| Message ID | 20200323034634.4157-1-jarkko.sakkinen@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/5] selftests/sgx: Add PHDRS to encl.lds | expand |
On Mon, Mar 23, 2020 at 05:46:30AM +0200, Jarkko Sakkinen wrote: > 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 > These changes have been squashed to my tree. Please provide patches if something feels not right. The changes were live coded on a Geminilake NUC that I brought home last week and are tested quite extensively. The place for improvement would be to call sgx_encl_build_segment() based on segments in the program header table so that the permissions would be assigned dynamically. /Jarkko
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)
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(-)