From: David Woodhouse <dwmw@amazon.co.uk>
To: tglx@linutronix.de, karahmed@amazon.de, x86@kernel.org,
kvm@vger.kernel.org, torvalds@linux-foundation.org,
pbonzini@redhat.com, linux-kernel@vger.kernel.org, bp@alien8.de,
peterz@infradead.org, jmattson@google.com, rkrcmar@redhat.com,
arjan.van.de.ven@intel.com, dave.hansen@intel.com,
mingo@kernel.org
Subject: [PATCH v3 4/4] x86/retpoline: Support retpoline build with Clang
Date: Mon, 19 Feb 2018 10:50:57 +0000 [thread overview]
Message-ID: <1519037457-7643-5-git-send-email-dwmw@amazon.co.uk> (raw)
In-Reply-To: <1519037457-7643-1-git-send-email-dwmw@amazon.co.uk>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
arch/x86/Makefile | 5 ++++-
include/linux/compiler-clang.h | 5 +++++
include/linux/compiler-gcc.h | 4 ++++
include/linux/init.h | 8 ++++----
4 files changed, 17 insertions(+), 5 deletions(-)
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index fad5516..dbc7d0e 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -232,7 +232,10 @@ KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
# Avoid indirect branches in kernel to deal with Spectre
ifdef CONFIG_RETPOLINE
- RETPOLINE_CFLAGS += $(call cc-option,-mindirect-branch=thunk-extern -mindirect-branch-register)
+ RETPOLINE_CFLAGS_GCC := -mindirect-branch=thunk-extern -mindirect-branch-register
+ 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
endif
diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
index d02a4df..d3f264a 100644
--- a/include/linux/compiler-clang.h
+++ b/include/linux/compiler-clang.h
@@ -27,3 +27,8 @@
#if __has_feature(address_sanitizer)
#define __SANITIZE_ADDRESS__
#endif
+
+/* Clang doesn't have a way to turn it off per-function, yet. */
+#ifdef __noretpoline
+#undef __noretpoline
+#endif
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index 73bc63e..673fbf9 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -93,6 +93,10 @@
#define __weak __attribute__((weak))
#define __alias(symbol) __attribute__((alias(#symbol)))
+#ifdef RETPOLINE
+#define __noretpoline __attribute__((indirect_branch("keep")))
+#endif
+
/*
* it doesn't make sense on ARM (currently the only user of __naked)
* to trace naked functions because then mcount is called without
diff --git a/include/linux/init.h b/include/linux/init.h
index 506a981..bc27cf0 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -6,10 +6,10 @@
#include <linux/types.h>
/* Built-in __init functions needn't be compiled with retpoline */
-#if defined(RETPOLINE) && !defined(MODULE)
-#define __noretpoline __attribute__((indirect_branch("keep")))
+#if defined(__noretpoline) && !defined(MODULE)
+#define __noinitretpoline __noretpoline
#else
-#define __noretpoline
+#define __noinitretpoline
#endif
/* These macros are used to mark some functions or
@@ -47,7 +47,7 @@
/* These are for everybody (although not all archs will actually
discard it in modules) */
-#define __init __section(.init.text) __cold __latent_entropy __noretpoline
+#define __init __section(.init.text) __cold __latent_entropy __noinitretpoline
#define __initdata __section(.init.data)
#define __initconst __section(.init.rodata)
#define __exitdata __section(.exit.data)
--
2.7.4
next prev parent reply other threads:[~2018-02-19 10:51 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-19 10:50 [PATCH v3 0/4] Speculation control improvements David Woodhouse
2018-02-19 10:50 ` [PATCH v3 1/4] x86/speculation: Use IBRS if available before calling into firmware David Woodhouse
2018-02-20 7:44 ` Thomas Gleixner
2018-02-20 10:29 ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-02-19 10:50 ` [PATCH v3 2/4] x86/speculation: Support "Enhanced IBRS" on future CPUs David Woodhouse
2018-02-20 8:31 ` Thomas Gleixner
2018-02-20 8:53 ` David Woodhouse
2018-02-20 10:37 ` Thomas Gleixner
2018-02-20 10:42 ` Thomas Gleixner
2018-02-20 11:22 ` David Woodhouse
2018-02-20 11:28 ` Paolo Bonzini
2018-02-26 19:55 ` Thomas Gleixner
2018-02-20 11:26 ` Paolo Bonzini
2018-02-19 10:50 ` [PATCH v3 3/4] Revert "x86/retpoline: Simplify vmexit_fill_RSB()" David Woodhouse
2018-02-20 8:35 ` Thomas Gleixner
2018-02-20 10:28 ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-02-19 10:50 ` David Woodhouse [this message]
2018-02-20 8:36 ` [PATCH v3 4/4] x86/retpoline: Support retpoline build with Clang Thomas Gleixner
2018-02-20 8:45 ` David Woodhouse
2018-02-20 10:29 ` [tip:x86/pti] x86/retpoline: Support retpoline builds " tip-bot for David Woodhouse
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1519037457-7643-5-git-send-email-dwmw@amazon.co.uk \
--to=dwmw@amazon.co.uk \
--cc=arjan.van.de.ven@intel.com \
--cc=bp@alien8.de \
--cc=dave.hansen@intel.com \
--cc=jmattson@google.com \
--cc=karahmed@amazon.de \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=pbonzini@redhat.com \
--cc=peterz@infradead.org \
--cc=rkrcmar@redhat.com \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.