/*
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 2023 Free Software Foundation, Inc.
 *
 *  GRUB is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  GRUB is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <grub/dl.h>
#include <grub/elf.h>
#include <grub/misc.h>
#include <grub/err.h>
#include <grub/mm.h>
#include <grub/i18n.h>
#include <grub/loongarch64/reloc.h>

/*
 * LoongArch relocations documentation:
 * https://github.com/loongson/la-abi-specs/blob/release/laelf.adoc#relocations
 */
static void grub_loongarch64_stack_push (grub_loongarch64_stack_t stack, grub_uint64_t x);
static grub_uint64_t grub_loongarch64_stack_pop (grub_loongarch64_stack_t stack);

void
grub_loongarch64_stack_init (grub_loongarch64_stack_t stack)
{
  stack->top = -1;
  stack->count = LOONGARCH64_STACK_MAX;
}

static void
grub_loongarch64_stack_push (grub_loongarch64_stack_t stack, grub_uint64_t x)
{
  if (stack->top == stack->count)
    return;
  stack->data[++stack->top] = x;
}

static grub_uint64_t
grub_loongarch64_stack_pop (grub_loongarch64_stack_t stack)
{
  if (stack->top == -1)
    return 0;
  return stack->data[stack->top--];
}

void
grub_loongarch64_sop_push (grub_loongarch64_stack_t stack, grub_int64_t offset)
{
  grub_loongarch64_stack_push (stack, offset);
}

/* opr2 = pop (), opr1 = pop (), push (opr1 - opr2) */
void
grub_loongarch64_sop_sub (grub_loongarch64_stack_t stack)
{
  grub_uint64_t a, b;
  b = grub_loongarch64_stack_pop (stack);
  a = grub_loongarch64_stack_pop (stack);
  grub_loongarch64_stack_push (stack, a - b);
}

/* opr2 = pop (), opr1 = pop (), push (opr1 << opr2) */
void
grub_loongarch64_sop_sl (grub_loongarch64_stack_t stack)
{
  grub_uint64_t a, b;
  b = grub_loongarch64_stack_pop (stack);
  a = grub_loongarch64_stack_pop (stack);
  grub_loongarch64_stack_push (stack, a << b);
}

/* opr2 = pop (), opr1 = pop (), push (opr1 >> opr2) */
void
grub_loongarch64_sop_sr (grub_loongarch64_stack_t stack)
{
  grub_uint64_t a, b;
  b = grub_loongarch64_stack_pop (stack);
  a = grub_loongarch64_stack_pop (stack);
  grub_loongarch64_stack_push (stack, a >> b);
}

/* opr2 = pop (), opr1 = pop (), push (opr1 + opr2) */
void
grub_loongarch64_sop_add (grub_loongarch64_stack_t stack)
{
  grub_uint64_t a, b;
  b = grub_loongarch64_stack_pop (stack);
  a = grub_loongarch64_stack_pop (stack);
  grub_loongarch64_stack_push (stack, a + b);
}

/* opr2 = pop (), opr1 = pop (), push (opr1 & opr2) */
void
grub_loongarch64_sop_and (grub_loongarch64_stack_t stack)
{
  grub_uint64_t a, b;
  b = grub_loongarch64_stack_pop (stack);
  a = grub_loongarch64_stack_pop (stack);
  grub_loongarch64_stack_push (stack, a & b);
}

/* opr3 = pop (), opr2 = pop (), opr1 = pop (), push (opr1 ? opr2 : opr3) */
void
grub_loongarch64_sop_if_else (grub_loongarch64_stack_t stack)
{
  grub_uint64_t a, b, c;
  c = grub_loongarch64_stack_pop (stack);
  b = grub_loongarch64_stack_pop (stack);
  a = grub_loongarch64_stack_pop (stack);

  if (a) {
      grub_loongarch64_stack_push (stack, b);
  } else {
      grub_loongarch64_stack_push (stack, c);
  }
}

/* opr1 = pop (), (*(uint32_t *) PC) [14 ... 10] = opr1 [4 ... 0] */
void
grub_loongarch64_sop_32_s_10_5 (grub_loongarch64_stack_t stack,
				grub_uint64_t *place)
{
  grub_uint64_t a = grub_loongarch64_stack_pop (stack);
  *place |= ((a & 0x1f) << 10);
}

/* opr1 = pop (), (*(uint32_t *) PC) [21 ... 10] = opr1 [11 ... 0] */
void
grub_loongarch64_sop_32_u_10_12 (grub_loongarch64_stack_t stack,
				 grub_uint64_t *place)
{
  grub_uint64_t a = grub_loongarch64_stack_pop (stack);
  *place = *place | ((a & 0xfff) << 10);
}

/* opr1 = pop (), (*(uint32_t *) PC) [21 ... 10] = opr1 [11 ... 0] */
void
grub_loongarch64_sop_32_s_10_12 (grub_loongarch64_stack_t stack,
				 grub_uint64_t *place)
{
  grub_uint64_t a = grub_loongarch64_stack_pop (stack);
  *place = (*place) | ((a & 0xfff) << 10);
}

/* opr1 = pop (), (*(uint32_t *) PC) [25 ... 10] = opr1 [15 ... 0] */
void
grub_loongarch64_sop_32_s_10_16 (grub_loongarch64_stack_t stack,
				 grub_uint64_t *place)
{
  grub_uint64_t a = grub_loongarch64_stack_pop (stack);
  *place = (*place) | ((a & 0xffff) << 10);
}

