# Tutorial 07 - Timestamps ## tl;dr - We add abstractions for timer hardware, and implement them for the ARM architectural timer in `_arch/aarch64`. - The new timer functions are used to annotate UART prints with timestamps, and to get rid of the cycle-based delays in the `GPIO` device driver, which boosts accuracy. - A `warn!()` macro is added. ## Test it Check it out via chainboot (added in previous tutorial): ```console $ make chainboot [...] Minipush 1.0 [MP] ⏳ Waiting for /dev/ttyUSB0 [MP] ✅ Serial connected [MP] 🔌 Please power the target now __ __ _ _ _ _ | \/ (_)_ _ (_) | ___ __ _ __| | | |\/| | | ' \| | |__/ _ \/ _` / _` | |_| |_|_|_||_|_|____\___/\__,_\__,_| Raspberry Pi 3 [ML] Requesting binary [MP] ⏩ Pushing 12 KiB =========================================🦀 100% 0 KiB/s Time: 00:00:00 [ML] Loaded! Executing the payload now [ 0.140431] mingo version 0.7.0 [ 0.140630] Booting on: Raspberry Pi 3 [ 0.141085] Architectural timer resolution: 52 ns [ 0.141660] Drivers loaded: [ 0.141995] 1. BCM GPIO [ 0.142353] 2. BCM PL011 UART [W 0.142777] Spin duration smaller than architecturally supported, skipping [ 0.143621] Spinning for 1 second [ 1.144023] Spinning for 1 second [ 2.144245] Spinning for 1 second ``` ## Diff to previous ```diff diff -uNr 06_uart_chainloader/Cargo.toml 07_timestamps/Cargo.toml --- 06_uart_chainloader/Cargo.toml +++ 07_timestamps/Cargo.toml @@ -1,6 +1,6 @@ [package] name = "mingo" -version = "0.6.0" +version = "0.7.0" authors = ["Andre Richter "] edition = "2018" Binary files 06_uart_chainloader/demo_payload_rpi3.img and 07_timestamps/demo_payload_rpi3.img differ Binary files 06_uart_chainloader/demo_payload_rpi4.img and 07_timestamps/demo_payload_rpi4.img differ diff -uNr 06_uart_chainloader/Makefile 07_timestamps/Makefile --- 06_uart_chainloader/Makefile +++ 07_timestamps/Makefile @@ -25,7 +25,6 @@ READELF_BINARY = aarch64-none-elf-readelf LINKER_FILE = src/bsp/raspberrypi/link.ld RUSTC_MISC_ARGS = -C target-cpu=cortex-a53 - CHAINBOOT_DEMO_PAYLOAD = demo_payload_rpi3.img else ifeq ($(BSP),rpi4) TARGET = aarch64-unknown-none-softfloat KERNEL_BIN = kernel8.img @@ -37,7 +36,6 @@ READELF_BINARY = aarch64-none-elf-readelf LINKER_FILE = src/bsp/raspberrypi/link.ld RUSTC_MISC_ARGS = -C target-cpu=cortex-a72 - CHAINBOOT_DEMO_PAYLOAD = demo_payload_rpi4.img endif # Export for build.rs @@ -82,8 +80,7 @@ EXEC_QEMU = $(QEMU_BINARY) -M $(QEMU_MACHINE_TYPE) EXEC_MINIPUSH = ruby ../utils/minipush.rb -.PHONY: all $(KERNEL_ELF) $(KERNEL_BIN) doc qemu qemuasm chainboot clippy clean readelf objdump nm \ - check +.PHONY: all $(KERNEL_ELF) $(KERNEL_BIN) doc qemu chainboot clippy clean readelf objdump nm check all: $(KERNEL_BIN) @@ -105,14 +102,10 @@ qemu: $(KERNEL_BIN) $(call colorecho, "\nLaunching QEMU") @$(DOCKER_QEMU) $(EXEC_QEMU) $(QEMU_RELEASE_ARGS) -kernel $(KERNEL_BIN) - -qemuasm: $(KERNEL_BIN) - $(call colorecho, "\nLaunching QEMU with ASM output") - @$(DOCKER_QEMU) $(EXEC_QEMU) $(QEMU_RELEASE_ARGS) -kernel $(KERNEL_BIN) -d in_asm endif -chainboot: - @$(DOCKER_CHAINBOOT) $(EXEC_MINIPUSH) $(DEV_SERIAL) $(CHAINBOOT_DEMO_PAYLOAD) +chainboot: $(KERNEL_BIN) + @$(DOCKER_CHAINBOOT) $(EXEC_MINIPUSH) $(DEV_SERIAL) $(KERNEL_BIN) clippy: @RUSTFLAGS="$(RUSTFLAGS_PEDANTIC)" $(CLIPPY_CMD) diff -uNr 06_uart_chainloader/src/_arch/aarch64/cpu/boot.s 07_timestamps/src/_arch/aarch64/cpu/boot.s --- 06_uart_chainloader/src/_arch/aarch64/cpu/boot.s +++ 07_timestamps/src/_arch/aarch64/cpu/boot.s @@ -18,17 +18,6 @@ add \register, \register, #:lo12:\symbol .endm -// Load the address of a symbol into a register, absolute. -// -// # Resources -// -// - https://sourceware.org/binutils/docs-2.36/as/AArch64_002dRelocations.html -.macro ADR_ABS register, symbol - movz \register, #:abs_g2:\symbol - movk \register, #:abs_g1_nc:\symbol - movk \register, #:abs_g0_nc:\symbol -.endm - .equ _core_id_mask, 0b11 //-------------------------------------------------------------------------------------------------- @@ -45,31 +34,20 @@ and x1, x1, _core_id_mask ldr x2, BOOT_CORE_ID // provided by bsp/__board_name__/cpu.rs cmp x1, x2 - b.ne 2f - - // If execution reaches here, it is the boot core. + b.ne 1f - // Next, relocate the binary. - ADR_REL x0, __binary_nonzero_start // The address the binary got loaded to. - ADR_ABS x1, __binary_nonzero_start // The address the binary was linked to. - ADR_ABS x2, __binary_nonzero_end_exclusive - -1: ldr x3, [x0], #8 - str x3, [x1], #8 - cmp x1, x2 - b.lo 1b + // If execution reaches here, it is the boot core. Now, prepare the jump to Rust code. // Set the stack pointer. - ADR_ABS x0, __boot_core_stack_end_exclusive + ADR_REL x0, __boot_core_stack_end_exclusive mov sp, x0 - // Jump to the relocated Rust code. - ADR_ABS x1, _start_rust - br x1 + // Jump to Rust code. + b _start_rust // Infinitely wait for events (aka "park the core"). -2: wfe - b 2b +1: wfe + b 1b .size _start, . - _start .type _start, function diff -uNr 06_uart_chainloader/src/_arch/aarch64/cpu.rs 07_timestamps/src/_arch/aarch64/cpu.rs --- 06_uart_chainloader/src/_arch/aarch64/cpu.rs +++ 07_timestamps/src/_arch/aarch64/cpu.rs @@ -19,15 +19,6 @@ pub use asm::nop; -/// Spin for `n` cycles. -#[cfg(feature = "bsp_rpi3")] -#[inline(always)] -pub fn spin_for_cycles(n: usize) { - for _ in 0..n { - asm::nop(); - } -} - /// Pause execution on the core. #[inline(always)] pub fn wait_forever() -> ! { diff -uNr 06_uart_chainloader/src/_arch/aarch64/time.rs 07_timestamps/src/_arch/aarch64/time.rs --- 06_uart_chainloader/src/_arch/aarch64/time.rs +++ 07_timestamps/src/_arch/aarch64/time.rs @@ -0,0 +1,118 @@ +// SPDX-License-Identifier: MIT OR Apache-2.0 +// +// Copyright (c) 2018-2021 Andre Richter + +//! Architectural timer primitives. +//! +//! # Orientation +//! +//! Since arch modules are imported into generic modules using the path attribute, the path of this +//! file is: +//! +//! crate::time::arch_time + +use crate::{time, warn}; +use core::time::Duration; +use cortex_a::{barrier, regs::*}; + +//-------------------------------------------------------------------------------------------------- +// Private Definitions +//-------------------------------------------------------------------------------------------------- + +const NS_PER_S: u64 = 1_000_000_000; + +/// ARMv8 Generic Timer. +struct GenericTimer; + +//-------------------------------------------------------------------------------------------------- +// Global instances +//-------------------------------------------------------------------------------------------------- + +static TIME_MANAGER: GenericTimer = GenericTimer; + +//-------------------------------------------------------------------------------------------------- +// Private Code +//-------------------------------------------------------------------------------------------------- + +impl GenericTimer { + #[inline(always)] + fn read_cntpct(&self) -> u64 { + // Prevent that the counter is read ahead of time due