[PATCH 1/2] powerpc/memcpy: Fix stack corruption for smaller sizes

[PATCH 1/2] powerpc/memcpy: Fix stack corruption for smaller sizes

[Santosh Sivaraj]

For sizes lesser than 128 bytes, the code branches out early without saving
the stack frame, which when restored later drops frame of the caller.

Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Santosh Sivaraj <santosh@fossix.org>
---
 arch/powerpc/lib/memcpy_mcsafe_64.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/lib/memcpy_mcsafe_64.S b/arch/powerpc/lib/memcpy_mcsafe_64.S
index 949976dc115d..cb882d9a6d8a 100644
--- a/arch/powerpc/lib/memcpy_mcsafe_64.S
+++ b/arch/powerpc/lib/memcpy_mcsafe_64.S
@@ -84,7 +84,6 @@ err1;	stw	r0,0(r3)
 
 3:	sub	r5,r5,r6
 	cmpldi	r5,128
-	blt	5f
 
 	mflr	r0
 	stdu	r1,-STACKFRAMESIZE(r1)
@@ -99,6 +98,7 @@ err1;	stw	r0,0(r3)
 	std	r22,STK_REG(R22)(r1)
 	std	r0,STACKFRAMESIZE+16(r1)
 
+	blt	5f
 	srdi	r6,r5,7
 	mtctr	r6
 
-- 
2.21.0

[PATCH 2/2] seltests/powerpc: Add a selftest for memcpy_mcsafe

[Santosh Sivaraj]

Appropriate self tests for memcpy_mcsafe

Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Santosh Sivaraj <santosh@fossix.org>
---
 tools/testing/selftests/powerpc/copyloops/.gitignore       | 1 +
 tools/testing/selftests/powerpc/copyloops/Makefile         | 7 ++++++-
 tools/testing/selftests/powerpc/copyloops/asm/export.h     | 1 +
 .../testing/selftests/powerpc/copyloops/memcpy_mcsafe_64.S | 1 +
 4 files changed, 9 insertions(+), 1 deletion(-)
 create mode 120000 tools/testing/selftests/powerpc/copyloops/memcpy_mcsafe_64.S

diff --git a/tools/testing/selftests/powerpc/copyloops/.gitignore b/tools/testing/selftests/powerpc/copyloops/.gitignore
index de158104912a..12ef5b031974 100644
--- a/tools/testing/selftests/powerpc/copyloops/.gitignore
+++ b/tools/testing/selftests/powerpc/copyloops/.gitignore
@@ -11,3 +11,4 @@ memcpy_p7_t1
 copyuser_64_exc_t0
 copyuser_64_exc_t1
 copyuser_64_exc_t2
+memcpy_mcsafe_64
diff --git a/tools/testing/selftests/powerpc/copyloops/Makefile b/tools/testing/selftests/powerpc/copyloops/Makefile
index 44574f3818b3..0917983a1c78 100644
--- a/tools/testing/selftests/powerpc/copyloops/Makefile
+++ b/tools/testing/selftests/powerpc/copyloops/Makefile
@@ -12,7 +12,7 @@ ASFLAGS = $(CFLAGS) -Wa,-mpower4
 TEST_GEN_PROGS := copyuser_64_t0 copyuser_64_t1 copyuser_64_t2 \
 		copyuser_p7_t0 copyuser_p7_t1 \
 		memcpy_64_t0 memcpy_64_t1 memcpy_64_t2 \
-		memcpy_p7_t0 memcpy_p7_t1 \
+		memcpy_p7_t0 memcpy_p7_t1 memcpy_mcsafe_64 \
 		copyuser_64_exc_t0 copyuser_64_exc_t1 copyuser_64_exc_t2
 
 EXTRA_SOURCES := validate.c ../harness.c stubs.S
@@ -45,6 +45,11 @@ $(OUTPUT)/memcpy_p7_t%:	memcpy_power7.S $(EXTRA_SOURCES)
 		-D SELFTEST_CASE=$(subst memcpy_p7_t,,$(notdir $@)) \
 		-o $@ $^
 
