1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * powerpc code to implement the kexec_file_load syscall
4 *
5 * Copyright (C) 2004  Adam Litke (agl@us.ibm.com)
6 * Copyright (C) 2004  IBM Corp.
7 * Copyright (C) 2004,2005  Milton D Miller II, IBM Corporation
8 * Copyright (C) 2005  R Sharada (sharada@in.ibm.com)
9 * Copyright (C) 2006  Mohan Kumar M (mohan@in.ibm.com)
10 * Copyright (C) 2016  IBM Corporation
11 *
12 * Based on kexec-tools' kexec-elf-ppc64.c, fs2dt.c.
13 * Heavily modified for the kernel by
14 * Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>.
15 */
16
17#include <linux/slab.h>
18#include <linux/kexec.h>
19#include <linux/of_fdt.h>
20#include <linux/libfdt.h>
21#include <asm/setup.h>
22
23#define SLAVE_CODE_SIZE		256	/* First 0x100 bytes */
24
25/**
26 * setup_kdump_cmdline - Prepend "elfcorehdr=<addr> " to command line
27 *                       of kdump kernel for exporting the core.
28 * @image:               Kexec image
29 * @cmdline:             Command line parameters to update.
30 * @cmdline_len:         Length of the cmdline parameters.
31 *
32 * kdump segment must be setup before calling this function.
33 *
34 * Returns new cmdline buffer for kdump kernel on success, NULL otherwise.
35 */
36char *setup_kdump_cmdline(struct kimage *image, char *cmdline,
37			  unsigned long cmdline_len)
38{
39	int elfcorehdr_strlen;
40	char *cmdline_ptr;
41
42	cmdline_ptr = kzalloc(COMMAND_LINE_SIZE, GFP_KERNEL);
43	if (!cmdline_ptr)
44		return NULL;
45
46	elfcorehdr_strlen = sprintf(cmdline_ptr, "elfcorehdr=0x%lx ",
47				    image->elf_load_addr);
48
49	if (elfcorehdr_strlen + cmdline_len > COMMAND_LINE_SIZE) {
50		pr_err("Appending elfcorehdr=<addr> exceeds cmdline size\n");
51		kfree(cmdline_ptr);
52		return NULL;
53	}
54
55	memcpy(cmdline_ptr + elfcorehdr_strlen, cmdline, cmdline_len);
56	// Ensure it's nul terminated
57	cmdline_ptr[COMMAND_LINE_SIZE - 1] = '\0';
58	return cmdline_ptr;
59}
60
61/**
62 * setup_purgatory - initialize the purgatory's global variables
63 * @image:		kexec image.
64 * @slave_code:		Slave code for the purgatory.
65 * @fdt:		Flattened device tree for the next kernel.
66 * @kernel_load_addr:	Address where the kernel is loaded.
67 * @fdt_load_addr:	Address where the flattened device tree is loaded.
68 *
69 * Return: 0 on success, or negative errno on error.
70 */
71int setup_purgatory(struct kimage *image, const void *slave_code,
72		    const void *fdt, unsigned long kernel_load_addr,
73		    unsigned long fdt_load_addr)
74{
75	unsigned int *slave_code_buf, master_entry;
76	int ret;
77
78	slave_code_buf = kmalloc(SLAVE_CODE_SIZE, GFP_KERNEL);
79	if (!slave_code_buf)
80		return -ENOMEM;
81
82	/* Get the slave code from the new kernel and put it in purgatory. */
83	ret = kexec_purgatory_get_set_symbol(image, "purgatory_start",
84					     slave_code_buf, SLAVE_CODE_SIZE,
85					     true);
86	if (ret) {
87		kfree(slave_code_buf);
88		return ret;
89	}
90
91	master_entry = slave_code_buf[0];
92	memcpy(slave_code_buf, slave_code, SLAVE_CODE_SIZE);
93	slave_code_buf[0] = master_entry;
94	ret = kexec_purgatory_get_set_symbol(image, "purgatory_start",
95					     slave_code_buf, SLAVE_CODE_SIZE,
96					     false);
97	kfree(slave_code_buf);
98
99	ret = kexec_purgatory_get_set_symbol(image, "kernel", &kernel_load_addr,
100					     sizeof(kernel_load_addr), false);
101	if (ret)
102		return ret;
103	ret = kexec_purgatory_get_set_symbol(image, "dt_offset", &fdt_load_addr,
104					     sizeof(fdt_load_addr), false);
105	if (ret)
106		return ret;
107
108	return 0;
109}
110