opensbi/include/sbi/sbi_trap.h

/*
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2019 Western Digital Corporation or its affiliates.
 *
 * Authors:
 *   Anup Patel <anup.patel@wdc.com>
 */

#ifndef __SBI_TRAP_H__
#define __SBI_TRAP_H__

#include <sbi/riscv_encoding.h>

/* clang-format off */

/** Index of zero member in sbi_trap_regs */
#define SBI_TRAP_REGS_zero			0
/** Index of ra member in sbi_trap_regs */
#define SBI_TRAP_REGS_ra			1
/** Index of sp member in sbi_trap_regs */
#define SBI_TRAP_REGS_sp			2
/** Index of gp member in sbi_trap_regs */
#define SBI_TRAP_REGS_gp			3
/** Index of tp member in sbi_trap_regs */
#define SBI_TRAP_REGS_tp			4
/** Index of t0 member in sbi_trap_regs */
#define SBI_TRAP_REGS_t0			5
/** Index of t1 member in sbi_trap_regs */
#define SBI_TRAP_REGS_t1			6
/** Index of t2 member in sbi_trap_regs */
#define SBI_TRAP_REGS_t2			7
/** Index of s0 member in sbi_trap_regs */
#define SBI_TRAP_REGS_s0			8
/** Index of s1 member in sbi_trap_regs */
#define SBI_TRAP_REGS_s1			9
/** Index of a0 member in sbi_trap_regs */
#define SBI_TRAP_REGS_a0			10
/** Index of a1 member in sbi_trap_regs */
#define SBI_TRAP_REGS_a1			11
/** Index of a2 member in sbi_trap_regs */
#define SBI_TRAP_REGS_a2			12
/** Index of a3 member in sbi_trap_regs */
#define SBI_TRAP_REGS_a3			13
/** Index of a4 member in sbi_trap_regs */
#define SBI_TRAP_REGS_a4			14
/** Index of a5 member in sbi_trap_regs */
#define SBI_TRAP_REGS_a5			15
/** Index of a6 member in sbi_trap_regs */
#define SBI_TRAP_REGS_a6			16
/** Index of a7 member in sbi_trap_regs */
#define SBI_TRAP_REGS_a7			17
/** Index of s2 member in sbi_trap_regs */
#define SBI_TRAP_REGS_s2			18
/** Index of s3 member in sbi_trap_regs */
#define SBI_TRAP_REGS_s3			19
/** Index of s4 member in sbi_trap_regs */
#define SBI_TRAP_REGS_s4			20
/** Index of s5 member in sbi_trap_regs */
#define SBI_TRAP_REGS_s5			21
/** Index of s6 member in sbi_trap_regs */
#define SBI_TRAP_REGS_s6			22
/** Index of s7 member in sbi_trap_regs */
#define SBI_TRAP_REGS_s7			23
/** Index of s8 member in sbi_trap_regs */
#define SBI_TRAP_REGS_s8			24
/** Index of s9 member in sbi_trap_regs */
#define SBI_TRAP_REGS_s9			25
/** Index of s10 member in sbi_trap_regs */
#define SBI_TRAP_REGS_s10			26
/** Index of s11 member in sbi_trap_regs */
#define SBI_TRAP_REGS_s11			27
/** Index of t3 member in sbi_trap_regs */
#define SBI_TRAP_REGS_t3			28
/** Index of t4 member in sbi_trap_regs */
#define SBI_TRAP_REGS_t4			29
/** Index of t5 member in sbi_trap_regs */
#define SBI_TRAP_REGS_t5			30
/** Index of t6 member in sbi_trap_regs */
#define SBI_TRAP_REGS_t6			31
/** Index of mepc member in sbi_trap_regs */
#define SBI_TRAP_REGS_mepc			32
/** Index of mstatus member in sbi_trap_regs */
#define SBI_TRAP_REGS_mstatus			33
/** Index of mstatusH member in sbi_trap_regs */
#define SBI_TRAP_REGS_mstatusH			34
/** Last member index in sbi_trap_regs */
#define SBI_TRAP_REGS_last			35

/** Index of cause member in sbi_trap_info */
#define SBI_TRAP_INFO_cause			0
/** Index of tval member in sbi_trap_info */
#define SBI_TRAP_INFO_tval			1
/** Index of tval2 member in sbi_trap_info */
#define SBI_TRAP_INFO_tval2			2
/** Index of tinst member in sbi_trap_info */
#define SBI_TRAP_INFO_tinst			3
/** Index of gva member in sbi_trap_info */
#define SBI_TRAP_INFO_gva			4
/** Last member index in sbi_trap_info */
#define SBI_TRAP_INFO_last			5

