[PAL/Linux-SGX] Prepare AEX handler to call C code in release mode

pal/src/host/linux-sgx/enclave_framework.c

@@ -63,27 +63,19 @@ bool sgx_is_valid_untrusted_ptr(const void* _addr, size_t size, size_t alignment
 }
 
 /*
- * When DEBUG is enabled, we run sgx_profile_sample() during asynchronous enclave exit (AEX), which
+ * We run some functions (e.g. sgx_profile_sample()) during asynchronous enclave exit (AEX), which
  * uses the stack. Make sure to update URSP so that the AEX handler does not overwrite the part of
  * the stack that we just allocated.
  *
  * (Recall that URSP is an outside stack pointer, saved by EENTER and restored on AEX by the SGX
  * hardware itself.)
  */
-#ifdef DEBUG
-
 #define UPDATE_USTACK(_ustack) \
  do { \
  SET_ENCLAVE_TCB(ustack, _ustack); \
  GET_ENCLAVE_TCB(gpr)->ursp = (uint64_t)_ustack; \
  } while(0)
 
-#else
-
-#define UPDATE_USTACK(_ustack) SET_ENCLAVE_TCB(ustack, _ustack)
-
-#endif
-
 void* sgx_prepare_ustack(void) {
  void* old_ustack = GET_ENCLAVE_TCB(ustack);
 

pal/src/host/linux-sgx/generated_offsets.c

@@ -106,7 +106,7 @@ const struct generated_offset generated_offsets[] = {
 
  /* struct pal_host_tcb aka PAL_HOST_TCB */
  OFFSET(PAL_HOST_TCB_TCS, pal_host_tcb, tcs),
- OFFSET(PAL_HOST_TCB_IN_AEX_PROF, pal_host_tcb, is_in_aex_profiling),
+ OFFSET(PAL_HOST_TCB_IN_AEX, pal_host_tcb, is_in_aex),
  OFFSET(PAL_HOST_TCB_EENTER_CNT, pal_host_tcb, eenter_cnt),
  OFFSET(PAL_HOST_TCB_EEXIT_CNT, pal_host_tcb, eexit_cnt),
  OFFSET(PAL_HOST_TCB_AEX_CNT, pal_host_tcb, aex_cnt),

pal/src/host/linux-sgx/host_entry.S

@@ -14,9 +14,8 @@
 
 #include "asm-offsets.h"
 
- .extern tcs_base
- .extern g_in_aex_profiling
  .extern maybe_dump_and_reset_stats
+ .extern maybe_raise_pending_signal
 
  .global sgx_ecall
  .type sgx_ecall, @function
@@ -54,9 +53,14 @@ sgx_ecall:
  leaq async_exit_pointer(%rip), %rcx
 
  movq $EENTER, %rax
+
+ .global eenter_pointer
+ .type eenter_pointer, @function
+
+eenter_pointer:
  enclu
 
- # currently only ECALL_THREAD_RESET returns
+ # currently only ECALL_THREAD_RESET ecall returns, as well as stage-1 signal handler
 .Lafter_resume:
  popq %r15
  .cfi_adjust_cfa_offset -8
@@ -80,12 +84,15 @@ async_exit_pointer:
  .cfi_startproc
  .cfi_undefined %rip
 
+ # Inform that we are in AEX code
+ movb $1, %gs:PAL_HOST_TCB_IN_AEX
+
  # increment per-thread AEX counter for stats
  lock incq %gs:PAL_HOST_TCB_AEX_CNT
 
-#ifdef DEBUG
- # Inform that we are in AEX profiling code
- movb $1, %gs:PAL_HOST_TCB_IN_AEX_PROF
+ subq $RED_ZONE_SIZE, %rsp
+ .cfi_adjust_cfa_offset RED_ZONE_SIZE
+
  # Save ERESUME parameters
  pushq %rax
  .cfi_adjust_cfa_offset 8
@@ -99,11 +106,15 @@ async_exit_pointer:
  .cfi_def_cfa_register %rbp
  andq $~0xF, %rsp
 
