From 1b6a04ca5504955c571d1c97504fb45ea0befee4 Mon Sep 17 00:00:00 2001 From: Valentin Popov Date: Mon, 8 Jan 2024 01:21:28 +0400 Subject: Initial vendor packages Signed-off-by: Valentin Popov --- vendor/portable-atomic/src/imp/interrupt/xtensa.rs | 47 ++++++++++++++++++++++ 1 file changed, 47 insertions(+) create mode 100644 vendor/portable-atomic/src/imp/interrupt/xtensa.rs (limited to 'vendor/portable-atomic/src/imp/interrupt/xtensa.rs') diff --git a/vendor/portable-atomic/src/imp/interrupt/xtensa.rs b/vendor/portable-atomic/src/imp/interrupt/xtensa.rs new file mode 100644 index 0000000..bc6d117 --- /dev/null +++ b/vendor/portable-atomic/src/imp/interrupt/xtensa.rs @@ -0,0 +1,47 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + +// Refs: +// - Xtensa Instruction Set Architecture (ISA) Reference Manual https://0x04.net/~mwk/doc/xtensa.pdf +// - Linux kernel's Xtensa atomic implementation https://github.com/torvalds/linux/blob/v6.1/arch/xtensa/include/asm/atomic.h + +use core::arch::asm; + +pub(super) use core::sync::atomic; + +pub(super) type State = u32; + +/// Disables interrupts and returns the previous interrupt state. +#[inline] +pub(super) fn disable() -> State { + let r: State; + // SAFETY: reading the PS special register and disabling all interrupts is safe. + // (see module-level comments of interrupt/mod.rs on the safety of using privileged instructions) + unsafe { + // Do not use `nomem` and `readonly` because prevent subsequent memory accesses from being reordered before interrupts are disabled. + // Interrupt level 15 to disable all interrupts. + // SYNC after RSIL is not required. + asm!("rsil {0}, 15", out(reg) r, options(nostack)); + } + r +} + +/// Restores the previous interrupt state. +/// +/// # Safety +/// +/// The state must be the one retrieved by the previous `disable`. +#[inline] +pub(super) unsafe fn restore(r: State) { + // SAFETY: the caller must guarantee that the state was retrieved by the previous `disable`, + // and we've checked that interrupts were enabled before disabling interrupts. + unsafe { + // Do not use `nomem` and `readonly` because prevent preceding memory accesses from being reordered after interrupts are enabled. + // SYNC after WSR is required to guarantee that subsequent RSIL read the written value. + asm!( + "wsr.ps {0}", + "rsync", + in(reg) r, + options(nostack), + ); + } +} -- cgit v1.2.3