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53 lines
1.9 KiB
Rust
53 lines
1.9 KiB
Rust
// SPDX-License-Identifier: MIT OR Apache-2.0
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//
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// Copyright (c) 2018-2020 Andre Richter <andre.o.richter@gmail.com>
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//! Relocation code.
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use crate::{bsp, runtime_init};
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//--------------------------------------------------------------------------------------------------
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// Public Code
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//--------------------------------------------------------------------------------------------------
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/// Relocates the own binary from `bsp::cpu::BOARD_DEFAULT_LOAD_ADDRESS` to the `__binary_start`
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/// address from the linker script.
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///
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/// # Safety
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///
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/// - Only a single core must be active and running this function.
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/// - Function must not use the `bss` section.
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pub unsafe fn relocate_self<T>() -> ! {
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extern "C" {
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static __binary_start: usize;
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static __binary_end: usize;
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}
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let binary_start_addr: usize = &__binary_start as *const _ as _;
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let binary_end_addr: usize = &__binary_end as *const _ as _;
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let binary_size_in_byte: usize = binary_end_addr - binary_start_addr;
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// Get the relocation destination address from the linker symbol.
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let mut reloc_dst_addr: *mut T = binary_start_addr as *mut T;
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// The address of where the previous firmware loaded us.
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let mut src_addr: *const T = bsp::memory::board_default_load_addr() as *const _;
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// Copy the whole binary.
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//
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// This is essentially a `memcpy()` optimized for throughput by transferring in chunks of T.
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let n = binary_size_in_byte / core::mem::size_of::<T>();
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for _ in 0..n {
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use core::ptr;
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ptr::write_volatile::<T>(reloc_dst_addr, ptr::read_volatile::<T>(src_addr));
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reloc_dst_addr = reloc_dst_addr.offset(1);
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src_addr = src_addr.offset(1);
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}
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// Call `runtime_init()` through a trait object, causing the jump to use an absolute address to
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// reach the relocated binary. An elaborate explanation can be found in the `runtime_init.rs`
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// source comments.
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runtime_init::get().runtime_init()
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}
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