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objtool/klp: Simplify reloc symbol conversion

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Inline section_reference_needed() and is_reloc_allowed() into
convert_reloc_sym() and remove the redundant is_reloc_allowed() check in
clone_reloc().

Move the is_sec_sym() checks into the convert callees so they become
no-ops when the reloc is already in the right format.  This allows
convert_reloc_sym() to unconditionally dispatch to the right converter
based on section type.

Acked-by: Song Liu <song@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
This commit is contained in:
Josh Poimboeuf 2026-04-29 20:07:28 -07:00
parent 3e01ab44af
commit 8fdc3585b3
1 changed files with 28 additions and 48 deletions
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76
tools/objtool/klp-diff.c
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@ -838,39 +838,6 @@ static int clone_included_functions(struct elfs *e)
return 0;
}
/*
* Determine whether a relocation should reference the section rather than the
* underlying symbol.
*/
static bool section_reference_needed(struct section *sec)
{
/*
* String symbols are zero-length and uncorrelated. It's easier to
* deal with them as section symbols.
*/
if (is_string_sec(sec))
return true;
/*
* .rodata has mostly anonymous data so there's no way to determine the
* length of a needed reference. just copy the whole section if needed.
*/
if (strstarts(sec->name, ".rodata"))
return true;
/* UBSAN anonymous data */
if (strstarts(sec->name, ".data..Lubsan") || /* GCC */
strstarts(sec->name, ".data..L__unnamed_")) /* Clang */
return true;
return false;
}
static bool is_reloc_allowed(struct reloc *reloc)
{
return section_reference_needed(reloc->sym->sec) == is_sec_sym(reloc->sym);
}
static struct export *find_export(struct symbol *sym)
{
struct export *export;
@ -979,11 +946,15 @@ static bool klp_reloc_needed(struct reloc *patched_reloc)
return true;
}
/* Return -1 error, 0 success, 1 skip */
static int convert_reloc_sym_to_secsym(struct elf *elf, struct reloc *reloc)
{
struct symbol *sym = reloc->sym;
struct section *sec = sym->sec;
if (is_sec_sym(sym))
return 0;
if (!sec->sym && !elf_create_section_symbol(elf, sec))
return -1;
@ -993,11 +964,15 @@ static int convert_reloc_sym_to_secsym(struct elf *elf, struct reloc *reloc)
return 0;
}
/* Return -1 error, 0 success, 1 skip */
static int convert_reloc_secsym_to_sym(struct elf *elf, struct reloc *reloc)
{
struct symbol *sym = reloc->sym;
struct section *sec = sym->sec;
if (!is_sec_sym(sym))
return 0;
/* If the symbol has a dedicated section, it's easy to find */
sym = find_symbol_by_offset(sec, 0);
if (sym && sym->len == sec_size(sec))
@ -1027,22 +1002,34 @@ static int convert_reloc_secsym_to_sym(struct elf *elf, struct reloc *reloc)
return 0;
}
/*
* Sections with anonymous or uncorrelated data (strings, UBSAN data)
* need section symbol references.
*/
static bool is_uncorrelated_section(struct section *sec)
{
return is_string_sec(sec) ||
strstarts(sec->name, ".rodata") ||
strstarts(sec->name, ".data..Lubsan") || /* GCC */
strstarts(sec->name, ".data..L__unnamed_"); /* Clang */
}
/*
* Convert a relocation symbol reference to the needed format: either a section
* symbol or the underlying symbol itself.
* symbol or the underlying symbol itself. Return -1 error, 0 success, 1 skip.
*/
static int convert_reloc_sym(struct elf *elf, struct reloc *reloc)
{
struct section *sec = reloc->sym->sec;
if (reloc_type(reloc) == R_NONE)
return 1;
if (is_reloc_allowed(reloc))
return 0;
if (section_reference_needed(reloc->sym->sec))
if (is_uncorrelated_section(sec))
return convert_reloc_sym_to_secsym(elf, reloc);
else
return convert_reloc_secsym_to_sym(elf, reloc);
/* Everything else: references should use named symbols. */
return convert_reloc_secsym_to_sym(elf, reloc);
}
/*
@ -1187,13 +1174,6 @@ static int clone_reloc(struct elfs *e, struct reloc *patched_reloc,
struct symbol *out_sym;
bool klp;
if (!is_reloc_allowed(patched_reloc)) {
ERROR_FUNC(patched_reloc->sec->base, reloc_offset(patched_reloc),
"missing symbol for reference to %s+%ld",
patched_sym->name, addend);
return -1;
}
klp = klp_reloc_needed(patched_reloc);
dbg_clone_reloc(sec, offset, patched_sym, addend, export, klp);
@ -1223,7 +1203,7 @@ static int clone_reloc(struct elfs *e, struct reloc *patched_reloc,
/*
* For strings, all references use section symbols, thanks to
* section_reference_needed(). clone_symbol() has cloned an empty
* convert_reloc_sym(). clone_symbol() has cloned an empty
* version of the string section. Now copy the string itself.
*/
if (is_string_sec(patched_sym->sec)) {