/* opr1 = pop (), (*(uint32_t *) PC) [25 ... 10] = opr1 [17 ... 2] */
void
grub_loongarch64_sop_32_s_10_16_s2 (grub_loongarch64_stack_t stack,
				    grub_uint64_t *place)
{
  grub_uint64_t a = grub_loongarch64_stack_pop (stack);
  *place = (*place) | (((a >> 2) & 0xffff) << 10);
}

/* opr1 = pop (), (*(uint32_t *) PC) [24 ... 5] = opr1 [19 ... 0] */
void
grub_loongarch64_sop_32_s_5_20 (grub_loongarch64_stack_t stack, grub_uint64_t *place)
{
  grub_uint64_t a = grub_loongarch64_stack_pop (stack);
  *place = (*place) | ((a & 0xfffff)<<5);
}

/* opr1 = pop (), (*(uint32_t *) PC) [4 ... 0] = opr1 [22 ... 18] */
void
grub_loongarch64_sop_32_s_0_5_10_16_s2 (grub_loongarch64_stack_t stack,
					grub_uint64_t *place)
{
  grub_uint64_t a = grub_loongarch64_stack_pop (stack);

  *place =(*place) | (((a >> 2) & 0xffff) << 10);
  *place =(*place) | ((a >> 18) & 0x1f);
}

/*
 * opr1 = pop ()
 * (*(uint32_t *) PC) [9 ... 0] = opr1 [27 ... 18],
 * (*(uint32_t *) PC) [25 ... 10] = opr1 [17 ... 2]
 */
void
grub_loongarch64_sop_32_s_0_10_10_16_s2 (grub_loongarch64_stack_t stack,
					 grub_uint64_t *place)
{
  grub_uint64_t a = grub_loongarch64_stack_pop (stack);
  *place =(*place) | (((a >> 2) & 0xffff) << 10);
  *place =(*place) | ((a >> 18) & 0x3ff);
}

/*
 * B26 relocation for the 28-bit PC-relative jump
 * (*(uint32_t *) PC) [9 ... 0] = (S + A - PC) [27 ... 18]
 * (*(uint32_t *) PC) [25 ... 10] = (S + A - PC) [17 ... 2]
 */
void grub_loongarch64_b26 (grub_uint32_t *place, grub_int64_t offset)
{
  grub_uint32_t val;
  const grub_uint32_t insmask = grub_cpu_to_le32_compile_time (0xfc000000);

  grub_dprintf ("dl", "  reloc_b26 %p %c= 0x%" PRIxGRUB_INT64_T "\n",
		place, offset > 0 ? '+' : '-',
		offset < 0 ? -offset : offset);

  val = ((offset >> 18) & 0x3ff) | (((offset >> 2) & 0xffff) << 10);

  *place &= insmask;
  *place |= grub_cpu_to_le32 (val) & ~insmask;
}

/*
 * ABS_HI20/PCALA_HI20 relocations for 32/64-bit absolute address/PC-relative offset
 * (*(uint32_t *) PC) [24 ... 5] = (S + A) [31 ... 12]
 */
void grub_loongarch64_xxx_hi20 (grub_uint32_t *place, grub_int64_t offset)
{
  const grub_uint32_t insmask = grub_cpu_to_le32_compile_time (0xfe00001f);
  grub_uint32_t val;

  offset >>= 12;
  val = ((offset & 0xfffff) << 5);

  *place &= insmask;
  *place |= grub_cpu_to_le32 (val) & ~insmask;
}

/*
 * ABS_LO12/PCALA_LO12 relocations for 32/64-bit absolute address
 * (*(uint32_t *) PC) [21 ... 10] = (S + A) [11 ... 0]
 */
void grub_loongarch64_xxx_lo12 (grub_uint32_t *place, grub_int64_t offset)
{
  const grub_uint32_t insmask = grub_cpu_to_le32_compile_time (0xffc003ff);

  *place &= insmask;
  *place |= grub_cpu_to_le32 (offset << 10) & ~insmask;
}

/*
 * ABS64_HI12 relocation for the 64-bit absolute address
 * (*(uint32_t *) PC) [21 ... 10] = (S + A) [63 ... 52]
 */
void grub_loongarch64_abs64_hi12 (grub_uint32_t *place, grub_int64_t offset)
{
  const grub_uint32_t insmask = grub_cpu_to_le32_compile_time (0xffc003ff);
  grub_uint32_t val;

  offset >>= 52;
  val = ((offset & 0xfff) << 10);

  *place &= insmask;
  *place |= grub_cpu_to_le32 (val) & ~insmask;
}

/*
 * ABS64_LO20 relocation for the 64-bit absolute address
 * (*(uint32_t *) PC) [24 ... 5] = (S + A) [51 ... 32]
 */
void grub_loongarch64_abs64_lo20 (grub_uint32_t *place, grub_int64_t offset)
{
  const grub_uint32_t insmask = grub_cpu_to_le32_compile_time (0xfe00001f);
  grub_uint32_t val;

  offset >>= 32;
  val = ((offset & 0xfffff) << 5);

  *place &= insmask;
  *place |= grub_cpu_to_le32 (val) & ~insmask;
}