[PATCH 4.19 032/139] x86/retpoline: Remove minimal retpoline support

From: Greg Kroah-Hartman
Date: Tue Dec 04 2018 - 06:31:53 EST


4.19-stable review patch. If anyone has any objections, please let me know.

------------------

From: Zhenzhong Duan zhenzhong.duan@xxxxxxxxxx

commit ef014aae8f1cd2793e4e014bbb102bed53f852b7 upstream

Now that CONFIG_RETPOLINE hard depends on compiler support, there is no
reason to keep the minimal retpoline support around which only provided
basic protection in the assembly files.

Suggested-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: David Woodhouse <dwmw@xxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: <srinivas.eeda@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/f06f0a89-5587-45db-8ed2-0a9d6638d5c0@default
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/include/asm/nospec-branch.h | 2 --
arch/x86/kernel/cpu/bugs.c | 13 ++-----------
2 files changed, 2 insertions(+), 13 deletions(-)

--- 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,
--- 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
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);
@@ -415,14 +408,12 @@ retpoline_auto:
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);
}