sergiotarxz/nuttx
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity
07ec18f088
nuttx/libs/libc/machine/risc-v/arch_elf.c
Ville Juven 90d73153fb riscv/arch_elf: Check for _HI20 relocation validity 
As pointed out in #11322 there is a hardware design issue in RISC-V that
affects RV64 relocations. The problem is with how address bits are loaded
into registers via lui / auipc and sign extension.

If the hi20 relocation value happens to have its 32-bit sign bit set, i.e.
value is 0x80000000 (but not negative! i.e. negative in 64-bit format) the
relocation will fail, as the address is erroneously sign extended:

0x00000000_80000000 becomes 0xffffffff_80000000 which is not correct.

Also, make sure the correct opcode is used with PCREL_HI20, it expects
AUIPC (not LUI). The C compiler will never emit such code but when hand-
writing assembly code this can happen.
2023-12-14 06:54:17 -08:00

775 lines
21 KiB
C
Raw Blame History

/****************************************************************************
* libs/libc/machine/risc-v/arch_elf.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <inttypes.h>
#include <stdlib.h>
#include <errno.h>
#include <debug.h>
#include <assert.h>
#include <nuttx/elf.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#define OPCODE_AUIPC 0x17
#define OPCODE_LUI 0x37
#define RVI_OPCODE_MASK 0x7F
/* ELF32 and ELF64 definitions */
#ifdef CONFIG_LIBC_ARCH_ELF_64BIT
# define ARCH_ELF_TYP_STR "64"
#else /* !CONFIG_LIBC_ARCH_ELF_64BIT */
# define ARCH_ELF_TYP_STR "32"
#endif /* CONFIG_LIBC_ARCH_ELF_64BIT */
/****************************************************************************
* Private Data Types
****************************************************************************/
struct rname_code_s
{
const char *name;
int type;
};
/****************************************************************************
* Private Data
****************************************************************************/
static struct rname_code_s _rname_table[] =
{
{"RELAX", R_RISCV_RELAX},
{"RISCV_32", R_RISCV_32},
{"RISCV_64", R_RISCV_64},
{"PCREL_LO12_I", R_RISCV_PCREL_LO12_I},
{"PCREL_LO12_S", R_RISCV_PCREL_LO12_S},
{"PCREL_HI20", R_RISCV_PCREL_HI20},
{"HI20", R_RISCV_HI20},
{"LO12_I", R_RISCV_LO12_I},
{"LO12_S", R_RISCV_LO12_S},
{"CALL", R_RISCV_CALL},
{"CALL_PLT", R_RISCV_CALL_PLT},
{"BRANCH", R_RISCV_BRANCH},
{"JAL", R_RISCV_JAL},
{"RVC_JUMP", R_RISCV_RVC_JUMP},
{"RVC_BRANCH", R_RISCV_RVC_BRANCH},
{"32_PCREL", R_RISCV_32_PCREL},
};
/****************************************************************************
* Private Functions
****************************************************************************/
static const char *_get_rname(int type)
{
int i = 0;
for (i = 0; i < sizeof(_rname_table) / sizeof(struct rname_code_s); i++)
{
if (_rname_table[i].type == type)
{
return _rname_table[i].name;
}
}
/* Not found in the table */
return "?????";
}
/****************************************************************************
* Name: _get_val, set_val, _add_val
*
* Description:
* These functions are used when relocating an instruction because we can
* not assume the instruction is word-aligned.
*
****************************************************************************/
static uint32_t _get_val(uint16_t *addr)
{
uint32_t ret;
ret = *addr | (*(addr + 1)) << 16;
return ret;
}
static void _set_val(uint16_t *addr, uint32_t val)
{
*addr = (val & 0xffff);
*(addr + 1) = (val >> 16);
/* NOTE: Ensure relocation before execution */
asm volatile ("fence.i");
}
static void _add_val(uint16_t *addr, uint32_t val)
{
uint32_t cur = _get_val(addr);
_set_val(addr, cur + val);
}
/****************************************************************************
* Name: _calc_imm
*
* Description:
* Given offset and obtain imm_hi (20bit) and imm_lo (12bit)
*
* Input Parameters:
* offset - signed 32bit
* imm_hi - signed 20bit
* imm_lo - signed 12bit
*
* Returned Value:
* none
*
****************************************************************************/
static void _calc_imm(long offset, long *imm_hi, long *imm_lo)
{
long lo;
long hi = offset / 4096;
long r = offset % 4096;
if (2047 < r)
{
hi++;
}
else if (r < -2048)
{
hi--;
}
lo = offset - (hi * 4096);
binfo("offset=%ld: hi=%ld lo=%ld\n",
offset, hi, lo);
ASSERT(-2048 <= lo && lo <= 2047);
*imm_lo = lo;
*imm_hi = hi;
}
/****************************************************************************
* Name: _add_hi20
*
* Description:
* Add PCREL_HI20 relocation offset to the LUT. When a PCREL_LO12_I/_S is
* encountered, the corresponding PCREL_HI20 value can be found from it.
