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grub/grub-core/kern/riscv/dl.c
Alexander Graf 893ed83b2e RISC-V: Add awareness for RISC-V reloations 
This patch adds awareness of RISC-V relocations throughout the grub tools
as well as dynamic linkage and elf->PE relocation conversion support.

Signed-off-by: Alexander Graf <agraf@suse.de>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2020-09-21 16:43:54 -04:00

340 lines
9.1 KiB
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/* dl.c - arch-dependent part of loadable module support */
/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2018 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>
/*
* Instructions and instruction encoding are documented in the RISC-V
* specification. This file is based on version 2.2:
*
* https://github.com/riscv/riscv-isa-manual/blob/master/release/riscv-spec-v2.2.pdf
*/
#define LDR 0x58000050
#define BR 0xd61f0200
/*
* Check if EHDR is a valid ELF header.
*/
grub_err_t
grub_arch_dl_check_header (void *ehdr)
{
Elf_Ehdr *e = ehdr;
/* Check the magic numbers. */
if (e->e_ident[EI_DATA] != ELFDATA2LSB || e->e_machine != EM_RISCV)
return grub_error (GRUB_ERR_BAD_OS,
N_("invalid arch-dependent ELF magic"));
return GRUB_ERR_NONE;
}
#pragma GCC diagnostic ignored "-Wcast-align"
/* Relocate symbols. */
grub_err_t
grub_arch_dl_relocate_symbols (grub_dl_t mod, void *ehdr,
Elf_Shdr *s, grub_dl_segment_t seg)
{
Elf_Rel *rel, *max;
for (rel = (Elf_Rel *) ((char *) ehdr + s->sh_offset),
max = (Elf_Rel *) ((char *) rel + s->sh_size);
rel < max;
rel = (Elf_Rel *) ((char *) rel + s->sh_entsize))
{
Elf_Sym *sym;
void *place;
grub_size_t sym_addr;
if (rel->r_offset >= seg->size)
return grub_error (GRUB_ERR_BAD_MODULE,
"reloc offset is out of the segment");
sym = (Elf_Sym *) ((char *) mod->symtab
+ mod->symsize * ELF_R_SYM (rel->r_info));
sym_addr = sym->st_value;
if (s->sh_type == SHT_RELA)
sym_addr += ((Elf_Rela *) rel)->r_addend;
place = (void *) ((grub_addr_t) seg->addr + rel->r_offset);
switch (ELF_R_TYPE (rel->r_info))
{
case R_RISCV_32:
{
grub_uint32_t *abs_place = place;
grub_dprintf ("dl", " reloc_abs32 %p => 0x%016llx\n",
place, (unsigned long long) sym_addr);
*abs_place = (grub_uint32_t) sym_addr;
}
break;
case R_RISCV_64:
{
grub_size_t *abs_place = place;
grub_dprintf ("dl", " reloc_abs64 %p => 0x%016llx\n",
place, (unsigned long long) sym_addr);
*abs_place = (grub_size_t) sym_addr;
}
break;
case R_RISCV_ADD8:
{
grub_uint8_t *abs_place = place;
*abs_place += (grub_uint8_t) sym_addr;
}
break;
case R_RISCV_ADD16:
{
grub_uint16_t *abs_place = place;
*abs_place += (grub_uint16_t) sym_addr;
}
break;
case R_RISCV_ADD32:
{
grub_uint32_t *abs_place = place;
