From 827280ca129dad1f5f5c5053c23c839f541fcdc2 Mon Sep 17 00:00:00 2001
From: TuxSH <tuxsh@sfr.fr>
Date: Mon, 5 Mar 2018 21:07:09 +0100
Subject: [PATCH] Fix lock_try_acquire(&g_is_user_smc_in_progress) calls

---
 exosphere/src/smc_api.c         | 9 ++++++---
 exosphere/src/smc_api.h         | 1 +
 exosphere/src/synchronization.h | 2 +-
 3 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/exosphere/src/smc_api.c b/exosphere/src/smc_api.c
index 66ec692dd..f246f47e2 100644
--- a/exosphere/src/smc_api.c
+++ b/exosphere/src/smc_api.c
@@ -129,6 +129,9 @@ uintptr_t get_exception_entry_stack_address(unsigned int core_id) {
     }
 }
 
+bool try_set_user_smc_in_progress(void) {
+    return lock_try_acquire(&g_is_user_smc_in_progress);
+}
 void set_user_smc_in_progress(void) {
     lock_acquire(&g_is_user_smc_in_progress);
 }
@@ -203,7 +206,7 @@ void call_smc_handler(uint32_t handler_id, smc_args_t *args) {
 
 uint32_t smc_wrapper_sync(smc_args_t *args, uint32_t (*handler)(smc_args_t *)) {
     uint32_t result;
-    if (!lock_try_acquire(&g_is_user_smc_in_progress)) {
+    if (!try_set_user_smc_in_progress()) {
         return 3;
     }
     result = handler(args);
@@ -214,7 +217,7 @@ uint32_t smc_wrapper_sync(smc_args_t *args, uint32_t (*handler)(smc_args_t *)) {
 uint32_t smc_wrapper_async(smc_args_t *args, uint32_t (*handler)(smc_args_t *), uint32_t (*callback)(void *, uint64_t)) {
     uint32_t result;
     uint64_t key;
-    if (!lock_try_acquire(&g_is_user_smc_in_progress)) {
+    if (!try_set_user_smc_in_progress()) {
         return 3;
     }
     if ((key = try_set_smc_callback(callback)) != 0) {
@@ -439,7 +442,7 @@ uint32_t smc_get_random_bytes_for_priv(smc_args_t *args) {
 
     uint32_t result;
 
-    if (!lock_try_acquire(&g_is_user_smc_in_progress)) {
+    if (!try_set_user_smc_in_progress()) {
         if (args->X[1] > 0x38) {
             return 2;
         }
diff --git a/exosphere/src/smc_api.h b/exosphere/src/smc_api.h
index 6b1960282..4d291cc58 100644
--- a/exosphere/src/smc_api.h
+++ b/exosphere/src/smc_api.h
@@ -10,6 +10,7 @@ typedef struct {
     uint64_t X[8];
 } smc_args_t;
 
+bool try_set_user_smc_in_progress(void);
 void set_user_smc_in_progress(void);
 void clear_user_smc_in_progress(void);
 
diff --git a/exosphere/src/synchronization.h b/exosphere/src/synchronization.h
index caa8c1c72..328186e35 100644
--- a/exosphere/src/synchronization.h
+++ b/exosphere/src/synchronization.h
@@ -55,7 +55,7 @@ static inline void lock_release(atomic_flag *flag) {
 
 /* Try to acquire a lock. */
 static inline bool lock_try_acquire(atomic_flag *flag) {
-    return atomic_flag_test_and_set_explicit(flag, memory_order_acquire);
+    return !atomic_flag_test_and_set_explicit(flag, memory_order_acquire);
 }
 
 /*