// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Mapping of DWARF debug register numbers into register names.
 *
 * Copyright (C) 2010 Ian Munsie, IBM Corporation.
 */

#include <stddef.h>
#include <errno.h>
#include <string.h>
#include <dwarf-regs.h>
#include <linux/ptrace.h>
#include <linux/kernel.h>
#include <linux/stringify.h>

struct pt_regs_dwarfnum {
	const char *name;
	unsigned int dwarfnum;
	unsigned int ptregs_offset;
};

#define REG_DWARFNUM_NAME(r, num)					\
		{.name = __stringify(%)__stringify(r), .dwarfnum = num,			\
		.ptregs_offset = offsetof(struct pt_regs, r)}
#define GPR_DWARFNUM_NAME(num)						\
		{.name = __stringify(%gpr##num), .dwarfnum = num,		\
		.ptregs_offset = offsetof(struct pt_regs, gpr[num])}
#define REG_DWARFNUM_END {.name = NULL, .dwarfnum = 0, .ptregs_offset = 0}

/*
 * Reference:
 * http://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi-1.9.html
 */
static const struct pt_regs_dwarfnum regdwarfnum_table[] = {
	GPR_DWARFNUM_NAME(0),
	GPR_DWARFNUM_NAME(1),
	GPR_DWARFNUM_NAME(2),
	GPR_DWARFNUM_NAME(3),
	GPR_DWARFNUM_NAME(4),
	GPR_DWARFNUM_NAME(5),
	GPR_DWARFNUM_NAME(6),
	GPR_DWARFNUM_NAME(7),
	GPR_DWARFNUM_NAME(8),
	GPR_DWARFNUM_NAME(9),
	GPR_DWARFNUM_NAME(10),
	GPR_DWARFNUM_NAME(11),
	GPR_DWARFNUM_NAME(12),
	GPR_DWARFNUM_NAME(13),
	GPR_DWARFNUM_NAME(14),
	GPR_DWARFNUM_NAME(15),
	GPR_DWARFNUM_NAME(16),
	GPR_DWARFNUM_NAME(17),
	GPR_DWARFNUM_NAME(18),
	GPR_DWARFNUM_NAME(19),
	GPR_DWARFNUM_NAME(20),
	GPR_DWARFNUM_NAME(21),
	GPR_DWARFNUM_NAME(22),
	GPR_DWARFNUM_NAME(23),
	GPR_DWARFNUM_NAME(24),
	GPR_DWARFNUM_NAME(25),
	GPR_DWARFNUM_NAME(26),
	GPR_DWARFNUM_NAME(27),
	GPR_DWARFNUM_NAME(28),
	GPR_DWARFNUM_NAME(29),
	GPR_DWARFNUM_NAME(30),
	GPR_DWARFNUM_NAME(31),
	REG_DWARFNUM_NAME(msr,   66),
	REG_DWARFNUM_NAME(ctr,   109),
	REG_DWARFNUM_NAME(link,  108),
	REG_DWARFNUM_NAME(xer,   101),
	REG_DWARFNUM_NAME(dar,   119),
	REG_DWARFNUM_NAME(dsisr, 118),
	REG_DWARFNUM_END,
};

/**
 * get_arch_regstr() - lookup register name from it's DWARF register number
 * @n:	the DWARF register number
 *
 * get_arch_regstr() returns the name of the register in struct
 * regdwarfnum_table from it's DWARF register number. If the register is not
 * found in the table, this returns NULL;
 */
const char *get_arch_regstr(unsigned int n)
{
	const struct pt_regs_dwarfnum *roff;
	for (roff = regdwarfnum_table; roff->name != NULL; roff++)
		if (roff->dwarfnum == n)
			return roff->name;
	return NULL;
}

int regs_query_register_offset(const char *name)
{
	const struct pt_regs_dwarfnum *roff;
	for (roff = regdwarfnum_table; roff->name != NULL; roff++)
		if (!strcmp(roff->name, name))
			return roff->ptregs_offset;
	return -EINVAL;
}

#define PPC_OP(op)	(((op) >> 26) & 0x3F)
#define PPC_RA(a)	(((a) >> 16) & 0x1f)
#define PPC_RT(t)	(((t) >> 21) & 0x1f)
#define PPC_RB(b)	(((b) >> 11) & 0x1f)
#define PPC_D(D)	((D) & 0xfffe)
#define PPC_DS(DS)	((DS) & 0xfffc)
#define OP_LD	58
#define OP_STD	62

static int get_source_reg(u32 raw_insn)
{
	return PPC_RA(raw_insn);
}

static int get_target_reg(u32 raw_insn)
{
	return PPC_RT(raw_insn);
}

static int get_offset_opcode(u32 raw_insn)
{
	int opcode = PPC_OP(raw_insn);

	/* DS- form */
	if ((opcode == OP_LD) || (opcode == OP_STD))
		return PPC_DS(raw_insn);
	else
		return PPC_D(raw_insn);
}

/*
 * Fills the required fields for op_loc depending on if it
 * is a source or target.
 * D form: ins RT,D(RA) -> src_reg1 = RA, offset = D, dst_reg1 = RT
 * DS form: ins RT,DS(RA) -> src_reg1 = RA, offset = DS, dst_reg1 = RT
 * X form: ins RT,RA,RB -> src_reg1 = RA, src_reg2 = RB, dst_reg1 = RT
 */
void get_powerpc_regs(u32 raw_insn, int is_source,
		struct annotated_op_loc *op_loc)
{
	if (is_source)
		op_loc->reg1 = get_source_reg(raw_insn);
	else
		op_loc->reg1 = get_target_reg(raw_insn);

	if (op_loc->multi_regs)
		op_loc->reg2 = PPC_RB(raw_insn);

	/* TODO: Implement offset handling for X Form */
	if ((op_loc->mem_ref) && (PPC_OP(raw_insn) != 31))
		op_loc->offset = get_offset_opcode(raw_insn);
}