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// Copyright 2016 The Fuchsia Authors
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file or at
// This file is used both in the kernel and in the vDSO implementation.
// So it must be compatible with both the kernel and userland header
// environments. It must use only the basic types so that struct
// layouts match exactly in both contexts.
#include <arch/defines.h> // Defines PAGE_SIZE usable from assembly.
// The constants are put on their own whole page though the actual struct
// is much smaller. Eventually, this will be used to change the contents
// after boot. For now, it just ensures that there's always a bunch of free
// space at the end where the version string can go.
#ifndef __ASSEMBLER__
#include <stdint.h>
#include <zircon/time.h>
// This struct contains constants that are initialized by the kernel
// once at boot time. From the vDSO code's perspective, they are
// read-only data that can never change. Hence, no synchronization is
// required to read them.
struct vdso_constants {
// Maximum number of CPUs that might be online during the lifetime
// of the booted system.
uint32_t max_num_cpus;
// Bit map indicating features. For specific feature bits, see
// zircon/features.h.
// TODO( This struct may need to grow over time as new features
// are added and/or supported. A mask may be needed to indicate which
// bits are valid.
struct {
uint32_t cpu;
// Total amount of debug registers available in the system.
uint32_t hw_breakpoint_count;
uint32_t hw_watchpoint_count;
// Bitmask indicating which address tagging features are available.
uint32_t address_tagging;
// Bitmask for vm related features.
uint32_t vm;
} features;
// Number of bytes in a data cache line.
uint32_t dcache_line_size;
// Number of bytes in an instruction cache line.
uint32_t icache_line_size;
// System page size in bytes. Guaranteed to be a power of 2.
uint32_t page_size;
uint32_t padding;
// Conversion factor for zx_ticks_get return values to seconds.
zx_ticks_t ticks_per_second;
// Offset for converting from the raw system timer to zx_ticks_t
zx_ticks_t raw_ticks_to_ticks_offset;
// Ratio which relates ticks (zx_ticks_get) to clock monotonic (zx_clock_get_monotonic).
// Specifically...
// ClockMono(ticks) = (ticks * N) / D
uint32_t ticks_to_mono_numerator;
uint32_t ticks_to_mono_denominator;
// Total amount of physical memory in the system, in bytes.
uint64_t physmem;
// Actual length of .version_string, not including the NUL terminator.
uint64_t version_string_len;
// A NUL-terminated UTF-8 string returned by zx_system_get_version_string.
char version_string[];
// This always leaves space for the NUL terminator.
constexpr size_t kMaxVersionString = VDSO_CONSTANTS_SIZE - sizeof(vdso_constants) - 1;
static_assert(VDSO_CONSTANTS_SIZE > sizeof(vdso_constants), "Need to adjust VDSO_CONSTANTS_SIZE");
static_assert(VDSO_CONSTANTS_ALIGN >= alignof(vdso_constants),
"Need to adjust VDSO_CONSTANTS_ALIGN");
#endif // __ASSEMBLER__