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 <dvyukov@xxxxxxxxxx>
---
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
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