OpenSBI 固件代码分析（四）：coldboot

// lib/sbi/sbi_init.c: 271

/* Note: This has to be first thing in coldboot init sequence */
rc = sbi_scratch_init(scratch);
if (rc)
	sbi_hart_hang();

// include/sbi/sbi_scartch.h: 57

struct sbi_scratch {
	/** Start (or base) address of firmware linked to OpenSBI library */
	unsigned long fw_start;
	/** Size (in bytes) of firmware linked to OpenSBI library */
	unsigned long fw_size;
	/** Offset (in bytes) of the R/W section */
	unsigned long fw_rw_offset;
	/** Offset (in bytes) of the heap area */
	unsigned long fw_heap_offset;
	/** Size (in bytes) of the heap area */
	unsigned long fw_heap_size;
	/** Arg1 (or 'a1' register) of next booting stage for this HART */
	unsigned long next_arg1;
	/** Address of next booting stage for this HART */
	unsigned long next_addr;
	/** Privilege mode of next booting stage for this HART */
	unsigned long next_mode;
	/** Warm boot entry point address for this HART */
	unsigned long warmboot_addr;
	/** Address of sbi_platform */
	unsigned long platform_addr;
	/** Address of HART ID to sbi_scratch conversion function */
	unsigned long hartid_to_scratch;
	/** Address of trap exit function */
	unsigned long trap_exit;
	/** Temporary storage */
	unsigned long tmp0;
	/** Options for OpenSBI library */
	unsigned long options;
};

// lib/sbi/sbi_init.c: 276

/* Note: This has to be second thing in coldboot init sequence */
rc = sbi_heap_init(scratch);
if (rc)
	sbi_hart_hang();

// opensbi/lib/sbi/sbi_heap.c: 185

SBI_INIT_LIST_HEAD(&hpctrl.free_node_list);
SBI_INIT_LIST_HEAD(&hpctrl.free_space_list);
SBI_INIT_LIST_HEAD(&hpctrl.used_space_list);
/* Prepare free node list */
for (i = 0; i < (hpctrl.hksize / sizeof(*n)); i++) {
	n = (struct heap_node *)(hpctrl.hkbase + (sizeof(*n) * i));
	SBI_INIT_LIST_HEAD(&n->head);
	n->addr = n->size = 0;
	sbi_list_add_tail(&n->head, &hpctrl.free_node_list);
}
/* Prepare free space list */
n = sbi_list_first_entry(&hpctrl.free_node_list,
			 struct heap_node, head);
sbi_list_del(&n->head);
n->addr = hpctrl.hkbase + hpctrl.hksize;
n->size = hpctrl.size - hpctrl.hksize;
sbi_list_add_tail(&n->head, &hpctrl.free_space_list);

// lib/sbi/sbi_init.c: 281

/* Note: This has to be the third thing in coldboot init sequence */
rc = sbi_domain_init(scratch, hartid);
if (rc)
	sbi_hart_hang();

// lib/sbi/sbi_init.c: 297

rc = sbi_hsm_init(scratch, hartid, true);
if (rc)
	sbi_hart_hang();

// lib/sbi/sbi_init.c: 301

rc = sbi_platform_early_init(plat, true);
if (rc)
	sbi_hart_hang();

// lib/sbi/sbi_init.c: 305

rc = sbi_hart_init(scratch, true);
if (rc)
	sbi_hart_hang();

// lib/sbi/sbi_init.c: 309

rc = sbi_console_init(scratch);
if (rc)
	sbi_hart_hang();

// lib/sbi/sbi_init.c: 313

	rc = sbi_pmu_init(scratch, true);
	if (rc) {
		sbi_printf("%s: pmu init failed (error %d)\n",
			   __func__, rc);
		sbi_hart_hang();
	}

// lib/sbi/sbi_scratch.c: 43
// 根据 size 在堆中分配一块内存，返回分配内存的首地址
unsigned long sbi_scratch_alloc_offset(unsigned long size)
{
        u32 i;
        void *ptr;
        unsigned long ret = 0;
        struct sbi_scratch *rscratch;

        /*
         * We have a simple brain-dead allocator which never expects
         * anything to be free-ed hence it keeps incrementing the
         * next allocation offset until it runs-out of space.
         *
         * In future, we will have more sophisticated allocator which
         * will allow us to re-claim free-ed space.
         */

        if (!size)
                return 0;

        // groot: 两步操作，将 size 对齐到比 size 的地址大并且最接近 size 的内存中
        size += __SIZEOF_POINTER__ - 1;
        size &= ~((unsigned long)__SIZEOF_POINTER__ - 1);

        // groot: 访问共享内存，加锁
        spin_lock(&extra_lock);

        // groot: 如果内存不能够给 size 分配，跳出
        if (SBI_SCRATCH_SIZE < (extra_offset + size))
                goto done;

        // groot: 将内存分配给 ret，并且记录内存分配的变量 extra_offset 增加 size
        ret = extra_offset;
        extra_offset += size;

done:
        spin_unlock(&extra_lock);

        // groot: 如果内存分配成功
        //        遍历所有的 hart，将每个有效的 hart 的对应内存都清零
        if (ret) {
                for (i = 0; i <= sbi_scratch_last_hartid(); i++) {
                        rscratch = sbi_hartid_to_scratch(i);
                        if (!rscratch)
                                continue;
                        ptr = sbi_scratch_offset_ptr(rscratch, ret);
                        sbi_memset(ptr, 0, size);
                }
        }

        // groot: 返回新开辟的地址
        return ret;
}