to out-of-order execution. + unsafe { barrier::isb(barrier::SY) }; + CNTPCT_EL0.get() + } +} + +//-------------------------------------------------------------------------------------------------- +// Public Code +//-------------------------------------------------------------------------------------------------- + +/// Return a reference to the time manager. +pub fn time_manager() -> &'static impl time::interface::TimeManager { + &TIME_MANAGER +} + +//------------------------------------------------------------------------------ +// OS Interface Code +//------------------------------------------------------------------------------ + +impl time::interface::TimeManager for GenericTimer { + fn resolution(&self) -> Duration { + Duration::from_nanos(NS_PER_S / (CNTFRQ_EL0.get() as u64)) + } + + fn uptime(&self) -> Duration { + let current_count: u64 = self.read_cntpct() * NS_PER_S; + let frq: u64 = CNTFRQ_EL0.get() as u64; + + Duration::from_nanos(current_count / frq) + } + + fn spin_for(&self, duration: Duration) { + // Instantly return on zero. + if duration.as_nanos() == 0 { + return; + } + + // Calculate the register compare value. + let frq = CNTFRQ_EL0.get(); + let x = match frq.checked_mul(duration.as_nanos() as u64) { + None => { + warn!("Spin duration too long, skipping"); + return; + } + Some(val) => val, + }; + let tval = x / NS_PER_S; + + // Check if it is within supported bounds. + let warn: Option<&str> = if tval == 0 { + Some("smaller") + // The upper 32 bits of CNTP_TVAL_EL0 are reserved. + } else if tval > u32::max_value().into() { + Some("bigger") + } else { + None + }; + + if let Some(w) = warn { + warn!( + "Spin duration {} than architecturally supported, skipping", + w + ); + return; + } + + // Set the compare value register. + CNTP_TVAL_EL0.set(tval); + + // Kick off the counting. // Disable timer interrupt. + CNTP_CTL_EL0.modify(CNTP_CTL_EL0::ENABLE::SET + CNTP_CTL_EL0::IMASK::SET); + + // ISTATUS will be '1' when cval ticks have passed. Busy-check it. + while !CNTP_CTL_EL0.matches_all(CNTP_CTL_EL0::ISTATUS::SET) {} + + // Disable counting again. + CNTP_CTL_EL0.modify(CNTP_CTL_EL0::ENABLE::CLEAR); + } +} diff -uNr 06_uart_chainloader/src/bsp/device_driver/bcm/bcm2xxx_gpio.rs 07_timestamps/src/bsp/device_driver/bcm/bcm2xxx_gpio.rs --- 06_uart_chainloader/src/bsp/device_driver/bcm/bcm2xxx_gpio.rs +++ 07_timestamps/src/bsp/device_driver/bcm/bcm2xxx_gpio.rs @@ -139,25 +139,19 @@ /// Disable pull-up/down on pins 14 and 15. #[cfg(feature = "bsp_rpi3")] fn disable_pud_14_15_bcm2837(&mut self) { - use crate::cpu; + use crate::{time, time::interface::TimeManager}; + use core::time::Duration; - // Make an educated guess for a good delay value (Sequence described in the BCM2837 - // peripherals PDF). - // - // - According to Wikipedia, the fastest RPi4 clocks around 1.5 GHz. - // - The Linux 2837 GPIO driver waits 1 µs between the steps. - // - // So lets try to be on the safe side and default to 2000 cycles, which would equal 1 µs - // would the CPU be clocked at 2 GHz. - const DELAY: usize = 2000; + // The Linux 2837 GPIO driver waits 1 µs between the steps. + const DELAY: Duration = Duration::from_micros(1); self.registers.GPPUD.write(GPPUD::PUD::Off); - cpu::spin_for_cycles(DELAY); + time::time_manager().spin_for(DELAY); self.registers .GPPUDCLK0 .write(GPPUDCLK0::PUDCLK15::AssertClock + GPPUDCLK0::PUDCLK14::AssertClock); - cpu::spin_for_cycles(DELAY); + time::time_manager().spin_for(DELAY); self.registers.GPPUD.write(GPPUD::PUD::Off); self.registers.GPPUDCLK0.set(0); diff -uNr 06_uart_chainloader/src/bsp/device_driver/bcm/bcm2xxx_pl011_uart.rs 07_timestamps/src/bsp/device_driver/bcm/bcm2xxx_pl011_uart.rs --- 06_uart_chainloader/src/bsp/device_driver/bcm/bcm2xxx_pl011_uart.rs +++ 07_timestamps/src/bsp/device_driver/bcm/bcm2xxx_pl011_uart.rs @@ -279,7 +279,7 @@ } /// Retrieve a character. - fn read_char(&mut self, blocking_mode: BlockingMode) -> Option { + fn read_char_converting(&mut self, blocking_mode: BlockingMode) -> Option { // If RX FIFO is empty, if self.registers.FR.matches_all(FR::RXFE::SET) { // immediately return in non-blocking mode. @@ -294,7 +294,12 @@ } // Read one character. - let ret = self.registers.DR.get() as u8 as char; + let mut ret = self.registers.DR.get() as u8 as char; + + // Convert carrige return to newline. + if ret == '\r' { + ret = '\n' + } // Update statistics. self.chars_read += 1; @@ -374,14 +379,14 @@ impl console::interface::Read for PL011Uart { fn read_char(&self) -> char { self.inner - .lock(|inner| inner.read_char(BlockingMode::Blocking).unwrap()) + .lock(|inner| inner.read_char_converting(BlockingMode::Blocking).unwrap()) } fn clear_rx(&self) { // Read from the RX FIFO until it is indicating empty. while self .inner - .lock(|inner| inner.read_char(BlockingMode::NonBlocking)) + .lock(|inner| inner.read_char_converting(BlockingMode::NonBlocking)) .is_some() {} } diff -uNr 06_uart_chainloader/src/bsp/raspberrypi/link.ld 07_timestamps/src/bsp/raspberrypi/link.ld --- 06_uart_chainloader/src/bsp/raspberrypi/link.ld +++ 07_timestamps/src/bsp/raspberrypi/link.ld @@ -16,8 +16,7 @@ SECTIONS { - /* Set the link address to 32 MiB */ - . = 0x2000000; + . = __rpi_load_addr; /* ^ */ /* | stack */ /* | growth */ @@ -27,7 +26,6 @@ /*********************************************************************************************** * Code + RO Data + Global Offset Table ***********************************************************************************************/ - __binary_nonzero_start = .; .text : { KEEP(*(.text._start)) @@ -44,12 +42,8 @@ ***********************************************************************************************/ .data : { *(.data*) } :segment_rw - /* Fill up to 8 byte, b/c relocating the binary is done in u64 chunks */ - . = ALIGN(8); - __binary_nonzero_end_exclusive = .; - /* Section is zeroed in u64 chunks, align start and end to 8 bytes */ - .bss : + .bss : ALIGN(8) { __bss_start = .; *(.bss*); diff -uNr 06_uart_chainloader/src/bsp/raspberrypi/memory.rs 07_timestamps/src/bsp/raspberrypi/memory.rs --- 06_uart_chainloader/src/bsp/raspberrypi/memory.rs +++ 07_timestamps/src/bsp/raspberrypi/memory.rs @@ -23,10 +23,9 @@ /// The board's physical memory map. #[rustfmt::skip] pub(super) mod map { - pub const BOARD_DEFAULT_LOAD_ADDRESS: usize = 0x8_0000; - pub const GPIO_OFFSET: usize = 0x0020_0000; - pub const UART_OFFSET: usize = 0x0020_1000; + pub const GPIO_OFFSET: usize = 0x0020_0000; + pub const UART_OFFSET: usize = 0x0020_1000; /// Physical devices. #[cfg(feature = "bsp_rpi3")] @@ -53,13 +52,7 @@ // Public Code //-------------------------------------------------------------------------------------------------- -/// The address on which the Raspberry firmware loads every binary by default. -#[inline(always)] -pub fn board_default_load_addr() -> *const u64 { - map::BOARD_DEFAULT_LOAD_ADDRESS as _ -} - -/// Return the inclusive range spanning