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Subject[PATCH] objtool: fix STACK_FRAME_NON_STANDARD macro checking for function symbols
Date
Mathieu Desnoyers reported that the STACK_FRAME_NON_STANDARD macro
wasn't working with the lttng_filter_interpret_bytecode() function in
the lttng-modules code.

Usually the relocation created by STACK_FRAME_NON_STANDARD creates a
reference to a section symbol like this:

Offset Type Value Addend Name
000000000000000000 X86_64_64 000000000000000000 +3136 .text

But in this case it created a reference to a function symbol:

Offset Type Value Addend Name
000000000000000000 X86_64_64 0x00000000000003a0 +0 lttng_filter_interpret_bytecode

To be honest I have no idea what causes gcc to decide to do one over the
other. But both are valid ELF, so add support for the function symbol.

Reported-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
tools/objtool/builtin-check.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index e8a1e69..25d8031 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -122,10 +122,14 @@ static bool ignore_func(struct objtool_file *file, struct symbol *func)

/* check for STACK_FRAME_NON_STANDARD */
if (file->whitelist && file->whitelist->rela)
- list_for_each_entry(rela, &file->whitelist->rela->rela_list, list)
- if (rela->sym->sec == func->sec &&
+ list_for_each_entry(rela, &file->whitelist->rela->rela_list, list) {
+ if (rela->sym->type == STT_SECTION &&
+ rela->sym->sec == func->sec &&
rela->addend == func->offset)
return true;
+ if (rela->sym->type == STT_FUNC && rela->sym == func)
+ return true;
+ }

/* check if it has a context switching instruction */
func_for_each_insn(file, func, insn)
--
2.4.11
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