This is a note to let you know that I've just added the patch titled
x86/retpoline: Do the necessary fixup to the Zen3/4 srso return thunk for !SRSO
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-retpoline-do-the-necessary-fixup-to-the-zen3-4-srso-return-thunk-for-srso.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From stable+bounces-36111-greg=kroah.com@xxxxxxxxxxxxxxx Fri Apr 5 16:05:28 2024
From: Borislav Petkov <bp@xxxxxxxxx>
Date: Fri, 5 Apr 2024 16:05:09 +0200
Subject: x86/retpoline: Do the necessary fixup to the Zen3/4 srso return thunk for !SRSO
To: gregkh@xxxxxxxxxxxxxxxxxxx
Cc: mingo@xxxxxxxxxx, torvalds@xxxxxxxxxxxxxxxxxxxx, stable@xxxxxxxxxxxxxxx
Message-ID: <20240405140509.GBZhAFFZd2X47gW62r@fat_crate.local>
Content-Disposition: inline
From: "Borislav Petkov (AMD)" <bp@xxxxxxxxx>
Commit 0e110732473e14d6520e49d75d2c88ef7d46fe67 upstream.
The srso_alias_untrain_ret() dummy thunk in the !CONFIG_MITIGATION_SRSO
case is there only for the altenative in CALL_UNTRAIN_RET to have
a symbol to resolve.
However, testing with kernels which don't have CONFIG_MITIGATION_SRSO
enabled, leads to the warning in patch_return() to fire:
missing return thunk: srso_alias_untrain_ret+0x0/0x10-0x0: eb 0e 66 66 2e
WARNING: CPU: 0 PID: 0 at arch/x86/kernel/alternative.c:826 apply_returns (arch/x86/kernel/alternative.c:826
Put in a plain "ret" there so that gcc doesn't put a return thunk in
in its place which special and gets checked.
In addition:
ERROR: modpost: "srso_alias_untrain_ret" [arch/x86/kvm/kvm-amd.ko] undefined!
make[2]: *** [scripts/Makefile.modpost:145: Module.symvers] Chyba 1
make[1]: *** [/usr/src/linux-6.8.3/Makefile:1873: modpost] Chyba 2
make: *** [Makefile:240: __sub-make] Chyba 2
since !SRSO builds would use the dummy return thunk as reported by
petr.pisar@xxxxxxxx, https://bugzilla.kernel.org/show_bug.cgi?id=218679.
Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
Closes: https://lore.kernel.org/oe-lkp/202404020901.da75a60f-oliver.sang@xxxxxxxxx
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Link: https://lore.kernel.org/all/202404020901.da75a60f-oliver.sang@xxxxxxxxx/
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/lib/retpoline.S | 1 +
1 file changed, 1 insertion(+)
--- a/arch/x86/lib/retpoline.S
+++ b/arch/x86/lib/retpoline.S
@@ -108,6 +108,7 @@ SYM_START(srso_alias_untrain_ret, SYM_L_
ret
int3
SYM_FUNC_END(srso_alias_untrain_ret)
+__EXPORT_THUNK(srso_alias_untrain_ret)
#endif
SYM_START(srso_alias_safe_ret, SYM_L_GLOBAL, SYM_A_NONE)
Patches currently in stable-queue which might be from kroah.com@xxxxxxxxxxxxxxx are
queue-5.15/x86-rfds-mitigate-register-file-data-sampling-rfds.patch
queue-5.15/vfio-pci-create-persistent-intx-handler.patch
queue-5.15/x86-entry_32-add-verw-just-before-userspace-transition.patch
queue-5.15/vfio-fsl-mc-block-calling-interrupt-handler-without-trigger.patch
queue-5.15/x86-bugs-add-asm-helpers-for-executing-verw.patch
queue-5.15/x86-asm-differentiate-between-code-and-function-alignment.patch
queue-5.15/vfio-pci-disable-auto-enable-of-exclusive-intx-irq.patch
queue-5.15/x86-bugs-fix-the-srso-mitigation-on-zen3-4.patch
queue-5.15/x86-retpoline-do-the-necessary-fixup-to-the-zen3-4-srso-return-thunk-for-srso.patch
queue-5.15/vfio-pci-lock-external-intx-masking-ops.patch
queue-5.15/x86-alternatives-teach-text_poke_bp-to-patch-jcc.d32-instructions.patch
queue-5.15/vfio-introduce-interface-to-flush-virqfd-inject-workqueue.patch
queue-5.15/kvm-x86-export-rfds_no-and-rfds_clear-to-guests.patch
queue-5.15/x86-asm-add-_asm_rip-macro-for-x86-64-rip-suffix.patch
queue-5.15/x86-entry_64-add-verw-just-before-userspace-transition.patch
queue-5.15/x86-alternatives-introduce-int3_emulate_jcc.patch
queue-5.15/x86-mmio-disable-kvm-mitigation-when-x86_feature_clear_cpu_buf-is-set.patch
queue-5.15/x86-bugs-use-alternative-instead-of-mds_user_clear-static-key.patch
queue-5.15/documentation-hw-vuln-add-documentation-for-rfds.patch
queue-5.15/kvm-vmx-use-bt-jnc-i.e.-eflags.cf-to-select-vmresume-vs.-vmlaunch.patch
queue-5.15/mm-migrate-set-swap-entry-values-of-thp-tail-pages-properly.patch
queue-5.15/kvm-vmx-move-verw-closer-to-vmentry-for-mds-mitigation.patch
queue-5.15/arch-introduce-config_function_alignment.patch
queue-5.15/x86-static_call-add-support-for-jcc-tail-calls.patch
queue-5.15/vfio-platform-create-persistent-irq-handlers.patch
