exosphere: support enabling usermode pmu regs (closes #703)

common/defaults/BCT.ini

@@ -12,6 +12,8 @@ debugmode_user = 0
 ; Note: Disabling usermode exception handlers will cause atmosphere to not fail gracefully under error conditions.
 ; Support will not be provided to users who disable these. If you do not know what you are doing, leave them on.
 disable_user_exception_handlers = 0
+; Note: It's currently unknown what effects enabling the usermode PMU register access may have on official code.
+enable_user_pmu_access = 0
 
 [stratosphere]
 ; To force-enable nogc, add nogc = 1

docs/changelog.md

@@ -47,6 +47,8 @@
   + An extension was added to pm:info to allow querying a process's override status.
 + Thanks to process override capture improvements, hbl html behavior has been greatly improved.
   + Web applets launched by hbl will now always see the /atmosphere/hbl_html filesystem
++ Support was added to exosphere for enabling usermode access to the PMU registers.
+  + This can be controlled via exosphere!enable_user_pmu_access in BCT.ini.
 + An enormous number of minor bugs were fixed.
   + dmnt's cheat VM had a fix for an inversion in opcode behavior.
   + An issue was fixed in fs.mitm's management of domain object IDs that could lead to system corruption in rare cases.

exosphere/src/configitem.c

@@ -38,6 +38,7 @@
 static bool g_hiz_mode_enabled = false;
 static bool g_debugmode_override_user = false, g_debugmode_override_priv = false;
 static bool g_enable_usermode_exception_handlers = true;
+static bool g_enable_usermode_pmu_access = false;
 
 uint32_t configitem_set(bool privileged, ConfigItem item, uint64_t value) {
     switch (item) {
@@ -168,6 +169,10 @@ void configitem_disable_usermode_exception_handlers(void) {
     g_enable_usermode_exception_handlers = false;
 }
 
+void configitem_enable_usermode_pmu_access(void) {
+    g_enable_usermode_pmu_access = true;
+}
+
 uint32_t configitem_get(bool privileged, ConfigItem item, uint64_t *p_outvalue) {
     uint32_t result = 0;
     switch (item) {
@@ -222,6 +227,10 @@ uint32_t configitem_get(bool privileged, ConfigItem item, uint64_t *p_outvalue)
                 if (g_enable_usermode_exception_handlers) {
                     config |= KERNELCONFIGFLAG_ENABLE_USER_EXCEPTION_HANDLERS;
                 }
+                /* Allow for enabling usermode pmu access. */
+                if (g_enable_usermode_pmu_access) {
+                    config |= KERNELCONFIGFLAG_ENABLE_USER_PMU_ACCESS;
+                }
                 *p_outvalue = config;
             }
             break;

exosphere/src/configitem.h

@@ -61,6 +61,7 @@ bool configitem_is_debugmode_priv(void);
 
 void configitem_set_debugmode_override(bool user, bool priv);
 void configitem_disable_usermode_exception_handlers(void);
+void configitem_enable_usermode_pmu_access(void);
 void configitem_set_hiz_mode_enabled(bool enabled);
 
 uint64_t configitem_get_hardware_type(void);

exosphere/src/exocfg.c

@@ -84,6 +84,14 @@ unsigned int exosphere_should_disable_usermode_exception_handlers(void) {
     return EXOSPHERE_CHECK_FLAG(EXOSPHERE_FLAG_DISABLE_USERMODE_EXCEPTION_HANDLERS);
 }
 
