arch/um/kernel/um_arch.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  */

 #include <linux/delay.h>
 #include <linux/init.h>
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/seq_file.h>
 #include <linux/string.h>
 #include <linux/utsname.h>
 #include <linux/sched.h>
 #include <linux/sched/task.h>
 #include <linux/kmsg_dump.h>

 #include <asm/pgtable.h>
 #include <asm/processor.h>
 #include <asm/sections.h>
 #include <asm/setup.h>
 #include <as-layout.h>
 #include <arch.h>
 #include <init.h>
 #include <kern.h>
 #include <kern_util.h>
 #include <mem_user.h>
 #include <os.h>

 #define DEFAULT_COMMAND_LINE "root=98:0"

 /* Changed in add_arg and setup_arch, which run before SMP is started */
 static char __initdata command_line[COMMAND_LINE_SIZE] = { 0 };

 static void __init add_arg(char *arg)
 {
 	if (strlen(command_line) + strlen(arg) + 1 > COMMAND_LINE_SIZE) {
 		os_warn("add_arg: Too many command line arguments!\n");
 		exit(1);
 	}
 	if (strlen(command_line) > 0)
 		strcat(command_line, " ");
 	strcat(command_line, arg);
 }

 /*
  * These fields are initialized at boot time and not changed.
  * XXX This structure is used only in the non-SMP case.  Maybe this
  * should be moved to smp.c.
  */
 struct cpuinfo_um boot_cpu_data = {
 	.loops_per_jiffy	= 0,
 	.ipi_pipe		= { -1, -1 }
 };

 union thread_union cpu0_irqstack
 	__attribute__((__section__(".data..init_irqstack"))) =
 		{ .thread_info = INIT_THREAD_INFO(init_task) };

 /* Changed in setup_arch, which is called in early boot */
 static char host_info[(__NEW_UTS_LEN + 1) * 5];

 static int show_cpuinfo(struct seq_file *m, void *v)
 {
 	int index = 0;

 	seq_printf(m, "processor\t: %d\n", index);
 	seq_printf(m, "vendor_id\t: User Mode Linux\n");
 	seq_printf(m, "model name\t: UML\n");
 	seq_printf(m, "mode\t\t: skas\n");
 	seq_printf(m, "host\t\t: %s\n", host_info);
 	seq_printf(m, "bogomips\t: %lu.%02lu\n\n",
 		   loops_per_jiffy/(500000/HZ),
 		   (loops_per_jiffy/(5000/HZ)) % 100);

 	return 0;
 }

 static void *c_start(struct seq_file *m, loff_t *pos)
 {
 	return *pos < NR_CPUS ? cpu_data + *pos : NULL;
 }

 static void *c_next(struct seq_file *m, void *v, loff_t *pos)
 {
 	++*pos;
 	return c_start(m, pos);
 }

 static void c_stop(struct seq_file *m, void *v)
 {
 }

 const struct seq_operations cpuinfo_op = {
 	.start	= c_start,
 	.next	= c_next,
 	.stop	= c_stop,
 	.show	= show_cpuinfo,
 };

 /* Set in linux_main */
 unsigned long uml_physmem;
 EXPORT_SYMBOL(uml_physmem);

 unsigned long uml_reserved; /* Also modified in mem_init */
 unsigned long start_vm;
 unsigned long end_vm;

 /* Set in uml_ncpus_setup */
 int ncpus = 1;

 /* Set in early boot */
 static int have_root __initdata = 0;

 /* Set in uml_mem_setup and modified in linux_main */
 long long physmem_size = 32 * 1024 * 1024;
 EXPORT_SYMBOL(physmem_size);

 static const char *usage_string =
 "User Mode Linux v%s\n"
 "	available at http://user-mode-linux.sourceforge.net/\n\n";

 static int __init uml_version_setup(char *line, int *add)
 {
 	/* Explicitly use printf() to show version in stdout */
 	printf("%s\n", init_utsname()->release);
 	exit(0);

 	return 0;
 }

 __uml_setup("--version", uml_version_setup,
 "--version\n"
 "    Prints the version number of the kernel.\n\n"
 );

 static int __init uml_root_setup(char *line, int *add)
 {
 	have_root = 1;
 	return 0;
 }

