linux-kernel - [PATCH v3 2/2] retpolines: Remove the minimal stuff of retpoline support

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Date:   Fri, 2 Nov 2018 01:45:41 -0700 (PDT)
From:   Zhenzhong Duan <zhenzhong.duan@...cle.com>
To:     <linux-kernel@...r.kernel.org>
Cc:     <mingo@...hat.com>, <konrad.wilk@...cle.com>, <dwmw@...zon.co.uk>,
        <tglx@...utronix.de>, <srinivas.eeda@...cle.com>, <bp@...e.de>,
        <peterz@...radead.org>, <hpa@...or.com>
Subject: [PATCH v3 2/2] retpolines: Remove the minimal stuff of retpoline
 support

Now that CONFIG_RETPOLINE hard depends on compiler support, there is no
reason for minimal stuff to still exist.

[peterz@...radead.org: initial suggestion]
Link: Link: https://lore.kernel.org/lkml/caeb3213f13e57191e362ca04f2892cfa2ccda65.camel@infradead.org
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@...cle.com>
Suggested-by: Peter Zijlstra <peterz@...radead.org>
Cc: David Woodhouse <dwmw@...zon.co.uk>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Borislav Petkov <bp@...e.de>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
---
 arch/x86/include/asm/nospec-branch.h |  2 --
 arch/x86/kernel/cpu/bugs.c           | 13 ++-----------
 2 files changed, 2 insertions(+), 13 deletions(-)

diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index 8b09cbb..c202a64 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -221,8 +221,6 @@
 /* The Spectre V2 mitigation variants */
 enum spectre_v2_mitigation {
 	SPECTRE_V2_NONE,
-	SPECTRE_V2_RETPOLINE_MINIMAL,
-	SPECTRE_V2_RETPOLINE_MINIMAL_AMD,
 	SPECTRE_V2_RETPOLINE_GENERIC,
 	SPECTRE_V2_RETPOLINE_AMD,
 	SPECTRE_V2_IBRS_ENHANCED,
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index d0108fb..7f6d815 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -135,8 +135,6 @@ enum spectre_v2_mitigation_cmd {
 
 static const char *spectre_v2_strings[] = {
 	[SPECTRE_V2_NONE]			= "Vulnerable",
-	[SPECTRE_V2_RETPOLINE_MINIMAL]		= "Vulnerable: Minimal generic ASM retpoline",
-	[SPECTRE_V2_RETPOLINE_MINIMAL_AMD]	= "Vulnerable: Minimal AMD ASM retpoline",
 	[SPECTRE_V2_RETPOLINE_GENERIC]		= "Mitigation: Full generic retpoline",
 	[SPECTRE_V2_RETPOLINE_AMD]		= "Mitigation: Full AMD retpoline",
 	[SPECTRE_V2_IBRS_ENHANCED]		= "Mitigation: Enhanced IBRS",
@@ -250,11 +248,6 @@ static void __init spec2_print_if_secure(const char *reason)
 		pr_info("%s selected on command line.\n", reason);
 }
 
-static inline bool retp_compiler(void)
-{
-	return __is_defined(CONFIG_RETPOLINE);
-}
-
 static inline bool match_option(const char *arg, int arglen, const char *opt)
 {
 	int len = strlen(opt);
@@ -417,14 +410,12 @@ static void __init spectre_v2_select_mitigation(void)
 			pr_err("Spectre mitigation: LFENCE not serializing, switching to generic retpoline\n");
 			goto retpoline_generic;
 		}
-		mode = retp_compiler() ? SPECTRE_V2_RETPOLINE_AMD :
-					 SPECTRE_V2_RETPOLINE_MINIMAL_AMD;
+		mode = SPECTRE_V2_RETPOLINE_AMD;
 		setup_force_cpu_cap(X86_FEATURE_RETPOLINE_AMD);
 		setup_force_cpu_cap(X86_FEATURE_RETPOLINE);
 	} else {
 	retpoline_generic:
-		mode = retp_compiler() ? SPECTRE_V2_RETPOLINE_GENERIC :
-					 SPECTRE_V2_RETPOLINE_MINIMAL;
+		mode = SPECTRE_V2_RETPOLINE_GENERIC;
 		setup_force_cpu_cap(X86_FEATURE_RETPOLINE);
 	}
 
-- 
1.8.3.1