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Commit 9842119a authored by Marc Zyngier's avatar Marc Zyngier Committed by Catalin Marinas
Browse files

arm64: Add CNTFRQ_EL0 trap handler 



We now trap accesses to CNTVCT_EL0 when the counter is broken
enough to require the kernel to mediate the access. But it
turns out that some existing userspace (such as OpenMPI) do
probe for the counter frequency, leading to an UNDEF exception
as CNTVCT_EL0 and CNTFRQ_EL0 share the same control bit.

The fix is to handle the exception the same way we do for CNTVCT_EL0.

Fixes: a86bd139 ("arm64: arch_timer: Enable CNTVCT_EL0 trap if workaround is enabled")
Reported-by: default avatarHanjun Guo <guohanjun@huawei.com>
Tested-by: default avatarHanjun Guo <guohanjun@huawei.com>
Reviewed-by: default avatarHanjun Guo <guohanjun@huawei.com>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 494bc3cd

arch/arm64/include/asm/esr.h

+4 −0
Original line number Original line Diff line number Diff line
@@ -177,6 +177,10 @@ 




#define ESR_ELx_SYS64_ISS_SYS_CNTVCT	(ESR_ELx_SYS64_ISS_SYS_VAL(3, 3, 2, 14, 0) | \

#define ESR_ELx_SYS64_ISS_SYS_CNTVCT	(ESR_ELx_SYS64_ISS_SYS_VAL(3, 3, 2, 14, 0) | \

					 ESR_ELx_SYS64_ISS_DIR_READ)

					 ESR_ELx_SYS64_ISS_DIR_READ)



#define ESR_ELx_SYS64_ISS_SYS_CNTFRQ	(ESR_ELx_SYS64_ISS_SYS_VAL(3, 3, 0, 14, 0) | \

					 ESR_ELx_SYS64_ISS_DIR_READ)



#ifndef __ASSEMBLY__

#ifndef __ASSEMBLY__

#include <asm/types.h>

#include <asm/types.h>

arch/arm64/kernel/traps.c

+14 −0
Original line number Original line Diff line number Diff line
@@ -513,6 +513,14 @@ static void cntvct_read_handler(unsigned int esr, struct pt_regs *regs) 
	regs->pc += 4;

	regs->pc += 4;

}

}





static void cntfrq_read_handler(unsigned int esr, struct pt_regs *regs)

{

	int rt = (esr & ESR_ELx_SYS64_ISS_RT_MASK) >> ESR_ELx_SYS64_ISS_RT_SHIFT;



	pt_regs_write_reg(regs, rt, read_sysreg(cntfrq_el0));

	regs->pc += 4;

}



struct sys64_hook {

struct sys64_hook {

	unsigned int esr_mask;

	unsigned int esr_mask;

	unsigned int esr_val;

	unsigned int esr_val;
@@ -537,6 +545,12 @@ static struct sys64_hook sys64_hooks[] = { 
		.esr_val = ESR_ELx_SYS64_ISS_SYS_CNTVCT,

		.esr_val = ESR_ELx_SYS64_ISS_SYS_CNTVCT,

		.handler = cntvct_read_handler,

		.handler = cntvct_read_handler,

	},

	},

	{

		/* Trap read access to CNTFRQ_EL0 */

		.esr_mask = ESR_ELx_SYS64_ISS_SYS_OP_MASK,

		.esr_val = ESR_ELx_SYS64_ISS_SYS_CNTFRQ,

		.handler = cntfrq_read_handler,

	},

	{},

	{},

};

};