+#ifdef DEBUG
  # Call sgx_profile_sample_aex with %rdi = TCS
  movq %rbx, %rdi
  call sgx_profile_sample_aex
 
  call maybe_dump_and_reset_stats
+#endif
+
+ call maybe_raise_pending_signal
 
  # Restore stack
  movq %rbp, %rsp
@@ -116,9 +127,11 @@ async_exit_pointer:
  .cfi_adjust_cfa_offset -8
  popq %rax
  .cfi_adjust_cfa_offset -8
- movb $0, %gs:PAL_HOST_TCB_IN_AEX_PROF
-#endif
 
+ addq $RED_ZONE_SIZE, %rsp
+ .cfi_adjust_cfa_offset -RED_ZONE_SIZE
+
+ movb $0, %gs:PAL_HOST_TCB_IN_AEX
  .cfi_endproc
 
  # fall-through to ERESUME

pal/src/host/linux-sgx/host_exception.c

@@ -88,8 +88,8 @@ static bool interrupted_in_enclave(struct ucontext* uc) {
  return rip >= (unsigned long)async_exit_pointer && rip < (unsigned long)async_exit_pointer_end;
 }
 
-static bool interrupted_in_aex_profiling(void) {
- return pal_get_host_tcb()->is_in_aex_profiling != 0;
+static bool interrupted_in_aex(void) {
+ return pal_get_host_tcb()->is_in_aex != 0;
 }
 
 static void handle_sync_signal(int signum, siginfo_t* info, struct ucontext* uc) {
@@ -153,7 +153,7 @@ static void handle_async_signal(int signum, siginfo_t* info, struct ucontext* uc
  for (size_t i = 0; i < g_rpc_queue->rpc_threads_cnt; i++)
  DO_SYSCALL(tkill, g_rpc_queue->rpc_threads[i], SIGUSR2);
 
- if (interrupted_in_enclave(uc) || interrupted_in_aex_profiling()) {
+ if (interrupted_in_enclave(uc) || interrupted_in_aex()) {
  /* signal arrived while in app/LibOS/trusted PAL code or when handling another AEX, handle
  * signal inside enclave */
  pal_get_host_tcb()->async_signal_cnt++;
@@ -287,3 +287,7 @@ void maybe_dump_and_reset_stats(void) {
  }
 }
 #endif
+
+void maybe_raise_pending_signal(void) {
+ /* TODO: check if there is any sync or async pending signal and raise it */
+}

pal/src/host/linux-sgx/host_internal.h

@@ -114,6 +114,7 @@ int sgx_ecall(long ecall_no, void* ms);
 int sgx_raise(int event);
 
 void async_exit_pointer(void);
+void eenter_pointer(void);
 void eresume_pointer(void);
 void async_exit_pointer_end(void);
 

pal/src/host/linux-sgx/pal_tcb.h

@@ -92,7 +92,7 @@ typedef struct pal_host_tcb {
  sgx_arch_tcs_t* tcs; /* TCS page of SGX corresponding to thread, for EENTER */
  void* stack; /* bottom of stack, for later freeing when thread exits */
  void* alt_stack; /* bottom of alt stack, for child thread to init alt stack */
- uint8_t is_in_aex_profiling; /* non-zero if thread is currently doing AEX profiling */
+ uint8_t is_in_aex;  /* non-zero if thread is currently running AEX code */
  atomic_ulong eenter_cnt; /* # of EENTERs, corresponds to # of ECALLs */
  atomic_ulong eexit_cnt; /* # of EEXITs, corresponds to # of OCALLs */
  atomic_ulong aex_cnt; /* # of AEXs, corresponds to # of interrupts/signals */
@@ -122,4 +122,6 @@ void collect_and_print_sgx_stats(void);
 void maybe_dump_and_reset_stats(void);
 #endif /* DEBUG */
 
+void maybe_raise_pending_signal(void);
+
 #endif /* IN_ENCLAVE */