 __uml_setup("root=", uml_root_setup,
 "root=<file containing the root fs>\n"
 "    This is actually used by the generic kernel in exactly the same\n"
 "    way as in any other kernel. If you configure a number of block\n"
 "    devices and want to boot off something other than ubd0, you \n"
 "    would use something like:\n"
 "        root=/dev/ubd5\n\n"
 );

 static int __init no_skas_debug_setup(char *line, int *add)
 {
 	os_warn("'debug' is not necessary to gdb UML in skas mode - run\n");
 	os_warn("'gdb linux'\n");

 	return 0;
 }

 __uml_setup("debug", no_skas_debug_setup,
 "debug\n"
 "    this flag is not needed to run gdb on UML in skas mode\n\n"
 );

 static int __init Usage(char *line, int *add)
 {
 	const char **p;

 	printf(usage_string, init_utsname()->release);
 	p = &__uml_help_start;
 	/* Explicitly use printf() to show help in stdout */
 	while (p < &__uml_help_end) {
 		printf("%s", *p);
 		p++;
 	}
 	exit(0);
 	return 0;
 }

 __uml_setup("--help", Usage,
 "--help\n"
 "    Prints this message.\n\n"
 );

 static void __init uml_checksetup(char *line, int *add)
 {
 	struct uml_param *p;

 	p = &__uml_setup_start;
 	while (p < &__uml_setup_end) {
 		size_t n;

 		n = strlen(p->str);
 		if (!strncmp(line, p->str, n) && p->setup_func(line + n, add))
 			return;
 		p++;
 	}
 }

 static void __init uml_postsetup(void)
 {
 	initcall_t *p;

 	p = &__uml_postsetup_start;
 	while (p < &__uml_postsetup_end) {
 		(*p)();
 		p++;
 	}
 	return;
 }

 static int panic_exit(struct notifier_block *self, unsigned long unused1,
 		      void *unused2)
 {
 	kmsg_dump(KMSG_DUMP_PANIC);
 	bust_spinlocks(1);
 	bust_spinlocks(0);
 	uml_exitcode = 1;
 	os_dump_core();
 	return 0;
 }

 static struct notifier_block panic_exit_notifier = {
 	.notifier_call 		= panic_exit,
 	.next 			= NULL,
 	.priority 		= 0
 };

 void uml_finishsetup(void)
 {
 	atomic_notifier_chain_register(&panic_notifier_list,
 				       &panic_exit_notifier);

 	uml_postsetup();

 	new_thread_handler();
 }

 /* Set during early boot */
 unsigned long task_size;
 EXPORT_SYMBOL(task_size);

 unsigned long host_task_size;

 unsigned long brk_start;
 unsigned long end_iomem;
 EXPORT_SYMBOL(end_iomem);

 #define MIN_VMALLOC (32 * 1024 * 1024)

 int __init linux_main(int argc, char **argv)
 {
 	unsigned long avail, diff;
 	unsigned long virtmem_size, max_physmem;
 	unsigned long stack;
 	unsigned int i;
 	int add;

 	for (i = 1; i < argc; i++) {
 		if ((i == 1) && (argv[i][0] == ' '))
 			continue;
 		add = 1;
 		uml_checksetup(argv[i], &add);
 		if (add)
 			add_arg(argv[i]);
 	}
 	if (have_root == 0)
 		add_arg(DEFAULT_COMMAND_LINE);

 	host_task_size = os_get_top_address();
 	/*
 	 * TASK_SIZE needs to be PGDIR_SIZE aligned or else exit_mmap craps
 	 * out
 	 */
 	task_size = host_task_size & PGDIR_MASK;

 	/* OS sanity checks that need to happen before the kernel runs */
 	os_early_checks();

 	brk_start = (unsigned long) sbrk(0);

 	/*
 	 * Increase physical memory size for exec-shield users
 	 * so they actually get what they asked for. This should
 	 * add zero for non-exec shield users
 	 */

 	diff = UML_ROUND_UP(brk_start) - UML_ROUND_UP(&_end);
 	if (diff > 1024 * 1024) {
 		os_info("Adding %ld bytes to physical memory to account for "
 			"exec-shield gap\n", diff);
 		physmem_size += UML_ROUND_UP(brk_start) - UML_ROUND_UP(&_end);
 	}

 	uml_physmem = (unsigned long) __binary_start & PAGE_MASK;

