time: do not sleep forever when no timers

Detect and record global timers (HPET or PIT) enablement in boot_flags. Detect and record APIC timer enablement in PERCPU variable. Check if corresponding timers are on and return -ENODEV otherwise in msleep() functions. Signed-off-by: Pawel Wieczorkiewicz <[email protected]>
KernelTestFramework · Nov 8, 2023 · ab50867 · ab50867
1 parent db7da0b
commit ab50867
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Showing 5 changed files with 39 additions and 20 deletions.
diff --git a/common/setup.c b/common/setup.c
@@ -165,22 +165,25 @@ static void __text_init init_vga_console(void) {
 }
 
 void __text_init init_timers(cpu_t *cpu) {
-    static bool __data_init hpet_initialized = false;
-
     if (cpu->bsp) {
         if (opt_hpet)
-            hpet_initialized = init_hpet(cpu);
+            boot_flags.timer_global = init_hpet(cpu);
 
-        if (!hpet_initialized && opt_pit)
+        if (!boot_flags.timer_global && opt_pit) {
             init_pit(cpu);
+            boot_flags.timer_global = true;
+        }
     }
 
     if (opt_apic_timer) {
-        if (hpet_initialized || opt_pit) /* Needed for APIC timer calibration */
+        if (!boot_flags.timer_global) { /* Needed for APIC timer calibration */
+            warning("CPU%u: Unable to initialize APIC timer - no calibration timers!",
+                    cpu->id);
+        }
+        else {
             init_apic_timer();
-        else
-            printk("CPU%u: Unable to initialize APIC timer - no calibration timers!\n",
-                   cpu->id);
+            PERCPU_SET(apic_timer_enabled, true);
+        }
     }
 }
 

diff --git a/include/percpu.h b/include/percpu.h
@@ -59,6 +59,7 @@ struct percpu {
 
     unsigned long usermode_private;
     volatile unsigned long apic_ticks;
+    bool apic_timer_enabled;
 } __aligned(PAGE_SIZE);
 typedef struct percpu percpu_t;
 

diff --git a/include/setup.h b/include/setup.h
@@ -34,7 +34,7 @@
 
 struct boot_flags {
     uint64_t virt : 1, legacy_devs : 1, i8042 : 1, vga : 1, msi : 1, aspm : 1, rtc : 1,
-        nosmp : 1, rsvd : 56;
+        nosmp : 1, timer_global : 1, rsvd : 55;
 };
 typedef struct boot_flags boot_flags_t;
 

diff --git a/include/time.h b/include/time.h
@@ -27,19 +27,19 @@
 
 typedef uint64_t time_t;
 
-extern void msleep(time_t ms);
+extern int msleep(time_t ms);
+extern int msleep_local(time_t ms);
 extern time_t get_timer_ticks(void);
-extern void msleep_local(time_t ms);
 extern time_t get_local_ticks(void);
 
 /* Static declarations */
 
-static inline void sleep(time_t s) {
-    msleep(s * 1000);
+static inline int sleep(time_t s) {
+    return msleep(s * 1000);
 }
 
-static inline void sleep_local(time_t s) {
-    msleep_local(s * 1000);
+static inline int sleep_local(time_t s) {
+    return msleep_local(s * 1000);
 }
 
 #endif
diff --git a/lib/time.c b/lib/time.c
@@ -23,9 +23,13 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 #include <apic.h>
+#include <errno.h>
 #include <percpu.h>
+#include <setup.h>
 #include <time.h>
 
+extern boot_flags_t boot_flags;
+
 static __aligned(16) volatile time_t ticks = 0;
 
 void timer_interrupt_handler(void) {
@@ -39,19 +43,30 @@ void apic_timer_interrupt_handler(void) {
     apic_EOI();
 }
 
-void msleep(time_t ms) {
+int msleep(time_t ms) {
     time_t end;
 
+    if (!boot_flags.timer_global)
+        return -ENODEV;
+
     end = ACCESS_ONCE(ticks) + ms;
     while (ACCESS_ONCE(ticks) < end)
         cpu_relax();
+
+    return 0;
 }
 
-void msleep_local(time_t ms) {
-    time_t end = PERCPU_GET(apic_ticks) + ms;
-    while (PERCPU_GET(apic_ticks) < end) {
+int msleep_local(time_t ms) {
+    time_t end;
+
+    if (!PERCPU_GET(apic_timer_enabled))
+        return -ENODEV;
+
+    end = PERCPU_GET(apic_ticks) + ms;
+    while (PERCPU_GET(apic_ticks) < end)
         cpu_relax();
-    }
+
+    return 0;
 }
 
 time_t get_timer_ticks(void) {