*
* Input Parameters:
* arch_data - Where the PCREL_HI20 relocations are listed.
* hi20_rel - The PCREL_HI20 relocation entry.
* hi20_offset - The corresponding offset value.
*
* Returned Value:
* None.
*
****************************************************************************/
static void _add_hi20(void *arch_data, uintptr_t hi20_rel,
uintptr_t hi20_offset)
{
arch_elfdata_t *data = (arch_elfdata_t *)arch_data;
int i;
/* Try to find a free slot from the list */
for (i = 0; i < ARCH_ELF_RELCNT; i++)
{
struct hi20_rels_s *hi20 = &data->hi20_rels[i];
if (hi20->hi20_rel == 0)
{
hi20->hi20_rel = hi20_rel;
hi20->hi20_offset = hi20_offset;
break;
}
}
}
/****************************************************************************
* Name: _find_hi20
*
* Description:
* Find PCREL_HI20 relocation offset from the LUT. When a PCREL_LO12_I/_S
* is encountered, the corresponding PCREL_HI20 value is needed to do the
* relocation.
*
* Input Parameters:
* arch_data - Where the PCREL_HI20 relocations are listed.
* hi20_rel - The PCREL_HI20 relocation entry.
*
* Returned Value:
* The corresponding hi20_offset value.
*
****************************************************************************/
static uintptr_t _find_hi20(void *arch_data, uintptr_t hi20_rel)
{
arch_elfdata_t *data = (arch_elfdata_t *)arch_data;
int i;
/* Try to find the hi20 value from the list */
for (i = 0; i < ARCH_ELF_RELCNT; i++)
{
struct hi20_rels_s *hi20 = &data->hi20_rels[i];
if (hi20->hi20_rel == hi20_rel)
{
/* Found it, we can clear the entry now */
hi20->hi20_rel = 0;
return hi20->hi20_offset;
}
}
return 0;
}
/****************************************************************************
* Name: _valid_hi20_imm
*
* Description:
* Check that any XX_HI20 relocation has a valid upper 20-bit immediate.
* Note that this test is not necessary for RV32 targets, the problem is
* related to RV64 sign extension.
*
* Input Parameters:
* imm_hi - The upper immediate value.
*
* Returned Value:
* true if imm_hi is valid; false otherwise
*
****************************************************************************/
#ifdef CONFIG_LIBC_ARCH_ELF_64BIT
static inline bool _valid_hi20_imm(long imm_hi)
{
/* 32-bit sign extend imm_hi and compare with the original value */
long hi = imm_hi & ((1 << 20) - 1); /* 32-bit signed value */
long sign = -((imm_hi >> 19) & 1); /* 32-bit sign value */
hi = ((hi << 12) | sign << 32) >> 12; /* 32-bit sign extend */
/* If the values do not match, the immediate is invalid */
return imm_hi == hi;
}
#else
# define _valid_hi20_imm(imm_hi) 1
#endif
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: up_checkarch
*
* Description:
* Given the ELF header in 'hdr', verify that the ELF file is appropriate
* for the current, configured architecture. Every architecture that uses
* the ELF loader must provide this function.
*
* Input Parameters:
* hdr - The ELF header read from the ELF file.
*
* Returned Value:
* True if the architecture supports this ELF file.
