From: Jo Van Bulck <jo.vanbulck@cs.kuleuven.be>
To: "Huang, Kai" <kai.huang@intel.com>,
"linux-sgx@vger.kernel.org" <linux-sgx@vger.kernel.org>,
"jarkko@kernel.org" <jarkko@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: "dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>
Subject: Re: [PATCH v3 3/9] selftests/sgx: Handle relocations in test enclave
Date: Fri, 25 Aug 2023 15:27:35 +0200 [thread overview]
Message-ID: <8c950b3d-0650-1a73-b7f7-eaddff2bc876@cs.kuleuven.be> (raw)
In-Reply-To: <90ad8638bc1c26505e33b3f436fdbc22c8d74ba9.camel@intel.com>
On 22.08.23 03:11, Huang, Kai wrote:>> +/*
>> + * Symbol placed at the start of the enclave image by the linker script.
>> + * Declare this extern symbol with visibility "hidden" to ensure the
>> + * compiler does not access it through the GOT.
>> + */
>> +extern const uint8_t __attribute__((visibility("hidden"))) __encl_base;
>> +static const uint64_t encl_base = (uint64_t)&__encl_base;
>
> I had hard time to understand this. The __encl_base is a symbol which is a
> fixed value set by the compiler/linker. encl_base has the real storage in the
> .data section, but the value is also build-time fixed. IIUC we need some code
> to explicitly override it, but I don't see where it's done. Perhaps I missed
> something?
Thank you for catching this. Such initialization would indeed have to be
explicitly overridden at runtime and I somehow overlooked this (it seems
I left the line to actually run the tests commented out after
compilation in my test script for all versions; this is now fixed).
Apologies for the confusion, my bad! I've reverted this back to an
explicit (uit64_t)&__encl_base cast in the next patch iteration to avoid
such confusion.
>> +
>> +typedef void (*encl_op_t)(void *);
>> +const encl_op_t encl_op_array[ENCL_OP_MAX] = {
>> + do_encl_op_put_to_buf,
>> + do_encl_op_get_from_buf,
>> + do_encl_op_put_to_addr,
>> + do_encl_op_get_from_addr,
>> + do_encl_op_nop,
>> + do_encl_eaccept,
>> + do_encl_emodpe,
>> + do_encl_init_tcs_page,
>> +};
>
> Any reason it cannot be 'static'?
I tested static indeed also works and will include this in the next
iteration.
>> diff --git a/tools/testing/selftests/sgx/test_encl.lds b/tools/testing/selftests/sgx/test_encl.lds
>> index 62d37160f..b86c86060 100644
>> --- a/tools/testing/selftests/sgx/test_encl.lds
>> +++ b/tools/testing/selftests/sgx/test_encl.lds
>> @@ -32,6 +32,8 @@ SECTIONS
>> *(.note*)
>> *(.debug*)
>> *(.eh_frame*)
>> + *(.dyn*)
>> + *(.gnu.hash)
>
> This looks can be in a separate patch, because it's not directly related to what
> you are trying to fix.
>
> But I don't want to make things unnecessarily complicated for selftests, so fine
> to me if you still want to keep it. But if you do, perhaps you can add some
> justification to the changelog saying something like: opportunistically discard
> ".dyn*" and ".gnu.hash" which the enclave loader cannot handle. Anyway, still
> better to make a separate patch for such purpose IMHO.
Thanks, splitting this off in a separate commit for the next iteration.
Best,
Jo
next prev parent reply other threads:[~2023-08-25 13:28 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-19 9:43 [PATCH v3 0/9] selftests/sgx: Fix compilation errors Jo Van Bulck
2023-08-19 9:43 ` [PATCH v3 1/9] selftests/sgx: Fix uninitialized pointer dereference in error path Jo Van Bulck
2023-08-19 9:43 ` [PATCH v3 2/9] selftests/sgx: Produce static-pie executable for test enclave Jo Van Bulck
2023-08-22 0:26 ` Huang, Kai
2023-08-23 13:19 ` Jo Van Bulck
2023-08-19 9:43 ` [PATCH v3 3/9] selftests/sgx: Handle relocations in " Jo Van Bulck
2023-08-22 1:11 ` Huang, Kai
2023-08-25 13:27 ` Jo Van Bulck [this message]
2023-08-22 10:08 ` Jarkko Sakkinen
2023-08-19 9:43 ` [PATCH v3 4/9] selftests/sgx: Fix linker script asserts Jo Van Bulck
2023-08-22 10:09 ` Jarkko Sakkinen
2023-08-19 9:43 ` [PATCH v3 5/9] selftests/sgx: Include memory clobber for inline asm in test enclave Jo Van Bulck
2023-08-22 10:10 ` Jarkko Sakkinen
2023-08-19 9:43 ` [PATCH v3 6/9] selftests/sgx: Ensure test enclave buffer is entirely preserved Jo Van Bulck
2023-08-21 11:10 ` Huang, Kai
2023-08-22 10:10 ` Jarkko Sakkinen
2023-08-19 9:43 ` [PATCH v3 7/9] selftests/sgx: Ensure expected location of test enclave buffer Jo Van Bulck
2023-08-21 11:10 ` Huang, Kai
2023-08-22 10:11 ` Jarkko Sakkinen
2023-08-19 9:43 ` [PATCH v3 8/9] selftests/sgx: Separate linker options Jo Van Bulck
2023-08-22 10:11 ` Jarkko Sakkinen
2023-08-19 9:43 ` [PATCH v3 9/9] selftests/sgx: Specify freestanding environment for enclave compilation Jo Van Bulck
2023-08-22 10:14 ` Jarkko Sakkinen
2023-08-23 12:57 ` Jo Van Bulck
2023-08-23 17:31 ` Jarkko Sakkinen
2023-08-22 10:31 ` [PATCH v3 0/9] selftests/sgx: Fix compilation errors Jarkko Sakkinen
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