From e4f4f43c20b34121c9022e761d689a62eef054cf Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Mon, 24 Apr 2017 09:04:03 +0100 Subject: [PATCH] BACKPORT: 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: a86bd139f2ae ("arm64: arch_timer: Enable CNTVCT_EL0 trap if workaround is enabled") Reported-by: Hanjun Guo Tested-by: Hanjun Guo Reviewed-by: Hanjun Guo Signed-off-by: Marc Zyngier Signed-off-by: Catalin Marinas (cherry picked from commit 9842119a238bfb92cbab63258dabb54f0e7b111b) Change-Id: I40401111d1e2ba52a9512536ff20c68dcef26c54 Signed-off-by: Greg Kroah-Hartman --- arch/arm64/include/asm/esr.h | 4 ++++ arch/arm64/kernel/traps.c | 15 +++++++++++++++ 2 files changed, 19 insertions(+) diff --git a/arch/arm64/include/asm/esr.h b/arch/arm64/include/asm/esr.h index ad42e79a5d4d..85997c0e5443 100644 --- a/arch/arm64/include/asm/esr.h +++ b/arch/arm64/include/asm/esr.h @@ -177,6 +177,10 @@ #define ESR_ELx_SYS64_ISS_SYS_CNTVCT (ESR_ELx_SYS64_ISS_SYS_VAL(3, 3, 2, 14, 0) | \ 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__ #include diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index b043f865d4c8..f4aad0176fa3 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -504,6 +504,15 @@ static void cntvct_read_handler(unsigned int esr, struct pt_regs *regs) 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; + + if (rt != 31) + regs->regs[rt] = read_sysreg(cntfrq_el0); + regs->pc += 4; +} + struct sys64_hook { unsigned int esr_mask; unsigned int esr_val; @@ -528,6 +537,12 @@ static struct sys64_hook sys64_hooks[] = { .esr_val = ESR_ELx_SYS64_ISS_SYS_CNTVCT, .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, + }, {}, };