the relocated .bss section. +/// Return the inclusive range spanning the .bss section. /// /// # Safety /// diff -uNr 06_uart_chainloader/src/cpu.rs 07_timestamps/src/cpu.rs --- 06_uart_chainloader/src/cpu.rs +++ 07_timestamps/src/cpu.rs @@ -14,6 +14,3 @@ // Architectural Public Reexports //-------------------------------------------------------------------------------------------------- pub use arch_cpu::{nop, wait_forever}; - -#[cfg(feature = "bsp_rpi3")] -pub use arch_cpu::spin_for_cycles; diff -uNr 06_uart_chainloader/src/main.rs 07_timestamps/src/main.rs --- 06_uart_chainloader/src/main.rs +++ 07_timestamps/src/main.rs @@ -107,7 +107,6 @@ //! [`runtime_init::runtime_init()`]: runtime_init/fn.runtime_init.html #![allow(clippy::clippy::upper_case_acronyms)] -#![feature(asm)] #![feature(const_fn_fn_ptr_basics)] #![feature(format_args_nl)] #![feature(global_asm)] @@ -125,6 +124,7 @@ mod print; mod runtime_init; mod synchronization; +mod time; /// Early init code. /// @@ -147,56 +147,38 @@ kernel_main() } -const MINILOAD_LOGO: &str = r#" - __ __ _ _ _ _ -| \/ (_)_ _ (_) | ___ __ _ __| | -| |\/| | | ' \| | |__/ _ \/ _` / _` | -|_| |_|_|_||_|_|____\___/\__,_\__,_| -"#; - /// The main function running after the early init. fn kernel_main() -> ! { - use bsp::console::console; - use console::interface::All; + use core::time::Duration; + use driver::interface::DriverManager; + use time::interface::TimeManager; - println!("{}", MINILOAD_LOGO); - println!("{:^37}", bsp::board_name()); - println!(); - println!("[ML] Requesting binary"); - console().flush(); - - // Discard any spurious received characters before starting with the loader protocol. - console().clear_rx(); - - // Notify `Minipush` to send the binary. - for _ in 0..3 { - console().write_char(3 as char); + info!( + "{} version {}", + env!("CARGO_PKG_NAME"), + env!("CARGO_PKG_VERSION") + ); + info!("Booting on: {}", bsp::board_name()); + + info!( + "Architectural timer resolution: {} ns", + time::time_manager().resolution().as_nanos() + ); + + info!("Drivers loaded:"); + for (i, driver) in bsp::driver::driver_manager() + .all_device_drivers() + .iter() + .enumerate() + { + info!(" {}. {}", i + 1, driver.compatible()); } - // Read the binary's size. - let mut size: u32 = u32::from(console().read_char() as u8); - size |= u32::from(console().read_char() as u8) << 8; - size |= u32::from(console().read_char() as u8) << 16; - size |= u32::from(console().read_char() as u8) << 24; - - // Trust it's not too big. - console().write_char('O'); - console().write_char('K'); - - let kernel_addr: *mut u8 = bsp::memory::board_default_load_addr() as *mut u8; - unsafe { - // Read the kernel byte by byte. - for i in 0..size { - core::ptr::write_volatile(kernel_addr.offset(i as isize), console().read_char() as u8) - } - } + // Test a failing timer case. + time::time_manager().spin_for(Duration::from_nanos(1)); - println!("[ML] Loaded! Executing the payload now\n"); - console().flush(); - - // Use black magic to create a function pointer. - let kernel: fn() -> ! = unsafe { core::mem::transmute(kernel_addr) }; - - // Jump to loaded kernel! - kernel() + loop { + info!("Spinning for 1 second"); + time::time_manager().spin_for(Duration::from_secs(1)); + } } diff -uNr 06_uart_chainloader/src/print.rs 07_timestamps/src/print.rs --- 06_uart_chainloader/src/print.rs +++ 07_timestamps/src/print.rs @@ -36,3 +36,71 @@ $crate::print::_print(format_args_nl!