/* 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

#if IS_ENABLED(CONFIG_KVM_INTEL)
.macro IDT_DO_EVENT_IRQOFF call_insn call_target
        /*
         * Unconditionally create a stack frame, getting the correct RSP on the
         * stack (for x86-64) would take two instructions anyways, and RBP can
         * be used to restore RSP to make objtool happy (see below).
         */
        push %_ASM_BP
        mov %_ASM_SP, %_ASM_BP

#ifdef CONFIG_X86_64
        /*
         * Align RSP to a 16-byte boundary (to emulate CPU behavior) before
         * creating the synthetic interrupt stack frame for the IRQ/NMI.
         */
        and  $-16, %rsp
        push $__KERNEL_DS
        push %rbp
#endif
        pushf
        push $__KERNEL_CS
        \call_insn \call_target

        /*
         * "Restore" RSP from RBP, even though IRET has already unwound RSP to
         * the correct value.  objtool doesn't know the callee will IRET and,
         * without the explicit restore, thinks the stack is getting walloped.
         * Using an unwind hint is problematic due to x86-64's dynamic alignment.
         */
        leave
        RET
.endm

#ifndef CONFIG_X86_64
.pushsection .text, "ax"
SYM_FUNC_START(idt_do_interrupt_irqoff)
        IDT_DO_EVENT_IRQOFF CALL_NOSPEC _ASM_ARG1
SYM_FUNC_END(idt_do_interrupt_irqoff)
.popsection
#endif

.pushsection .noinstr.text, "ax"
SYM_FUNC_START(idt_do_nmi_irqoff)
        IDT_DO_EVENT_IRQOFF call asm_exc_nmi_kvm_vmx
SYM_FUNC_END(idt_do_nmi_irqoff)
.popsection
#endif