lkml.org 
[lkml]   [2022]   [May]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[RFC PATCH v2 3/7] objtool: Use target file class size instead of a compiled constant
    Date
    In order to allow using objtool on cross-built kernels,
    determine size of long from elf data instead of using
    sizeof(long) at build time.

    For the time being this covers only mcount.

    Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
    ---
    tools/objtool/check.c | 16 +++++++++-------
    tools/objtool/elf.c | 8 ++++++--
    tools/objtool/include/objtool/elf.h | 8 ++++++++
    3 files changed, 23 insertions(+), 9 deletions(-)

    diff --git a/tools/objtool/check.c b/tools/objtool/check.c
    index cef1dd54d505..fabc0ea88747 100644
    --- a/tools/objtool/check.c
    +++ b/tools/objtool/check.c
    @@ -802,9 +802,9 @@ static int create_ibt_endbr_seal_sections(struct objtool_file *file)
    static int create_mcount_loc_sections(struct objtool_file *file)
    {
    struct section *sec;
    - unsigned long *loc;
    struct instruction *insn;
    int idx;
    + int size = elf_class_size(file->elf);

    sec = find_section_by_name(file->elf, "__mcount_loc");
    if (sec) {
    @@ -820,23 +820,25 @@ static int create_mcount_loc_sections(struct objtool_file *file)
    list_for_each_entry(insn, &file->mcount_loc_list, call_node)
    idx++;

    - sec = elf_create_section(file->elf, "__mcount_loc", 0, sizeof(unsigned long), idx);
    + sec = elf_create_section(file->elf, "__mcount_loc", 0, size, idx);
    if (!sec)
    return -1;

    + sec->sh.sh_addralign = size;
    +
    idx = 0;
    list_for_each_entry(insn, &file->mcount_loc_list, call_node) {
    + void *loc;

    - loc = (unsigned long *)sec->data->d_buf + idx;
    - memset(loc, 0, sizeof(unsigned long));
    + loc = sec->data->d_buf + idx;
    + memset(loc, 0, size);

    - if (elf_add_reloc_to_insn(file->elf, sec,
    - idx * sizeof(unsigned long),
    + if (elf_add_reloc_to_insn(file->elf, sec, idx,
    R_X86_64_64,
    insn->sec, insn->offset))
    return -1;

    - idx++;
    + idx += size;
    }

    return 0;
    diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
    index c25e957c1e52..63218f5799c2 100644
    --- a/tools/objtool/elf.c
    +++ b/tools/objtool/elf.c
    @@ -1124,6 +1124,7 @@ static struct section *elf_create_rela_reloc_section(struct elf *elf, struct sec
    {
    char *relocname;
    struct section *sec;
    + int size = elf_class_size(elf);

    relocname = malloc(strlen(base->name) + strlen(".rela") + 1);
    if (!relocname) {
    @@ -1133,7 +1134,10 @@ static struct section *elf_create_rela_reloc_section(struct elf *elf, struct sec
    strcpy(relocname, ".rela");
    strcat(relocname, base->name);

    - sec = elf_create_section(elf, relocname, 0, sizeof(GElf_Rela), 0);
    + if (size == sizeof(u32))
    + sec = elf_create_section(elf, relocname, 0, sizeof(Elf32_Rela), 0);
    + else
    + sec = elf_create_section(elf, relocname, 0, sizeof(GElf_Rela), 0);
    free(relocname);
    if (!sec)
    return NULL;
    @@ -1142,7 +1146,7 @@ static struct section *elf_create_rela_reloc_section(struct elf *elf, struct sec
    sec->base = base;

    sec->sh.sh_type = SHT_RELA;
    - sec->sh.sh_addralign = 8;
    + sec->sh.sh_addralign = size;
    sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
    sec->sh.sh_info = base->idx;
    sec->sh.sh_flags = SHF_INFO_LINK;
    diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
    index adebfbc2b518..c720c4476828 100644
    --- a/tools/objtool/include/objtool/elf.h
    +++ b/tools/objtool/include/objtool/elf.h
    @@ -141,6 +141,14 @@ static inline bool has_multiple_files(struct elf *elf)
    return elf->num_files > 1;
    }

    +static inline int elf_class_size(struct elf *elf)
    +{
    + if (elf->ehdr.e_ident[EI_CLASS] == ELFCLASS32)
    + return sizeof(u32);
    + else
    + return sizeof(u64);
    +}
    +
    struct elf *elf_open_read(const char *name, int flags);
    struct section *elf_create_section(struct elf *elf, const char *name, unsigned int sh_flags, size_t entsize, int nr);

    --
    2.35.3
    \
     
     \ /
      Last update: 2022-05-24 15:19    [W:3.243 / U:0.416 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site