1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Common place for both 32- and 64-bit entry routines.
4 */
5
6#include <linux/export.h>
7#include <linux/linkage.h>
8#include <linux/objtool.h>
9#include <asm/msr-index.h>
10#include <asm/unwind_hints.h>
11#include <asm/segment.h>
12#include <asm/cache.h>
13#include <asm/cpufeatures.h>
14#include <asm/nospec-branch.h>
15
16#include "calling.h"
17
18.pushsection .noinstr.text, "ax"
19
20/* Clobbers AX, CX, DX */
21SYM_FUNC_START(write_ibpb)
22 ANNOTATE_NOENDBR
23 movl $MSR_IA32_PRED_CMD, %ecx
24 movl _ASM_RIP(x86_pred_cmd), %eax
25 xorl %edx, %edx
26 wrmsr
27
28 /* Make sure IBPB clears return stack preductions too. */
29 FILL_RETURN_BUFFER %rax, RSB_CLEAR_LOOPS, X86_BUG_IBPB_NO_RET
30 RET
31SYM_FUNC_END(write_ibpb)
32/* For KVM */
33EXPORT_SYMBOL_GPL(write_ibpb);
34
35.popsection
36
37/*
38 * Define the VERW operand that is disguised as entry code so that
39 * it can be referenced with KPTI enabled. This ensures VERW can be
40 * used late in exit-to-user path after page tables are switched.
41 */
42.pushsection .entry.text, "ax"
43
44.align L1_CACHE_BYTES, 0xcc
45SYM_CODE_START_NOALIGN(x86_verw_sel)
46 UNWIND_HINT_UNDEFINED
47 ANNOTATE_NOENDBR
48 .word __KERNEL_DS
49.align L1_CACHE_BYTES, 0xcc
50SYM_CODE_END(x86_verw_sel);
51/* For KVM */
52EXPORT_SYMBOL_GPL(x86_verw_sel);
53
54.popsection
55
56THUNK warn_thunk_thunk, __warn_thunk
57
58/*
59 * Clang's implementation of TLS stack cookies requires the variable in
60 * question to be a TLS variable. If the variable happens to be defined as an
61 * ordinary variable with external linkage in the same compilation unit (which
62 * amounts to the whole of vmlinux with LTO enabled), Clang will drop the
63 * segment register prefix from the references, resulting in broken code. Work
64 * around this by avoiding the symbol used in -mstack-protector-guard-symbol=
65 * entirely in the C code, and use an alias emitted by the linker script
66 * instead.
67 */
68#if defined(CONFIG_STACKPROTECTOR) && defined(CONFIG_SMP)
69EXPORT_SYMBOL(__ref_stack_chk_guard);
70#endif
71