As we're about to enable trapping of some of the userspace-visible timer registers, let's add a handler for CNTVCT.
Signed-off-by: Marc Zyngier <[email protected]> --- arch/arm/kernel/traps.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c index b697e9234a07..bda12a243b40 100644 --- a/arch/arm/kernel/traps.c +++ b/arch/arm/kernel/traps.c @@ -30,6 +30,7 @@ #include <linux/irq.h> #include <linux/atomic.h> +#include <asm/arch_timer.h> #include <asm/cacheflush.h> #include <asm/exception.h> #include <asm/unistd.h> @@ -735,6 +736,34 @@ late_initcall(arm_mrc_hook_init); #endif +#ifdef CONFIG_ARM_ARCH_TIMER +static int read_cntvct_trap(struct pt_regs *regs, unsigned int instr) +{ + int rt = (instr >> 12) & 15; + int rt2 = (instr >> 16) & 15; + u64 val = arch_counter_get_cntvct(); + + regs->uregs[rt] = lower_32_bits(val); + regs->uregs[rt2] = upper_32_bits(val); + regs->ARM_pc += 4; + return 0; +} + +static struct undef_hook cntvct_hook = { + .instr_mask = 0x0ff00fff, + .instr_val = 0x0c500f1e, + .fn = read_cntvct_trap, +}; + +static int __init arch_timer_hook_init(void) +{ + register_undef_hook(&cntvct_hook); + return 0; +} + +late_initcall(arch_timer_hook_init); +#endif + /* * A data abort trap was taken, but we did not handle the instruction. * Try to abort the user program, or panic if it was the kernel. -- 2.11.0