*abs_place += (grub_uint32_t) sym_addr;
}
break;
case R_RISCV_ADD64:
{
grub_size_t *abs_place = place;
*abs_place += (grub_size_t) sym_addr;
}
break;
case R_RISCV_SUB8:
{
grub_uint8_t *abs_place = place;
*abs_place -= (grub_uint8_t) sym_addr;
}
break;
case R_RISCV_SUB16:
{
grub_uint16_t *abs_place = place;
*abs_place -= (grub_uint16_t) sym_addr;
}
break;
case R_RISCV_SUB32:
{
grub_uint32_t *abs_place = place;
*abs_place -= (grub_uint32_t) sym_addr;
}
break;
case R_RISCV_SUB64:
{
grub_size_t *abs_place = place;
*abs_place -= (grub_size_t) sym_addr;
}
break;
case R_RISCV_BRANCH:
{
grub_uint32_t *abs_place = place;
grub_ssize_t off = sym_addr - (grub_addr_t) place;
grub_uint32_t imm12 = (off & 0x1000) << (31 - 12);
grub_uint32_t imm11 = (off & 0x800) >> (11 - 7);
grub_uint32_t imm10_5 = (off & 0x7e0) << (30 - 10);
grub_uint32_t imm4_1 = (off & 0x1e) << (11 - 4);
*abs_place = (*abs_place & 0x1fff07f)
| imm12 | imm11 | imm10_5 | imm4_1;
}
break;
case R_RISCV_JAL:
{
grub_uint32_t *abs_place = place;
grub_ssize_t off = sym_addr - (grub_addr_t) place;
grub_uint32_t imm20 = (off & 0x100000) << (31 - 20);
grub_uint32_t imm19_12 = (off & 0xff000);
grub_uint32_t imm11 = (off & 0x800) << (20 - 11);
grub_uint32_t imm10_1 = (off & 0x7fe) << (30 - 10);
*abs_place = (*abs_place & 0xfff)
| imm20 | imm19_12 | imm11 | imm10_1;
}
break;
case R_RISCV_CALL:
{
grub_uint32_t *abs_place = place;
grub_ssize_t off = sym_addr - (grub_addr_t) place;
grub_uint32_t hi20, lo12;
if (off != (grub_int32_t) off)
return grub_error (GRUB_ERR_BAD_MODULE, "relocation overflow");
hi20 = (off + 0x800) & 0xfffff000;
lo12 = (off - hi20) & 0xfff;
abs_place[0] = (abs_place[0] & 0xfff) | hi20;
abs_place[1] = (abs_place[1] & 0xfffff) | (lo12 << 20);
}
break;
case R_RISCV_RVC_BRANCH:
{
grub_uint16_t *abs_place = place;
grub_ssize_t off = sym_addr - (grub_addr_t) place;
grub_uint16_t imm8 = (off & 0x100) << (12 - 8);
grub_uint16_t imm7_6 = (off & 0xc0) >> (6 - 5);
grub_uint16_t imm5 = (off & 0x20) >> (5 - 2);
grub_uint16_t imm4_3 = (off & 0x18) << (12 - 5);
grub_uint16_t imm2_1 = (off & 0x6) << (12 - 10);
*abs_place = (*abs_place & 0xe383)
| imm8 | imm7_6 | imm5 | imm4_3 | imm2_1;
}
break;
case R_RISCV_RVC_JUMP:
{
grub_uint16_t *abs_place = place;
grub_ssize_t off = sym_addr - (grub_addr_t) place;
grub_uint16_t imm11 = (off & 0x800) << (12 - 11);
grub_uint16_t imm10 = (off & 0x400) >> (10 - 8);
grub_uint16_t imm9_8 = (off & 0x300) << (12 - 11);
grub_uint16_t imm7 = (off & 0x80) >> (7 - 6);
grub_uint16_t imm6 = (off & 0x40) << (12 - 11);
grub_uint16_t imm5 = (off & 0x20) >> (5 - 2);
grub_uint16_t imm4 = (off & 0x10) << (12 - 5);
grub_uint16_t imm3_1 = (off & 0xe) << (12 - 10);
