Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932242AbdDDRSl (ORCPT ); Tue, 4 Apr 2017 13:18:41 -0400 Received: from foss.arm.com ([217.140.101.70]:47638 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754601AbdDDRSi (ORCPT ); Tue, 4 Apr 2017 13:18:38 -0400 From: Marc Zyngier To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: Mark Rutland , Catalin Marinas , Daniel Lezcano , Will Deacon , Scott Wood , Hanjun Guo , Ding Tianhong , dann frazier , Thomas Gleixner Subject: [PATCH v3 02/18] arm64: Add CNTVCT_EL0 trap handler Date: Tue, 4 Apr 2017 18:18:10 +0100 Message-Id: <20170404171826.25030-3-marc.zyngier@arm.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20170404171826.25030-1-marc.zyngier@arm.com> References: <20170404171826.25030-1-marc.zyngier@arm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1781 Lines: 58 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: Mark Rutland Signed-off-by: Marc Zyngier --- arch/arm64/include/asm/esr.h | 2 ++ arch/arm64/kernel/traps.c | 14 ++++++++++++++ 2 files changed, 16 insertions(+) diff --git a/arch/arm64/include/asm/esr.h b/arch/arm64/include/asm/esr.h index d14c478976d0..ad42e79a5d4d 100644 --- a/arch/arm64/include/asm/esr.h +++ b/arch/arm64/include/asm/esr.h @@ -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 diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index e52be6aa44ee..1de444e6c669 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -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, + }, {}, }; -- 2.11.0