 	/* Reserve up to 4M after the current brk */
 	uml_reserved = ROUND_4M(brk_start) + (1 << 22);

 	setup_machinename(init_utsname()->machine);

 	highmem = 0;
 	iomem_size = (iomem_size + PAGE_SIZE - 1) & PAGE_MASK;
 	max_physmem = TASK_SIZE - uml_physmem - iomem_size - MIN_VMALLOC;

 	/*
 	 * Zones have to begin on a 1 << MAX_ORDER page boundary,
 	 * so this makes sure that's true for highmem
 	 */
 	max_physmem &= ~((1 << (PAGE_SHIFT + MAX_ORDER)) - 1);
 	if (physmem_size + iomem_size > max_physmem) {
 		highmem = physmem_size + iomem_size - max_physmem;
 		physmem_size -= highmem;
 	}

 	high_physmem = uml_physmem + physmem_size;
 	end_iomem = high_physmem + iomem_size;
 	high_memory = (void *) end_iomem;

 	start_vm = VMALLOC_START;

 	virtmem_size = physmem_size;
 	stack = (unsigned long) argv;
 	stack &= ~(1024 * 1024 - 1);
 	avail = stack - start_vm;
 	if (physmem_size > avail)
 		virtmem_size = avail;
 	end_vm = start_vm + virtmem_size;

 	if (virtmem_size < physmem_size)
 		os_info("Kernel virtual memory size shrunk to %lu bytes\n",
 			virtmem_size);

 	os_flush_stdout();

 	return start_uml();
 }

 int __init __weak read_initrd(void)
 {
 	return 0;
 }

 void __init setup_arch(char **cmdline_p)
 {
 	stack_protections((unsigned long) &init_thread_info);
 	setup_physmem(uml_physmem, uml_reserved, physmem_size, highmem);
 	mem_total_pages(physmem_size, iomem_size, highmem);
 	read_initrd();

 	paging_init();
 	strlcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
 	*cmdline_p = command_line;
 	setup_hostinfo(host_info, sizeof host_info);
 }

 void __init check_bugs(void)
 {
 	arch_check_bugs();
 	os_check_bugs();
 }

 void apply_alternatives(struct alt_instr *start, struct alt_instr *end)
 {
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
	*/

	#include <linux/delay.h>
	#include <linux/init.h>
	#include <linux/mm.h>
	#include <linux/module.h>
	#include <linux/seq_file.h>
	#include <linux/string.h>
	#include <linux/utsname.h>
	#include <linux/sched.h>
	#include <linux/sched/task.h>
	#include <linux/kmsg_dump.h>

	#include <asm/pgtable.h>
	#include <asm/processor.h>
	#include <asm/sections.h>
	#include <asm/setup.h>
	#include <as-layout.h>
	#include <arch.h>
	#include <init.h>
	#include <kern.h>
	#include <kern_util.h>
	#include <mem_user.h>
	#include <os.h>

	#define DEFAULT_COMMAND_LINE "root=98:0"

	/* Changed in add_arg and setup_arch, which run before SMP is started */
	static char __initdata command_line[COMMAND_LINE_SIZE] = { 0 };

	static void __init add_arg(char *arg)
	{
	if (strlen(command_line) + strlen(arg) + 1 > COMMAND_LINE_SIZE) {
	os_warn("add_arg: Too many command line arguments!\n");
	exit(1);
	}
	if (strlen(command_line) > 0)
	strcat(command_line, " ");
	strcat(command_line, arg);
	}

	/*
	* These fields are initialized at boot time and not changed.
	* XXX This structure is used only in the non-SMP case. Maybe this
	* should be moved to smp.c.
	*/
	struct cpuinfo_um boot_cpu_data = {
	.loops_per_jiffy = 0,
	.ipi_pipe = { -1, -1 }
	};

	union thread_union cpu0_irqstack
	__attribute__((__section__(".data..init_irqstack"))) =
	{ .thread_info = INIT_THREAD_INFO(init_task) };

