* [PATCH v2] kasan: account for destructor sections
@ 2016-06-23 16:06 Dmitry Vyukov
2016-06-24 15:26 ` Andrey Ryabinin
0 siblings, 1 reply; 2+ messages in thread
From: Dmitry Vyukov @ 2016-06-23 16:06 UTC (permalink / raw)
To: tglx, mingo, hpa, x86, arnd, linux-arch, ryabinin.a.a
Cc: kasan-dev, glider, Dmitry Vyukov
If CONFIG_KASAN is enabled and gcc is configured with
--disable-initfini-array, 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. 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
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.
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
---
Changes since v1:
- discard .dtors
- don't define .mem sections
---
include/asm-generic/vmlinux.lds.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 6a67ab9..081d0f2 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -542,15 +542,19 @@
#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 \
--
2.8.0.rc3.226.g39d4020
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2] kasan: account for destructor sections
2016-06-23 16:06 [PATCH v2] kasan: account for destructor sections Dmitry Vyukov
@ 2016-06-24 15:26 ` Andrey Ryabinin
0 siblings, 0 replies; 2+ messages in thread
From: Andrey Ryabinin @ 2016-06-24 15:26 UTC (permalink / raw)
To: Dmitry Vyukov
Cc: Thomas Gleixner, Ingo Molnar, H. Peter Anvin, x86@kernel.org,
Arnd Bergmann, linux-arch, kasan-dev, Alexander Potapenko
2016-06-23 19:06 GMT+03:00 Dmitry Vyukov <dvyukov@google.com>:
Subsystem prefix in subject is wrong. Change it to vmlinux.lds
> If CONFIG_KASAN is enabled and gcc is configured with
> --disable-initfini-array, 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. Want:
As far as I found out this happens if gold linker has been used.
Gcc configuration is irrelevant here.
> 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
>
> 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.
>
> Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
>
> ---
>
> Changes since v1:
> - discard .dtors
> - don't define .mem sections
> ---
> include/asm-generic/vmlinux.lds.h | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index 6a67ab9..081d0f2 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -542,15 +542,19 @@
>
> #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 \
> --
> 2.8.0.rc3.226.g39d4020
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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