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[Qemu-devel] [PULL 42/55] target/arm: support reading of CNT[VCT|FRQ]_EL
From: |
Peter Maydell |
Subject: |
[Qemu-devel] [PULL 42/55] target/arm: support reading of CNT[VCT|FRQ]_EL0 from user-space |
Date: |
Fri, 29 Jun 2018 15:53:34 +0100 |
From: Alex Bennée <address@hidden>
Since kernel commit a86bd139f2 (arm64: arch_timer: Enable CNTVCT_EL0
trap..), released in kernel version v4.12, user-space has been able
to read these system registers. As we can't use QEMUTimer's in
linux-user mode we just directly call cpu_get_clock().
Signed-off-by: Alex Bennée <address@hidden>
Reviewed-by: Richard Henderson <address@hidden>
Message-id: address@hidden
Reviewed-by: Peter Maydell <address@hidden>
Signed-off-by: Peter Maydell <address@hidden>
---
target/arm/helper.c | 27 ++++++++++++++++++++++++---
1 file changed, 24 insertions(+), 3 deletions(-)
diff --git a/target/arm/helper.c b/target/arm/helper.c
index b19c7ace785..d0786e0c210 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -2167,11 +2167,32 @@ static const ARMCPRegInfo generic_timer_cp_reginfo[] = {
};
#else
-/* In user-mode none of the generic timer registers are accessible,
- * and their implementation depends on QEMU_CLOCK_VIRTUAL and qdev gpio
outputs,
- * so instead just don't register any of them.
+
+/* In user-mode most of the generic timer registers are inaccessible
+ * however modern kernels (4.12+) allow access to cntvct_el0
*/
+
+static uint64_t gt_virt_cnt_read(CPUARMState *env, const ARMCPRegInfo *ri)
+{
+ /* Currently we have no support for QEMUTimer in linux-user so we
+ * can't call gt_get_countervalue(env), instead we directly
+ * call the lower level functions.
+ */
+ return cpu_get_clock() / GTIMER_SCALE;
+}
+
static const ARMCPRegInfo generic_timer_cp_reginfo[] = {
+ { .name = "CNTFRQ_EL0", .state = ARM_CP_STATE_AA64,
+ .opc0 = 3, .opc1 = 3, .crn = 14, .crm = 0, .opc2 = 0,
+ .type = ARM_CP_CONST, .access = PL0_R /* no PL1_RW in linux-user */,
+ .fieldoffset = offsetof(CPUARMState, cp15.c14_cntfrq),
+ .resetvalue = NANOSECONDS_PER_SECOND / GTIMER_SCALE,
+ },
+ { .name = "CNTVCT_EL0", .state = ARM_CP_STATE_AA64,
+ .opc0 = 3, .opc1 = 3, .crn = 14, .crm = 0, .opc2 = 2,
+ .access = PL0_R, .type = ARM_CP_NO_RAW | ARM_CP_IO,
+ .readfn = gt_virt_cnt_read,
+ },
REGINFO_SENTINEL
};
--
2.17.1
- [Qemu-devel] [PULL 34/55] target/arm: Implement SVE floating-point complex add, (continued)
- [Qemu-devel] [PULL 34/55] target/arm: Implement SVE floating-point complex add, Peter Maydell, 2018/06/29
- [Qemu-devel] [PULL 41/55] target/arm: Implement ARMv8.2-DotProd, Peter Maydell, 2018/06/29
- [Qemu-devel] [PULL 48/55] target/arm: Mark PMINTENSET accesses as possibly doing IO, Peter Maydell, 2018/06/29
- [Qemu-devel] [PULL 49/55] sd: Don't trace SDRequest crc field, Peter Maydell, 2018/06/29
- [Qemu-devel] [PULL 45/55] i.mx7d: Change IRQ number type from hwaddr to int, Peter Maydell, 2018/06/29
- [Qemu-devel] [PULL 51/55] target/arm: Fix SVE signed division vs x86 overflow exception, Peter Maydell, 2018/06/29
- [Qemu-devel] [PULL 52/55] target/arm: Fix SVE system register access checks, Peter Maydell, 2018/06/29
- [Qemu-devel] [PULL 47/55] target/arm: Remove redundant DIV detection for KVM, Peter Maydell, 2018/06/29
- [Qemu-devel] [PULL 31/55] target/arm: Implement SVE floating-point round to integral value, Peter Maydell, 2018/06/29
- [Qemu-devel] [PULL 40/55] target/arm: Enable SVE for aarch64-linux-user, Peter Maydell, 2018/06/29
- [Qemu-devel] [PULL 42/55] target/arm: support reading of CNT[VCT|FRQ]_EL0 from user-space,
Peter Maydell <=
- [Qemu-devel] [PULL 46/55] target/arm: Add ARM_FEATURE_V7VE for v7 Virtualization Extensions, Peter Maydell, 2018/06/29
- [Qemu-devel] [PULL 53/55] target/arm: Prune a57 features from max, Peter Maydell, 2018/06/29
- [Qemu-devel] [PULL 54/55] target/arm: Prune a15 features from max, Peter Maydell, 2018/06/29
- [Qemu-devel] [PULL 55/55] target/arm: Add ID_ISAR6, Peter Maydell, 2018/06/29
- [Qemu-devel] [PULL 50/55] sdcard: Use the ldst API, Peter Maydell, 2018/06/29
- Re: [Qemu-devel] [PULL 00/55] target-arm queue, Peter Maydell, 2018/06/30