The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x 9a48d604672220545d209e9996c2a1edbb5637f6 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2023051308-reflected-pessimism-42d1@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..

Possible dependencies:

9a48d6046722 ("x86/retbleed: Fix return thunk alignment") a149180fbcf3 ("x86: Add magic AMD return-thunk") d9e9d2300681 ("x86,objtool: Create .return_sites") 15e67227c49a ("x86: Undo return-thunk damage") 0b53c374b9ef ("x86/retpoline: Use -mfunction-return") 369ae6ffc41a ("x86/retpoline: Cleanup some #ifdefery") a883d624aed4 ("x86/cpufeatures: Move RETPOLINE flags to word 11") 22922deae13f ("Merge tag 'objtool-core-2022-05-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 9a48d604672220545d209e9996c2a1edbb5637f6 Mon Sep 17 00:00:00 2001 From: "Borislav Petkov (AMD)" bp@alien8.de Date: Fri, 12 May 2023 23:12:26 +0200 Subject: [PATCH] x86/retbleed: Fix return thunk alignment

SYM_FUNC_START_LOCAL_NOALIGN() adds an endbr leading to this layout (leaving only the last 2 bytes of the address):

3bff <zen_untrain_ret>: 3bff: f3 0f 1e fa endbr64 3c03: f6 test $0xcc,%bl

3c04 <__x86_return_thunk>: 3c04: c3 ret 3c05: cc int3 3c06: 0f ae e8 lfence

However, "the RET at __x86_return_thunk must be on a 64 byte boundary, for alignment within the BTB."

Use SYM_START instead.

Signed-off-by: Borislav Petkov (AMD) bp@alien8.de Reviewed-by: Thomas Gleixner tglx@linutronix.de Cc: stable@kernel.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org

diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S index 27ef53fab6bd..b3b1e376dce8 100644 --- a/arch/x86/lib/retpoline.S +++ b/arch/x86/lib/retpoline.S @@ -144,8 +144,8 @@ SYM_CODE_END(__x86_indirect_jump_thunk_array) */ .align 64 .skip 63, 0xcc -SYM_FUNC_START_NOALIGN(zen_untrain_ret); - +SYM_START(zen_untrain_ret, SYM_L_GLOBAL, SYM_A_NONE) + ANNOTATE_NOENDBR /* * As executed from zen_untrain_ret, this is: *