Fix selftest and kcsan_test() module fail when KCSAN_STRICT
and KCSAN_WEAK_MEMORY enabled on ARM64.
v4:
- Use 2 spaces after a sentence-ending '.', suggested by Marco
- Collect Ack/Review
v3:
- update dma_mb()'s description and add the generic definition,
also asm-generic change is moved into patch1, suggested by Marco.
v2:
- Add documents about dma_mb(), suggested by Mike and Will.
- drop Fixes tag and update changlog, suggested by Mike.
Kefeng Wang (2):
asm-generic: Add memory barrier dma_mb()
arm64: kcsan: Support detecting more missing memory barriers
Documentation/memory-barriers.txt | 11 ++++++-----
arch/arm64/include/asm/barrier.h | 12 ++++++------
include/asm-generic/barrier.h | 8 ++++++++
3 files changed, 20 insertions(+), 11 deletions(-)
--
2.35.3
As "kcsan: Support detecting a subset of missing memory barriers"[1]
introduced KCSAN_STRICT/KCSAN_WEAK_MEMORY which make kcsan detects
more missing memory barrier, but arm64 don't have KCSAN instrumentation
for barriers, so the new selftest test_barrier() and test cases for
memory barrier instrumentation in kcsan_test module will fail, even
panic on selftest.
Let's prefix all barriers with __ on arm64, as asm-generic/barriers.h
defined the final instrumented version of these barriers, which will
fix the above issues.
Note, barrier instrumentation that can be disabled via __no_kcsan with
appropriate compiler-support (and not just with objtool help), see
commit bd3d5bd1a0ad ("kcsan: Support WEAK_MEMORY with Clang where no
objtool support exists"), it adds disable_sanitizer_instrumentation to
__no_kcsan attribute which will remove all sanitizer instrumentation fully
(with Clang 14.0). Meanwhile, GCC does the same thing with no_sanitize.
[1] https://lore.kernel.org/linux-mm/[email protected]/
Acked-by: Marco Elver <[email protected]>
Signed-off-by: Kefeng Wang <[email protected]>
---
arch/arm64/include/asm/barrier.h | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h
index 9f3e2c3d2ca0..2cfc4245d2e2 100644
--- a/arch/arm64/include/asm/barrier.h
+++ b/arch/arm64/include/asm/barrier.h
@@ -50,13 +50,13 @@
#define pmr_sync() do {} while (0)
#endif
-#define mb() dsb(sy)
-#define rmb() dsb(ld)
-#define wmb() dsb(st)
+#define __mb() dsb(sy)
+#define __rmb() dsb(ld)
+#define __wmb() dsb(st)
-#define dma_mb() dmb(osh)
-#define dma_rmb() dmb(oshld)
-#define dma_wmb() dmb(oshst)
+#define __dma_mb() dmb(osh)
+#define __dma_rmb() dmb(oshld)
+#define __dma_wmb() dmb(oshst)
#define io_stop_wc() dgh()
--
2.35.3
On Mon, May 23, 2022 at 07:31:26PM +0800, Kefeng Wang wrote:
> As "kcsan: Support detecting a subset of missing memory barriers"[1]
> introduced KCSAN_STRICT/KCSAN_WEAK_MEMORY which make kcsan detects
> more missing memory barrier, but arm64 don't have KCSAN instrumentation
> for barriers, so the new selftest test_barrier() and test cases for
> memory barrier instrumentation in kcsan_test module will fail, even
> panic on selftest.
>
> Let's prefix all barriers with __ on arm64, as asm-generic/barriers.h
> defined the final instrumented version of these barriers, which will
> fix the above issues.
>
> Note, barrier instrumentation that can be disabled via __no_kcsan with
> appropriate compiler-support (and not just with objtool help), see
> commit bd3d5bd1a0ad ("kcsan: Support WEAK_MEMORY with Clang where no
> objtool support exists"), it adds disable_sanitizer_instrumentation to
> __no_kcsan attribute which will remove all sanitizer instrumentation fully
> (with Clang 14.0). Meanwhile, GCC does the same thing with no_sanitize.
>
> [1] https://lore.kernel.org/linux-mm/[email protected]/
>
> Acked-by: Marco Elver <[email protected]>
> Signed-off-by: Kefeng Wang <[email protected]>
Having built this with GCC 12.1.0 and LLVM 14.0.0, I think this patch itself
doesn't introduce any new problems, and logically makes sense. With that in
mind:
Acked-by: Mark Rutland <[email protected]>
As an aside, having scanned the resulting vmlinux with objdump, there are
plenty of latent issues where we get KCSAN instrumentation where we don't want
it (e.g. early/late in arm64's entry-common.o). The bulk of those are due to
missing `nonistr` or `__always_inline`, which we'll need to fix up.
Thanks,
Mark.
> ---
> arch/arm64/include/asm/barrier.h | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h
> index 9f3e2c3d2ca0..2cfc4245d2e2 100644
> --- a/arch/arm64/include/asm/barrier.h
> +++ b/arch/arm64/include/asm/barrier.h
> @@ -50,13 +50,13 @@
> #define pmr_sync() do {} while (0)
> #endif
>
> -#define mb() dsb(sy)
> -#define rmb() dsb(ld)
> -#define wmb() dsb(st)
> +#define __mb() dsb(sy)
> +#define __rmb() dsb(ld)
> +#define __wmb() dsb(st)
>
> -#define dma_mb() dmb(osh)
> -#define dma_rmb() dmb(oshld)
> -#define dma_wmb() dmb(oshst)
> +#define __dma_mb() dmb(osh)
> +#define __dma_rmb() dmb(oshld)
> +#define __dma_wmb() dmb(oshst)
>
> #define io_stop_wc() dgh()
>
> --
> 2.35.3
>
Hi Will and Catalin, kindly ping...
