On Thu, Jul 14, 2022 at 08:49:09AM +0200, Greg Kroah-Hartman wrote: > On Thu, Jul 14, 2022 at 12:50:16AM +0200, Ben Hutchings wrote: > > On Wed, Jul 13, 2022 at 05:38:47AM +0800, kernel test robot wrote: > > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-5.10.y > > > head: 53b881e19526bcc3e51d9668cab955c80dcf584c > > > commit: 7575d3f3bbd1c68d6833b45d1b98ed182832bd44 [7082/7120] x86: Use return-thunk in asm code > > > config: x86_64-rhel-8.3-syz (https://download.01.org/0day-ci/archive/20220713/202207130531.SkRjrrn8-lkp@xxxxxxxxx/config) > > > compiler: gcc-11 (Debian 11.3.0-3) 11.3.0 > > > reproduce (this is a W=1 build): > > > # https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git/commit/?id=7575d3f3bbd1c68d6833b45d1b98ed182832bd44 > > > git remote add linux-stable-rc https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git > > > git fetch --no-tags linux-stable-rc linux-5.10.y > > > git checkout 7575d3f3bbd1c68d6833b45d1b98ed182832bd44 > > > # save the config file > > > mkdir build_dir && cp config build_dir/.config > > > make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash arch/x86/ > > > > > > If you fix the issue, kindly add following tag where applicable > > > Reported-by: kernel test robot <lkp@xxxxxxxxx> > > > > > > All warnings (new ones prefixed by >>): > > > > > > >> arch/x86/kernel/head_64.o: warning: objtool: xen_hypercall_mmu_update(): can't find starting instruction > > > > > > -- > > > 0-DAY CI Kernel Test Service > > > https://01.org/lkp > > > > Please add the following patch to fix this. This would also be > > needed for 5.15-stable. > > > > Ben. > > > > From: Ben Hutchings <ben@xxxxxxxxxxxxxxx> > > Date: Thu, 14 Jul 2022 00:39:33 +0200 > > Subject: [PATCH] x86/xen: Fix initialisation in hypercall_page after rethunk > > > > The hypercall_page is special and the RETs there should not be changed > > into rethunk calls (but can have SLS mitigation). Change the initial > > instructions to ret + int3 padding, as was done in upstream commit > > 5b2fc51576ef "x86/ibt,xen: Sprinkle the ENDBR". > > > > Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> > > --- > > arch/x86/xen/xen-head.S | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S > > index 38b73e7e54ba..2a3ef5fcba34 100644 > > --- a/arch/x86/xen/xen-head.S > > +++ b/arch/x86/xen/xen-head.S > > @@ -69,9 +69,9 @@ SYM_CODE_END(asm_cpu_bringup_and_idle) > > SYM_CODE_START(hypercall_page) > > .rept (PAGE_SIZE / 32) > > UNWIND_HINT_FUNC > > - .skip 31, 0x90 > > ANNOTATE_UNRET_SAFE > > - RET > > + ret > > + .skip 31, 0xcc > > .endr > > > > #define HYPERCALL(n) \ > > > > > > That's really odd, I swear I tried this myself: > https://lore.kernel.org/r/Ys2jlGMqAe6+h1SX@xxxxxxxxx > > I'll go queue this up and see if that solves the issue on my side. But > see Boris's comment about how this shouldn't be an issue in the end. Ah, yes, it does fix that warning, but causes this new one: arch/x86/kernel/head_64.o: warning: objtool: .text+0x5: unreachable instruction I'll keep your patch here, as it makes sense, but it does just exchange one warning for another one... thanks, greg k-h
