This is a note to let you know that I've just added the patch titled x86/retpoline: Avoid retpolines for built-in __init functions to the 4.9-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-avoid-retpolines-for-built-in-__init-functions.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Thu Feb 8 03:32:24 CET 2018 From: David Woodhouse <dwmw@xxxxxxxxxxxx> Date: Thu, 1 Feb 2018 11:27:20 +0000 Subject: x86/retpoline: Avoid retpolines for built-in __init functions From: David Woodhouse <dwmw@xxxxxxxxxxxx> (cherry picked from commit 66f793099a636862a71c59d4a6ba91387b155e0c) There's no point in building init code with retpolines, since it runs before any potentially hostile userspace does. And before the retpoline is actually ALTERNATIVEd into place, for much of it. Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: karahmed@xxxxxxxxx Cc: peterz@xxxxxxxxxxxxx Cc: bp@xxxxxxxxx Link: https://lkml.kernel.org/r/1517484441-1420-2-git-send-email-dwmw@xxxxxxxxxxxx Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- include/linux/init.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) --- a/include/linux/init.h +++ b/include/linux/init.h @@ -4,6 +4,13 @@ #include <linux/compiler.h> #include <linux/types.h> +/* Built-in __init functions needn't be compiled with retpoline */ +#if defined(RETPOLINE) && !defined(MODULE) +#define __noretpoline __attribute__((indirect_branch("keep"))) +#else +#define __noretpoline +#endif + /* These macros are used to mark some functions or * initialized data (doesn't apply to uninitialized data) * as `initialization' functions. The kernel can take this @@ -39,7 +46,7 @@ /* These are for everybody (although not all archs will actually discard it in modules) */ -#define __init __section(.init.text) __cold notrace __latent_entropy +#define __init __section(.init.text) __cold notrace __latent_entropy __noretpoline #define __initdata __section(.init.data) #define __initconst __section(.init.rodata) #define __exitdata __section(.exit.data) Patches currently in stable-queue which might be from dwmw@xxxxxxxxxxxx are queue-4.9/x86-entry-64-push-extra-regs-right-away.patch queue-4.9/kvm-vmx-introduce-alloc_loaded_vmcs.patch queue-4.9/kvm-nvmx-eliminate-vmcs02-pool.patch queue-4.9/kvm-vmx-allow-direct-access-to-msr_ia32_spec_ctrl.patch queue-4.9/kvm-x86-add-ibpb-support.patch queue-4.9/kvm-svm-allow-direct-access-to-msr_ia32_spec_ctrl.patch queue-4.9/x86-cpufeatures-add-intel-feature-bits-for-speculation-control.patch queue-4.9/x86-retpoline-simplify-vmexit_fill_rsb.patch queue-4.9/x86-paravirt-remove-noreplace-paravirt-cmdline-option.patch queue-4.9/x86-cpufeatures-clean-up-spectre-v2-related-cpuid-flags.patch queue-4.9/documentation-document-array_index_nospec.patch queue-4.9/x86-usercopy-replace-open-coded-stac-clac-with-__uaccess_-begin-end.patch queue-4.9/x86-asm-move-status-from-thread_struct-to-thread_info.patch queue-4.9/x86-cpufeatures-add-cpuid_7_edx-cpuid-leaf.patch queue-4.9/kvm-x86-make-indirect-calls-in-emulator-speculation-safe.patch queue-4.9/x86-entry-64-remove-the-syscall64-fast-path.patch queue-4.9/x86-cpufeature-blacklist-spec_ctrl-pred_cmd-on-early-spectre-v2-microcodes.patch queue-4.9/x86-nospec-fix-header-guards-names.patch queue-4.9/x86-retpoline-avoid-retpolines-for-built-in-__init-functions.patch queue-4.9/vfs-fdtable-prevent-bounds-check-bypass-via-speculative-execution.patch queue-4.9/x86-uaccess-use-__uaccess_begin_nospec-and-uaccess_try_nospec.patch queue-4.9/x86-cpu-bugs-make-retpoline-module-warning-conditional.patch queue-4.9/x86-spectre-check-config_retpoline-in-command-line-parser.patch queue-4.9/x86-implement-array_index_mask_nospec.patch queue-4.9/x86-alternative-print-unadorned-pointers.patch queue-4.9/x86-cpuid-fix-up-virtual-ibrs-ibpb-stibp-feature-bits-on-intel.patch queue-4.9/array_index_nospec-sanitize-speculative-array-de-references.patch queue-4.9/kvm-vmx-make-indirect-call-speculation-safe.patch queue-4.9/x86-cpufeatures-add-amd-feature-bits-for-speculation-control.patch queue-4.9/x86-spectre-fix-spelling-mistake-vunerable-vulnerable.patch queue-4.9/module-retpoline-warn-about-missing-retpoline-in-module.patch queue-4.9/x86-kvm-update-spectre-v1-mitigation.patch queue-4.9/x86-get_user-use-pointer-masking-to-limit-speculation.patch queue-4.9/x86-syscall-sanitize-syscall-table-de-references-under-speculation.patch queue-4.9/kvm-nvmx-vmx_complete_nested_posted_interrupt-can-t-fail.patch queue-4.9/x86-spectre-simplify-spectre_v2-command-line-parsing.patch queue-4.9/x86-msr-add-definitions-for-new-speculation-control-msrs.patch queue-4.9/x86-pti-make-unpoison-of-pgd-for-trusted-boot-work-for-real.patch queue-4.9/kvm-vmx-make-msr-bitmaps-per-vcpu.patch queue-4.9/x86-speculation-add-basic-ibpb-indirect-branch-prediction-barrier-support.patch queue-4.9/kvm-nvmx-mark-vmcs12-pages-dirty-on-l2-exit.patch queue-4.9/x86-pti-mark-constant-arrays-as-__initconst.patch queue-4.9/x86-speculation-fix-typo-ibrs_att-which-should-be-ibrs_all.patch queue-4.9/x86-spectre-report-get_user-mitigation-for-spectre_v1.patch queue-4.9/x86-introduce-barrier_nospec.patch queue-4.9/kvm-vmx-emulate-msr_ia32_arch_capabilities.patch queue-4.9/x86-bugs-drop-one-mitigation-from-dmesg.patch queue-4.9/x86-retpoline-remove-the-esp-rsp-thunk.patch queue-4.9/x86-pti-do-not-enable-pti-on-cpus-which-are-not-vulnerable-to-meltdown.patch queue-4.9/x86-introduce-__uaccess_begin_nospec-and-uaccess_try_nospec.patch queue-4.9/nl80211-sanitize-array-index-in-parse_txq_params.patch