hekate/bdk/ianos/elfload/elfload.c
CTCaer 185526d134 Introducing Bootloader Development Kit (BDK)
BDK will allow developers to use the full collection of drivers,
with limited editing, if any, for making payloads for Nintendo Switch.

Using a single source for everything will also help decoupling
Switch specific code and easily port it to other Tegra X1/X1+ platforms.
And maybe even to lower targets.

Everything is now centrilized into bdk folder.
Every module or project can utilize it by simply including it.

This is just the start and it will continue to improve.
2020-06-14 15:25:21 +03:00

325 lines
6.5 KiB
C

/*
* Copyright © 2018, M4xw
* Copyright © 2014, Owen Shepherd
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
* OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*/
#include <string.h>
#include "elfload.h"
el_status el_pread(el_ctx *ctx, void *def, size_t nb, size_t offset)
{
return ctx->pread(ctx, def, nb, offset) ? EL_OK : EL_EIO;
}
#define EL_PHOFF(ctx, num) (((ctx)->ehdr.e_phoff + (num) *(ctx)->ehdr.e_phentsize))
el_status el_findphdr(el_ctx *ctx, Elf_Phdr *phdr, uint32_t type, unsigned *i)
{
el_status rv = EL_OK;
for (; *i < ctx->ehdr.e_phnum; (*i)++)
{
if ((rv = el_pread(ctx, phdr, sizeof *phdr, EL_PHOFF(ctx, *i))))
return rv;
if (phdr->p_type == type)
{
return rv;
}
}
*i = -1;
return rv;
}
#define EL_SHOFF(ctx, num) (((ctx)->ehdr.e_shoff + (num) *(ctx)->ehdr.e_shentsize))
el_status el_findshdr(el_ctx *ctx, Elf_Shdr *shdr, uint32_t type, unsigned *i)
{
el_status rv = EL_OK;
for (; *i < ctx->ehdr.e_shnum; (*i)++)
{
if ((rv = el_pread(ctx, shdr, sizeof *shdr, EL_SHOFF(ctx, *i))))
return rv;
if (shdr->sh_type == type)
{
return rv;
}
}
*i = -1;
return rv;
}
el_status el_init(el_ctx *ctx)
{
el_status rv = EL_OK;
if ((rv = el_pread(ctx, &ctx->ehdr, sizeof ctx->ehdr, 0)))
return rv;
/* validate header */
if (!IS_ELF(ctx->ehdr))
return EL_NOTELF;
if (ctx->ehdr.e_ident[EI_CLASS] != ELFCLASS)
return EL_WRONGBITS;
if (ctx->ehdr.e_ident[EI_DATA] != ELFDATATHIS)
return EL_WRONGENDIAN;
if (ctx->ehdr.e_ident[EI_VERSION] != EV_CURRENT)
return EL_NOTELF;
if (ctx->ehdr.e_type != ET_EXEC && ctx->ehdr.e_type != ET_DYN)
return EL_NOTEXEC;
if (ctx->ehdr.e_machine != EM_THIS)
return EL_WRONGARCH;
if (ctx->ehdr.e_version != EV_CURRENT)
return EL_NOTELF;
/* load phdrs */
Elf_Phdr ph;
/* iterate through, calculate extents */
ctx->base_load_paddr = ctx->base_load_vaddr = 0;
ctx->align = 1;
ctx->memsz = 0;
unsigned i = 0;
for (;;)
{
if ((rv = el_findphdr(ctx, &ph, PT_LOAD, &i)))
return rv;
if (i == (unsigned)-1)
break;
Elf_Addr phend = ph.p_vaddr + ph.p_memsz;
if (phend > ctx->memsz)
ctx->memsz = phend;
if (ph.p_align > ctx->align)
ctx->align = ph.p_align;
i++;
}
// Program Header
if (ctx->ehdr.e_type == ET_DYN)
{
i = 0;
if ((rv = el_findphdr(ctx, &ph, PT_DYNAMIC, &i)))
return rv;
if (i == (unsigned)-1)
return EL_NODYN;
ctx->dynoff = ph.p_offset;
ctx->dynsize = ph.p_filesz;
}
else
{
ctx->dynoff = 0;
ctx->dynsize = 0;
}
// Section String Table
if (ctx->ehdr.e_type == ET_DYN)
{
i = ctx->ehdr.e_shstrndx - 1;
if ((rv = el_findshdr(ctx, &ctx->shstr, SHT_STRTAB, &i)))
return rv;
// Reset
i = 0;