/* clang-format on */

/** Get offset of member with name 'x' in sbi_trap_regs */
#define SBI_TRAP_REGS_OFFSET(x) ((SBI_TRAP_REGS_##x) * __SIZEOF_POINTER__)
/** Size (in bytes) of sbi_trap_regs */
#define SBI_TRAP_REGS_SIZE SBI_TRAP_REGS_OFFSET(last)

/** Get offset of member with name 'x' in sbi_trap_info */
#define SBI_TRAP_INFO_OFFSET(x) ((SBI_TRAP_INFO_##x) * __SIZEOF_POINTER__)
/** Size (in bytes) of sbi_trap_info */
#define SBI_TRAP_INFO_SIZE SBI_TRAP_INFO_OFFSET(last)

#define STACK_BOUNDARY 16
#define ALIGN_TO_BOUNDARY(x, a) (((x) + (a) - 1) & ~((a) - 1))

/** Size (in bytes) of sbi_trap_context */
#define SBI_TRAP_CONTEXT_SIZE ALIGN_TO_BOUNDARY((SBI_TRAP_REGS_SIZE + \
			       SBI_TRAP_INFO_SIZE + \
			       __SIZEOF_POINTER__), STACK_BOUNDARY)

#ifndef __ASSEMBLER__

#include <sbi/sbi_types.h>
#include <sbi/sbi_scratch.h>

/** Representation of register state at time of trap/interrupt */
struct sbi_trap_regs {
	union {
		unsigned long gprs[32];
		struct {
			/** zero register state */
			unsigned long zero;
			/** ra register state */
			unsigned long ra;
			/** sp register state */
			unsigned long sp;
			/** gp register state */
			unsigned long gp;
			/** tp register state */
			unsigned long tp;
			/** t0 register state */
			unsigned long t0;
			/** t1 register state */
			unsigned long t1;
			/** t2 register state */
			unsigned long t2;
			/** s0 register state */
			unsigned long s0;
			/** s1 register state */
			unsigned long s1;
			/** a0 register state */
			unsigned long a0;
			/** a1 register state */
			unsigned long a1;
			/** a2 register state */
			unsigned long a2;
			/** a3 register state */
			unsigned long a3;
			/** a4 register state */
			unsigned long a4;
			/** a5 register state */
			unsigned long a5;
			/** a6 register state */
			unsigned long a6;
			/** a7 register state */
			unsigned long a7;
			/** s2 register state */
			unsigned long s2;
			/** s3 register state */
			unsigned long s3;
			/** s4 register state */
			unsigned long s4;
			/** s5 register state */
			unsigned long s5;
			/** s6 register state */
			unsigned long s6;
			/** s7 register state */
			unsigned long s7;
			/** s8 register state */
			unsigned long s8;
			/** s9 register state */
			unsigned long s9;
			/** s10 register state */
			unsigned long s10;
			/** s11 register state */
			unsigned long s11;
			/** t3 register state */
			unsigned long t3;
			/** t4 register state */
			unsigned long t4;
			/** t5 register state */
			unsigned long t5;
			/** t6 register state */
			unsigned long t6;
		};
	};
	/** mepc register state */
	unsigned long mepc;
	/** mstatus register state */
	unsigned long mstatus;
	/** mstatusH register state (only for 32-bit) */
	unsigned long mstatusH;
};

_Static_assert(
	sizeof(((struct sbi_trap_regs *)0)->gprs) ==
	offsetof(struct sbi_trap_regs, t6) +
	sizeof(((struct sbi_trap_regs *)0)->t6),
	"struct sbi_trap_regs's layout differs between gprs and named members");

#define REG_VAL(idx, regs)		((regs)->gprs[(idx)])

#define GET_RS1(insn, regs)		REG_VAL(GET_RS1_NUM(insn), regs)
#define GET_RS2(insn, regs)		REG_VAL(GET_RS2_NUM(insn), regs)
#define GET_RS1S(insn, regs)		REG_VAL(GET_RS1S_NUM(insn), regs)
#define GET_RS2S(insn, regs)		REG_VAL(GET_RS2S_NUM(insn), regs)
#define GET_RS2C(insn, regs)		REG_VAL(GET_RS2C_NUM(insn), regs)
#define SET_RD(insn, regs, val)		(REG_VAL(GET_RD_NUM(insn), regs) = (val))

