This is a note to let you know that I've just added the patch titled
x86/ftrace: Use alternative RET encoding
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-ftrace-use-alternative-ret-encoding.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 foo@baz Tue Jul 12 05:06:57 PM CEST 2022
From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Date: Tue, 14 Jun 2022 23:15:40 +0200
Subject: x86/ftrace: Use alternative RET encoding
From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
commit 1f001e9da6bbf482311e45e48f53c2bd2179e59c upstream.
Use the return thunk in ftrace trampolines, if needed.
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Reviewed-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
[cascardo: still copy return from ftrace_stub]
[cascardo: use memcpy(text_gen_insn) as there is no __text_gen_insn]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/ftrace.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -308,7 +308,7 @@ union ftrace_op_code_union {
} __attribute__((packed));
};
-#define RET_SIZE 1 + IS_ENABLED(CONFIG_SLS)
+#define RET_SIZE (IS_ENABLED(CONFIG_RETPOLINE) ? 5 : 1 + IS_ENABLED(CONFIG_SLS))
static unsigned long
create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
@@ -367,7 +367,10 @@ create_trampoline(struct ftrace_ops *ops
/* The trampoline ends with ret(q) */
retq = (unsigned long)ftrace_stub;
- ret = copy_from_kernel_nofault(ip, (void *)retq, RET_SIZE);
+ if (cpu_feature_enabled(X86_FEATURE_RETHUNK))
+ memcpy(ip, text_gen_insn(JMP32_INSN_OPCODE, ip, &__x86_return_thunk), JMP32_INSN_SIZE);
+ else
+ ret = copy_from_kernel_nofault(ip, (void *)retq, RET_SIZE);
if (WARN_ON(ret < 0))
goto fail;
Patches currently in stable-queue which might be from peterz@xxxxxxxxxxxxx are
queue-5.15/x86-sev-avoid-using-__x86_return_thunk.patch
queue-5.15/x86-ftrace-use-alternative-ret-encoding.patch
queue-5.15/objtool-re-add-unwind_hint_-save_restore.patch
queue-5.15/x86-bugs-add-retbleed-ibpb.patch
queue-5.15/x86-bugs-enable-stibp-for-jmp2ret.patch
queue-5.15/x86-retpoline-cleanup-some-ifdefery.patch
queue-5.15/kvm-vmx-flatten-__vmx_vcpu_run.patch
queue-5.15/x86-kvm-vmx-make-noinstr-clean.patch
queue-5.15/objtool-x86-replace-alternatives-with-.retpoline_sites.patch
queue-5.15/x86-retbleed-add-fine-grained-kconfig-knobs.patch
queue-5.15/x86-cpu-amd-add-spectral-chicken.patch
queue-5.15/kvm-vmx-fix-ibrs-handling-after-vmexit.patch
queue-5.15/kvm-vmx-prevent-guest-rsb-poisoning-attacks-with-eibrs.patch
queue-5.15/x86-vsyscall_emu-64-don-t-use-ret-in-vsyscall-emulation.patch
queue-5.15/x86-add-magic-amd-return-thunk.patch
queue-5.15/x86-bugs-keep-a-per-cpu-ia32_spec_ctrl-value.patch
queue-5.15/x86-objtool-create-.return_sites.patch
queue-5.15/x86-alternative-handle-jcc-__x86_indirect_thunk_-reg.patch
queue-5.15/x86-kvm-fix-setcc-emulation-for-return-thunks.patch
queue-5.15/x86-retpoline-swizzle-retpoline-thunk.patch
queue-5.15/x86-speculation-fix-firmware-entry-spec_ctrl-handling.patch
queue-5.15/x86-retpoline-remove-unused-replacement-symbols.patch
queue-5.15/x86-speculation-add-spectre_v2-ibrs-option-to-support-kernel-ibrs.patch
queue-5.15/x86-xen-add-untrain_ret.patch
queue-5.15/bpf-x86-respect-x86_feature_retpoline.patch
queue-5.15/x86-undo-return-thunk-damage.patch
queue-5.15/x86-entry-avoid-very-early-ret.patch
queue-5.15/x86-entry-move-push_and_clear_regs-back-into-error_entry.patch
queue-5.15/x86-retpoline-create-a-retpoline-thunk-array.patch
queue-5.15/x86-asm-fix-register-order.patch
queue-5.15/x86-speculation-fill-rsb-on-vmexit-for-ibrs.patch
queue-5.15/objtool-add-entry-unret-validation.patch
queue-5.15/objtool-shrink-struct-instruction.patch
queue-5.15/kvm-vmx-convert-launched-argument-to-flags.patch
queue-5.15/x86-bpf-use-alternative-ret-encoding.patch
queue-5.15/x86-common-stamp-out-the-stepping-madness.patch
queue-5.15/x86-bugs-split-spectre_v2_select_mitigation-and-spectre_v2_user_select_mitigation.patch
queue-5.15/x86-bugs-report-intel-retbleed-vulnerability.patch
queue-5.15/bpf-x86-simplify-computing-label-offsets.patch
queue-5.15/x86-cpufeatures-move-retpoline-flags-to-word-11.patch
queue-5.15/x86-speculation-fix-spec_ctrl-write-on-smt-state-change.patch
queue-5.15/x86-retpoline-use-mfunction-return.patch
queue-5.15/x86-xen-rename-sys-entry-points.patch
queue-5.15/x86-bugs-optimize-spec_ctrl-msr-writes.patch
queue-5.15/x86-bugs-report-amd-retbleed-vulnerability.patch
queue-5.15/x86-static_call-use-alternative-ret-encoding.patch
queue-5.15/x86-speculation-fix-rsb-filling-with-config_retpoline-n.patch
queue-5.15/x86-asm-fixup-odd-gen-for-each-reg.h-usage.patch
queue-5.15/x86-alternative-add-debug-prints-to-apply_retpolines.patch
queue-5.15/x86-use-return-thunk-in-asm-code.patch
queue-5.15/objtool-classify-symbols.patch
queue-5.15/intel_idle-disable-ibrs-during-long-idle.patch
queue-5.15/x86-retpoline-move-the-retpoline-thunk-declarations-to-nospec-branch.h.patch
queue-5.15/x86-alternative-implement-.retpoline_sites-support.patch
queue-5.15/x86-alternative-try-inline-spectre_v2-retpoline-amd.patch
queue-5.15/x86-entry-remove-skip_r11rcx.patch
queue-5.15/objtool-explicitly-avoid-self-modifying-code-in-.altinstr_replacement.patch
queue-5.15/x86-speculation-use-cached-host-spec_ctrl-value-for-guest-entry-exit.patch
queue-5.15/x86-bugs-add-amd-retbleed-boot-parameter.patch
queue-5.15/x86-entry-add-kernel-ibrs-implementation.patch
queue-5.15/objtool-treat-.text.__x86.-as-noinstr.patch
queue-5.15/objtool-introduce-cfi-hash.patch
queue-5.15/objtool-default-ignore-int3-for-unreachable.patch
queue-5.15/objtool-update-retpoline-validation.patch
