1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Macros for Flexible Return and Event Delivery (FRED)
4 */
5
6#ifndef ASM_X86_FRED_H
7#define ASM_X86_FRED_H
8
9#include <linux/const.h>
10
11#include <asm/asm.h>
12#include <asm/msr.h>
13#include <asm/trapnr.h>
14
15/*
16 * FRED event return instruction opcodes for ERET{S,U}; supported in
17 * binutils >= 2.41.
18 */
19#define ERETS _ASM_BYTES(0xf2,0x0f,0x01,0xca)
20#define ERETU _ASM_BYTES(0xf3,0x0f,0x01,0xca)
21
22/*
23 * RSP is aligned to a 64-byte boundary before used to push a new stack frame
24 */
25#define FRED_STACK_FRAME_RSP_MASK _AT(unsigned long, (~0x3f))
26
27/*
28 * Used for the return address for call emulation during code patching,
29 * and measured in 64-byte cache lines.
30 */
31#define FRED_CONFIG_REDZONE_AMOUNT 1
32#define FRED_CONFIG_REDZONE (_AT(unsigned long, FRED_CONFIG_REDZONE_AMOUNT) << 6)
33#define FRED_CONFIG_INT_STKLVL(l) (_AT(unsigned long, l) << 9)
34#define FRED_CONFIG_ENTRYPOINT(p) _AT(unsigned long, (p))
35
36#ifndef __ASSEMBLER__
37
38#ifdef CONFIG_X86_FRED
39#include <linux/kernel.h>
40#include <linux/sched/task_stack.h>
41
42#include <asm/ptrace.h>
43
44struct fred_info {
45 /* Event data: CR2, DR6, ... */
46 unsigned long edata;
47 unsigned long resv;
48};
49
50/* Full format of the FRED stack frame */
51struct fred_frame {
52 struct pt_regs regs;
53 struct fred_info info;
54};
55
56static __always_inline struct fred_info *fred_info(struct pt_regs *regs)
57{
58 return &container_of(regs, struct fred_frame, regs)->info;
59}
60
61static __always_inline unsigned long fred_event_data(struct pt_regs *regs)
62{
63 return fred_info(regs)->edata;
64}
65
66void asm_fred_entrypoint_user(void);
67void asm_fred_entrypoint_kernel(void);
68void asm_fred_entry_from_kvm(struct fred_ss);
69
70__visible void fred_entry_from_user(struct pt_regs *regs);
71__visible void fred_entry_from_kernel(struct pt_regs *regs);
72__visible void __fred_entry_from_kvm(struct pt_regs *regs);
73
74/* Can be called from noinstr code, thus __always_inline */
75static __always_inline void fred_entry_from_kvm(unsigned int type, unsigned int vector)
76{
77 struct fred_ss ss = {
78 .ss =__KERNEL_DS,
79 .type = type,
80 .vector = vector,
81 .nmi = type == EVENT_TYPE_NMI,
82 .l = 1,
83 };
84
85 asm_fred_entry_from_kvm(ss);
86}
87
88void cpu_init_fred_exceptions(void);
89void cpu_init_fred_rsps(void);
90void fred_complete_exception_setup(void);
91
92DECLARE_PER_CPU(unsigned long, fred_rsp0);
93
94static __always_inline void fred_sync_rsp0(unsigned long rsp0)
95{
96 __this_cpu_write(fred_rsp0, rsp0);
97}
98
99static __always_inline void fred_update_rsp0(void)
100{
101 unsigned long rsp0 = (unsigned long) task_stack_page(current) + THREAD_SIZE;
102
103 if (cpu_feature_enabled(X86_FEATURE_FRED) && (__this_cpu_read(fred_rsp0) != rsp0)) {
104 wrmsrns(MSR_IA32_FRED_RSP0, val: rsp0);
105 __this_cpu_write(fred_rsp0, rsp0);
106 }
107}
108#else /* CONFIG_X86_FRED */
109static __always_inline unsigned long fred_event_data(struct pt_regs *regs) { return 0; }
110static inline void cpu_init_fred_exceptions(void) { }
111static inline void cpu_init_fred_rsps(void) { }
112static inline void fred_complete_exception_setup(void) { }
113static inline void fred_entry_from_kvm(unsigned int type, unsigned int vector) { }
114static inline void fred_sync_rsp0(unsigned long rsp0) { }
115static inline void fred_update_rsp0(void) { }
116#endif /* CONFIG_X86_FRED */
117#endif /* !__ASSEMBLER__ */
118
119#endif /* ASM_X86_FRED_H */
120

source code of linux/arch/x86/include/asm/fred.h