	/* Changed in setup_arch, which is called in early boot */
	static char host_info[(__NEW_UTS_LEN + 1) * 5];

	static int show_cpuinfo(struct seq_file m, void v)
	{
	int index = 0;

	seq_printf(m, "processor\t: %d\n", index);
	seq_printf(m, "vendor_id\t: User Mode Linux\n");
	seq_printf(m, "model name\t: UML\n");
	seq_printf(m, "mode\t\t: skas\n");
	seq_printf(m, "host\t\t: %s\n", host_info);
	seq_printf(m, "bogomips\t: %lu.%02lu\n\n",
	loops_per_jiffy/(500000/HZ),
	(loops_per_jiffy/(5000/HZ)) % 100);

	return 0;
	}

	static void c_start(struct seq_file m, loff_t *pos)
	{
	return pos < NR_CPUS ? cpu_data + pos : NULL;
	}

	static void c_next(struct seq_file m, void v, loff_t pos)
	{
	++*pos;
	return c_start(m, pos);
	}

	static void c_stop(struct seq_file m, void v)
	{
	}

	const struct seq_operations cpuinfo_op = {
	.start = c_start,
	.next = c_next,
	.stop = c_stop,
	.show = show_cpuinfo,
	};

	/* Set in linux_main */
	unsigned long uml_physmem;
	EXPORT_SYMBOL(uml_physmem);

	unsigned long uml_reserved; /* Also modified in mem_init */
	unsigned long start_vm;
	unsigned long end_vm;

	/* Set in uml_ncpus_setup */
	int ncpus = 1;

	/* Set in early boot */
	static int have_root __initdata = 0;

	/* Set in uml_mem_setup and modified in linux_main */
	long long physmem_size = 32 * 1024 * 1024;
	EXPORT_SYMBOL(physmem_size);

	static const char *usage_string =
	"User Mode Linux v%s\n"
	" available at http://user-mode-linux.sourceforge.net/\n\n";

	static int __init uml_version_setup(char line, int add)
	{
	/* Explicitly use printf() to show version in stdout */
	printf("%s\n", init_utsname()->release);
	exit(0);

	return 0;
	}

	__uml_setup("--version", uml_version_setup,
	"--version\n"
	" Prints the version number of the kernel.\n\n"
	);

	static int __init uml_root_setup(char line, int add)
	{
	have_root = 1;
	return 0;
	}

	__uml_setup("root=", uml_root_setup,
	"root=<file containing the root fs>\n"
	" This is actually used by the generic kernel in exactly the same\n"
	" way as in any other kernel. If you configure a number of block\n"
	" devices and want to boot off something other than ubd0, you \n"
	" would use something like:\n"
	" root=/dev/ubd5\n\n"
	);

	static int __init no_skas_debug_setup(char line, int add)
	{
	os_warn("'debug' is not necessary to gdb UML in skas mode - run\n");
	os_warn("'gdb linux'\n");

	return 0;
	}

	__uml_setup("debug", no_skas_debug_setup,
	"debug\n"
	" this flag is not needed to run gdb on UML in skas mode\n\n"
	);

	static int __init Usage(char line, int add)
	{
	const char **p;

	printf(usage_string, init_utsname()->release);
	p = &__uml_help_start;
	/* Explicitly use printf() to show help in stdout */
	while (p < &__uml_help_end) {
	printf("%s", *p);
	p++;
	}
	exit(0);
	return 0;
	}

	__uml_setup("--help", Usage,
	"--help\n"
	" Prints this message.\n\n"
	);

	static void __init uml_checksetup(char line, int add)
	{
	struct uml_param *p;

	p = &__uml_setup_start;
	while (p < &__uml_setup_end) {
	size_t n;

	n = strlen(p->str);
	if (!strncmp(line, p->str, n) && p->setup_func(line + n, add))
	return;
	p++;
	}
	}

	static void __init uml_postsetup(void)
	{
	initcall_t *p;

	p = &__uml_postsetup_start;
	while (p < &__uml_postsetup_end) {
	(*p)();
	p++;
	}
	return;
	}

	static int panic_exit(struct notifier_block *self, unsigned long unused1,
	void *unused2)
	{
	kmsg_dump(KMSG_DUMP_PANIC);
	bust_spinlocks(1);
	bust_spinlocks(0);
	uml_exitcode = 1;
	os_dump_core();
	return 0;
	}

	static struct notifier_block panic_exit_notifier = {
	.notifier_call = panic_exit,
	.next = NULL,
	.priority = 0
	};

	void uml_finishsetup(void)
	{
	atomic_notifier_chain_register(&panic_notifier_list,
	&panic_exit_notifier);

	uml_postsetup();

	new_thread_handler();
	}

	/* Set during early boot */
	unsigned long task_size;
	EXPORT_SYMBOL(task_size);

	unsigned long host_task_size;

	unsigned long brk_start;
	unsigned long end_iomem;
	EXPORT_SYMBOL(end_iomem);

