fred.h

  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, 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 */