libsgxstep: opt set TCS.FLAGS.DBGOPTIN only

jovanbulck · Apr 11, 2024 · 1f139de · 1f139de
1 parent 86786e6
commit 1f139de
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Showing 2 changed files with 6 additions and 2 deletions.
diff --git a/libsgxstep/enclave.c b/libsgxstep/enclave.c
@@ -198,8 +198,10 @@ void* get_enclave_ssa_gprsgx_adrs(void)
 void set_debug_optin(void) 
 {
     void *tcs_addr = sgx_get_tcs();
-    uint64_t flags = 0x1;
-    edbgwr(tcs_addr + 8, &flags, sizeof(flags));
+    uint64_t flags;
+    edbgrd(tcs_addr + SGX_TCS_FLAGS_OFFSET, &flags, sizeof(flags));
+    flags |= SGX_FLAGS_DBGOPTIN;
+    edbgwr(tcs_addr + SGX_TCS_FLAGS_OFFSET, &flags, sizeof(flags));
 }
 
 void print_enclave_info(void)

diff --git a/libsgxstep/enclave.h b/libsgxstep/enclave.h
@@ -51,10 +51,12 @@ int edbgrdwr(void *adrs, void* res, int len, int write);
 #define edbgwr(adrs, res, len)  edbgrdwr(adrs, res, len, 1)
 
 /* NOTE: incorrect GPRSGX size in Intel manual vol. 3D June 2016 p.38-7 */
+#define SGX_TCS_FLAGS_OFFSET        8
 #define SGX_TCS_OSSA_OFFSET         16
 #define SGX_TCS_CSSA_OFFSET         24
 #define SGX_GPRSGX_SIZE             184
 #define SGX_GPRSGX_RIP_OFFSET       136
+#define SGX_FLAGS_DBGOPTIN          0x1
 
 /* HACK: to avoid having to retrieve the SSA framesize from the untrusted
    runtime (driver), we assume a standard/hard-coded SSA framesize of 1 page */