	#define MIN_VMALLOC (32 * 1024 * 1024)

	int __init linux_main(int argc, char **argv)
	{
	unsigned long avail, diff;
	unsigned long virtmem_size, max_physmem;
	unsigned long stack;
	unsigned int i;
	int add;

	for (i = 1; i < argc; i++) {
	if ((i == 1) && (argv[i][0] == ' '))
	continue;
	add = 1;
	uml_checksetup(argv[i], &add);
	if (add)
	add_arg(argv[i]);
	}
	if (have_root == 0)
	add_arg(DEFAULT_COMMAND_LINE);

	host_task_size = os_get_top_address();
	/*
	* TASK_SIZE needs to be PGDIR_SIZE aligned or else exit_mmap craps
	* out
	*/
	task_size = host_task_size & PGDIR_MASK;

	/* OS sanity checks that need to happen before the kernel runs */
	os_early_checks();

	brk_start = (unsigned long) sbrk(0);

	/*
	* Increase physical memory size for exec-shield users
	* so they actually get what they asked for. This should
	* add zero for non-exec shield users
	*/

	diff = UML_ROUND_UP(brk_start) - UML_ROUND_UP(&_end);
	if (diff > 1024 * 1024) {
	os_info("Adding %ld bytes to physical memory to account for "
	"exec-shield gap\n", diff);
	physmem_size += UML_ROUND_UP(brk_start) - UML_ROUND_UP(&_end);
	}

	uml_physmem = (unsigned long) __binary_start & PAGE_MASK;

	/* Reserve up to 4M after the current brk */
	uml_reserved = ROUND_4M(brk_start) + (1 << 22);

	setup_machinename(init_utsname()->machine);

	highmem = 0;
	iomem_size = (iomem_size + PAGE_SIZE - 1) & PAGE_MASK;
	max_physmem = TASK_SIZE - uml_physmem - iomem_size - MIN_VMALLOC;

	/*
	* Zones have to begin on a 1 << MAX_ORDER page boundary,
	* so this makes sure that's true for highmem
	*/
	max_physmem &= ~((1 << (PAGE_SHIFT + MAX_ORDER)) - 1);
	if (physmem_size + iomem_size > max_physmem) {
	highmem = physmem_size + iomem_size - max_physmem;
	physmem_size -= highmem;
	}

	high_physmem = uml_physmem + physmem_size;
	end_iomem = high_physmem + iomem_size;
	high_memory = (void *) end_iomem;

	start_vm = VMALLOC_START;

	virtmem_size = physmem_size;
	stack = (unsigned long) argv;
	stack &= ~(1024 * 1024 - 1);
	avail = stack - start_vm;
	if (physmem_size > avail)
	virtmem_size = avail;
	end_vm = start_vm + virtmem_size;

	if (virtmem_size < physmem_size)
	os_info("Kernel virtual memory size shrunk to %lu bytes\n",
	virtmem_size);

	os_flush_stdout();

	return start_uml();
	}

	int __init __weak read_initrd(void)
	{
	return 0;
	}

	void __init setup_arch(char **cmdline_p)
	{
	stack_protections((unsigned long) &init_thread_info);
	setup_physmem(uml_physmem, uml_reserved, physmem_size, highmem);
	mem_total_pages(physmem_size, iomem_size, highmem);
	read_initrd();

	paging_init();
	strlcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
	*cmdline_p = command_line;
	setup_hostinfo(host_info, sizeof host_info);
	}

	void __init check_bugs(void)
	{
	arch_check_bugs();
	os_check_bugs();
	}

	void apply_alternatives(struct alt_instr start, struct alt_instr end)
	{
	}