zircon/kernel/include/mexec.h

// Copyright 2017 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
// https://opensource.org/licenses/MIT

#pragma once

#define MEMMOV_OPS_DST_OFFSET (0)
#define MEMMOV_OPS_SRC_OFFSET (8)
#define MEMMOV_OPS_LEN_OFFSET (16)

#ifndef __ASSEMBLER__

#include <zircon/compiler.h>
#include <fbl/ref_ptr.h>
#include <vm/vm_object.h>
#include <zircon/types.h>
#include <stddef.h>
#include <stdint.h>

// Warning: The geometry of this struct is depended upon by the mexec assembly
//          function. Do not modify without also updating mexec.S.
typedef struct __PACKED {
    void* dst;
    void* src;
    size_t len;
} memmov_ops_t;

// Implemented in assembly. Copies the new kernel into place and branches to it.
typedef void (*mexec_asm_func)(uint64_t arg0, uint64_t arg1, uint64_t arg2,
                               uint64_t aux, memmov_ops_t* ops,
                               void* new_kernel_addr);

// Save the crashlog for propagation to the next kernel.
void mexec_stash_crashlog(fbl::RefPtr<VmObject> vmo);

/* Allow the platform to patch the zbi structure with any platform specific
 * data that might be necessary for the kernel that mexec is chain-loading.
 */
zx_status_t platform_mexec_patch_zbi(uint8_t* bootdata, const size_t len);

/* This function is called at the beginning of mexec.  Interrupts are not yet
 * disabled, but only one CPU is running.
 */
void platform_mexec_prep(uintptr_t new_bootimage_addr, size_t new_bootimage_len);

/* Ask the platform to mexec into the next kernel.
 * This function is called after platform_mexec_prep(), with interrupts disabled.
 */
void platform_mexec(mexec_asm_func mexec_assembly, memmov_ops_t* ops,
                    uintptr_t new_bootimage_addr, size_t new_bootimage_len,
                    uintptr_t entry64_addr);

static_assert(__offsetof(memmov_ops_t, dst) == MEMMOV_OPS_DST_OFFSET, "");
static_assert(__offsetof(memmov_ops_t, src) == MEMMOV_OPS_SRC_OFFSET, "");
static_assert(__offsetof(memmov_ops_t, len) == MEMMOV_OPS_LEN_OFFSET, "");

#endif // __ASSEMBLER__