*abs_place = ((*abs_place & 0xe003)
| imm11 | imm10 | imm9_8 | imm7 | imm6
| imm5 | imm4 | imm3_1);
}
break;
case R_RISCV_PCREL_HI20:
{
grub_uint32_t *abs_place = place;
grub_ssize_t off = sym_addr - (grub_addr_t) place;
grub_int32_t hi20;
if (off != (grub_int32_t)off)
return grub_error (GRUB_ERR_BAD_MODULE, "relocation overflow");
hi20 = (off + 0x800) & 0xfffff000;
*abs_place = (*abs_place & 0xfff) | hi20;
}
break;
case R_RISCV_PCREL_LO12_I:
case R_RISCV_PCREL_LO12_S:
{
grub_uint32_t *t32 = place;
Elf_Rela *rel2;
/* Search backwards for matching HI20 reloc. */
for (rel2 = (Elf_Rela *) ((char *) rel - s->sh_entsize);
(unsigned long)rel2 >= ((unsigned long)ehdr + s->sh_offset);
rel2 = (Elf_Rela *) ((char *) rel2 - s->sh_entsize))
{
Elf_Addr rel2_info;
Elf_Addr rel2_offset;
Elf_Addr rel2_sym_addr;
Elf_Addr rel2_loc;
grub_ssize_t rel2_off;
grub_ssize_t off;
Elf_Sym *sym2;
rel2_offset = rel2->r_offset;
rel2_info = rel2->r_info;
rel2_loc = (grub_addr_t) seg->addr + rel2_offset;
if (ELF_R_TYPE (rel2_info) == R_RISCV_PCREL_HI20
&& rel2_loc == sym_addr)
{
sym2 = (Elf_Sym *) ((char *) mod->symtab
+ mod->symsize * ELF_R_SYM (rel2->r_info));
rel2_sym_addr = sym2->st_value;
if (s->sh_type == SHT_RELA)
rel2_sym_addr += ((Elf_Rela *) rel2)->r_addend;
rel2_off = rel2_sym_addr - rel2_loc;
off = rel2_off - ((rel2_off + 0x800) & 0xfffff000);
if (ELF_R_TYPE (rel->r_info) == R_RISCV_PCREL_LO12_I)
*t32 = (*t32 & 0xfffff) | (off & 0xfff) << 20;
else
{
grub_uint32_t imm11_5 = (off & 0xfe0) << (31 - 11);
grub_uint32_t imm4_0 = (off & 0x1f) << (11 - 4);
*t32 = (*t32 & 0x1fff07f) | imm11_5 | imm4_0;
}
break;
}
}
if ((unsigned long)rel2 < ((unsigned long)ehdr + s->sh_offset))
return grub_error (GRUB_ERR_BAD_MODULE, "cannot find matching HI20 relocation");
}
break;
case R_RISCV_HI20:
{
grub_uint32_t *abs_place = place;
*abs_place = (*abs_place & 0xfff) |
(((grub_int32_t) sym_addr + 0x800) & 0xfffff000);
}
break;
case R_RISCV_LO12_I:
{
grub_uint32_t *abs_place = place;
grub_int32_t lo12 = (grub_int32_t) sym_addr -
(((grub_int32_t) sym_addr + 0x800) & 0xfffff000);
*abs_place = (*abs_place & 0xfffff) | ((lo12 & 0xfff) << 20);
}
break;
case R_RISCV_LO12_S:
{
grub_uint32_t *abs_place = place;
grub_int32_t lo12 = (grub_int32_t) sym_addr -
(((grub_int32_t) sym_addr + 0x800) & 0xfffff000);
grub_uint32_t imm11_5 = (lo12 & 0xfe0) << (31 - 11);
grub_uint32_t imm4_0 = (lo12 & 0x1f) << (11 - 4);
*abs_place = (*abs_place & 0x1fff07f) | imm11_5 | imm4_0;
}
break;
case R_RISCV_RELAX:
break;
default:
return grub_error (GRUB_ERR_NOT_IMPLEMENTED_YET,
N_("relocation 0x%x is not implemented yet"),
ELF_R_TYPE (rel->r_info));
}
}
return GRUB_ERR_NONE;
}
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