From 59d4b8c48e5040af7e02b34eb26ea602ec82a38e Mon Sep 17 00:00:00 2001 From: James Cowgill 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 --- 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-0.164/libelf/gelf_getrel.c =================================================================== --- elfutils-0.164.orig/libelf/gelf_getrel.c +++ elfutils-0.164/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-0.164/libelf/gelf_getrela.c =================================================================== --- elfutils-0.164.orig/libelf/gelf_getrela.c +++ elfutils-0.164/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-0.164/libelf/gelf_update_rel.c =================================================================== --- elfutils-0.164.orig/libelf/gelf_update_rel.c +++ elfutils-0.164/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-0.164/libelf/gelf_update_rela.c =================================================================== --- elfutils-0.164.orig/libelf/gelf_update_rela.c +++ elfutils-0.164/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-0.164/src/strip.c =================================================================== --- elfutils-0.164.orig/src/strip.c +++ elfutils-0.164/src/strip.c @@ -546,6 +546,23 @@ 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 (ehdr->e_type != ET_REL) for (cnt = 0; cnt < phnum; ++cnt)