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From 59d4b8c48e5040af7e02b34eb26ea602ec82a38e Mon Sep 17 00:00:00 2001
From: James Cowgill <james410@cowgill.org.uk>
Date: Mon, 5 Jan 2015 15:17:02 +0000
Subject: [PATCH 3/3] Add mips n64 relocation format hack
MIPSEL N64 ELF files use a slightly different format for storing relocation
entries which is incompatible with the normal R_SYM / R_INFO macros.
To workaround this, we rearrange the bytes in the relocation's r_info field
when reading and writing the relocations.
This patch also ensures that strip.c sets the correct value of e_machine
before manipulating relocations so that these changes take effect.
Signed-off-by: James Cowgill <james410@cowgill.org.uk>
---
libelf/gelf_getrel.c | 25 +++++++++++++++++++++++--
libelf/gelf_getrela.c | 25 +++++++++++++++++++++++--
libelf/gelf_update_rel.c | 20 +++++++++++++++++++-
libelf/gelf_update_rela.c | 20 +++++++++++++++++++-
src/strip.c | 17 +++++++++++++++++
5 files changed, 101 insertions(+), 6 deletions(-)
Index: elfutils-0.175/libelf/gelf_getrel.c
===================================================================
--- elfutils-0.175.orig/libelf/gelf_getrel.c
+++ elfutils-0.175/libelf/gelf_getrel.c
@@ -36,6 +36,7 @@
#include "libelfP.h"
+#define EF_MIPS_ABI 0x0000F000
GElf_Rel *
gelf_getrel (Elf_Data *data, int ndx, GElf_Rel *dst)
@@ -89,8 +90,28 @@ gelf_getrel (Elf_Data *data, int ndx, GE
result = NULL;
}
else
- result = memcpy (dst, &((Elf64_Rel *) data_scn->d.d_buf)[ndx],
- sizeof (Elf64_Rel));
+ {
+ GElf_Ehdr hdr;
+ result = memcpy (dst, &((Elf64_Rel *) data_scn->d.d_buf)[ndx],
+ sizeof (Elf64_Rel));
+
+ if (gelf_getehdr(scn->elf, &hdr) != NULL &&
+ hdr.e_ident[EI_DATA] == ELFDATA2LSB &&
+ hdr.e_machine == EM_MIPS &&
+ (hdr.e_flags & EF_MIPS_ABI) == 0)
+ {
+ /*
+ * The relocation format is mangled on MIPSEL N64
+ * We'll adjust it so at least R_SYM will work on it
+ */
+ GElf_Xword r_info = dst->r_info;
+ dst->r_info = (r_info << 32) |
+ ((r_info >> 8) & 0xFF000000) |
+ ((r_info >> 24) & 0x00FF0000) |
+ ((r_info >> 40) & 0x0000FF00) |
+ ((r_info >> 56) & 0x000000FF);
+ }
+ }
}
rwlock_unlock (scn->elf->lock);
Index: elfutils-0.175/libelf/gelf_getrela.c
===================================================================
--- elfutils-0.175.orig/libelf/gelf_getrela.c
+++ elfutils-0.175/libelf/gelf_getrela.c
@@ -36,6 +36,7 @@
#include "libelfP.h"
+#define EF_MIPS_ABI 0x0000F000
GElf_Rela *
gelf_getrela (Elf_Data *data, int ndx, GElf_Rela *dst)
@@ -90,8 +91,28 @@ gelf_getrela (Elf_Data *data, int ndx, G
result = NULL;
}
else
- result = memcpy (dst, &((Elf64_Rela *) data_scn->d.d_buf)[ndx],
- sizeof (Elf64_Rela));
+ {
+ GElf_Ehdr hdr;
+ result = memcpy (dst, &((Elf64_Rela *) data_scn->d.d_buf)[ndx],
+ sizeof (Elf64_Rela));
+
+ if (gelf_getehdr(scn->elf, &hdr) != NULL &&
+ hdr.e_ident[EI_DATA] == ELFDATA2LSB &&
+ hdr.e_machine == EM_MIPS &&
+ (hdr.e_flags & EF_MIPS_ABI) == 0)
+ {
+ /*
+ * The relocation format is mangled on MIPSEL N64
+ * We'll adjust it so at least R_SYM will work on it
+ */
+ GElf_Xword r_info = dst->r_info;
+ dst->r_info = (r_info << 32) |
+ ((r_info >> 8) & 0xFF000000) |
+ ((r_info >> 24) & 0x00FF0000) |
+ ((r_info >> 40) & 0x0000FF00) |
+ ((r_info >> 56) & 0x000000FF);
+ }
+ }
}
