ARM: 8947/1: Fix __arch_get_hw_counter() access to CNTVCT

__arch_get_hw_counter() should check clock_mode to see if it can access
CNTVCT. With the conversion to unified vDSO this check has been left out.

This causes on imx v6 and v7 (imx_v6_v7_defconfig) and other platforms to
hang at boot during the execution of the init process as per below:

[   19.976852] Run /sbin/init as init process
[   20.044931] Kernel panic - not syncing: Attempted to kill init!
exitcode=0x00000004

Fix the problem verifying that clock_mode is set coherently before
accessing CNTVCT.

Investigated-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

diff --git a/arch/arm/include/asm/vdso/gettimeofday.h b/arch/arm/include/asm/vdso/gettimeofday.h
index 5b879ae..0ad2429 100644 (file)
--- a/arch/arm/include/asm/vdso/gettimeofday.h
+++ b/arch/arm/include/asm/vdso/gettimeofday.h
@@ -75,6 +75,9 @@ static __always_inline u64 __arch_get_hw_counter(int clock_mode)
 #ifdef CONFIG_ARM_ARCH_TIMER
        u64 cycle_now;
 
+       if (!clock_mode)
+               return -EINVAL;
+
        isb();
        cycle_now = read_sysreg(CNTVCT);