From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>,
Zhenzhong Duan <zhenzhong.duan@oracle.com>,
Thomas Gleixner <tglx@linutronix.de>,
David Woodhouse <dwmw@amazon.co.uk>, Borislav Petkov <bp@suse.de>,
Daniel Borkmann <daniel@iogearbox.net>,
"H. Peter Anvin" <hpa@zytor.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Andy Lutomirski <luto@kernel.org>,
Masahiro Yamada <yamada.masahiro@socionext.com>,
Michal Marek <michal.lkml@markovi.net>,
srinivas.eeda@oracle.com, Ben Hutchings <ben@decadent.org.uk>
Subject: [PATCH 4.9 02/24] x86/retpoline: Make CONFIG_RETPOLINE depend on compiler support
Date: Wed, 9 Mar 2022 16:59:15 +0100 [thread overview]
Message-ID: <20220309155856.369868546@linuxfoundation.org> (raw)
In-Reply-To: <20220309155856.295480966@linuxfoundation.org>
From: Zhenzhong Duan <zhenzhong.duan@oracle.com>
commit 4cd24de3a0980bf3100c9dcb08ef65ca7c31af48 upstream.
Since retpoline capable compilers are widely available, make
CONFIG_RETPOLINE hard depend on the compiler capability.
Break the build when CONFIG_RETPOLINE is enabled and the compiler does not
support it. Emit an error message in that case:
"arch/x86/Makefile:226: *** You are building kernel with non-retpoline
compiler, please update your compiler.. Stop."
[dwmw: Fail the build with non-retpoline compiler]
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Borislav Petkov <bp@suse.de>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: <srinivas.eeda@oracle.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/cca0cb20-f9e2-4094-840b-fb0f8810cd34@default
[bwh: Backported to 4.9:
- Drop change to objtool options
- Adjust context, indentation]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/Kconfig | 4 ----
arch/x86/Makefile | 5 +++--
arch/x86/include/asm/nospec-branch.h | 10 ++++++----
arch/x86/kernel/cpu/bugs.c | 2 +-
4 files changed, 10 insertions(+), 11 deletions(-)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -418,10 +418,6 @@ config RETPOLINE
branches. Requires a compiler with -mindirect-branch=thunk-extern
support for full protection. The kernel may run slower.
- Without compiler support, at least indirect branches in assembler
- code are eliminated. Since this includes the syscall entry path,
- it is not entirely pointless.
-
if X86_32
config X86_EXTENDED_PLATFORM
bool "Support for extended (non-PC) x86 platforms"
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -221,9 +221,10 @@ ifdef CONFIG_RETPOLINE
RETPOLINE_CFLAGS_CLANG := -mretpoline-external-thunk
RETPOLINE_CFLAGS += $(call cc-option,$(RETPOLINE_CFLAGS_GCC),$(call cc-option,$(RETPOLINE_CFLAGS_CLANG)))
- ifneq ($(RETPOLINE_CFLAGS),)
- KBUILD_CFLAGS += $(RETPOLINE_CFLAGS) -DRETPOLINE
+ ifeq ($(RETPOLINE_CFLAGS),)
+ $(error You are building kernel with non-retpoline compiler, please update your compiler.)
endif
+ KBUILD_CFLAGS += $(RETPOLINE_CFLAGS)
endif
archscripts: scripts_basic
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -164,11 +164,12 @@
_ASM_PTR " 999b\n\t" \
".popsection\n\t"
-#if defined(CONFIG_X86_64) && defined(RETPOLINE)
+#ifdef CONFIG_RETPOLINE
+#ifdef CONFIG_X86_64
/*
- * Since the inline asm uses the %V modifier which is only in newer GCC,
- * the 64-bit one is dependent on RETPOLINE not CONFIG_RETPOLINE.
+ * Inline asm uses the %V modifier which is only in newer GCC
+ * which is ensured when CONFIG_RETPOLINE is defined.
