On Thu, Feb 08, 2018 at 02:02:32PM +0100, Peter Zijlstra wrote: > > Linus reported that GCC-7.3 generated a switch-table construct that > confused objtool. It turns out that, in particular due to KASAN, it is > possible to have unrelated .rodata usage in between the .rodata setup > for the switch-table and the following indirect jump. > > The simple linear reverse search from the indirect jump would hit upon > the KASAN .rodata usage first and fail to find a switch_table, > resulting in a spurious 'sibling call with modified stack frame' > warning. > > Fix this by creating a 'jump-stack' which we can 'unwind' during > reversal, thereby skipping over much of the in-between code. > > This is not fool proof by any means, but is sufficient to make the > known cases work. Future work would be to construct more comprehensive > flow analysis code. > > Also, since Josh keeps asking, add myself to MAINTAINERS. > > Cc: Josh Poimboeuf <jpoim...@redhat.com> > Reported-by: Linus Torvalds <torva...@linux-foundation.org> > Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Thanks again for helping out with objtool maintainership! No complaints from the 0-day bot, so: Acked-by: Josh Poimboeuf <jpoim...@redhat.com> -- Josh
