LinuxLists.cc - [PATCH] x86/mm: disable instrumentations of mm/pgprot.c

2022-08-24 09:13:12

Subject: [PATCH] x86/mm: disable instrumentations of mm/pgprot.c

The commit 4867fbbdd6b3 ("x86/mm: move protection_map[] inside the
platform") moved accesses to protection_map[] from mem_encrypt_amd.c to
pgprot.c. As a result, the accesses are now targets of KASAN (and other
instrumentations), leading to the crash during the boot process.

Disable the instrumentations for pgprot.c like commit 67bb8e999e0a
("x86/mm: Disable various instrumentations of mm/mem_encrypt.c and
mm/tlb.c").

Before this patch, my AMD machine cannot boot since v6.0-rc1 with KASAN
enabled, without anything printed. After the change, it successfully boots
up.

Cc: Anshuman Khandual <[email protected]>
Signed-off-by: Naohiro Aota <[email protected]>
---
arch/x86/mm/Makefile | 3 +++
1 file changed, 3 insertions(+)

diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile
index f8220fd2c169..829c1409ffbd 100644
--- a/arch/x86/mm/Makefile
+++ b/arch/x86/mm/Makefile
@@ -4,10 +4,12 @@ KCOV_INSTRUMENT_tlb.o := n
KCOV_INSTRUMENT_mem_encrypt.o := n
KCOV_INSTRUMENT_mem_encrypt_amd.o := n
KCOV_INSTRUMENT_mem_encrypt_identity.o := n
+KCOV_INSTRUMENT_pgprot.o := n

KASAN_SANITIZE_mem_encrypt.o := n
KASAN_SANITIZE_mem_encrypt_amd.o := n
KASAN_SANITIZE_mem_encrypt_identity.o := n
+KASAN_SANITIZE_pgprot.o := n

# Disable KCSAN entirely, because otherwise we get warnings that some functions
# reference __initdata sections.
@@ -17,6 +19,7 @@ ifdef CONFIG_FUNCTION_TRACER
CFLAGS_REMOVE_mem_encrypt.o = -pg
CFLAGS_REMOVE_mem_encrypt_amd.o = -pg
CFLAGS_REMOVE_mem_encrypt_identity.o = -pg
+CFLAGS_REMOVE_pgprot.o = -pg
endif

obj-y := init.o init_$(BITS).o fault.o ioremap.o extable.o mmap.o \
--
2.37.2

2022-08-31 00:27:23

by Naohiro Aota

[permalink] [raw]

Subject: Re: [PATCH] x86/mm: disable instrumentations of mm/pgprot.c

On Wed, Aug 24, 2022 at 05:47:26PM +0900, Naohiro Aota wrote:
> The commit 4867fbbdd6b3 ("x86/mm: move protection_map[] inside the
> platform") moved accesses to protection_map[] from mem_encrypt_amd.c to
> pgprot.c. As a result, the accesses are now targets of KASAN (and other
> instrumentations), leading to the crash during the boot process.
>
> Disable the instrumentations for pgprot.c like commit 67bb8e999e0a
> ("x86/mm: Disable various instrumentations of mm/mem_encrypt.c and
> mm/tlb.c").
>
> Before this patch, my AMD machine cannot boot since v6.0-rc1 with KASAN
> enabled, without anything printed. After the change, it successfully boots
> up.
>
> Cc: Anshuman Khandual <[email protected]>
> Signed-off-by: Naohiro Aota <[email protected]>
> ---
> arch/x86/mm/Makefile | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile
> index f8220fd2c169..829c1409ffbd 100644
> --- a/arch/x86/mm/Makefile
> +++ b/arch/x86/mm/Makefile
> @@ -4,10 +4,12 @@ KCOV_INSTRUMENT_tlb.o := n
> KCOV_INSTRUMENT_mem_encrypt.o := n
> KCOV_INSTRUMENT_mem_encrypt_amd.o := n
> KCOV_INSTRUMENT_mem_encrypt_identity.o := n
> +KCOV_INSTRUMENT_pgprot.o := n
>
> KASAN_SANITIZE_mem_encrypt.o := n
> KASAN_SANITIZE_mem_encrypt_amd.o := n
> KASAN_SANITIZE_mem_encrypt_identity.o := n
> +KASAN_SANITIZE_pgprot.o := n
>
> # Disable KCSAN entirely, because otherwise we get warnings that some functions
> # reference __initdata sections.
> @@ -17,6 +19,7 @@ ifdef CONFIG_FUNCTION_TRACER
> CFLAGS_REMOVE_mem_encrypt.o = -pg
> CFLAGS_REMOVE_mem_encrypt_amd.o = -pg
> CFLAGS_REMOVE_mem_encrypt_identity.o = -pg
> +CFLAGS_REMOVE_pgprot.o = -pg
> endif
>
> obj-y := init.o init_$(BITS).o fault.o ioremap.o extable.o mmap.o \
> --
> 2.37.2
>

Hello, maintainers.

Gentle ping on this patch. I need this patch to boot up my AMD machine with
KASAN enabled.

2022-09-21 09:08:35

by Niklas Cassel

[permalink] [raw]