/****************************************************************************
* arch/arm/src/armv7-m/up_elf.c
*
* Copyright (C) 2012 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdlib.h>
#include <elf32.h>
#include <errno.h>
#include <debug.h>
#include <arch/elf.h>
#include <nuttx/arch.h>
#include <nuttx/binfmt/elf.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: arch_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 arch_checkarch(FAR const Elf32_Ehdr *ehdr)
{
/* Make sure it's an ARM executable */
if (ehdr->e_machine != EM_ARM)
{
bdbg("Not for ARM: e_machine=%04x\n", ehdr->e_machine);
return -ENOEXEC;
}
/* Make sure that 32-bit objects are supported */
if (ehdr->e_ident[EI_CLASS] != ELFCLASS32)
{
bdbg("Need 32-bit objects: e_ident[EI_CLASS]=%02x\n", ehdr->e_ident[EI_CLASS]);
return -ENOEXEC;
}
/* Verify endian-ness */
#ifdef CONFIG_ENDIAN_BIG
if (ehdr->e_ident[EI_DATA] != ELFDATA2MSB)
#else
if (ehdr->e_ident[EI_DATA] != ELFDATA2LSB)
#endif
{
bdbg("Wrong endian-ness: e_ident[EI_DATA]=%02x\n", ehdr->e_ident[EI_DATA]);
return -ENOEXEC;
}
/* TODO: Check ABI here. */
return OK;
}
/****************************************************************************
* Name: arch_relocate and arch_relocateadd
*
* Description:
* Perform on 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.
* 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 arch_relocate(FAR const Elf32_Rel *rel, FAR const Elf32_Sym *sym,
uintptr_t addr)
{
int32_t offset;
uint32_t upper_insn;
uint32_t lower_insn;
switch (ELF32_R_TYPE(rel->r_info))
{
case R_ARM_NONE:
{
/* No relocation */
}
break;
case R_ARM_PC24:
case R_ARM_CALL:
case R_ARM_JUMP24:
{
bvdbg("Performing PC24 [%d] link at addr %08lx [%08lx] to sym '%s' st_value=%08lx\n",
ELF32_R_TYPE(rel->r_info), (long)addr, (long)(*(uint32_t*)addr),
sym, (long)sym->st_value);
offset = (*(uint32_t*)addr & 0x00ffffff) << 2;
if (offset & 0x02000000)
{
offset -= 0x04000000;
}
offset += sym->st_value - addr;
if (offset & 3 || offset <= (int32_t) 0xfe000000 || offset >= (int32_t) 0x02000000)
{
bdbg(" ERROR: PC24 [%d] relocation out of range, offset=%08lx\n",
ELF32_R_TYPE(rel->r_info), offset);
return -EINVAL;
}
offset >>= 2;
*(uint32_t*)addr &= 0xff000000;
*(uint32_t*)addr |= offset & 0x00ffffff;
}
break;
case R_ARM_ABS32:
case R_ARM_TARGET1: /* New ABI: TARGET1 always treated as ABS32 */
{
bvdbg("Performing ABS32 link at addr=%08lx [%08lx] to sym=%p st_value=%08lx\n",
(long)addr, (long)(*(uint32_t*)addr), sym, (long)sym->st_value);
*(uint32_t*)addr += sym->st_value;
}
break;
case R_ARM_THM_CALL:
case R_ARM_THM_JUMP24:
{
uint32_t S;
uint32_t J1;
uint32_t J2;
/* Thumb BL and B.W instructions. Encoding:
*
* upper_insn:
*
* 1 1 1 1 1 1
* 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
* +----------+---+-------------------------------+--------------+
* |1 1 1 |OP1| OP2 | | 32-Bit Instructions
* +----------+---+--+-----+----------------------+--------------+
* |1 1 1 | 1 0| S | imm10 | BL Instruction
* +----------+------+-----+-------------------------------------+
*
* lower_insn:
*
* 1 1 1 1 1 1
* 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