($($arg)*)); }) } + +/// Prints an info, with a newline. +#[macro_export] +macro_rules! info { + ($string:expr) => ({ + #[allow(unused_imports)] + use crate::time::interface::TimeManager; + + let timestamp = $crate::time::time_manager().uptime(); + let timestamp_subsec_us = timestamp.subsec_micros(); + + $crate::print::_print(format_args_nl!( + concat!("[ {:>3}.{:03}{:03}] ", $string), + timestamp.as_secs(), + timestamp_subsec_us / 1_000, + timestamp_subsec_us modulo 1_000 + )); + }); + ($format_string:expr, $($arg:tt)*) => ({ + #[allow(unused_imports)] + use crate::time::interface::TimeManager; + + let timestamp = $crate::time::time_manager().uptime(); + let timestamp_subsec_us = timestamp.subsec_micros(); + + $crate::print::_print(format_args_nl!( + concat!("[ {:>3}.{:03}{:03}] ", $format_string), + timestamp.as_secs(), + timestamp_subsec_us / 1_000, + timestamp_subsec_us modulo 1_000, + $($arg)* + )); + }) +} + +/// Prints a warning, with a newline. +#[macro_export] +macro_rules! warn { + ($string:expr) => ({ + #[allow(unused_imports)] + use crate::time::interface::TimeManager; + + let timestamp = $crate::time::time_manager().uptime(); + let timestamp_subsec_us = timestamp.subsec_micros(); + + $crate::print::_print(format_args_nl!( + concat!("[W {:>3}.{:03}{:03}] ", $string), + timestamp.as_secs(), + timestamp_subsec_us / 1_000, + timestamp_subsec_us modulo 1_000 + )); + }); + ($format_string:expr, $($arg:tt)*) => ({ + #[allow(unused_imports)] + use crate::time::interface::TimeManager; + + let timestamp = $crate::time::time_manager().uptime(); + let timestamp_subsec_us = timestamp.subsec_micros(); + + $crate::print::_print(format_args_nl!( + concat!("[W {:>3}.{:03}{:03}] ", $format_string), + timestamp.as_secs(), + timestamp_subsec_us / 1_000, + timestamp_subsec_us modulo 1_000, + $($arg)* + )); + }) +} diff -uNr 06_uart_chainloader/src/time.rs 07_timestamps/src/time.rs --- 06_uart_chainloader/src/time.rs +++ 07_timestamps/src/time.rs @@ -0,0 +1,37 @@ +// SPDX-License-Identifier: MIT OR Apache-2.0 +// +// Copyright (c) 2020-2021 Andre Richter + +//! Timer primitives. + +#[cfg(target_arch = "aarch64")] +#[path = "_arch/aarch64/time.rs"] +mod arch_time; + +//-------------------------------------------------------------------------------------------------- +// Architectural Public Reexports +//-------------------------------------------------------------------------------------------------- +pub use arch_time::time_manager; + +//-------------------------------------------------------------------------------------------------- +// Public Definitions +//-------------------------------------------------------------------------------------------------- + +/// Timekeeping interfaces. +pub mod interface { + use core::time::Duration; + + /// Time management functions. + pub trait TimeManager { + /// The timer's resolution. + fn resolution(&self) -> Duration; + + /// The uptime since power-on of the device. + /// + /// This includes time consumed by firmware and bootloaders. + fn uptime(&self) -> Duration; + + /// Spin for a given duration. + fn spin_for(&self, duration: Duration); + } +} diff -uNr 06_uart_chainloader/update.sh 07_timestamps/update.sh --- 06_uart_chainloader/update.sh +++ 07_timestamps/update.sh @@ -1,8 +0,0 @@ -#!/usr/bin/env bash - -cd ../05_drivers_gpio_uart -BSP=rpi4 make -cp kernel8.img ../06_uart_chainloader/demo_payload_rpi4.img -make -cp kernel8.img ../06_uart_chainloader/demo_payload_rpi3.img -rm kernel8.img ```