+unsigned int exosphere_should_enable_usermode_pmu_access(void) {
+    if (!g_has_loaded_config) {
+        generic_panic();
+    }
+
+    return EXOSPHERE_CHECK_FLAG(EXOSPHERE_FLAG_ENABLE_USERMODE_PMU_ACCESS);
+}
+
 const exo_emummc_config_t *exosphere_get_emummc_config(void) {
     if (!g_has_loaded_config) {
         generic_panic();

exosphere/src/exocfg.h

@@ -40,6 +40,7 @@
 #define EXOSPHERE_FLAG_IS_DEBUGMODE_PRIV                    (1 << 1u)
 #define EXOSPHERE_FLAG_IS_DEBUGMODE_USER                    (1 << 2u)
 #define EXOSPHERE_FLAG_DISABLE_USERMODE_EXCEPTION_HANDLERS  (1 << 3u)
+#define EXOSPHERE_FLAG_ENABLE_USERMODE_PMU_ACCESS           (1 << 4u)
 #define EXOSPHERE_FLAGS_DEFAULT (EXOSPHERE_FLAG_IS_DEBUGMODE_PRIV)
 
 typedef struct {
@@ -58,6 +59,7 @@ unsigned int exosphere_should_perform_620_keygen(void);
 unsigned int exosphere_should_override_debugmode_priv(void);
 unsigned int exosphere_should_override_debugmode_user(void);
 unsigned int exosphere_should_disable_usermode_exception_handlers(void);
+unsigned int exosphere_should_enable_usermode_pmu_access(void);
 
 const exo_emummc_config_t *exosphere_get_emummc_config(void);
 

exosphere/src/package2.c

@@ -512,6 +512,9 @@ void load_package2(coldboot_crt0_reloc_list_t *reloc_list) {
     if (exosphere_should_disable_usermode_exception_handlers() != 0) {
         configitem_disable_usermode_exception_handlers();
     }
+    if (exosphere_should_enable_usermode_pmu_access()) {
+        configitem_enable_usermode_pmu_access();
+    }
 
     /* Setup the Security Engine. */
     setup_se();

fusee/fusee-secondary/src/exocfg.h

@@ -30,6 +30,7 @@
 #define EXOSPHERE_FLAG_IS_DEBUGMODE_PRIV                    (1 << 1u)
 #define EXOSPHERE_FLAG_IS_DEBUGMODE_USER                    (1 << 2u)
 #define EXOSPHERE_FLAG_DISABLE_USERMODE_EXCEPTION_HANDLERS  (1 << 3u)
+#define EXOSPHERE_FLAG_ENABLE_USERMODE_PMU_ACCESS           (1 << 4u)
 #define EXOSPHERE_FLAGS_DEFAULT (EXOSPHERE_FLAG_IS_DEBUGMODE_PRIV)
 
 typedef struct {
@@ -48,5 +49,6 @@ _Static_assert(sizeof(exosphere_config_t) == 0x20 + sizeof(exo_emummc_config_t),
 #define EXOSPHERE_DEBUGMODE_PRIV_KEY "debugmode"
 #define EXOSPHERE_DEBUGMODE_USER_KEY "debugmode_user"
 #define EXOSPHERE_DISABLE_USERMODE_EXCEPTION_HANDLERS_KEY "disable_user_exception_handlers"
+#define EXOSPHERE_ENABLE_USERMODE_PMU_ACCESS_KEY "enable_user_pmu_access"
 
 #endif

fusee/fusee-secondary/src/nxboot.c

@@ -158,6 +158,13 @@ static int exosphere_ini_handler(void *user, const char *section, const char *na
             } else {
                 exo_cfg->flags &= ~(EXOSPHERE_FLAG_DISABLE_USERMODE_EXCEPTION_HANDLERS);
             }
+        } else if (strcmp(name, EXOSPHERE_ENABLE_USERMODE_PMU_ACCESS_KEY) == 0) {
+            sscanf(value, "%d", &tmp);
+            if (tmp) {
+                exo_cfg->flags |= EXOSPHERE_FLAG_ENABLE_USERMODE_PMU_ACCESS;
+            } else {
+                exo_cfg->flags &= ~(EXOSPHERE_FLAG_ENABLE_USERMODE_PMU_ACCESS);
+            }
         } else {
             return 0;
         }