*/
# define CALL_NOSPEC \
ANNOTATE_NOSPEC_ALTERNATIVE \
@@ -183,7 +184,7 @@
X86_FEATURE_RETPOLINE_AMD)
# define THUNK_TARGET(addr) [thunk_target] "r" (addr)
-#elif defined(CONFIG_X86_32) && defined(CONFIG_RETPOLINE)
+#else /* CONFIG_X86_32 */
/*
* For i386 we use the original ret-equivalent retpoline, because
* otherwise we'll run out of registers. We don't care about CET
@@ -213,6 +214,7 @@
X86_FEATURE_RETPOLINE_AMD)
# define THUNK_TARGET(addr) [thunk_target] "rm" (addr)
+#endif
#else /* No retpoline for C / inline asm */
# define CALL_NOSPEC "call *%[thunk_target]\n"
# define THUNK_TARGET(addr) [thunk_target] "rm" (addr)
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -812,7 +812,7 @@ static void __init spec_v2_print_cond(co
static inline bool retp_compiler(void)
{
- return __is_defined(RETPOLINE);
+ return __is_defined(CONFIG_RETPOLINE);
}
static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void)
next prev parent reply other threads:[~2022-03-09 16:01 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-09 15:59 [PATCH 4.9 00/24] 4.9.306-rc1 review Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 01/24] x86/speculation: Add RETPOLINE_AMD support to the inline asm CALL_NOSPEC variant Greg Kroah-Hartman
2022-03-09 15:59 ` Greg Kroah-Hartman [this message]
2022-03-09 19:58 ` [PATCH 4.9 02/24] x86/retpoline: Make CONFIG_RETPOLINE depend on compiler support Ben Hutchings
2022-03-09 22:39 ` Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 03/24] x86/retpoline: Remove minimal retpoline support Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 04/24] Documentation: Add section about CPU vulnerabilities for Spectre Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 05/24] Documentation: Add swapgs description to the Spectre v1 documentation Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 06/24] Documentation: refer to config RANDOMIZE_BASE for kernel address-space randomization Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 07/24] x86/speculation: Merge one test in spectre_v2_user_select_mitigation() Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 08/24] x86,bugs: Unconditionally allow spectre_v2=retpoline,amd Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 09/24] x86/speculation: Rename RETPOLINE_AMD to RETPOLINE_LFENCE Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 10/24] x86/speculation: Add eIBRS + Retpoline options Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 11/24] Documentation/hw-vuln: Update spectre doc Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 12/24] x86/speculation: Include unprivileged eBPF status in Spectre v2 mitigation reporting Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 13/24] x86/speculation: Use generic retpoline by default on AMD Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 14/24] x86/speculation: Update link to AMD speculation whitepaper Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 15/24] x86/speculation: Warn about Spectre v2 LFENCE mitigation Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 16/24] x86/speculation: Warn about eIBRS + LFENCE + Unprivileged eBPF + SMT Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 17/24] arm/arm64: Provide a wrapper for SMCCC 1.1 calls Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 18/24] arm/arm64: smccc/psci: add arm_smccc_1_1_get_conduit() Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 19/24] ARM: report Spectre v2 status through sysfs Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 20/24] ARM: early traps initialisation Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 21/24] ARM: use LOADADDR() to get load address of sections Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 22/24] ARM: Spectre-BHB workaround Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 23/24] ARM: include unprivileged BPF status in Spectre V2 reporting Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 4.9 24/24] ARM: fix build error when BPF_SYSCALL is disabled Greg Kroah-Hartman
2022-03-09 18:40 ` [PATCH 4.9 00/24] 4.9.306-rc1 review Daniel Díaz
2022-03-09 19:18 ` Daniel Díaz
2022-03-10 3:32 ` Florian Fainelli
2022-03-10 11:41 ` Pavel Machek
2022-03-10 11:48 ` Greg Kroah-Hartman
2022-03-09 20:26 ` Shuah Khan
2022-03-10 3:45 ` Florian Fainelli
2022-03-10 11:39 ` Pavel Machek
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