ARM/arm64: vdso: Use common vdso clock mode storage

Convert ARM/ARM64 to the generic VDSO clock mode storage. This needs to
happen in one go as they share the clocksource driver.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://lkml.kernel.org/r/20200207124403.363235229@linutronix.de

arch/arm/Kconfig

@@ -3,7 +3,6 @@ config ARM
 	bool
 	default y
 	select ARCH_32BIT_OFF_T
-	select ARCH_CLOCKSOURCE_DATA
 	select ARCH_HAS_BINFMT_FLAT
 	select ARCH_HAS_DEBUG_VIRTUAL if MMU
 	select ARCH_HAS_DEVMEM_IS_ALLOWED

arch/arm/include/asm/clocksource.h

@@ -1,8 +1,7 @@
 #ifndef _ASM_CLOCKSOURCE_H
 #define _ASM_CLOCKSOURCE_H
 
-struct arch_clocksource_data {
+#define VDSO_ARCH_CLOCKMODES	\
-	bool vdso_direct;	/* Usable for direct VDSO access? */
+	VDSO_CLOCKMODE_ARCHTIMER
-};
 
 #endif

arch/arm/include/asm/vdso/gettimeofday.h

@@ -117,15 +117,21 @@ static __always_inline u64 __arch_get_hw_counter(int clock_mode)
 #ifdef CONFIG_ARM_ARCH_TIMER
 	u64 cycle_now;
 
-	if (!clock_mode)
+	/*
-		return -EINVAL;
+	 * Core checks for mode already, so this raced against a concurrent
+	 * update. Return something. Core will do another round and then
+	 * see the mode change and fallback to the syscall.
+	 */
+	if (clock_mode == VDSO_CLOCKMODE_NONE)
+		return 0;
 
 	isb();
 	cycle_now = read_sysreg(CNTVCT);
 
 	return cycle_now;
 #else
-	return -EINVAL; /* use fallback */
+	/* Make GCC happy. This is compiled out anyway */
+	return 0;
 #endif
 }
 

arch/arm/include/asm/vdso/vsyscall.h

@@ -11,18 +11,6 @@
 extern struct vdso_data *vdso_data;
 extern bool cntvct_ok;
 
-static __always_inline
-bool tk_is_cntvct(const struct timekeeper *tk)
-{
-	if (!IS_ENABLED(CONFIG_ARM_ARCH_TIMER))
-		return false;
-
-	if (!tk->tkr_mono.clock->archdata.vdso_direct)
-		return false;
-
-	return true;
-}
-
 /*
  * Update the vDSO data page to keep in sync with kernel timekeeping.
  */
@@ -40,15 +28,6 @@ bool __arm_update_vdso_data(void)
 }
 #define __arch_update_vdso_data __arm_update_vdso_data
 
-static __always_inline
-int __arm_get_clock_mode(struct timekeeper *tk)
-{
-	u32 __tk_is_cntvct = tk_is_cntvct(tk);
-
-	return __tk_is_cntvct;
-}
-#define __arch_get_clock_mode __arm_get_clock_mode
-
 static __always_inline
 void __arm_sync_vdso_data(struct vdso_data *vdata)
 {

arch/arm/mm/Kconfig

@@ -900,6 +900,7 @@ config VDSO
 	select GENERIC_TIME_VSYSCALL
 	select GENERIC_VDSO_32
 	select GENERIC_GETTIMEOFDAY
+	select GENERIC_VDSO_CLOCK_MODE
 	help
 	  Place in the process address space an ELF shared object
 	  providing fast implementations of gettimeofday and

arch/arm64/Kconfig

@@ -9,7 +9,6 @@ config ARM64
 	select ACPI_MCFG if (ACPI && PCI)
 	select ACPI_SPCR_TABLE if ACPI
 	select ACPI_PPTT if ACPI
-	select ARCH_CLOCKSOURCE_DATA
 	select ARCH_HAS_DEBUG_VIRTUAL
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
 	select ARCH_HAS_DMA_PREP_COHERENT
@@ -111,6 +110,7 @@ config ARM64
 	select GENERIC_STRNLEN_USER
 	select GENERIC_TIME_VSYSCALL
 	select GENERIC_GETTIMEOFDAY
+	select GENERIC_VDSO_CLOCK_MODE
 	select HANDLE_DOMAIN_IRQ
 	select HARDIRQS_SW_RESEND
 	select HAVE_PCI

arch/arm64/include/asm/clocksource.h

@@ -2,8 +2,7 @@
 #ifndef _ASM_CLOCKSOURCE_H
 #define _ASM_CLOCKSOURCE_H
 
-struct arch_clocksource_data {
+#define VDSO_ARCH_CLOCKMODES	\
-	bool vdso_direct;	/* Usable for direct VDSO access? */
+	VDSO_CLOCKMODE_ARCHTIMER
-};
 
