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objtool: Use target file class size instead of a compiled constant 

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.

[Sathvika Vasireddy: Rename variable "size" to "addrsize" and function
"elf_class_size()" to "elf_class_addrsize()", and modify
create_mcount_loc_sections() function to follow reverse christmas tree
format to order local variable declarations.]

Tested-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Sathvika Vasireddy <sv@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221114175754.1131267-11-sv@linux.ibm.com
This commit is contained in:
Christophe Leroy 2022-11-14 23:27:48 +05:30 committed by Michael Ellerman
parent 0646c28b41
commit 86ea7f3615
3 changed files with 24 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
tools/objtool/check.c
View File

@ -852,9 +852,9 @@ 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;
int addrsize = elf_class_addrsize(file->elf);
struct instruction *insn;
struct section *sec;
int idx;
sec = find_section_by_name(file->elf, "__mcount_loc");
@ -871,23 +871,25 @@ 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, addrsize, idx);
if (!sec)
return -1;
sec->sh.sh_addralign = addrsize;
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, addrsize);
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 += addrsize;
}
return 0;

8
tools/objtool/elf.c
View File

@ -1129,6 +1129,7 @@ static struct section *elf_create_rela_reloc_section(struct elf *elf, struct sec
{
char *relocname;
struct section *sec;
int addrsize = elf_class_addrsize(elf);
relocname = malloc(strlen(base->name) + strlen(".rela") + 1);
if (!relocname) {
@ -1138,7 +1139,10 @@ 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 (addrsize == 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;
@ -1147,7 +1151,7 @@ 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 = addrsize;
sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
sec->sh.sh_info = base->idx;
sec->sh.sh_flags = SHF_INFO_LINK;

8
tools/objtool/include/objtool/elf.h
View File

@ -142,6 +142,14 @@ static inline bool has_multiple_files(struct elf *elf)
return elf->num_files > 1;
}
static inline int elf_class_addrsize(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);