linux-kernel - [RFC PATCH 14/32] x86/fred: header file with FRED definitions

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Message-Id: <20221220063658.19271-15-xin3.li@intel.com>
Date:   Mon, 19 Dec 2022 22:36:40 -0800
From:   Xin Li <xin3.li@...el.com>
To:     linux-kernel@...r.kernel.org, x86@...nel.org, kvm@...r.kernel.org
Cc:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, hpa@...or.com, peterz@...radead.org,
        andrew.cooper3@...rix.com, seanjc@...gle.com, pbonzini@...hat.com,
        ravi.v.shankar@...el.com
Subject: [RFC PATCH 14/32] x86/fred: header file with FRED definitions

From: "H. Peter Anvin (Intel)" <hpa@...or.com>

Add a header file for FRED prototypes and definitions.

Signed-off-by: H. Peter Anvin (Intel) <hpa@...or.com>
Signed-off-by: Xin Li <xin3.li@...el.com>
---
 arch/x86/include/asm/fred.h | 99 +++++++++++++++++++++++++++++++++++++
 1 file changed, 99 insertions(+)
 create mode 100644 arch/x86/include/asm/fred.h

diff --git a/arch/x86/include/asm/fred.h b/arch/x86/include/asm/fred.h
new file mode 100644
index 000000000000..6292b28d461d
--- /dev/null
+++ b/arch/x86/include/asm/fred.h
@@ -0,0 +1,99 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * arch/x86/include/asm/fred.h
+ *
+ * Macros for Flexible Return and Event Delivery (FRED)
+ */
+
+#ifndef ASM_X86_FRED_H
+#define ASM_X86_FRED_H
+
+#ifdef CONFIG_X86_FRED
+
+#include <linux/const.h>
+#include <asm/asm.h>
+
+/*
+ * FRED return instructions
+ *
+ * Replace with "ERETS"/"ERETU" once binutils support FRED return instructions.
+ */
+#define ERETS			_ASM_BYTES(0xf2,0x0f,0x01,0xca)
+#define ERETU			_ASM_BYTES(0xf3,0x0f,0x01,0xca)
+
+/*
+ * Event stack level macro for the FRED_STKLVLS MSR.
+ * Usage example: FRED_STKLVL(X86_TRAP_DF, 3)
+ * Multiple values can be ORd together.
+ */
+#define FRED_STKLVL(v,l)	(_AT(unsigned long, l) << (2*(v)))
+
+/* FRED_CONFIG MSR */
+#define FRED_CONFIG_CSL_MASK		0x3
+#define FRED_CONFIG_SHADOW_STACK_SPACE	_BITUL(3)
+#define FRED_CONFIG_REDZONE(b)		__ALIGN_KERNEL_MASK((b), _UL(0x3f))
+#define FRED_CONFIG_INT_STKLVL(l)	(_AT(unsigned long, l) << 9)
+#define FRED_CONFIG_ENTRYPOINT(p)	_AT(unsigned long, (p))
+
+/* FRED event type and vector bit width and counts */
+#define FRED_EVENT_TYPE_BITS		3 /* only 3 bits used in FRED 3.0 */
+#define FRED_EVENT_TYPE_COUNT		_BITUL(FRED_EVENT_TYPE_BITS)
+#define FRED_EVENT_VECTOR_BITS		8
+#define FRED_EVENT_VECTOR_COUNT		_BITUL(FRED_EVENT_VECTOR_BITS)
+
+/* FRED EVENT_TYPE_OTHER vector numbers */
+#define FRED_SYSCALL			1
+#define FRED_SYSENTER			2
+
+/* Flags above the CS selector (regs->csl) */
+#define FRED_CSL_ENABLE_NMI		_BITUL(28)
+#define FRED_CSL_ALLOW_SINGLE_STEP	_BITUL(25)
+#define FRED_CSL_INTERRUPT_SHADOW	_BITUL(24)
+
+#ifndef __ASSEMBLY__
+
+#include <linux/kernel.h>
+#include <asm/ptrace.h>
+
+/* FRED stack frame information */
+struct fred_info {
+	unsigned long edata;	/* Event data: CR2, DR6, ... */
+	unsigned long resv;
+};
+
+/* Full format of the FRED stack frame */
+struct fred_frame {
+	struct pt_regs   regs;
+	struct fred_info info;
+};
+
+/* Getting the FRED frame information from a pt_regs pointer */
+static __always_inline struct fred_info *fred_info(struct pt_regs *regs)
+{
+	return &container_of(regs, struct fred_frame, regs)->info;
+}
+
+static __always_inline unsigned long fred_event_data(struct pt_regs *regs)
+{
+	return fred_info(regs)->edata;
+}
+
+/*
+ * How FRED event handlers are called.
+ *
+ * FRED event delivery establishes the full supervisor context
+ * by pushing everything related to the event being delivered
+ * to the FRED stack frame, e.g., the faulting linear address
+ * of a #PF is pushed as event data of the FRED #PF stack frame.
+ * Thus a struct pt_regs has everything needed and it's the only
+ * input parameter required for a FRED event handler.
+ */
+#define DECLARE_FRED_HANDLER(f) void f (struct pt_regs *regs)
+#define DEFINE_FRED_HANDLER(f) noinstr DECLARE_FRED_HANDLER(f)
+typedef DECLARE_FRED_HANDLER((*fred_handler));
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* CONFIG_X86_FRED */
+
+#endif /* ASM_X86_FRED_H */
-- 
2.34.1