linux-kernel - [PATCH 4.4 14/68] vmlinux.lds: account for destructor sections

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Date:	Mon,  8 Aug 2016 21:10:49 +0200
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Dmitry Vyukov <dvyukov@...gle.com>,
	Andrey Ryabinin <aryabinin@...tuozzo.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4.4 14/68] vmlinux.lds: account for destructor sections

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

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

From: Dmitry Vyukov <dvyukov@...gle.com>

commit e41f501d391265ff568f3e49d6128cc30856a36f upstream.

If CONFIG_KASAN is enabled and gcc is configured with
--disable-initfini-array and/or gold linker is used, gcc emits
.ctors/.dtors and .text.startup/.text.exit sections instead of
.init_array/.fini_array.  .dtors section is not explicitly accounted in
the linker script and messes vvar/percpu layout.

We want:
  ffffffff822bfd80 D _edata
  ffffffff822c0000 D __vvar_beginning_hack
  ffffffff822c0000 A __vvar_page
  ffffffff822c0080 0000000000000098 D vsyscall_gtod_data
  ffffffff822c1000 A __init_begin
  ffffffff822c1000 D init_per_cpu__irq_stack_union
  ffffffff822c1000 A __per_cpu_load
  ffffffff822d3000 D init_per_cpu__gdt_page

We got:
  ffffffff8279a600 D _edata
  ffffffff8279b000 A __vvar_page
  ffffffff8279c000 A __init_begin
  ffffffff8279c000 D init_per_cpu__irq_stack_union
  ffffffff8279c000 A __per_cpu_load
  ffffffff8279e000 D __vvar_beginning_hack
  ffffffff8279e080 0000000000000098 D vsyscall_gtod_data
  ffffffff827ae000 D init_per_cpu__gdt_page

This happens because __vvar_page and .vvar get different addresses in
arch/x86/kernel/vmlinux.lds.S:

	. = ALIGN(PAGE_SIZE);
	__vvar_page = .;

	.vvar : AT(ADDR(.vvar) - LOAD_OFFSET) {
		/* work around gold bug 13023 */
		__vvar_beginning_hack = .;

Discard .dtors/.fini_array/.text.exit, since we don't call dtors.
Merge .text.startup into init text.

Link: http://lkml.kernel.org/r/1467386363-120030-1-git-send-email-dvyukov@google.com
Signed-off-by: Dmitry Vyukov <dvyukov@...gle.com>
Reviewed-by: Andrey Ryabinin <aryabinin@...tuozzo.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 include/asm-generic/vmlinux.lds.h |    4 ++++
 1 file changed, 4 insertions(+)

--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -531,15 +531,19 @@
 
 #define INIT_TEXT							\
 	*(.init.text)							\
+	*(.text.startup)						\
 	MEM_DISCARD(init.text)
 
 #define EXIT_DATA							\
 	*(.exit.data)							\
+	*(.fini_array)							\
+	*(.dtors)							\
 	MEM_DISCARD(exit.data)						\
 	MEM_DISCARD(exit.rodata)
 
 #define EXIT_TEXT							\
 	*(.exit.text)							\
+	*(.text.exit)							\
 	MEM_DISCARD(exit.text)
 
 #define EXIT_CALL							\