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@i...) 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/c... 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@intel.com
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@decadent.org.uk 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@decadent.org.uk
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, 0x90RET
ret.skip 31, 0xcc#define HYPERCALL(n) \
That's really odd, I swear I tried this myself: https://lore.kernel.org/r/Ys2jlGMqAe6+h1SX@kroah.com
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