 #endif

arch/arm64/include/asm/vdso/compat_gettimeofday.h

@@ -12,8 +12,6 @@
 
 #include <asm/vdso/compat_barrier.h>
 
-#define __VDSO_USE_SYSCALL		ULLONG_MAX
-
 #define VDSO_HAS_CLOCK_GETRES		1
 
 #define BUILD_VDSO32			1
@@ -117,11 +115,12 @@ static __always_inline u64 __arch_get_hw_counter(s32 clock_mode)
 	u64 res;
 
 	/*
-	 * clock_mode == 0 implies that vDSO are enabled otherwise
+	 * Core checks for mode already, so this raced against a concurrent
-	 * fallback on syscall.
+	 * update. Return something. Core will do another round and then
+	 * see the mode change and fallback to the syscall.
 	 */
-	if (clock_mode)
+	if (clock_mode == VDSO_CLOCKMODE_NONE)
-		return __VDSO_USE_SYSCALL;
+		return 0;
 
 	/*
 	 * This isb() is required to prevent that the counter value

arch/arm64/include/asm/vdso/gettimeofday.h

@@ -10,8 +10,6 @@
 #include <asm/unistd.h>
 #include <uapi/linux/time.h>
 
-#define __VDSO_USE_SYSCALL		ULLONG_MAX
-
 #define VDSO_HAS_CLOCK_GETRES		1
 
 static __always_inline
@@ -71,11 +69,12 @@ static __always_inline u64 __arch_get_hw_counter(s32 clock_mode)
 	u64 res;
 
 	/*
-	 * clock_mode == 0 implies that vDSO are enabled otherwise
+	 * Core checks for mode already, so this raced against a concurrent
-	 * fallback on syscall.
+	 * update. Return something. Core will do another round and then
+	 * see the mode change and fallback to the syscall.
 	 */
-	if (clock_mode)
+	if (clock_mode == VDSO_CLOCKMODE_NONE)
-		return __VDSO_USE_SYSCALL;
+		return 0;
 
 	/*
 	 * This isb() is required to prevent that the counter value

arch/arm64/include/asm/vdso/vsyscall.h

@@ -21,15 +21,6 @@ struct vdso_data *__arm64_get_k_vdso_data(void)
 }
 #define __arch_get_k_vdso_data __arm64_get_k_vdso_data
 
-static __always_inline
-int __arm64_get_clock_mode(struct timekeeper *tk)
-{
-	u32 use_syscall = !tk->tkr_mono.clock->archdata.vdso_direct;
-
-	return use_syscall;
-}
-#define __arch_get_clock_mode __arm64_get_clock_mode
-
 static __always_inline
 void __arm64_update_vsyscall(struct vdso_data *vdata, struct timekeeper *tk)
 {

drivers/clocksource/arm_arch_timer.c

@@ -69,7 +69,7 @@ static enum arch_timer_ppi_nr arch_timer_uses_ppi = ARCH_TIMER_VIRT_PPI;
 static bool arch_timer_c3stop;
 static bool arch_timer_mem_use_virtual;
 static bool arch_counter_suspend_stop;
-static bool vdso_default = true;
+static enum vdso_clock_mode vdso_default = VDSO_CLOCKMODE_ARCHTIMER;
 
 static cpumask_t evtstrm_available = CPU_MASK_NONE;
 static bool evtstrm_enable = IS_ENABLED(CONFIG_ARM_ARCH_TIMER_EVTSTREAM);
@@ -560,8 +560,8 @@ void arch_timer_enable_workaround(const struct arch_timer_erratum_workaround *wa
 	 * change both the default value and the vdso itself.
 	 */
 	if (wa->read_cntvct_el0) {
-		clocksource_counter.archdata.vdso_direct = false;
+		clocksource_counter.vdso_clock_mode = VDSO_CLOCKMODE_NONE;
-		vdso_default = false;
+		vdso_default = VDSO_CLOCKMODE_NONE;
 	}
 }
 
@@ -979,7 +979,7 @@ static void __init arch_counter_register(unsigned type)
 		}
 
 		arch_timer_read_counter = rd;
-		clocksource_counter.archdata.vdso_direct = vdso_default;
+		clocksource_counter.vdso_clock_mode = vdso_default;
 	} else {
 		arch_timer_read_counter = arch_counter_get_cntvct_mem;
 	}