Re: [Bpf] [PATCH bpf-next v3 11/17] selftests/bpf: Add unit tests for new sign-extension load insns

From: Yonghong Song <yhs=40meta.com@dmarc.ietf.org>
To: Yonghong Song <yhs@fb.com>, bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
	Andrii Nakryiko <andrii@kernel.org>,
	 bpf@ietf.org, Daniel Borkmann <daniel@iogearbox.net>,
	Fangrui Song <maskray@google.com>,
	kernel-team@fb.com
Subject: Re: [Bpf] [PATCH bpf-next v3 11/17] selftests/bpf: Add unit tests for new sign-extension load insns
Date: Wed, 19 Jul 2023 23:36:05 -0700	[thread overview]
Message-ID: <02e666bf-82a5-9b80-0cc0-2c50b8da5126@meta.com> (raw)
In-Reply-To: <6be0dc44-c781-a3e9-e2b5-f26e3ffa42e8@meta.com>

On 7/19/23 11:31 PM, Yonghong Song wrote:
> 
> 
> On 7/19/23 5:02 PM, Yonghong Song wrote:
>> Add unit tests for new ldsx insns. The test includes sign-extension
>> with a single value or with a value range.
>>
>> Signed-off-by: Yonghong Song <yhs@fb.com>
>> ---
>>   .../selftests/bpf/prog_tests/verifier.c       |   2 +
>>   .../selftests/bpf/progs/verifier_ldsx.c       | 117 ++++++++++++++++++
>>   2 files changed, 119 insertions(+)
>>   create mode 100644 tools/testing/selftests/bpf/progs/verifier_ldsx.c
>>
>> diff --git a/tools/testing/selftests/bpf/prog_tests/verifier.c 
>> b/tools/testing/selftests/bpf/prog_tests/verifier.c
>> index c375e59ff28d..6eec6a9463c8 100644
>> --- a/tools/testing/selftests/bpf/prog_tests/verifier.c
>> +++ b/tools/testing/selftests/bpf/prog_tests/verifier.c
>> @@ -31,6 +31,7 @@
>>   #include "verifier_int_ptr.skel.h"
>>   #include "verifier_jeq_infer_not_null.skel.h"
>>   #include "verifier_ld_ind.skel.h"
>> +#include "verifier_ldsx.skel.h"
>>   #include "verifier_leak_ptr.skel.h"
>>   #include "verifier_loops1.skel.h"
>>   #include "verifier_lwt.skel.h"
>> @@ -133,6 +134,7 @@ void test_verifier_helper_value_access(void)  { 
>> RUN(verifier_helper_value_access
>>   void test_verifier_int_ptr(void)              { 
>> RUN(verifier_int_ptr); }
>>   void test_verifier_jeq_infer_not_null(void)   { 
>> RUN(verifier_jeq_infer_not_null); }
>>   void test_verifier_ld_ind(void)               { RUN(verifier_ld_ind); }
>> +void test_verifier_ldsx(void)                  { RUN(verifier_ldsx); }
>>   void test_verifier_leak_ptr(void)             { 
>> RUN(verifier_leak_ptr); }
>>   void test_verifier_loops1(void)               { RUN(verifier_loops1); }
>>   void test_verifier_lwt(void)                  { RUN(verifier_lwt); }
>> diff --git a/tools/testing/selftests/bpf/progs/verifier_ldsx.c 
>> b/tools/testing/selftests/bpf/progs/verifier_ldsx.c
>> new file mode 100644
>> index 000000000000..4163e9ffffe9
>> --- /dev/null
>> +++ b/tools/testing/selftests/bpf/progs/verifier_ldsx.c
>> @@ -0,0 +1,117 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +
>> +#include <linux/bpf.h>
>> +#include <bpf/bpf_helpers.h>
>> +#include "bpf_misc.h"
>> +
>> +SEC("socket")
>> +__description("LDSX, S8")
>> +__success __success_unpriv __retval(-2)
>> +__naked void ldsx_s8(void)
>> +{
>> +    asm volatile ("                    \
>> +    r1 = 0x3fe;                    \
>> +    *(u64 *)(r10 - 8) = r1;                \
>> +    r0 = *(s8 *)(r10 - 8);                \
>> +    exit;                        \
>> +"    ::: __clobber_all);
> 
> Looks like latest llvm17 is okay with the above asm syntax
> but llvm16 is not okay.
> 
> https://github.com/kernel-patches/bpf/pull/5377
> 
> Will check and fix the problem in the next revision.

I may need to guard this and other similar tests
with llvm compiler versions.

> 
> 
>> +}
>> +
>> +SEC("socket")
>> +__description("LDSX, S16")
>> +__success __success_unpriv __retval(-2)
>> +__naked void ldsx_s16(void)
>> +{
>> +    asm volatile ("                    \
>> +    r1 = 0x3fffe;                    \
>> +    *(u64 *)(r10 - 8) = r1;                \
>> +    r0 = *(s16 *)(r10 - 8);                \
>> +    exit;                        \
>> +"    ::: __clobber_all);
>> +}
>> +
> [...]

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