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arm64: Add CNTVCT_EL0 trap handler

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Since people seem to make a point in breaking the userspace visible
counter, we have no choice but to trap the access. Add the required
handler.

Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This commit is contained in:
Marc Zyngier 2017-02-01 11:48:58 +00:00
parent 8f41375882
commit 6126ce0588
2 changed files with 16 additions and 0 deletions
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2
arch/arm64/include/asm/esr.h
View File

@ -175,6 +175,8 @@
#define ESR_ELx_SYS64_ISS_SYS_CTR_READ (ESR_ELx_SYS64_ISS_SYS_CTR | \
ESR_ELx_SYS64_ISS_DIR_READ)
#define ESR_ELx_SYS64_ISS_SYS_CNTVCT (ESR_ELx_SYS64_ISS_SYS_VAL(3, 3, 2, 14, 0) | \
ESR_ELx_SYS64_ISS_DIR_READ)
#ifndef __ASSEMBLY__
#include <asm/types.h>

14
arch/arm64/kernel/traps.c
View File

@ -505,6 +505,14 @@ static void ctr_read_handler(unsigned int esr, struct pt_regs *regs)
regs->pc += 4;
}
static void cntvct_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, arch_counter_get_cntvct());
regs->pc += 4;
}
struct sys64_hook {
unsigned int esr_mask;
unsigned int esr_val;
@ -523,6 +531,12 @@ static struct sys64_hook sys64_hooks[] = {
.esr_val = ESR_ELx_SYS64_ISS_SYS_CTR_READ,
.handler = ctr_read_handler,
},
{
/* Trap read access to CNTVCT_EL0 */
.esr_mask = ESR_ELx_SYS64_ISS_SYS_OP_MASK,
.esr_val = ESR_ELx_SYS64_ISS_SYS_CNTVCT,
.handler = cntvct_read_handler,
},
{},
};