[RFC PATCH v3 03/12] objtool: Use target file class size instead of a compiled constant

[Sathvika Vasireddy]

From: Christophe Leroy <christophe.le...@csgroup.eu>

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.le...@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);
 
-- 
2.25.1