* +---+---------------------------------------------------------+
* |OP | | 32-Bit Instructions
* +---+--+---+---+---+------------------------------------------+
* |1 1 |J1 | 1 |J2 | imm11 | BL Instruction
* +------+---+---+---+------------------------------------------+
*
* The branch target is encoded in these bits:
*
* S = upper_insn[10]
* imm10 = upper_insn[0:9]
* imm11 = lower_insn[0:10]
* J1 = lower_insn[13]
* J2 = lower_insn[11]
*/
upper_insn = (uint32_t)(*(uint16_t*)addr);
lower_insn = (uint32_t)(*(uint16_t*)(addr + 2));
bvdbg("Performing THM_JUMP24 [%d] link at addr=%08lx [%04x %04x] to sym=%p st_value=%08lx\n",
ELF32_R_TYPE(rel->r_info), (long)addr, (int)upper_insn, (int)lower_insn,
sym, (long)sym->st_value);
/* Extract the 25-bit offset from the 32-bit instruction:
*
* offset[24] = S
* offset[23] = ~(J1 ^ S)
* offset[22] = ~(J2 ^ S)]
* offset[12:21] = imm10
* offset[1:11] = imm11
* offset[0] = 0
*/
S = (upper_insn >> 10) & 1;
J1 = (lower_insn >> 13) & 1;
J2 = (lower_insn >> 11) & 1;
offset = (S << 24) | /* S - > offset[24] */
((~(J1 ^ S) & 1) << 23) | /* J1 -> offset[23] */
((~(J2 ^ S) & 1) << 22) | /* J2 -> offset[22] */
((upper_insn & 0x03ff) << 12) | /* imm10 -> offset[12:21] */
((lower_insn & 0x07ff) << 1); /* imm11 -> offset[1:11] */
/* 0 -> offset[0] */
/* Sign extend */
if (offset & 0x01000000)
{
offset -= 0x02000000;
}
/* And perform the relocation */
bvdbg(" S=%d J1=%d J2=%d offset=%08lx branch target=%08lx\n",
S, J1, J2, (long)offset, offset + sym->st_value - addr);
offset += sym->st_value - addr;
/* Is this a function symbol? If so, then the branch target must be
* an odd Thumb address
*/
if (ELF32_ST_TYPE(sym->st_info) == STT_FUNC && (offset & 1) == 0)
{
bdbg(" ERROR: JUMP24 [%d] requires odd offset, offset=%08lx\n",
ELF32_R_TYPE(rel->r_info), offset);
return -EINVAL;
}
/* Check the range of the offset */
if (offset <= (int32_t)0xff000000 || offset >= (int32_t)0x01000000)
{
bdbg(" ERROR: JUMP24 [%d] relocation out of range, branch taget=%08lx\n",
ELF32_R_TYPE(rel->r_info), offset);
return -EINVAL;
}
/* Now, reconstruct the 32-bit instruction using the new, relocated
* branch target.
*/
S = (offset >> 24) & 1;
J1 = S ^ (~(offset >> 23) & 1);
J2 = S ^ (~(offset >> 22) & 1);
upper_insn = ((upper_insn & 0xf800) | (S << 10) | ((offset >> 12) & 0x03ff));
*(uint16_t*)addr = (uint16_t)upper_insn;
lower_insn = ((lower_insn & 0xd000) | (J1 << 13) | (J2 << 11) | ((offset >> 1) & 0x07ff));
*(uint16_t*)(addr + 2) = (uint16_t)lower_insn;
bvdbg(" S=%d J1=%d J2=%d insn [%04x %04x]\n",
S, J1, J2, (int)upper_insn, (int)lower_insn);
}
break;
case R_ARM_V4BX:
{
bvdbg("Performing V4BX link at addr=%08lx [%08lx]\n",
(long)addr, (long)(*(uint32_t*)addr));
/* Preserve only Rm and the condition code */
*(uint32_t*)addr &= 0xf000000f;
/* Change instruction to 'mov pc, Rm' */
*(uint32_t*)addr |= 0x01a0f000;
}
break;
case R_ARM_PREL31:
{
bvdbg("Performing PREL31 link at addr=%08lx [%08lx] to sym=%p st_value=%08lx\n",
(long)addr, (long)(*(uint32_t*)addr), sym, (long)sym->st_value);
offset = *(uint32_t*)addr + sym->st_value - addr;
*(uint32_t*)addr = offset & 0x7fffffff;
}
break;
case R_ARM_MOVW_ABS_NC:
case R_ARM_MOVT_ABS:
