From: Marc Zyngier <marc.zyngier@arm.com>
Date: Thu, 27 Sep 2018 16:15:33 +0000 (+0100)
Subject: arm64: compat: Add CNTFRQ trap handler
X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=32a3e635fb0ecc1b197d54f710e76c6481cf19f0;p=openwrt%2Fstaging%2Fblogic.git

arm64: compat: Add CNTFRQ trap handler

Just like CNTVCT, we need to handle userspace trapping into the
kernel if we're decided that the timer wasn't fit for purpose...
64bit userspace is already dealt with, but we're missing the
equivalent compat handling.

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>
---

diff --git a/arch/arm64/include/asm/esr.h b/arch/arm64/include/asm/esr.h
index 5548712ce6e5..fb7dfe1b51bb 100644
--- a/arch/arm64/include/asm/esr.h
+++ b/arch/arm64/include/asm/esr.h
@@ -318,6 +318,9 @@
 #define ESR_ELx_CP15_64_ISS_SYS_CNTVCT	(ESR_ELx_CP15_64_ISS_SYS_VAL(1, 14) | \
 					 ESR_ELx_CP15_64_ISS_DIR_READ)
 
+#define ESR_ELx_CP15_32_ISS_SYS_CNTFRQ	(ESR_ELx_CP15_32_ISS_SYS_VAL(0, 0, 14, 0) |\
+					 ESR_ELx_CP15_32_ISS_DIR_READ)
+
 #ifndef __ASSEMBLY__
 #include <asm/types.h>
 
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 3602b900ff1c..58134a97928f 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -625,7 +625,20 @@ static void arm64_compat_skip_faulting_instruction(struct pt_regs *regs,
 	arm64_skip_faulting_instruction(regs, sz);
 }
 
+static void compat_cntfrq_read_handler(unsigned int esr, struct pt_regs *regs)
+{
+	int reg = (esr & ESR_ELx_CP15_32_ISS_RT_MASK) >> ESR_ELx_CP15_32_ISS_RT_SHIFT;
+
+	pt_regs_write_reg(regs, reg, arch_timer_get_rate());
+	arm64_compat_skip_faulting_instruction(regs, 4);
+}
+
 static struct sys64_hook cp15_32_hooks[] = {
+	{
+		.esr_mask = ESR_ELx_CP15_32_ISS_SYS_MASK,
+		.esr_val = ESR_ELx_CP15_32_ISS_SYS_CNTFRQ,
+		.handler = compat_cntfrq_read_handler,
+	},
 	{},
 };