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From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: linux-sgx@vger.kernel.org
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
	Sean Christopherson <sean.j.christopherson@intel.com>
Subject: [PATCH 1/5] selftests/sgx: Add PHDRS to encl.lds
Date: Mon, 23 Mar 2020 05:46:30 +0200
Message-ID: <20200323034634.4157-1-jarkko.sakkinen@linux.intel.com> (raw)

Improve encl.lds to create an ELF image that can be easily loaded without
needing the conversion to a raw binary. This is achieved by adding PHDRS to
encl.lds that describes the different segments.

With a simple Python program it is easy to see that the changes result in a
sane memory layout [1]:

Flags Start              End
rw-   0x0000000000200000 0x0000000000201000
r-x   0x0000000000201000 0x0000000000202000
rw-   0x0000000000202000 0x0000000000205000

These are the start and end positions in the enclave ELF image for
different enclave memory areas. Since all the sections are marked as being
allocated, an ELF enclave loader can be solely based on p_offset, p_memsz
and p_flags fields of struct Elf64_Phdr.

[1]
import sys
from elftools.elf.elffile import ELFFile

PAGE_SIZE = 0x1000

if __name__ == '__main__':
    flags2str = ['---', '--x', '-w-', '-wx', 'r--', 'r-x', 'rw-', 'rwx']

    if len(sys.argv) != 2:
        sys.exit(1)

    with open(sys.argv[1], 'rb') as file:
        file = ELFFile(file)

        print('{:<5} {:<18} {:<18}'.format('Flags', 'Start', 'End'))

        for seg in file.iter_segments():
            if seg['p_type'] != 'PT_LOAD':
                continue

            flags = flags2str[seg['p_flags']]

            start = seg['p_offset'] & ~(PAGE_SIZE - 1)
            end = start +
	          (seg['p_filesz'] + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1)

            print('{:<5} 0x{:0>16x} 0x{:0>16x}'.format(flags, start, end))

Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
 tools/testing/selftests/sgx/encl.lds         | 14 ++++++++++----
 tools/testing/selftests/sgx/encl_bootstrap.S |  2 +-
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/sgx/encl.lds b/tools/testing/selftests/sgx/encl.lds
index 9a56d3064104..0fbbda7e665e 100644
--- a/tools/testing/selftests/sgx/encl.lds
+++ b/tools/testing/selftests/sgx/encl.lds
@@ -1,25 +1,31 @@
 OUTPUT_FORMAT(elf64-x86-64)
 
+PHDRS
+{
+	tcs PT_LOAD;
+	text PT_LOAD;
+	data PT_LOAD;
+}
+
 SECTIONS
 {
 	. = 0;
 	.tcs : {
 		*(.tcs*)
-	}
+	} : tcs
 
 	. = ALIGN(4096);
 	.text : {
 		*(.text*)
 		*(.rodata*)
-	}
+	} : text
 
 	. = ALIGN(4096);
 	.data : {
 		*(.data*)
-	}
+	} : data
 
 	/DISCARD/ : {
-		*(.data*)
 		*(.comment*)
 		*(.note*)
 		*(.debug*)
diff --git a/tools/testing/selftests/sgx/encl_bootstrap.S b/tools/testing/selftests/sgx/encl_bootstrap.S
index 3a1479f1cdcf..b9ea6130e422 100644
--- a/tools/testing/selftests/sgx/encl_bootstrap.S
+++ b/tools/testing/selftests/sgx/encl_bootstrap.S
@@ -7,7 +7,7 @@
 	.byte 0x0f, 0x01, 0xd7
 	.endm
 
-	.section ".tcs", "a"
+	.section ".tcs", "aw"
 	.balign	4096
 
 	.fill	1, 8, 0			# STATE (set by CPU)
-- 
2.25.1


             reply index

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-23  3:46 Jarkko Sakkinen [this message]
2020-03-23  3:46 ` [PATCH 2/5] selftests/sgx: Manage encl_fd in the main function Jarkko Sakkinen
2020-03-23  3:46 ` [PATCH 3/5] selftests/sgx: Move EINIT out of encl_build() Jarkko Sakkinen
2020-03-23  3:46 ` [PATCH 4/5] selftest/sgx: Replace encl_build() with encl_build_segment() Jarkko Sakkinen
2020-03-23  3:46 ` [PATCH 5/5] selftests/sgx: Load encl.elf directly in the test program Jarkko Sakkinen
2020-03-23  3:52 ` [PATCH 1/5] selftests/sgx: Add PHDRS to encl.lds Jarkko Sakkinen

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