| Message ID | 20230825133252.9056-3-jo.vanbulck@cs.kuleuven.be (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | selftests/sgx: Fix compilation errors | expand |
On Fri, 2023-08-25 at 15:32 +0200, Jo Van Bulck wrote: > The current combination of -static and -fPIC creates a static executable > with position-dependent addresses for global variables. Use -static-pie > and -fPIE to create a proper static position independent executable that > can be loaded at any address without a dynamic linker. > > Link: https://lore.kernel.org/all/f9c24d89-ed72-7d9e-c650-050d722c6b04@cs.kuleuven.be/ > Signed-off-by: Jo Van Bulck <jo.vanbulck@cs.kuleuven.be> > Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org> > --- > tools/testing/selftests/sgx/Makefile | 2 +- > tools/testing/selftests/sgx/test_encl.lds | 1 + > tools/testing/selftests/sgx/test_encl_bootstrap.S | 9 ++++++--- > 3 files changed, 8 insertions(+), 4 deletions(-) > > diff --git a/tools/testing/selftests/sgx/Makefile b/tools/testing/selftests/sgx/Makefile > index 50aab6b57da3..1d6315a2e5f5 100644 > --- a/tools/testing/selftests/sgx/Makefile > +++ b/tools/testing/selftests/sgx/Makefile > @@ -13,7 +13,7 @@ endif > > INCLUDES := -I$(top_srcdir)/tools/include > HOST_CFLAGS := -Wall -Werror -g $(INCLUDES) -fPIC -z noexecstack > -ENCL_CFLAGS := -Wall -Werror -static -nostdlib -nostartfiles -fPIC \ > +ENCL_CFLAGS := -Wall -Werror -static-pie -nostdlib -nostartfiles -fPIE \ > -fno-stack-protector -mrdrnd $(INCLUDES) > > TEST_CUSTOM_PROGS := $(OUTPUT)/test_sgx > diff --git a/tools/testing/selftests/sgx/test_encl.lds b/tools/testing/selftests/sgx/test_encl.lds > index a1ec64f7d91f..62d37160f59b 100644 > --- a/tools/testing/selftests/sgx/test_encl.lds > +++ b/tools/testing/selftests/sgx/test_encl.lds > @@ -10,6 +10,7 @@ PHDRS > SECTIONS > { > . = 0; > + __encl_base = .; > .tcs : { > *(.tcs*) > } : tcs > diff --git a/tools/testing/selftests/sgx/test_encl_bootstrap.S b/tools/testing/selftests/sgx/test_encl_bootstrap.S > index 03ae0f57e29d..4e55d91566c4 100644 > --- a/tools/testing/selftests/sgx/test_encl_bootstrap.S > +++ b/tools/testing/selftests/sgx/test_encl_bootstrap.S > @@ -42,9 +42,12 @@ > encl_entry: > # RBX contains the base address for TCS, which is the first address > # inside the enclave for TCS #1 and one page into the enclave for > - # TCS #2. By adding the value of encl_stack to it, we get > - # the absolute address for the stack. > - lea (encl_stack)(%rbx), %rax > + # TCS #2. First make it relative by substracting __encl_base and > + # then add the address of encl_stack to get the address for the stack. > + lea __encl_base(%rip), %rax > + sub %rax, %rbx > + lea encl_stack(%rip), %rax > + add %rbx, %rax Could you please add the linker error (as you mentioned in the v3) to the changelog to justify this code change? And sigh.. I still don't quite understand why linker complains lea (encl_stack)(%rbx), %rax because .... > jmp encl_entry_core > encl_dyn_entry: > # Entry point for dynamically created TCS page expected to follow we have a lea -1(%rbx), %rax right here. Can't the compiler/linker just treat it as an immediate just like -1? :-( Anyway, I like this code change: Acked-by: Kai Huang <kai.huang@intel.com>
On 29.08.23 12:55, Huang, Kai wrote:> Could you please add the linker error (as you mentioned in the v3) to the > changelog to justify this code change? Makes sense, done. > And sigh.. I still don't quite understand why linker complains > > lea (encl_stack)(%rbx), %rax > > because .... > >> jmp encl_entry_core >> encl_dyn_entry: >> # Entry point for dynamically created TCS page expected to follow > > we have a > > lea -1(%rbx), %rax > > right here. > > Can't the compiler/linker just treat it as an immediate just like -1? :-( I think the linker complains because with -static-pie -fPIE afaik all local symbols need to have RIP-relative addressing "encl_stack(%rip)". Best, Jo
diff --git a/tools/testing/selftests/sgx/Makefile b/tools/testing/selftests/sgx/Makefile index 50aab6b57da3..1d6315a2e5f5 100644 --- a/tools/testing/selftests/sgx/Makefile +++ b/tools/testing/selftests/sgx/Makefile @@ -13,7 +13,7 @@ endif INCLUDES := -I$(top_srcdir)/tools/include HOST_CFLAGS := -Wall -Werror -g $(INCLUDES) -fPIC -z noexecstack -ENCL_CFLAGS := -Wall -Werror -static -nostdlib -nostartfiles -fPIC \ +ENCL_CFLAGS := -Wall -Werror -static-pie -nostdlib -nostartfiles -fPIE \ -fno-stack-protector -mrdrnd $(INCLUDES) TEST_CUSTOM_PROGS := $(OUTPUT)/test_sgx diff --git a/tools/testing/selftests/sgx/test_encl.lds b/tools/testing/selftests/sgx/test_encl.lds index a1ec64f7d91f..62d37160f59b 100644 --- a/tools/testing/selftests/sgx/test_encl.lds +++ b/tools/testing/selftests/sgx/test_encl.lds @@ -10,6 +10,7 @@ PHDRS SECTIONS { . = 0; + __encl_base = .; .tcs : { *(.tcs*) } : tcs diff --git a/tools/testing/selftests/sgx/test_encl_bootstrap.S b/tools/testing/selftests/sgx/test_encl_bootstrap.S index 03ae0f57e29d..4e55d91566c4 100644 --- a/tools/testing/selftests/sgx/test_encl_bootstrap.S +++ b/tools/testing/selftests/sgx/test_encl_bootstrap.S @@ -42,9 +42,12 @@ encl_entry: # RBX contains the base address for TCS, which is the first address # inside the enclave for TCS #1 and one page into the enclave for - # TCS #2. By adding the value of encl_stack to it, we get - # the absolute address for the stack. - lea (encl_stack)(%rbx), %rax + # TCS #2. First make it relative by substracting __encl_base and + # then add the address of encl_stack to get the address for the stack. + lea __encl_base(%rip), %rax + sub %rax, %rbx + lea encl_stack(%rip), %rax + add %rbx, %rax jmp encl_entry_core encl_dyn_entry: # Entry point for dynamically created TCS page expected to follow