+$(OUTPUT)/memcpy_mcsafe_64: memcpy_mcsafe_64.S $(EXTRA_SOURCES)
+	$(CC) $(CPPFLAGS) $(CFLAGS) \
+		-D COPY_LOOP=test_memcpy_mcsafe \
+		-o $@ $^
+
 $(OUTPUT)/copyuser_64_exc_t%: copyuser_64.S exc_validate.c ../harness.c \
 		copy_tofrom_user_reference.S stubs.S
 	$(CC) $(CPPFLAGS) $(CFLAGS) \
diff --git a/tools/testing/selftests/powerpc/copyloops/asm/export.h b/tools/testing/selftests/powerpc/copyloops/asm/export.h
index 05c1663c89b0..e6b80d5fbd14 100644
--- a/tools/testing/selftests/powerpc/copyloops/asm/export.h
+++ b/tools/testing/selftests/powerpc/copyloops/asm/export.h
@@ -1,3 +1,4 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #define EXPORT_SYMBOL(x)
+#define EXPORT_SYMBOL_GPL(x)
 #define EXPORT_SYMBOL_KASAN(x)
diff --git a/tools/testing/selftests/powerpc/copyloops/memcpy_mcsafe_64.S b/tools/testing/selftests/powerpc/copyloops/memcpy_mcsafe_64.S
new file mode 120000
index 000000000000..f0feef3062f6
--- /dev/null
+++ b/tools/testing/selftests/powerpc/copyloops/memcpy_mcsafe_64.S
@@ -0,0 +1 @@
+../../../../../arch/powerpc/lib/memcpy_mcsafe_64.S
\ No newline at end of file
-- 
2.21.0

Re: [PATCH 1/2] powerpc/memcpy: Fix stack corruption for smaller sizes

[Christophe Leroy]

Hi,

The subjet is misleading. This isn't powerpc but only powerpc/64, and 
this is not memcpy() but memcpy_mcsafe()

Christophe

Le 03/09/2019 à 23:43, Santosh Sivaraj a écrit :
> For sizes lesser than 128 bytes, the code branches out early without saving
> the stack frame, which when restored later drops frame of the caller.
> 
> Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> Signed-off-by: Santosh Sivaraj <santosh@fossix.org>
> ---
>   arch/powerpc/lib/memcpy_mcsafe_64.S | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/lib/memcpy_mcsafe_64.S b/arch/powerpc/lib/memcpy_mcsafe_64.S
> index 949976dc115d..cb882d9a6d8a 100644
> --- a/arch/powerpc/lib/memcpy_mcsafe_64.S
> +++ b/arch/powerpc/lib/memcpy_mcsafe_64.S
> @@ -84,7 +84,6 @@ err1;	stw	r0,0(r3)
>   
>   3:	sub	r5,r5,r6
>   	cmpldi	r5,128
> -	blt	5f
>   
>   	mflr	r0
>   	stdu	r1,-STACKFRAMESIZE(r1)
> @@ -99,6 +98,7 @@ err1;	stw	r0,0(r3)
>   	std	r22,STK_REG(R22)(r1)
>   	std	r0,STACKFRAMESIZE+16(r1)
>   
> +	blt	5f
>   	srdi	r6,r5,7
>   	mtctr	r6
>   
> 

Re: [PATCH 1/2] powerpc/memcpy: Fix stack corruption for smaller sizes

[Michael Ellerman]

On Tue, 2019-09-03 at 21:43:58 UTC, Santosh Sivaraj wrote:
> For sizes lesser than 128 bytes, the code branches out early without saving
> the stack frame, which when restored later drops frame of the caller.
> 
> Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> Signed-off-by: Santosh Sivaraj <santosh@fossix.org>

Series applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/20055a8bfaaa75f2cb9c23ecc8ab12b4abd8dc84

cheers