*
****************************************************************************/
bool up_checkarch(const Elf_Ehdr *ehdr)
{
/* Make sure it's an RISCV executable */
if (ehdr->e_machine != EM_RISCV)
{
berr("ERROR: Not for RISCV: e_machine=%04x\n", ehdr->e_machine);
return false;
}
/* Make sure that current objects are supported */
if (ehdr->e_ident[EI_CLASS] != ELF_CLASS)
{
berr("ERROR: Need " ARCH_ELF_TYP_STR "-bit "
"objects: e_ident[EI_CLASS]=%02x\n",
ehdr->e_ident[EI_CLASS]);
return false;
}
/* Verify endian-ness */
#ifdef CONFIG_ENDIAN_BIG
if (ehdr->e_ident[EI_DATA] != ELFDATA2MSB)
#else
if (ehdr->e_ident[EI_DATA] != ELFDATA2LSB)
#endif
{
berr("ERROR: Wrong endian-ness: e_ident[EI_DATA]=%02x\n",
ehdr->e_ident[EI_DATA]);
return false;
}
/* Make sure the entry point address is properly aligned */
if ((ehdr->e_entry & 1) != 0)
{
berr("ERROR: Entry point is not properly aligned: %08lx\n",
ehdr->e_entry);
}
/* TODO: Check ABI here. */
return true;
}
/****************************************************************************
* Name: up_relocate and up_relocateadd
*
* Description:
* Perform an architecture-specific ELF relocation. Every architecture
* that uses the ELF loader must provide this function.
*
* Input Parameters:
* rel - The relocation type
* sym - The ELF symbol structure containing the fully resolved value.
* There are a few relocation types for a few architectures that do
* not require symbol information. For those, this value will be
* NULL. Implementations of these functions must be able to handle
* that case.
* addr - The address that requires the relocation.
*
* Returned Value:
* Zero (OK) if the relocation was successful. Otherwise, a negated errno
* value indicating the cause of the relocation failure.
*
****************************************************************************/
int up_relocate(const Elf_Rel *rel, const Elf_Sym *sym, uintptr_t addr,
void *arch_data)
{
berr("Not implemented\n");
return -ENOSYS;
}
int up_relocateadd(const Elf_Rela *rel, const Elf_Sym *sym,
uintptr_t addr, void *arch_data)
{
long offset;
unsigned int relotype;
/* All relocations depend upon having valid symbol information */
relotype = ELF_R_TYPE(rel->r_info);
if (relotype == R_RISCV_RELAX)
{
/* NOTE: RELAX has no symbol, so just return */
binfo("%s at %08" PRIxPTR " [%08" PRIx32 "]\n",
_get_rname(relotype),
addr, _get_val((uint16_t *)addr));
return OK;
}
if (sym == NULL && relotype != R_RISCV_NONE)
{
return -EINVAL;
}
/* Do relocation based on relocation type */
switch (relotype)
{
case R_RISCV_32:
case R_RISCV_64:
{
binfo("%s at %08" PRIxPTR " [%08" PRIx32 "] "
"to sym=%p st_value=%08lx\n",
_get_rname(relotype),
addr, _get_val((uint16_t *)addr),
sym, sym->st_value);
_set_val((uint16_t *)addr,
(uint32_t)(sym->st_value + rel->r_addend));
}
break;
case R_RISCV_PCREL_LO12_I:
{
long imm_hi;
long imm_lo;
binfo("%s at %08" PRIxPTR " [%08" PRIx32 "] "
"to sym=%p st_value=%08lx\n",
_get_rname(relotype),
addr, _get_val((uint16_t *)addr),
sym, sym->st_value);
offset = _find_hi20(arch_data, sym->st_value);
/* Adjust imm for MV(ADDI) / JR (JALR) : I-type */
_calc_imm(offset, &imm_hi, &imm_lo);
_add_val((uint16_t *)addr, (int32_t)imm_lo << 20);
}
break;
case R_RISCV_PCREL_LO12_S:
{
uint32_t val;
long imm_hi;
long imm_lo;
binfo("%s at %08" PRIxPTR " [%08" PRIx32 "] "
"to sym=%p st_value=%08lx\n",
_get_rname(relotype),
addr, _get_val((uint16_t *)addr),
sym, sym->st_value);
offset = _find_hi20(arch_data, sym->st_value);
/* Adjust imm for SW : S-type */
_calc_imm(offset, &imm_hi, &imm_lo);
val = (((int32_t)imm_lo >> 5) << 25) +
(((int32_t)imm_lo & 0x1f) << 7);
binfo("imm_lo=%ld (%lx), val=%" PRIx32 "\n", imm_lo, imm_lo, val);
_add_val((uint16_t *)addr, val);
}
break;
case R_RISCV_PCREL_HI20:
{
uint32_t insn;
long imm_hi;
long imm_lo;
binfo("%s at %08" PRIxPTR " [%08" PRIx32 "] "
"to sym=%p st_value=%08lx\n",
_get_rname(relotype),
addr, _get_val((uint16_t *)addr),
sym, sym->st_value);
offset = (long)sym->st_value + (long)rel->r_addend - (long)addr;
insn = _get_val((uint16_t *)addr);
ASSERT(OPCODE_AUIPC == (insn & RVI_OPCODE_MASK));
_calc_imm(offset, &imm_hi, &imm_lo);
if (!_valid_hi20_imm(imm_hi))
{
berr("ERROR: %s at %08" PRIxPTR " bad:%08lx\n",
_get_rname(relotype), addr, imm_hi << 12);
return -EINVAL;
}
/* Adjust auipc (add upper immediate to pc) : 20bit */
_add_val((uint16_t *)addr, imm_hi << 12);
/* Add the hi20 value to the cache */
_add_hi20(arch_data, addr, offset);
}
break;
case R_RISCV_CALL:
case R_RISCV_CALL_PLT:
{
long imm_hi;
long imm_lo;
binfo("%s at %08" PRIxPTR " [%08" PRIx32 "] "
"to sym=%p st_value=%08lx\n",
_get_rname(relotype),
addr, _get_val((uint16_t *)addr),
sym, sym->st_value);
offset = (long)sym->st_value + (long)rel->r_addend - (long)addr;
_calc_imm(offset, &imm_hi, &imm_lo);
if (!_valid_hi20_imm(imm_hi))
{
berr("ERROR: %s at %08" PRIxPTR " bad:%08lx\n",
_get_rname(relotype), addr, imm_hi << 12);
return -EINVAL;
}
/* Adjust auipc (add upper immediate to pc) : 20bit */
_add_val((uint16_t *)addr, imm_hi << 12);
/* Adjust imm for CALL (JALR) : I-type */
_add_val((uint16_t *)(addr + 4), (int32_t)imm_lo << 20);
}
break;
case R_RISCV_BRANCH:
{
binfo("%s at %08" PRIxPTR " [%08" PRIx32 "] "
"to sym=%p st_value=%08lx\n",
_get_rname(relotype),
addr, _get_val((uint16_t *)addr),
sym, sym->st_value);
/* P.23 Conditinal Branches : B type (imm=12bit) */
offset = (long)sym->st_value + (long)rel->r_addend - (long)addr;
uint32_t val = _get_val((uint16_t *)addr) & 0xfe000f80;
/* NOTE: we assume that a compiler adds an immediate value */
ASSERT(offset && val);
binfo("offset for Bx=%ld (0x%lx) (val=0x%08" PRIx32 ") "
"already set!\n",
offset, offset, val);
}
break;
case R_RISCV_JAL:
{
binfo("%s at %08" PRIxPTR " [%08" PRIx32 "] "
"to sym=%p st_value=%08lx\n",
_get_rname(relotype),
addr, _get_val((uint16_t *)addr),
sym, sym->st_value);
/* P.21 Unconditinal Jumps : UJ type (imm=20bit) */
offset = (long)sym->st_value + (long)rel->r_addend - (long)addr;
uint32_t val = _get_val((uint16_t *)addr) & 0xfffff000;
ASSERT(offset && val);
/* NOTE: we assume that a compiler adds an immediate value */
binfo("offset for JAL=%ld (0x%lx) (val=0x%08" PRIx32 ") "
"already set!\n",
offset, offset, val);
}
break;
case R_RISCV_HI20:
{
binfo("%s at %08" PRIxPTR " [%08" PRIx32 "] "
"to sym=%p st_value=%08lx\n",
_get_rname(relotype),
addr, _get_val((uint16_t *)addr),
sym, sym->st_value);
/* P.19 LUI */
offset = (long)sym->st_value + (long)rel->r_addend;
uint32_t insn = _get_val((uint16_t *)addr);
ASSERT(OPCODE_LUI == (insn & RVI_OPCODE_MASK));
long imm_hi;
long imm_lo;
_calc_imm(offset, &imm_hi, &imm_lo);
if (!_valid_hi20_imm(imm_hi))
{
berr("ERROR: %s at %08" PRIxPTR " bad:%08lx\n",
_get_rname(relotype), addr, imm_hi << 12);
return -EINVAL;
}
insn = (insn & 0x00000fff) | (imm_hi << 12);
_set_val((uint16_t *)addr, insn);
}
break;
case R_RISCV_LO12_I:
{
binfo("%s at %08" PRIxPTR " [%08" PRIx32 "] "
"to sym=%p st_value=%08lx\n",
_get_rname(relotype),
addr, _get_val((uint16_t *)addr),
sym, sym->st_value);
/* ADDI, FLW, LD, ... : I-type */
offset = (long)sym->st_value + (long)rel->r_addend;
uint32_t insn = _get_val((uint16_t *)addr);
long imm_hi;
long imm_lo;
_calc_imm(offset, &imm_hi, &imm_lo);
insn = (insn & 0x000fffff) | (imm_lo << 20);
_set_val((uint16_t *)addr, insn);
}
break;
case R_RISCV_LO12_S:
{
binfo("%s at %08" PRIxPTR " [%08" PRIx32 "] "
"to sym=%p st_value=%08lx\n",
_get_rname(relotype),
addr, _get_val((uint16_t *)addr),
sym, sym->st_value);
/* SW : S-type.
* not merge with R_RISCV_HI20 since the compiler
* may not generates these two instructions continuously.
*/
offset = (long)sym->st_value + (long)rel->r_addend;
long imm_hi;
long imm_lo;
_calc_imm(offset, &imm_hi, &imm_lo);
uint32_t val =
(((int32_t)imm_lo >> 5) << 25) +
(((int32_t)imm_lo & 0x1f) << 7);
binfo("imm_lo=%ld (%lx), val=%" PRIx32 "\n", imm_lo, imm_lo, val);
_add_val((uint16_t *)addr, val);
}
break;
case R_RISCV_RVC_JUMP:
{
binfo("%s at %08" PRIxPTR " [%08" PRIx32 "] "
"to sym=%p st_value=%08lx\n",
_get_rname(relotype),
addr, _get_val((uint16_t *)addr),
sym, sym->st_value);
/* P.111 Table 16.6 : Instruction listings for RVC */
offset = (long)sym->st_value + (long)rel->r_addend - (long)addr;
ASSERT(-2048 <= offset && offset <= 2047);
uint16_t val = (*(uint16_t *)addr) & 0x1ffc;
binfo("offset for C.J=%ld (0x%lx) (val=0x%04x) already set!\n",
offset, offset, val);
}
break;
case R_RISCV_RVC_BRANCH:
{
binfo("%s at %08" PRIxPTR " [%08" PRIx32 "] "
"to sym=%p st_value=%08lx\n",
_get_rname(relotype),
addr, _get_val((uint16_t *)addr),
sym, sym->st_value);
/* P.111 Table 16.6 : Instruction listings for RVC */
offset = (long)sym->st_value + (long)rel->r_addend - (long)addr;
ASSERT(-256 <= offset && offset <= 255);
uint16_t val = (*(uint16_t *)addr) & 0x1c7c;
/* NOTE: we assume that a compiler adds an immediate value */
ASSERT(offset && val);
binfo("offset for C.Bx=%ld (0x%lx) (val=0x%04x) already set!\n",
offset, offset, val);
}
break;
case R_RISCV_32_PCREL:
{
/* P.29 https://github.com/riscv-non-isa/riscv-elf-psabi-doc */
binfo("%s at %08" PRIxPTR " [%08" PRIx32 "] "
"to sym=%p st_value=%08lx\n",
_get_rname(relotype),
addr, _get_val((uint16_t *)addr),
sym, sym->st_value);
addr = (long)sym->st_value + (long)rel->r_addend - (long)addr;
}
break;
case R_RISCV_ADD32:
{
*(uint32_t *)addr += (uint32_t)(sym->st_value + rel->r_addend);
}
break;
case R_RISCV_ADD64:
{
*(uint64_t *)addr += (uint64_t)(sym->st_value + rel->r_addend);
}
break;
case R_RISCV_SUB16:
{
*(uint16_t *)addr -= (uint16_t)(sym->st_value + rel->r_addend);
}
break;
case R_RISCV_SUB32:
{
*(uint32_t *)addr -= (uint32_t)(sym->st_value + rel->r_addend);
}
break;
case R_RISCV_SUB64:
{
*(uint64_t *)addr -= (uint64_t)(sym->st_value + rel->r_addend);
}
break;
case R_RISCV_SET16:
{
*(uint16_t *)addr = (uint16_t)(sym->st_value + rel->r_addend);
}
break;
default:
berr("ERROR: Unsupported relocation: %ld\n",
ELF_R_TYPE(rel->r_info));
PANIC();
return -EINVAL;
}
return OK;
}
Reference in New Issue View Git Blame Copy Permalink