[PATCH] powerpc/kasan: KASAN is not supported on RELOCATABLE && FSL_BOOKE

CONFIG_RELOCATABLE and CONFIG_KASAN cannot be enabled at the same time
on ppce500 fsl_booke. All functions called before kasan_early_init()
should be disabled with kasan check. When CONFIG_RELOCATABLE is enabled
on ppce500 fsl_booke, relocate_init() is called before kasan_early_init()
which triggers kasan check and results in boot failure.
Call trace and functions which triggers kasan check(*):
  - _start
   - set_ivor
    - relocate_init(*)
     - early_get_first_memblock_info(*)
      - of_scan_flat_dt(*)
	...
    - kasan_early_init

Potential solutions could be 1. implement relocate_init and all its children
function in a seperate file or 2. introduce a global vairable in KASAN, only
enable KASAN check when init is done.

Disable KASAN when RELOCATABLE is selected on fsl_booke for now until
it is supported.

Signed-off-by: Lexi Shao <redacted>
---
 arch/powerpc/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 3e56c9c2f16e..14f3da63c088 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig

@@ -171,7 +171,7 @@ config PPC
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_HUGE_VMAP		if PPC_BOOK3S_64 && PPC_RADIX_MMU
 	select HAVE_ARCH_JUMP_LABEL
-	select HAVE_ARCH_KASAN			if PPC32
+	select HAVE_ARCH_KASAN			if PPC32 && !(RELOCATABLE && FSL_BOOKE)
 	select HAVE_ARCH_KGDB
 	select HAVE_ARCH_MMAP_RND_BITS
 	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if COMPAT

-- 
2.12.3

Le 29/11/2019 à 08:04, Lexi Shao a écrit :

CONFIG_RELOCATABLE and CONFIG_KASAN cannot be enabled at the same time
on ppce500 fsl_booke. All functions called before kasan_early_init()
should be disabled with kasan check. When CONFIG_RELOCATABLE is enabled
on ppce500 fsl_booke, relocate_init() is called before kasan_early_init()
which triggers kasan check and results in boot failure.
Call trace and functions which triggers kasan check(*):
   - _start
    - set_ivor
     - relocate_init(*)
      - early_get_first_memblock_info(*)
       - of_scan_flat_dt(*)
	...
     - kasan_early_init

Potential solutions could be 1. implement relocate_init and all its children
function in a seperate file or 2. introduce a global vairable in KASAN, only
enable KASAN check when init is done.

Solution 1 seems uneasy. of_scan_flat_dt() and children are general 
functions that can't be set aside.
Solution 2 would destroy performance, and would anyway not work with 
inline instrumentation.

Have you tried moving the call to kasan_early_init() before the call of 
relocate_init() ?
On other PPC32, kasan_early_init() is the first thing done after 
activating the MMU. But AFAIU, MMU is always active on BOOKE though.

Christophe

Le 29/11/2019 à 08:46, Christophe Leroy a écrit :

Le 29/11/2019 à 08:04, Lexi Shao a écrit :

quoted

CONFIG_RELOCATABLE and CONFIG_KASAN cannot be enabled at the same time
on ppce500 fsl_booke. All functions called before kasan_early_init()
should be disabled with kasan check. When CONFIG_RELOCATABLE is enabled
on ppce500 fsl_booke, relocate_init() is called before kasan_early_init()
which triggers kasan check and results in boot failure.
Call trace and functions which triggers kasan check(*):
   - _start
    - set_ivor
     - relocate_init(*)
      - early_get_first_memblock_info(*)
       - of_scan_flat_dt(*)
    ...
     - kasan_early_init

Potential solutions could be 1. implement relocate_init and all its 
children
function in a seperate file or 2. introduce a global vairable in 
KASAN, only
enable KASAN check when init is done.

Solution 1 seems uneasy. of_scan_flat_dt() and children are general 
functions that can't be set aside.
Solution 2 would destroy performance, and would anyway not work with 
inline instrumentation.

Have you tried moving the call to kasan_early_init() before the call of 
relocate_init() ?

I just tried it with QEMU, it works. I'll send a patch out soon.

Christophe

On other PPC32, kasan_early_init() is the first thing done after 
activating the MMU. But AFAIU, MMU is always active on BOOKE though.

Christophe

quoted

Disable KASAN when RELOCATABLE is selected on fsl_booke for now until
it is supported.

Signed-off-by: Lexi Shao <redacted>
---
  arch/powerpc/Kconfig | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 3e56c9c2f16e..14f3da63c088 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig

@@ -171,7 +171,7 @@ config PPC

      select HAVE_ARCH_AUDITSYSCALL
      select HAVE_ARCH_HUGE_VMAP        if PPC_BOOK3S_64 && PPC_RADIX_MMU
      select HAVE_ARCH_JUMP_LABEL
-    select HAVE_ARCH_KASAN            if PPC32
+    select HAVE_ARCH_KASAN            if PPC32 && !(RELOCATABLE && 
FSL_BOOKE)
      select HAVE_ARCH_KGDB
      select HAVE_ARCH_MMAP_RND_BITS
      select HAVE_ARCH_MMAP_RND_COMPAT_BITS    if COMPAT