Re: [PATCH v4 01/10] objtool: Handle various symbol types of rodata

From: Tiezhu Yang
Date: Tue Nov 26 2024 - 05:42:01 EST


On 11/26/2024 02:44 PM, Josh Poimboeuf wrote:
On Fri, Nov 22, 2024 at 12:49:56PM +0800, Tiezhu Yang wrote:
@@ -2094,12 +2095,19 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn,
if (prev_offset && reloc_offset(reloc) != prev_offset + 8)
break;

+ if (reloc->sym->type == STT_SECTION) {
+ /* Addend field in the relocation entry associated with the symbol */
+ offset = reloc_addend(reloc);
+ } else {
+ /* The address of the symbol in the relocation entry */
+ offset = reloc->sym->offset;

The comments don't seem helpful.

Will remove it.


In the case of STT_SECTION, sym->offset is always zero. Therefore the
if-else can be converted to a simple unconditional statement:

offset = reloc->sym->offset + reloc_addend(reloc);

OK, let me test it.


'prev_offset' needs to be updated as well.

I am not sure I understand your comment correctly, I can not see
what should to do about 'prev_offset'.


@@ -2137,6 +2145,7 @@ static struct reloc *find_jump_table(struct objtool_file *file,
{
struct reloc *table_reloc;
struct instruction *dest_insn, *orig_insn = insn;
+ unsigned long offset;

/*
* Backward search using the @first_jump_src links, these help avoid
@@ -2160,7 +2169,16 @@ static struct reloc *find_jump_table(struct objtool_file *file,
table_reloc = arch_find_switch_table(file, insn);
if (!table_reloc)
continue;
- dest_insn = find_insn(file, table_reloc->sym->sec, reloc_addend(table_reloc));
+
+ if (table_reloc->sym->type == STT_SECTION) {
+ /* Addend field in the relocation entry associated with the symbol */
+ offset = reloc_addend(table_reloc);
+ } else {
+ /* The address of the symbol in the relocation entry */
+ offset = table_reloc->sym->offset;
+ }

Same comment here.

OK, will do it.

Thanks,
Tiezhu