kdebuginfo.c

/* Copyright 2018  Google, Inc.
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */
#include <linux/kallsyms.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/of_address.h>
#include <linux/bldr_debug_tools.h>

/*
 * These will be re-linked against their real values
 * during the second link stage.
 */
extern const unsigned long kallsyms_addresses[] __weak;
extern const int kallsyms_offsets[] __weak;
extern const u8 kallsyms_names[] __weak;

/*
 * Tell the compiler that the count isn't in the small data section if the arch
 * has one (eg: FRV).
 */
extern const unsigned long kallsyms_num_syms
__attribute__((weak, section(".rodata")));

extern const unsigned long kallsyms_relative_base
__attribute__((weak, section(".rodata")));

extern const u8 kallsyms_token_table[] __weak;
extern const u16 kallsyms_token_index[] __weak;

extern const unsigned long kallsyms_markers[] __weak;

struct kernel_info {
	/* For kallsyms */
	u8 enabled_all;
	u8 enabled_base_relative;
	u8 enabled_absolute_percpu;
	u8 enabled_cfi_clang;
	u32 num_syms;
	u16 name_len;
	u16 bit_per_long;
	u16 module_name_len;
	u16 symbol_len;
	phys_addr_t _addresses_va;
	phys_addr_t _relative_va;
	phys_addr_t _stext_va;
	phys_addr_t _etext_va;
	phys_addr_t _sinittext_va;
	phys_addr_t _einittext_va;
	phys_addr_t _end_va;
	phys_addr_t _offsets_va;
	phys_addr_t _names_va;
	phys_addr_t _token_table_va;
	phys_addr_t _token_index_va;
	phys_addr_t _markers_va;

	/* For frame pointer */
	u32 thread_size;

	/* For virt_to_phys */
	u32 va_bits;
	u64 page_offset;
	u64 phys_offset;
	u64 kimage_voffset;
};

struct kernel_all_info {
	u32 magic_number;
	u32 combined_checksum;
	struct kernel_info info;
};

static void backup_kernel_info(void)
{
	struct device_node *np;
	struct resource res;
	struct kernel_all_info *all_info;
	struct kernel_info *info;
	u32 *checksum_info;
	int num_reg = 0;
	int ret, index;

	np = of_find_compatible_node(NULL, NULL, "bootloader_kinfo");
	if (!np) {
		pr_warn("%s: bootloader_kinfo node does not exist\n", __func__);
		return;
	}

	ret = of_address_to_resource(np, num_reg, &res);
	if(ret) {
		pr_warn("%s: invalid argument, ret %d\n", __func__, ret);
		return;
	}

	if ((!res.start) ||
		(resource_size(&res) < sizeof(struct kernel_all_info))) {
		pr_warn("%s: unexpected resource start %llx and size %llx\n",
				__func__, res.start, resource_size(&res));
		return;
	}

	ret = strcmp(res.name, "kinfo");
	if (ret) {
		pr_warn("%s: unexpected resource name %s, ret %d\n", __func__,
				res.name, ret);
		return;
	}

	all_info = (struct kernel_all_info *)
			   ioremap(res.start, resource_size(&res));
	if (!all_info) {
		pr_warn("%s: failed to map kernel_all_info\n", __func__);
		return;
	}

	memset_io(all_info, 0, resource_size(&res));
	info = &(all_info->info);
	info->enabled_all = IS_ENABLED(CONFIG_KALLSYMS_ALL);
	info->enabled_base_relative = IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE);
	info->enabled_absolute_percpu =
		  IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU);
	info->enabled_cfi_clang = IS_ENABLED(CONFIG_CFI_CLANG);
	info->num_syms = kallsyms_num_syms;
	info->name_len = KSYM_NAME_LEN;
	info->bit_per_long = BITS_PER_LONG;
	info->module_name_len = MODULE_NAME_LEN;
	info->symbol_len = KSYM_SYMBOL_LEN;
	info->_addresses_va = (phys_addr_t)kallsyms_addresses;
	info->_relative_va = (phys_addr_t)kallsyms_relative_base;
	info->_stext_va = (phys_addr_t)_stext;
	info->_etext_va = (phys_addr_t)_etext;
	info->_sinittext_va = (phys_addr_t)_sinittext;
	info->_einittext_va = (phys_addr_t)_einittext;
	info->_end_va = (phys_addr_t)_end;
	info->_offsets_va = (phys_addr_t)kallsyms_offsets;
	info->_names_va = (phys_addr_t)kallsyms_names;
	info->_token_table_va = (phys_addr_t)kallsyms_token_table;
	info->_token_index_va = (phys_addr_t)kallsyms_token_index;
	info->_markers_va = (phys_addr_t)kallsyms_markers;
	info->thread_size = THREAD_SIZE;
	info->va_bits = VA_BITS;
	info->page_offset = PAGE_OFFSET;
	info->phys_offset = PHYS_OFFSET;
	info->kimage_voffset = kimage_voffset;

	for (index = 0; index < sizeof(struct kernel_info)/sizeof(u32);
		index++) {
		checksum_info = (u32 *)info;
		all_info->combined_checksum ^= checksum_info[index];
	}

	all_info->magic_number = BOOT_DEBUG_MAGIC;

	/* Ensure all information written to kernel_info is completed */
	mb();
	iounmap(all_info);
}

static int __init kdebuginfo_init(void)
{
	/* Backup kernel information for bootloader */
	backup_kernel_info();

	return 0;
}
device_initcall(kdebuginfo_init);