b3aaddadc8
A structure, system_config, which is dynamically defined by the definitions/sysconf.yaml config, is now mapped into every user address space. The kernel fills this with information about itself and the running machine. User programs access this through the new j6_sysconf fake syscall in libj6. See: Github bug #242 See: [frobozz blog post](https://jsix.dev/posts/frobozz/) Tags:
85 lines
2.5 KiB
C++
85 lines
2.5 KiB
C++
#pragma once
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// vim: ft=cpp
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/// \file memory.h
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/// Import memory layout constants necessary for boot
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#include <stddef.h>
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#include <stdint.h>
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#include <arch/memory.h>
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void * operator new (size_t, void *p) noexcept;
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/// Allocate from the default allocator.
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/// \arg size The size in bytes requested
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/// \returns A pointer to the newly allocated memory,
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/// or nullptr on error
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void * kalloc(size_t size);
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/// Free memory allocated by `kalloc`.
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/// \arg p Pointer that was returned from a `kalloc` call
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void kfree(void *p);
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/// Kernel space virtual memory layout
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namespace mem {
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using arch::frame_size;
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using arch::kernel_offset;
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/// Max number of pages for a kernel stack
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constexpr unsigned kernel_stack_pages = 2;
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/// Max number of pages for a kernel buffer
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constexpr unsigned kernel_buffer_pages = 16;
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/*[[[cog code generation
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from os.path import join
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from memory import Layout
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layout = Layout(join(definitions_path, "memory_layout.yaml"))
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l = max([len(r.name) for r in layout.regions])
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for region in layout.regions:
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cog.outl(f"constexpr size_t {region.name:>{l}}_size = {region.size:#14x};")
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cog.outl("")
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for region in layout.regions:
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cog.outl(f"constexpr uintptr_t {region.name:>{l}}_offset = {region.start:#x};")
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]]]*/
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///[[[end]]]
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/// Helper to determine if a physical address can be accessed
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/// through the linear_offset area.
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constexpr bool linear_mappable(uintptr_t a) { return (a & linear_offset) == 0; }
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/// Get the number of pages needed to hold `bytes` bytes
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inline constexpr size_t bytes_to_pages(size_t bytes) {
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return ((bytes - 1) / frame_size) + 1;
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}
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/// Convert a physical address to a virtual one (in the linear-mapped area)
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template <typename T> T * to_virtual(uintptr_t a) {
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return reinterpret_cast<T*>(a|linear_offset);
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}
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/// Convert a physical address to a virtual one (in the linear-mapped area)
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template <typename T> T * to_virtual(T *p) {
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return to_virtual<T>(reinterpret_cast<uintptr_t>(p));
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}
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/// Get the number of pages needed for a given number of bytes.
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/// \arg bytes The number of bytes desired
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/// \returns The number of pages needed to contain the desired bytes
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constexpr size_t page_count(size_t bytes) { return ((bytes - 1) >> 12) + 1; }
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/// Get the given address, aligned to the next lowest page
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constexpr uintptr_t page_align_down(uintptr_t a) { return a & ~(frame_size-1); }
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/// Get the given address, aligned to the next page
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constexpr uintptr_t page_align_up(uintptr_t a) { return page_align_down(a-1) + frame_size; }
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} // namespace mem
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