/** Representation of trap details */
struct sbi_trap_info {
	/** cause Trap exception cause */
	unsigned long cause;
	/** tval Trap value */
	unsigned long tval;
	/** tval2 Trap value 2 */
	unsigned long tval2;
	/** tinst Trap instruction */
	unsigned long tinst;
	/** gva Guest virtual address in tval flag */
	unsigned long gva;
};

/** Representation of trap context saved on stack */
struct sbi_trap_context {
	/** Register state */
	struct sbi_trap_regs regs;
	/** Trap details */
	struct sbi_trap_info trap;
	/** Pointer to previous trap context */
	struct sbi_trap_context *prev_context;
};

static inline unsigned long sbi_regs_gva(const struct sbi_trap_regs *regs)
{
	/*
	 * If the hypervisor extension is not implemented, mstatus[h].GVA is a
	 * WPRI field, which is guaranteed to read as zero. In addition, in this
	 * case we don't read mstatush and instead pretend it is zero, which
	 * handles privileged spec version < 1.12.
	 */

#if __riscv_xlen == 32
	return (regs->mstatusH & MSTATUSH_GVA) ? 1 : 0;
#else
	return (regs->mstatus & MSTATUS_GVA) ? 1 : 0;
#endif
}

static inline bool sbi_regs_from_virt(const struct sbi_trap_regs *regs)
{
#if __riscv_xlen == 32
	return (regs->mstatusH & MSTATUSH_MPV) ? true : false;
#else
	return (regs->mstatus & MSTATUS_MPV) ? true : false;
#endif
}

static inline int sbi_mstatus_prev_mode(unsigned long mstatus)
{
	return (mstatus & MSTATUS_MPP) >> MSTATUS_MPP_SHIFT;
}

#if __riscv_xlen == 32
static inline int sbi_regs_prev_xlen(const struct sbi_trap_regs *regs)
{
	return __riscv_xlen;
}
#else
static inline int sbi_mstatus_sxl(unsigned long mstatus)
{
	return (mstatus & MSTATUS_SXL) >> MSTATUS_SXL_SHIFT;
}

static inline int sbi_mstatus_uxl(unsigned long mstatus)
{
	return (mstatus & MSTATUS_UXL) >> MSTATUS_UXL_SHIFT;
}

static inline int sbi_hstatus_vsxl(unsigned long hstatus)
{
	return (hstatus & HSTATUS_VSXL) >> HSTATUS_VSXL_SHIFT;
}

static inline int sbi_regs_prev_xlen(const struct sbi_trap_regs *regs)
{
	unsigned long hstatus, vsstatus;

	if (!sbi_regs_from_virt(regs)) {
		switch (sbi_mstatus_prev_mode(regs->mstatus)) {
		case PRV_M:
			return __riscv_xlen;
		case PRV_S:
			return MXL_TO_XLEN(sbi_mstatus_sxl(regs->mstatus));
		case PRV_U:
			return MXL_TO_XLEN(sbi_mstatus_uxl(regs->mstatus));
		default:
			__builtin_unreachable();
		}
	}

	/* V=1, Check HSXLEN first */
	if (sbi_mstatus_sxl(regs->mstatus) < MXL_XLEN_64)
		return 32;

	hstatus = csr_read(CSR_HSTATUS);
	/* Check VSXLEN */
	if (sbi_hstatus_vsxl(hstatus) < MXL_XLEN_64)
		return 32;

	vsstatus = csr_read(CSR_VSSTATUS);
	switch (sbi_mstatus_prev_mode(regs->mstatus)) {
		case PRV_S:
			return MXL_TO_XLEN(sbi_hstatus_vsxl(hstatus));
		case PRV_U:
			return MXL_TO_XLEN(sbi_mstatus_uxl(vsstatus));
	}
	__builtin_unreachable();
}
#endif

int sbi_trap_redirect(struct sbi_trap_regs *regs,
		      const struct sbi_trap_info *trap);

static inline struct sbi_trap_context *sbi_trap_get_context(struct sbi_scratch *scratch)
{
	return (scratch) ? (void *)scratch->trap_context : NULL;
}

static inline void sbi_trap_set_context(struct sbi_scratch *scratch,
					struct sbi_trap_context *tcntx)
{
	scratch->trap_context = (unsigned long)tcntx;
}

struct sbi_trap_context *sbi_trap_handler(struct sbi_trap_context *tcntx);

struct sbi_trap_context *sbi_trap_rnmi_handler(struct sbi_trap_context *tcntx);

#endif

#endif