linux-kernel - Re: Reference to non-existing CONFIG_X86_FEATURE_CALL

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Date:   Mon, 31 Oct 2022 11:10:55 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Lukas Bulwahn <lukas.bulwahn@...il.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        X86 ML <x86@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        kernel-janitors <kernel-janitors@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Reference to non-existing CONFIG_X86_FEATURE_CALL_DEPTH

On Mon, Oct 31, 2022 at 10:14:03AM +0100, Lukas Bulwahn wrote:
> Dear Thomas, dear Peter,
> 
> in your work on call depth tracking mitigation, commit 5d8213864ade
> ("x86/retbleed: Add SKL return thunk") on linux-next references the
> configuration symbol CONFIG_X86_FEATURE_CALL_DEPTH, which is not
> introduced in any Kconfig file.
> 
> Is this just some left-over from some previous iteration of this
> feature or is there still a patch to come that will introduce that
> configuration symbol in some Kconfig file?
> 
> This issue was identified with ./scripts/checkkconfigsymbols.py.

Thanks!

---
Subject: x86: Unconfuse CONFIG_ and X86_FEATURE_ namespaces
From: Peter Zijlstra <peterz@...radead.org>

Lukas reported someone fat fingered the CONFIG_ symbol; fix er up.

Fixes: 5d8213864ade ("x86/retbleed: Add SKL return thunk") 
Reported-by: Lukas Bulwahn <lukas.bulwahn@...il.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---

diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index 82580adbca4b..3ab90f23e7f7 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -285,7 +285,7 @@
  */
 .macro UNTRAIN_RET
 #if defined(CONFIG_CPU_UNRET_ENTRY) || defined(CONFIG_CPU_IBPB_ENTRY) || \
-	defined(CONFIG_X86_FEATURE_CALL_DEPTH)
+	defined(CONFIG_CALL_DEPTH_TRACKING)
 	ANNOTATE_UNRET_END
 	ALTERNATIVE_3 "",						\
 		      CALL_ZEN_UNTRAIN_RET, X86_FEATURE_UNRET,		\
@@ -296,7 +296,7 @@
 
 .macro UNTRAIN_RET_FROM_CALL
 #if defined(CONFIG_CPU_UNRET_ENTRY) || defined(CONFIG_CPU_IBPB_ENTRY) || \
-	defined(CONFIG_X86_FEATURE_CALL_DEPTH)
+	defined(CONFIG_CALL_DEPTH_TRACKING)
 	ANNOTATE_UNRET_END
 	ALTERNATIVE_3 "",						\
 		      CALL_ZEN_UNTRAIN_RET, X86_FEATURE_UNRET,		\