996625ec58
There is a problem with the current elf loader for risc-v: when a pair of PCREL_HI20 / LO12 relocations are encountered, it is assumed that these will follow each other immediately, as follows: label: auipc a0, %pcrel_hi(symbol) // R_RISCV_PCREL_HI20 load/store a0, %pcrel_lo(label)(a0) // R_RISCV_PCREL_LO12_I/S With this assumption, the hi/lo relocations are both done when a hi20 relocation entry is encountered, first to the current instruction (addr) and to the next instruction (addr + 4). However, this assumption is wrong. There is nothing in the elf relocation specification[1] that mandates this. Thus, the hi/lo relocation always needs to first fixup the hi-part, and when the lo-part is encountered, it needs to find the corresponding hi relocation entry, via the given "label". This necessitates (re-)visiting the relocation entries for the current section as well as looking for "label" in the symbol table. The NuttX elf loader does not allow such operations to be done in the machine specific part, so this patch fixes the relocation issue by introducing an architecture specific cache for the hi20 relocation and symbol table entries. When a lo12 relocation is encountered, the cache can be consulted to find the hi20 part. [1] https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/master/riscv-elf.adoc
128 lines
4.1 KiB
C
128 lines
4.1 KiB
C
/****************************************************************************
|
|
* libs/libc/machine/sim/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 <stdlib.h>
|
|
#include <errno.h>
|
|
#include <debug.h>
|
|
|
|
#include <nuttx/elf.h>
|
|
|
|
/****************************************************************************
|
|
* Pre-processor Definitions
|
|
****************************************************************************/
|
|
|
|
#define R_386_32 1
|
|
#define R_386_PC32 2
|
|
|
|
#define ELF_BITS 32
|
|
#define ELF_ARCH EM_386
|
|
|
|
/****************************************************************************
|
|
* 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 Elf32_Ehdr *hdr)
|
|
{
|
|
return hdr->e_machine == EM_386 || hdr->e_machine == EM_486;
|
|
}
|
|
|
|
/****************************************************************************
|
|
* 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 Elf32_Rel *rel, const Elf32_Sym *sym, uintptr_t addr,
|
|
void *arch_data)
|
|
{
|
|
uint32_t *ptr = (uint32_t *)addr;
|
|
|
|
/* All relocations depend upon having valid symbol information. */
|
|
|
|
if (sym == NULL)
|
|
{
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* Handle the relocation by relocation type */
|
|
|
|
switch (ELF32_R_TYPE(rel->r_info))
|
|
{
|
|
case R_386_32:
|
|
*ptr += sym->st_value;
|
|
break;
|
|
|
|
case R_386_PC32:
|
|
*ptr += sym->st_value - (uint32_t)((uintptr_t)ptr);
|
|
break;
|
|
|
|
default:
|
|
berr("ERROR: Unsupported type %u\n", ELF32_R_TYPE(rel->r_info));
|
|
return -EINVAL;
|
|
}
|
|
|
|
return OK;
|
|
}
|
|
|
|
int up_relocateadd(const Elf32_Rela *rel, const Elf32_Sym *sym,
|
|
uintptr_t addr, void *arch_data)
|
|
{
|
|
berr("ERROR: Not supported\n");
|
|
return -ENOSYS;
|
|
}
|