if ((rv = el_findshdr(ctx, &ctx->symtab, SHT_SYMTAB, &i)))
return rv;
if (i == (unsigned)-1)
return EL_NODYN;
}
return rv;
}
/*
typedef void* (*el_alloc_cb)(
el_ctx *ctx,
Elf_Addr phys,
Elf_Addr virt,
Elf_Addr size);
*/
el_status el_load(el_ctx *ctx, el_alloc_cb alloc)
{
el_status rv = EL_OK;
/* address deltas */
Elf_Addr pdelta = ctx->base_load_paddr;
Elf_Addr vdelta = ctx->base_load_vaddr;
/* iterate paddrs */
Elf_Phdr ph;
unsigned i = 0;
for (;;)
{
if ((rv = el_findphdr(ctx, &ph, PT_LOAD, &i)))
return rv;
if (i == (unsigned)-1)
break;
Elf_Addr pload = ph.p_paddr + pdelta;
Elf_Addr vload = ph.p_vaddr + vdelta;
/* allocate mem */
char *dest = alloc(ctx, pload, vload, ph.p_memsz);
if (!dest)
return EL_ENOMEM;
EL_DEBUG("Loading seg fileoff %x, vaddr %x to %p\n",
ph.p_offset, ph.p_vaddr, dest);
/* read loaded portion */
if ((rv = el_pread(ctx, dest, ph.p_filesz, ph.p_offset)))
return rv;
/* zero mem-only portion */
memset(dest + ph.p_filesz, 0, ph.p_memsz - ph.p_filesz);
i++;
}
return rv;
}
el_status el_finddyn(el_ctx *ctx, Elf_Dyn *dyn, uint32_t tag)
{
el_status rv = EL_OK;
size_t ndyn = ctx->dynsize / sizeof(Elf_Dyn);
for (unsigned i = 0; i < ndyn; i++)
{
if ((rv = el_pread(ctx, dyn, sizeof *dyn, ctx->dynoff + i * sizeof *dyn)))
return rv;
if (dyn->d_tag == tag)
return EL_OK;
}
dyn->d_tag = DT_NULL;
return EL_OK;
}
el_status el_findrelocs(el_ctx *ctx, el_relocinfo *ri, uint32_t type)
{
el_status rv = EL_OK;
Elf_Dyn rel, relsz, relent;
if ((rv = el_finddyn(ctx, &rel, type)))
return rv;
if ((rv = el_finddyn(ctx, &relsz, type + 1)))
return rv;
if ((rv = el_finddyn(ctx, &relent, type + 2)))
return rv;
if (rel.d_tag == DT_NULL || relsz.d_tag == DT_NULL || relent.d_tag == DT_NULL)
{
ri->entrysize = 0;
ri->tablesize = 0;
ri->tableoff = 0;
}
else
{
ri->tableoff = rel.d_un.d_ptr;
ri->tablesize = relsz.d_un.d_val;
ri->entrysize = relent.d_un.d_val;
}
return rv;
}
extern el_status el_applyrel(el_ctx *ctx, Elf_Rel *rel);
extern el_status el_applyrela(el_ctx *ctx, Elf_RelA *rela);
el_status el_relocate(el_ctx *ctx)
{
el_status rv = EL_OK;
// not dynamic
if (ctx->ehdr.e_type != ET_DYN)
return EL_OK;
char *base = (char *)ctx->base_load_paddr;
el_relocinfo ri;
#ifdef EL_ARCH_USES_REL
if ((rv = el_findrelocs(ctx, &ri, DT_REL)))
return rv;
if (ri.entrysize != sizeof(Elf_Rel) && ri.tablesize)
{
EL_DEBUG("Relocation size %u doesn't match expected %u\n",
ri.entrysize, sizeof(Elf_Rel));
return EL_BADREL;
}
size_t relcnt = ri.tablesize / sizeof(Elf_Rel);
Elf_Rel *reltab = (Elf_Rel *)(base + ri.tableoff);
for (size_t i = 0; i < relcnt; i++)
{
if ((rv = el_applyrel(ctx, &reltab[i])))
return rv;
}
#endif
#ifdef EL_ARCH_USES_RELA
if ((rv = el_findrelocs(ctx, &ri, DT_RELA)))
return rv;
if (ri.entrysize != sizeof(Elf_RelA) && ri.tablesize)
{
EL_DEBUG("Relocation size %u doesn't match expected %u\n",
ri.entrysize, sizeof(Elf_RelA));
return EL_BADREL;
}
size_t relacnt = ri.tablesize / sizeof(Elf_RelA);
Elf_RelA *relatab = (Elf_RelA *)(base + ri.tableoff);
for (size_t i = 0; i < relacnt; i++)
{
if ((rv = el_applyrela(ctx, &relatab[i])))
return rv;
}
#endif
#if !defined(EL_ARCH_USES_REL) && !defined(EL_ARCH_USES_RELA)
#error No relocation type defined!
#endif
return rv;
}