rwlock_unlock (scn->elf->lock);
Index: elfutils-0.175/libelf/gelf_update_rel.c
===================================================================
--- elfutils-0.175.orig/libelf/gelf_update_rel.c
+++ elfutils-0.175/libelf/gelf_update_rel.c
@@ -36,6 +36,7 @@
#include "libelfP.h"
+#define EF_MIPS_ABI 0x0000F000
int
gelf_update_rel (Elf_Data *dst, int ndx, GElf_Rel *src)
@@ -86,6 +87,9 @@ gelf_update_rel (Elf_Data *dst, int ndx,
}
else
{
+ GElf_Ehdr hdr;
+ GElf_Rel value = *src;
+
/* Check whether we have to resize the data buffer. */
if (INVALID_NDX (ndx, Elf64_Rel, &data_scn->d))
{
@@ -93,7 +97,21 @@ gelf_update_rel (Elf_Data *dst, int ndx,
goto out;
}
- ((Elf64_Rel *) data_scn->d.d_buf)[ndx] = *src;
+ if (gelf_getehdr(scn->elf, &hdr) != NULL &&
+ hdr.e_ident[EI_DATA] == ELFDATA2LSB &&
+ hdr.e_machine == EM_MIPS &&
+ (hdr.e_flags & EF_MIPS_ABI) == 0)
+ {
+ /* Undo the MIPSEL N64 hack from gelf_getrel */
+ GElf_Xword r_info = value.r_info;
+ value.r_info = (r_info >> 32) |
+ ((r_info << 8) & 0x000000FF00000000) |
+ ((r_info << 24) & 0x0000FF0000000000) |
+ ((r_info << 40) & 0x00FF000000000000) |
+ ((r_info << 56) & 0xFF00000000000000);
+ }
+
+ ((Elf64_Rel *) data_scn->d.d_buf)[ndx] = value;
}
result = 1;
Index: elfutils-0.175/libelf/gelf_update_rela.c
===================================================================
--- elfutils-0.175.orig/libelf/gelf_update_rela.c
+++ elfutils-0.175/libelf/gelf_update_rela.c
@@ -36,6 +36,7 @@
#include "libelfP.h"
+#define EF_MIPS_ABI 0x0000F000
int
gelf_update_rela (Elf_Data *dst, int ndx, GElf_Rela *src)
@@ -89,6 +90,9 @@ gelf_update_rela (Elf_Data *dst, int ndx
}
else
{
+ GElf_Ehdr hdr;
+ GElf_Rela value = *src;
+
/* Check whether we have to resize the data buffer. */
if (INVALID_NDX (ndx, Elf64_Rela, &data_scn->d))
{
@@ -96,7 +100,21 @@ gelf_update_rela (Elf_Data *dst, int ndx
goto out;
}
- ((Elf64_Rela *) data_scn->d.d_buf)[ndx] = *src;
+ if (gelf_getehdr(scn->elf, &hdr) != NULL &&
+ hdr.e_ident[EI_DATA] == ELFDATA2LSB &&
+ hdr.e_machine == EM_MIPS &&
+ (hdr.e_flags & EF_MIPS_ABI) == 0)
+ {
+ /* Undo the MIPSEL N64 hack from gelf_getrel */
+ GElf_Xword r_info = value.r_info;
+ value.r_info = (r_info >> 32) |
+ ((r_info << 8) & 0x000000FF00000000) |
+ ((r_info << 24) & 0x0000FF0000000000) |
+ ((r_info << 40) & 0x00FF000000000000) |
+ ((r_info << 56) & 0xFF00000000000000);
+ }
+
+ ((Elf64_Rela *) data_scn->d.d_buf)[ndx] = value;
}
result = 1;
Index: elfutils-0.175/src/strip.c
===================================================================
--- elfutils-0.175.orig/src/strip.c
+++ elfutils-0.175/src/strip.c
@@ -1062,6 +1062,23 @@ handle_elf (int fd, Elf *elf, const char
goto fail;
}
+ /* Copy identity part of the ELF header now */
+ newehdr = gelf_getehdr (newelf, &newehdr_mem);
+ if (newehdr == NULL)
+ INTERNAL_ERROR (fname);
+
+ memcpy (newehdr->e_ident, ehdr->e_ident, EI_NIDENT);
+ newehdr->e_type = ehdr->e_type;
+ newehdr->e_machine = ehdr->e_machine;
+ newehdr->e_version = ehdr->e_version;
+
+ if (gelf_update_ehdr (newelf, newehdr) == 0)
+ {
+ error (0, 0, gettext ("%s: error while creating ELF header: %s"),
+ fname, elf_errmsg (-1));
+ return 1;
+ }
+
/* Copy over the old program header if needed. */
if (phnum > 0)
{
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