From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Vyukov Subject: [PATCH] kasan: account for new sections when instrumenting globals Date: Wed, 22 Jun 2016 19:07:18 +0200 Message-ID: <1466615238-57411-1-git-send-email-dvyukov@google.com> Return-path: Received: from mail-wm0-f46.google.com ([74.125.82.46]:36951 "EHLO mail-wm0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752196AbcFVRHY (ORCPT ); Wed, 22 Jun 2016 13:07:24 -0400 Received: by mail-wm0-f46.google.com with SMTP id a66so15086325wme.0 for ; Wed, 22 Jun 2016 10:07:23 -0700 (PDT) Sender: linux-arch-owner@vger.kernel.org List-ID: To: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, arnd@arndb.de, linux-arch@vger.kernel.org, ryabinin.a.a@gmail.com Cc: kasan-dev@googlegroups.com, glider@google.com, Dmitry Vyukov When I build kernel with CONFIG_KASAN and gcc6 (which instruments globals and inserts global constructors and destructors), vmlinux contains some new unaccounted sections: .text.exit .text.startup .dtors. This messes vvar/percpu layout. 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 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 If my reading of the linker script is correct, this happens because __vvar_page and .vvar get different addresses here: //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 = .; Merge .text.exit into EXIT_TEXT, .text.startup into INIT_TEXT and .dtors into INIT_DATA. Signed-off-by: Dmitry Vyukov --- I can't say I fully understand what happens here, but it fixes my build and boot. I think we need something along these lines, but I am not sure about details. --- include/asm-generic/vmlinux.lds.h | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 6a67ab9..6067d01 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -510,6 +510,7 @@ #define KERNEL_CTORS() . = ALIGN(8); \ VMLINUX_SYMBOL(__ctors_start) = .; \ *(.ctors) \ + *(.dtors) \ *(SORT(.init_array.*)) \ *(.init_array) \ VMLINUX_SYMBOL(__ctors_end) = .; @@ -542,7 +543,9 @@ #define INIT_TEXT \ *(.init.text) \ - MEM_DISCARD(init.text) + *(.text.startup) \ + MEM_DISCARD(init.text) \ + MEM_DISCARD(text.startup) #define EXIT_DATA \ *(.exit.data) \ @@ -551,7 +554,9 @@ #define EXIT_TEXT \ *(.exit.text) \ - MEM_DISCARD(exit.text) + *(.text.exit) \ + MEM_DISCARD(exit.text) \ + MEM_DISCARD(text.exit) #define EXIT_CALL \ *(.exitcall.exit) -- 2.8.0.rc3.226.g39d4020