Commit 8374a271 authored by Pawan Gupta's avatar Pawan Gupta Committed by Borislav Petkov (AMD)
Browse files

x86/bugs: Introduce cdt_possible() 



In preparation to allow ITS to also enable stuffing aka Call Depth
Tracking (CDT) independently of retbleed, introduce a helper
cdt_possible().

Signed-off-by: default avatarPawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250611-eibrs-fix-v4-5-5ff86cac6c61@linux.intel.com
parent 7e44909e

arch/x86/kernel/cpu/bugs.c

+14 −1
Original line number Diff line number Diff line
@@ -1119,6 +1119,19 @@ early_param("nospectre_v1", nospectre_v1_cmdline); 


enum spectre_v2_mitigation spectre_v2_enabled __ro_after_init = SPECTRE_V2_NONE;



/* Depends on spectre_v2 mitigation selected already */

static inline bool cdt_possible(enum spectre_v2_mitigation mode)

{

	if (!IS_ENABLED(CONFIG_MITIGATION_CALL_DEPTH_TRACKING) ||

	    !IS_ENABLED(CONFIG_MITIGATION_RETPOLINE))

		return false;



	if (mode == SPECTRE_V2_RETPOLINE)

		return true;



	return false;

}



#undef pr_fmt

#define pr_fmt(fmt)     "RETBleed: " fmt
@@ -1267,7 +1280,7 @@ static void __init retbleed_update_mitigation(void) 
		retbleed_mitigation = RETBLEED_MITIGATION_STUFF;



	if (retbleed_mitigation == RETBLEED_MITIGATION_STUFF &&

	    spectre_v2_enabled != SPECTRE_V2_RETPOLINE) {

	    !cdt_possible(spectre_v2_enabled)) {

		pr_err("WARNING: retbleed=stuff depends on spectre_v2=retpoline\n");

		retbleed_mitigation = RETBLEED_MITIGATION_NONE;

	}