mm: kasan: mark file report so ftrace doesn't trace it

Message ID 20190603091148.24898-1-anders.roxell@linaro.org
State New
Headers show
Series
  • mm: kasan: mark file report so ftrace doesn't trace it
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Commit Message

Anders Roxell June 3, 2019, 9:11 a.m.
__kasan_report() triggers ftrace and the preempt_count() in ftrace
causes a call to __asan_load4(), breaking the circular dependency by
making report as no trace for ftrace.

Signed-off-by: Anders Roxell <anders.roxell@linaro.org>

---
 mm/kasan/Makefile | 3 +++
 1 file changed, 3 insertions(+)

-- 
2.20.1

Comments

Dmitry Vyukov June 3, 2019, 10:50 a.m. | #1
On Mon, Jun 3, 2019 at 11:11 AM Anders Roxell <anders.roxell@linaro.org> wrote:
>

> __kasan_report() triggers ftrace and the preempt_count() in ftrace

> causes a call to __asan_load4(), breaking the circular dependency by

> making report as no trace for ftrace.

>

> Signed-off-by: Anders Roxell <anders.roxell@linaro.org>

> ---

>  mm/kasan/Makefile | 3 +++

>  1 file changed, 3 insertions(+)

>

> diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile

> index 08b43de2383b..2b2da731483c 100644

> --- a/mm/kasan/Makefile

> +++ b/mm/kasan/Makefile

> @@ -3,12 +3,14 @@ KASAN_SANITIZE := n

>  UBSAN_SANITIZE_common.o := n

>  UBSAN_SANITIZE_generic.o := n

>  UBSAN_SANITIZE_generic_report.o := n

> +UBSAN_SANITIZE_report.o := n

>  UBSAN_SANITIZE_tags.o := n

>  KCOV_INSTRUMENT := n

>

>  CFLAGS_REMOVE_common.o = $(CC_FLAGS_FTRACE)

>  CFLAGS_REMOVE_generic.o = $(CC_FLAGS_FTRACE)

>  CFLAGS_REMOVE_generic_report.o = $(CC_FLAGS_FTRACE)

> +CFLAGS_REMOVE_report.o = $(CC_FLAGS_FTRACE)

>  CFLAGS_REMOVE_tags.o = $(CC_FLAGS_FTRACE)

>

>  # Function splitter causes unnecessary splits in __asan_load1/__asan_store1

> @@ -17,6 +19,7 @@ CFLAGS_REMOVE_tags.o = $(CC_FLAGS_FTRACE)

>  CFLAGS_common.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)

>  CFLAGS_generic.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)

>  CFLAGS_generic_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)

> +CFLAGS_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)

>  CFLAGS_tags.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)

>

>  obj-$(CONFIG_KASAN) := common.o init.o report.o



Acked-by: Dmitry Vyukov <dvyukov@google.com>


Is it needed in all section? Or you just followed the pattern?
Different flag changes were initially done on very specific files for
specific reasons. E.g. -fno-conserve-stack is only for performance
reasons, so report* should not be there. But I see Peter already added
generic_report.o there. Perhaps we need to give up on selective
per-file changes, because this causes constant flow of new bugs in the
absence of testing and just do something like:

KASAN_SANITIZE := n
KCOV_INSTRUMENT := n
UBSAN_SANITIZE := n
CFLAGS_REMOVE = $(CC_FLAGS_FTRACE)
CFLAGS := $(call cc-option, -fno-conserve-stack -fno-stack-protector)

Patch

diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile
index 08b43de2383b..2b2da731483c 100644
--- a/mm/kasan/Makefile
+++ b/mm/kasan/Makefile
@@ -3,12 +3,14 @@  KASAN_SANITIZE := n
 UBSAN_SANITIZE_common.o := n
 UBSAN_SANITIZE_generic.o := n
 UBSAN_SANITIZE_generic_report.o := n
+UBSAN_SANITIZE_report.o := n
 UBSAN_SANITIZE_tags.o := n
 KCOV_INSTRUMENT := n
 
 CFLAGS_REMOVE_common.o = $(CC_FLAGS_FTRACE)
 CFLAGS_REMOVE_generic.o = $(CC_FLAGS_FTRACE)
 CFLAGS_REMOVE_generic_report.o = $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_report.o = $(CC_FLAGS_FTRACE)
 CFLAGS_REMOVE_tags.o = $(CC_FLAGS_FTRACE)
 
 # Function splitter causes unnecessary splits in __asan_load1/__asan_store1
@@ -17,6 +19,7 @@  CFLAGS_REMOVE_tags.o = $(CC_FLAGS_FTRACE)
 CFLAGS_common.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)
 CFLAGS_generic.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)
 CFLAGS_generic_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)
+CFLAGS_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)
 CFLAGS_tags.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)
 
 obj-$(CONFIG_KASAN) := common.o init.o report.o