On Mon, Oct 28, 2024 at 05:16:44PM -0700, Kees Cook wrote: > On Fri, Oct 25, 2024 at 10:14:04PM -0700, Rong Xu wrote: > > In the presence of both weak and strong function definitions, the > > linker drops the weak symbol in favor of a strong symbol, but > > leaves the code in place. Code in ignore_unreachable_insn() has > > some heuristics to suppress the warning, but it does not work when > > -ffunction-sections is enabled. > > > > Suppose function foo has both strong and weak definitions. > > Case 1: The strong definition has an annotated section name, > > like .init.text. Only the weak definition will be placed into > > .text.foo. But since the section has no symbols, there will be no > > "hole" in the section. > > > > Case 2: Both sections are without an annotated section name. > > Both will be placed into .text.foo section, but there will be only one > > symbol (the strong one). If the weak code is before the strong code, > > there is no "hole" as it fails to find the right-most symbol before > > the offset. > > > > The fix is to use the first node to compute the hole if hole.sym > > is empty. If there is no symbol in the section, the first node > > will be NULL, in which case, -1 is returned to skip the whole > > section. > > > > Co-developed-by: Han Shen <shenhan@xxxxxxxxxx> > > Signed-off-by: Han Shen <shenhan@xxxxxxxxxx> > > This seems logically correct to me, but I'd love to see review from Josh > and/or Peter Z on this change too. > > Reviewed-by: Kees Cook <kees@xxxxxxxxxx> LGTM, thanks! Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> -- Josh