{
bvdbg("Performing MOVx_ABS [%d] link at addr=%08lx [%08lx] to sym=%p st_value=%08lx\n",
ELF32_R_TYPE(rel->r_info), (long)addr, (long)(*(uint32_t*)addr),
sym, (long)sym->st_value);
offset = *(uint32_t*)addr;
offset = ((offset & 0xf0000) >> 4) | (offset & 0xfff);
offset = (offset ^ 0x8000) - 0x8000;
offset += sym->st_value;
if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_ABS)
{
offset >>= 16;
}
*(uint32_t*)addr &= 0xfff0f000;
*(uint32_t*)addr |= ((offset & 0xf000) << 4) | (offset & 0x0fff);
}
break;
case R_ARM_THM_MOVW_ABS_NC:
case R_ARM_THM_MOVT_ABS:
{
/* Thumb BL and B.W instructions. Encoding:
*
* upper_insn:
*
* 1 1 1 1 1 1
* 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
* +----------+---+-------------------------------+--------------+
* |1 1 1 |OP1| OP2 | | 32-Bit Instructions
* +----------+---+--+-----+----------------------+--------------+
* |1 1 1 | 1 0| i | 1 0 1 1 0 0 | imm4 | MOVT Instruction
* +----------+------+-----+----------------------+--------------+
*
* lower_insn:
*
* 1 1 1 1 1 1
* 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
* +---+---------------------------------------------------------+
* |OP | | 32-Bit Instructions
* +---+----------+--------------+-------------------------------+
* |0 | imm3 | Rd | imm8 | MOVT Instruction
* +---+----------+--------------+-------------------------------+
*
* The 16-bit immediate value is encoded in these bits:
*
* i = imm16[11] = upper_insn[10]
* imm4 = imm16[12:15] = upper_insn[3:0]
* imm3 = imm16[8:10] = lower_insn[14:12]
* imm8 = imm16[0:7] = lower_insn[7:0]
*/
upper_insn = (uint32_t)(*(uint16_t*)addr);
lower_insn = (uint32_t)(*(uint16_t*)(addr + 2));
bvdbg("Performing THM_MOVx [%d] link at addr=%08lx [%04x %04x] to sym=%p st_value=%08lx\n",
ELF32_R_TYPE(rel->r_info), (long)addr, (int)upper_insn, (int)lower_insn,
sym, (long)sym->st_value);
/* Extract the 16-bit offset from the 32-bit instruction */
offset = ((upper_insn & 0x000f) << 12) | /* imm4 -> imm16[8:10] */
((upper_insn & 0x0400) << 1) | /* i -> imm16[11] */
((lower_insn & 0x7000) >> 4) | /* imm3 -> imm16[8:10] */
(lower_insn & 0x00ff); /* imm8 -> imm16[0:7] */
/* Sign extend */
offset = (offset ^ 0x8000) - 0x8000;
/* And perform the relocation */
bvdbg(" offset=%08lx branch target=%08lx\n",
(long)offset, offset + sym->st_value);
offset += sym->st_value;
/* Update the immediate value in the instruction. For MOVW we want the bottom
* 16-bits; for MOVT we want the top 16-bits.
*/
if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_ABS)
{
offset >>= 16;
}
upper_insn = ((upper_insn & 0xfbf0) | ((offset & 0xf000) >> 12) | ((offset & 0x0800) >> 1));
*(uint16_t*)addr = (uint16_t)upper_insn;
lower_insn = ((lower_insn & 0x8f00) | ((offset & 0x0700) << 4) | (offset & 0x00ff));
*(uint16_t*)(addr + 2) = (uint16_t)lower_insn;
bvdbg(" insn [%04x %04x]\n",
(int)upper_insn, (int)lower_insn);
}
break;
default:
bdbg("Unsupported relocation: %d\n", ELF32_R_TYPE(rel->r_info));
return -EINVAL;
}
return OK;
}
int arch_relocateadd(FAR const Elf32_Rela *rel, FAR const Elf32_Sym *sym,
uintptr_t addr)
{
bdbg("RELA relocation not supported\n");
return -ENOSYS;
}
