On 28/07/23 10:33, Josh Poimboeuf wrote:
On Thu, Jul 20, 2023 at 05:30:47PM +0100, Valentin Schneider wrote:
I had to look into objtool itself to understand what this warning was about; make it more explicit.
Signed-off-by: Valentin Schneider vschneid@redhat.com
tools/objtool/check.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 8936a05f0e5ac..d308330f2910e 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -3360,7 +3360,7 @@ static bool pv_call_dest(struct objtool_file *file, struct instruction *insn)
list_for_each_entry(target, &file->pv_ops[idx].targets, pv_target) { if (!target->sec->noinstr) {
WARN("pv_ops[%d]: %s", idx, target->name);
WARN("pv_ops[%d]: indirect call to %s() leaves .noinstr.text section", idx, target->name); file->pv_ops[idx].clean = false;This is an improvement, though I think it still results in two warnings, with the second not-so-useful warning happening in validate_call().
Ideally it would only show a single warning, I guess that would need a little bit of restructuring the code.
You're quite right - fabricating an artificial warning with a call to __flush_tlb_local():
vmlinux.o: warning: objtool: pv_ops[1]: indirect call to native_flush_tlb_local() leaves .noinstr.text section vmlinux.o: warning: objtool: __flush_tlb_all_noinstr+0x4: call to {dynamic}() leaves .noinstr.text section
Interestingly the second one doesn't seem to have triggered the "pv_ops" bit of call_dest_name. Seems like any call to insn_reloc(NULL, x) will return NULL.
Trickling down the file yields:
vmlinux.o: warning: objtool: pv_ops[1]: indirect call to native_flush_tlb_local() leaves .noinstr.text section vmlinux.o: warning: objtool: __flush_tlb_all_noinstr+0x4: call to pv_ops[0]() leaves .noinstr.text section
In my case (!PARAVIRT_XXL) pv_ops should look like: [0]: .cpu.io_delay [1]: .mmu.flush_tlb_user()
so pv_ops[1] looks right. Seems like pv_call_dest() gets it right because it uses arch_dest_reloc_offset().
If I use the above to fix up validate_call(), would we still need pv_call_dest() & co?
-- Josh