[PATCH 5.10 025/148] objtool: Rework the elf_rebuild_reloc_section() logic

Greg Kroah-Hartman
2022-07-23T09:59:40Z

From: Peter Zijlstra <peterz@infradead.org>

commit 3a647607b57ad8346e659ddd3b951ac292c83690 upstream.

Instead of manually calling elf_rebuild_reloc_section() on sections
we've called elf_add_reloc() on, have elf_write() DTRT.

This makes it easier to add random relocations in places without
carefully tracking when we're done and need to flush what section.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151259.754213408@infradead.org
[bwh: Backported to 5.10: drop changes in create_mcount_loc_sections()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
tools/objtool/check.c | 3 ---
tools/objtool/elf.c | 20 ++++++++++++++------
tools/objtool/elf.h | 1 -
tools/objtool/orc_gen.c | 3 ---
4 files changed, 14 insertions(+), 13 deletions(-)

--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -542,9 +542,6 @@ static int create_static_call_sections(s
idx++;
}

- if (elf_rebuild_reloc_section(file->elf, reloc_sec))
- return -1;
-
return 0;
}

--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -530,6 +530,8 @@ void elf_add_reloc(struct elf *elf, stru

list_add_tail(&reloc->list, &sec->reloc_list);
elf_hash_add(elf->reloc_hash, &reloc->hash, reloc_hash(reloc));
+
+ sec->changed = true;
}

static int read_rel_reloc(struct section *sec, int i, struct reloc *reloc, unsigned int *symndx)
@@ -609,7 +611,9 @@ static int read_relocs(struct elf *elf)
return -1;
}

- elf_add_reloc(elf, reloc);
+ list_add_tail(&reloc->list, &sec->reloc_list);
+ elf_hash_add(elf->reloc_hash, &reloc->hash, reloc_hash(reloc));
+
nr_reloc++;
}
max_reloc = max(max_reloc, nr_reloc);
@@ -920,14 +924,11 @@ static int elf_rebuild_rela_reloc_sectio
return 0;
}

-int elf_rebuild_reloc_section(struct elf *elf, struct section *sec)
+static int elf_rebuild_reloc_section(struct elf *elf, struct section *sec)
{
struct reloc *reloc;
int nr;

- sec->changed = true;
- elf->changed = true;
-
nr = 0;
list_for_each_entry(reloc, &sec->reloc_list, list)
nr++;
@@ -991,9 +992,15 @@ int elf_write(struct elf *elf)
struct section *sec;
Elf_Scn *s;

- /* Update section headers for changed sections: */
+ /* Update changed relocation sections and section headers: */
list_for_each_entry(sec, &elf->sections, list) {
if (sec->changed) {
+ if (sec->base &&
+ elf_rebuild_reloc_section(elf, sec)) {
+ WARN("elf_rebuild_reloc_section");
+ return -1;
+ }
+
s = elf_getscn(elf->elf, sec->idx);
if (!s) {
WARN_ELF("elf_getscn");
@@ -1005,6 +1012,7 @@ int elf_write(struct elf *elf)
}

sec->changed = false;
+ elf->changed = true;
}
}

--- a/tools/objtool/elf.h
+++ b/tools/objtool/elf.h
@@ -142,7 +142,6 @@ struct reloc *find_reloc_by_dest_range(c
struct symbol *find_func_containing(struct section *sec, unsigned long offset);
void insn_to_reloc_sym_addend(struct section *sec, unsigned long offset,
struct reloc *reloc);
-int elf_rebuild_reloc_section(struct elf *elf, struct section *sec);

#define for_each_sec(file, sec) \
list_for_each_entry(sec, &file->elf->sections, list)
--- a/tools/objtool/orc_gen.c
+++ b/tools/objtool/orc_gen.c
@@ -251,8 +251,5 @@ int orc_create(struct objtool_file *file
return -1;
}

- if (elf_rebuild_reloc_section(file->elf, ip_rsec))
- return -1;
-
return 0;
}