[PATCH v4 01/30] objtool: Make validate_call() recognize indirect calls to pv_ops[]

Valentin Schneider
2025-01-14T17:53:24Z

call_dest_name() does not get passed the file pointer of validate_call(),
which means its invocation of insn_reloc() will always return NULL. Make it
take a file pointer.

While at it, make sure call_dest_name() uses arch_dest_reloc_offset(),
otherwise it gets the pv_ops[] offset wrong.

Fabricating an intentional warning shows the change; previously:

vmlinux.o: warning: objtool: __flush_tlb_all_noinstr+0x4: call to {dynamic}() leaves .noinstr.text section

now:

vmlinux.o: warning: objtool: __flush_tlb_all_noinstr+0x4: call to pv_ops[1]() leaves .noinstr.text section

Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/check.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 76060da755b5c..b35763f05a548 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -3448,7 +3448,7 @@ static inline bool func_uaccess_safe(struct symbol *func)
return false;
}

-static inline const char *call_dest_name(struct instruction *insn)
+static inline const char *call_dest_name(struct objtool_file *file, struct instruction *insn)
{
static char pvname[19];
struct reloc *reloc;
@@ -3457,9 +3457,9 @@ static inline const char *call_dest_name(struct instruction *insn)
if (insn_call_dest(insn))
return insn_call_dest(insn)->name;

- reloc = insn_reloc(NULL, insn);
+ reloc = insn_reloc(file, insn);
if (reloc && !strcmp(reloc->sym->name, "pv_ops")) {
- idx = (reloc_addend(reloc) / sizeof(void *));
+ idx = (arch_dest_reloc_offset(reloc_addend(reloc)) / sizeof(void *));
snprintf(pvname, sizeof(pvname), "pv_ops[%d]", idx);
return pvname;
}
@@ -3538,17 +3538,19 @@ static int validate_call(struct objtool_file *file,
{
if (state->noinstr && state->instr <= 0 &&
!noinstr_call_dest(file, insn, insn_call_dest(insn))) {
- WARN_INSN(insn, "call to %s() leaves .noinstr.text section", call_dest_name(insn));
+ WARN_INSN(insn, "call to %s() leaves .noinstr.text section", call_dest_name(file, insn));
return 1;
}

if (state->uaccess && !func_uaccess_safe(insn_call_dest(insn))) {
- WARN_INSN(insn, "call to %s() with UACCESS enabled", call_dest_name(insn));
+ WARN_INSN(insn, "call to %s() with UACCESS enabled",
+ call_dest_name(file, insn));
return 1;
}

if (state->df) {
- WARN_INSN(insn, "call to %s() with DF set", call_dest_name(insn));
+ WARN_INSN(insn, "call to %s() with DF set",
+ call_dest_name(file, insn));
return 1;
}

--
2.43.0