANNOTATE_NOENDBR
+	ANNOTATE_REACHABLE
+	ud1 (%edx), %_ASM_ARG1
+	RET
+SYM_FUNC_END(__WARN_trap)
+EXPORT_SYMBOL(__WARN_trap)
+
+.popsection
+
+/*
+ * Define the VERW operand that is disguised as entry code so that
+ * it can be referenced with KPTI enabled. This ensures VERW can be
+ * used late in exit-to-user path after page tables are switched.
+ */
+.pushsection .entry.text, "ax"
+
+.align L1_CACHE_BYTES, 0xcc
+SYM_CODE_START_NOALIGN(x86_verw_sel)
+	UNWIND_HINT_UNDEFINED
+	ANNOTATE_NOENDBR
+	.word __KERNEL_DS
+.align L1_CACHE_BYTES, 0xcc
+SYM_CODE_END(x86_verw_sel);
+EXPORT_SYMBOL_FOR_KVM(x86_verw_sel);
+
+.popsection
+
+THUNK warn_thunk_thunk, __warn_thunk
+
+/*
+ * Clang's implementation of TLS stack cookies requires the variable in
+ * question to be a TLS variable. If the variable happens to be defined as an
+ * ordinary variable with external linkage in the same compilation unit (which
+ * amounts to the whole of vmlinux with LTO enabled), Clang will drop the
+ * segment register prefix from the references, resulting in broken code. Work
+ * around this by avoiding the symbol used in -mstack-protector-guard-symbol=
+ * entirely in the C code, and use an alias emitted by the linker script
+ * instead.
+ */
+#if defined(CONFIG_STACKPROTECTOR) && defined(CONFIG_SMP)
+EXPORT_SYMBOL(__ref_stack_chk_guard);
+#endif