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From: Andi Kleen <andi@firstfloor.org>
To: linux-kernel@vger.kernel.org
Cc: x86@kernel.org, samitolvanen@google.com, alxmtvv@gmail.com,
	linux-kbuild@vger.kernel.org, yamada.masahiro@socionext.com,
	akpm@linux-foundation.org, Andi Kleen <ak@linux.intel.com>
Subject: [PATCH 16/21] lto: Add __noreorder and mark initcalls __noreorder
Date: Mon, 27 Nov 2017 13:34:18 -0800	[thread overview]
Message-ID: <20171127213423.27218-17-andi@firstfloor.org> (raw)
In-Reply-To: <20171127213423.27218-1-andi@firstfloor.org>

From: Andi Kleen <ak@linux.intel.com>

gcc 5 has a new no_reorder attribute that prevents top level
reordering only for that symbol.

Kernels don't like any reordering of initcalls between files, as several
initcalls depend on each other. LTO previously needed to use
-fno-toplevel-reordering to prevent boot failures.

Add a __noreorder wrapper for the no_reorder attribute and use
it for initcalls.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 include/linux/compiler-gcc.h   | 5 +++++
 include/linux/compiler_types.h | 3 +++
 include/linux/init.h           | 2 +-
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index 2272ded07496..0d562baeb379 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -324,6 +324,11 @@
 #define __no_sanitize_address
 #endif
 
+#if __GNUC__ >= 5
+/* Avoid reordering a top level statement */
+#define __noreorder    __attribute__((no_reorder))
+#endif
+
 /*
  * A trick to suppress uninitialized variable warning without generating any
  * code
diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index 6b79a9bba9a7..fe4604603f5e 100644
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -260,6 +260,9 @@ struct ftrace_likely_data {
 #define __assume_aligned(a, ...)
 #endif
 
+#ifndef __noreorder
+#define __noreorder
+#endif
 
 /* Are two types/vars the same type (ignoring qualifiers)? */
 #ifndef __same_type
diff --git a/include/linux/init.h b/include/linux/init.h
index ea1b31101d9e..abf1980367b7 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -161,7 +161,7 @@ extern bool initcall_debug;
  */
 
 #define __define_initcall(fn, id) \
-	static initcall_t __initcall_##fn##id __used \
+	static initcall_t __initcall_##fn##id __used __noreorder \
 	__attribute__((__section__(".initcall" #id ".init"))) = fn;
 
 /*
-- 
2.13.6


  parent reply	other threads:[~2017-11-27 21:34 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-27 21:34 Link time optimization for LTO/x86 Andi Kleen
2017-11-27 21:34 ` [PATCH 01/21] x86/xen: Mark pv stub assembler symbol visible Andi Kleen
2017-11-27 21:34 ` [PATCH 02/21] afs: Fix const confusion in AFS Andi Kleen
2017-11-27 21:34 ` [PATCH 03/21] x86/timer: Don't inline __const_udelay Andi Kleen
2017-11-27 21:34 ` [PATCH 04/21] locking/spinlocks: Mark spinlocks noinline when inline spinlocks are disabled Andi Kleen
2017-11-27 21:34 ` [PATCH 05/21] x86/kvm: Make steal_time visible Andi Kleen
2017-11-27 21:34 ` [PATCH 06/21] x86/syscalls: Make x86 syscalls use real prototypes Andi Kleen
2017-11-27 21:34 ` [PATCH 07/21] x86: Make exception handler functions visible Andi Kleen
2017-11-27 21:34 ` [PATCH 08/21] x86/idt: Make const __initconst Andi Kleen
2017-11-27 21:34 ` [PATCH 09/21] lto: Use C version for SYSCALL_ALIAS Andi Kleen
2017-11-27 21:34 ` [PATCH 10/21] Fix read buffer overflow in delta-ipc Andi Kleen
2017-11-27 21:34 ` [PATCH 11/21] trace: Use -mcount-record for dynamic ftrace Andi Kleen
2017-12-01  0:22   ` Steven Rostedt
2018-05-01 18:42     ` Steven Rostedt
2017-11-27 21:34 ` [PATCH 12/21] ftrace: Mark function tracer test functions noinline/noclone Andi Kleen
2017-11-27 21:34 ` [PATCH 13/21] ftrace: Disable LTO for ftrace self tests Andi Kleen
2017-11-27 21:34 ` [PATCH 14/21] lto, fs: Avoid static variable in linux/fs.h Andi Kleen
2017-11-27 21:34 ` [PATCH 15/21] lto, x86, mm: Disable vmalloc BUILD_BUG_ON for LTO Andi Kleen
2017-11-27 21:34 ` Andi Kleen [this message]
2017-11-27 21:34 ` [PATCH 17/21] lto, workaround: Disable LTO for BPF Andi Kleen
2017-11-27 21:34 ` [PATCH 18/21] lto, crypto: Disable LTO for camelia glue Andi Kleen
2017-11-27 21:34 ` [PATCH 19/21] lto, x86: Disable LTO for realmode / vDSO / head64 Andi Kleen
2017-11-27 21:34 ` [PATCH 20/21] Kbuild, lto: Add Link Time Optimization support Andi Kleen
2018-01-27  0:15   ` Arnd Bergmann
2018-01-27  0:55     ` Andi Kleen
2018-01-27 14:26       ` Arnd Bergmann
2018-01-28 18:33         ` Andi Kleen
2017-11-27 21:34 ` [PATCH 21/21] x86: Enable Link Time Optimization Andi Kleen
2017-11-28 16:04 ` [PATCH 02/21] afs: Fix const confusion in AFS David Howells
2017-11-28 16:50   ` Andi Kleen
2017-11-29 23:09 ` Link time optimization for LTO/x86 Sami Tolvanen

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