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Date: Tue, 4 Apr 2017 18:18:10 +0100 From: Marc Zyngier <marc.zyngier@....com> To: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org Cc: Mark Rutland <mark.rutland@....com>, Catalin Marinas <catalin.marinas@....com>, Daniel Lezcano <daniel.lezcano@...aro.org>, Will Deacon <will.deacon@....com>, Scott Wood <oss@...error.net>, Hanjun Guo <hanjun.guo@...aro.org>, Ding Tianhong <dingtianhong@...wei.com>, dann frazier <dann.frazier@...onical.com>, Thomas Gleixner <tglx@...utronix.de> Subject: [PATCH v3 02/18] arm64: Add CNTVCT_EL0 trap handler 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 <mark.rutland@....com> Signed-off-by: Marc Zyngier <marc.zyngier@....com> --- 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 <asm/types.h> 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
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