On 2022/5/23 22:16, Mark Rutland wrote:
> On Mon, May 23, 2022 at 07:31:26PM +0800, Kefeng Wang wrote:
>> As "kcsan: Support detecting a subset of missing memory barriers"[1]
>> introduced KCSAN_STRICT/KCSAN_WEAK_MEMORY which make kcsan detects
>> more missing memory barrier, but arm64 don't have KCSAN instrumentation
>> for barriers, so the new selftest test_barrier() and test cases for
>> memory barrier instrumentation in kcsan_test module will fail, even
>> panic on selftest.
>>
>> Let's prefix all barriers with __ on arm64, as asm-generic/barriers.h
>> defined the final instrumented version of these barriers, which will
>> fix the above issues.
>>
>> Note, barrier instrumentation that can be disabled via __no_kcsan with
>> appropriate compiler-support (and not just with objtool help), see
>> commit bd3d5bd1a0ad ("kcsan: Support WEAK_MEMORY with Clang where no
>> objtool support exists"), it adds disable_sanitizer_instrumentation to
>> __no_kcsan attribute which will remove all sanitizer instrumentation fully
>> (with Clang 14.0). Meanwhile, GCC does the same thing with no_sanitize.
>>
>> [1] https://lore.kernel.org/linux-mm/[email protected]/
>>
>> Acked-by: Marco Elver <[email protected]>
>> Signed-off-by: Kefeng Wang <[email protected]>
> Having built this with GCC 12.1.0 and LLVM 14.0.0, I think this patch itself
> doesn't introduce any new problems, and logically makes sense. With that in
> mind:
>
> Acked-by: Mark Rutland <[email protected]>
>
> As an aside, having scanned the resulting vmlinux with objdump, there are
> plenty of latent issues where we get KCSAN instrumentation where we don't want
> it (e.g. early/late in arm64's entry-common.o). The bulk of those are due to
> missing `nonistr` or `__always_inline`, which we'll need to fix up.
>
> Thanks,
> Mark.
>
>> ---
>> arch/arm64/include/asm/barrier.h | 12 ++++++------
>> 1 file changed, 6 insertions(+), 6 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h
>> index 9f3e2c3d2ca0..2cfc4245d2e2 100644
>> --- a/arch/arm64/include/asm/barrier.h
>> +++ b/arch/arm64/include/asm/barrier.h
>> @@ -50,13 +50,13 @@
>> #define pmr_sync() do {} while (0)
>> #endif
>>
>> -#define mb() dsb(sy)
>> -#define rmb() dsb(ld)
>> -#define wmb() dsb(st)
>> +#define __mb() dsb(sy)
>> +#define __rmb() dsb(ld)
>> +#define __wmb() dsb(st)
>>
>> -#define dma_mb() dmb(osh)
>> -#define dma_rmb() dmb(oshld)
>> -#define dma_wmb() dmb(oshst)
>> +#define __dma_mb() dmb(osh)
>> +#define __dma_rmb() dmb(oshld)
>> +#define __dma_wmb() dmb(oshst)
>>
>> #define io_stop_wc() dgh()
>>
>> --
>> 2.35.3
>>
> .
On Mon, May 23, 2022 at 07:31:26PM +0800, Kefeng Wang wrote:
> As "kcsan: Support detecting a subset of missing memory barriers"[1]
> introduced KCSAN_STRICT/KCSAN_WEAK_MEMORY which make kcsan detects
> more missing memory barrier, but arm64 don't have KCSAN instrumentation
> for barriers, so the new selftest test_barrier() and test cases for
> memory barrier instrumentation in kcsan_test module will fail, even
> panic on selftest.
>
> Let's prefix all barriers with __ on arm64, as asm-generic/barriers.h
> defined the final instrumented version of these barriers, which will
> fix the above issues.
>
> Note, barrier instrumentation that can be disabled via __no_kcsan with
> appropriate compiler-support (and not just with objtool help), see
> commit bd3d5bd1a0ad ("kcsan: Support WEAK_MEMORY with Clang where no
> objtool support exists"), it adds disable_sanitizer_instrumentation to
> __no_kcsan attribute which will remove all sanitizer instrumentation fully
> (with Clang 14.0). Meanwhile, GCC does the same thing with no_sanitize.
>
> [1] https://lore.kernel.org/linux-mm/[email protected]/
>
> Acked-by: Marco Elver <[email protected]>
> Signed-off-by: Kefeng Wang <[email protected]>
Acked-by: Catalin Marinas <[email protected]>
I'll leave the series to Will to queue for 5.20.
Thanks.
--
Catalin
On Mon, 23 May 2022 19:31:24 +0800, Kefeng Wang wrote:
> Fix selftest and kcsan_test() module fail when KCSAN_STRICT
> and KCSAN_WEAK_MEMORY enabled on ARM64.
>
> v4:
> - Use 2 spaces after a sentence-ending '.', suggested by Marco
> - Collect Ack/Review
>
> [...]
Applied to arm64 (for-next/kcsan), thanks!
[1/2] asm-generic: Add memory barrier dma_mb()
https://git.kernel.org/arm64/c/ed59dfd9509d
[2/2] arm64: kcsan: Support detecting more missing memory barriers
https://git.kernel.org/arm64/c/4d09caec2fab
Cheers,
--
Will
https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev