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arm64: compat: Add CNTVCT trap handler 

Since people seem to make a point in breaking the userspace visible
counter, we have no choice but to trap the access. We already do this
for 64bit userspace, but this is lacking for compat. Let's provide
the required handler.

Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Marc Zyngier 2018-09-27 17:15:32 +01:00 committed by Catalin Marinas
parent 2a8905e18c
commit 50de013d22
2 changed files with 19 additions and 0 deletions
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3
arch/arm64/include/asm/esr.h
View File

@ -315,6 +315,9 @@
ESR_ELx_CP15_64_ISS_CRM_MASK | \
ESR_ELx_CP15_64_ISS_DIR_MASK)
#define ESR_ELx_CP15_64_ISS_SYS_CNTVCT (ESR_ELx_CP15_64_ISS_SYS_VAL(1, 14) | \
ESR_ELx_CP15_64_ISS_DIR_READ)
#ifndef __ASSEMBLY__
#include <asm/types.h>

16
arch/arm64/kernel/traps.c
View File

@ -629,7 +629,23 @@ static struct sys64_hook cp15_32_hooks[] = {
{},
};
static void compat_cntvct_read_handler(unsigned int esr, struct pt_regs *regs)
{
int rt = (esr & ESR_ELx_CP15_64_ISS_RT_MASK) >> ESR_ELx_CP15_64_ISS_RT_SHIFT;
int rt2 = (esr & ESR_ELx_CP15_64_ISS_RT2_MASK) >> ESR_ELx_CP15_64_ISS_RT2_SHIFT;
u64 val = arch_counter_get_cntvct();
pt_regs_write_reg(regs, rt, lower_32_bits(val));
pt_regs_write_reg(regs, rt2, upper_32_bits(val));
arm64_compat_skip_faulting_instruction(regs, 4);
}
static struct sys64_hook cp15_64_hooks[] = {
{
.esr_mask = ESR_ELx_CP15_64_ISS_SYS_MASK,
.esr_val = ESR_ELx_CP15_64_ISS_SYS_CNTVCT,
.handler = compat_cntvct_read_handler,
},
{},
};