cregit-Linux how code gets into the kernel

Release 4.14 arch/metag/kernel/setup.c

Directory: arch/metag/kernel
/*
 * Copyright (C) 2005-2012 Imagination Technologies Ltd.
 *
 * This file contains the architecture-dependant parts of system setup.
 *
 */

#include <linux/export.h>
#include <linux/bootmem.h>
#include <linux/console.h>
#include <linux/cpu.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/genhd.h>
#include <linux/init.h>
#include <linux/initrd.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/memblock.h>
#include <linux/mm.h>
#include <linux/of_fdt.h>
#include <linux/pfn.h>
#include <linux/root_dev.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/start_kernel.h>
#include <linux/string.h>

#include <asm/cachepart.h>
#include <asm/clock.h>
#include <asm/core_reg.h>
#include <asm/cpu.h>
#include <asm/da.h>
#include <asm/highmem.h>
#include <asm/hwthread.h>
#include <asm/l2cache.h>
#include <asm/mach/arch.h>
#include <asm/metag_mem.h>
#include <asm/metag_regs.h>
#include <asm/mmu.h>
#include <asm/mmzone.h>
#include <asm/processor.h>
#include <asm/sections.h>
#include <asm/setup.h>
#include <asm/traps.h>

/* Priv protect as many registers as possible. */

#define DEFAULT_PRIV	(TXPRIVEXT_COPRO_BITS           | \
                         TXPRIVEXT_TXTRIGGER_BIT        | \
                         TXPRIVEXT_TXGBLCREG_BIT        | \
                         TXPRIVEXT_ILOCK_BIT            | \
                         TXPRIVEXT_TXITACCYC_BIT        | \
                         TXPRIVEXT_TXDIVTIME_BIT        | \
                         TXPRIVEXT_TXAMAREGX_BIT        | \
                         TXPRIVEXT_TXTIMERI_BIT         | \
                         TXPRIVEXT_TXSTATUS_BIT         | \
                         TXPRIVEXT_TXDISABLE_BIT)

/* Meta2 specific bits. */
#ifdef CONFIG_METAG_META12

#define META2_PRIV	0
#else

#define META2_PRIV	(TXPRIVEXT_TXTIMER_BIT          | \
                         TXPRIVEXT_TRACE_BIT)
#endif

/* Unaligned access checking bits. */
#ifdef CONFIG_METAG_UNALIGNED

#define UNALIGNED_PRIV	TXPRIVEXT_ALIGNREW_BIT
#else

#define UNALIGNED_PRIV	0
#endif


#define PRIV_BITS 	(DEFAULT_PRIV                   | \
                         META2_PRIV                     | \
                         UNALIGNED_PRIV)

/*
 * Protect access to:
 * 0x06000000-0x07ffffff Direct mapped region
 * 0x05000000-0x05ffffff MMU table region (Meta1)
 * 0x04400000-0x047fffff Cache flush region
 * 0x84000000-0x87ffffff Core cache memory region (Meta2)
 *
 * Allow access to:
 * 0x80000000-0x81ffffff Core code memory region (Meta2)
 */
#ifdef CONFIG_METAG_META12

#define PRIVSYSR_BITS	TXPRIVSYSR_ALL_BITS
#else

#define PRIVSYSR_BITS	(TXPRIVSYSR_ALL_BITS & ~TXPRIVSYSR_CORECODE_BIT)
#endif

/* Protect all 0x02xxxxxx and 0x048xxxxx. */

#define PIOREG_BITS	0xffffffff

/*
 * Protect all 0x04000xx0 (system events)
 * except write combiner flush and write fence (system events 4 and 5).
 */

#define PSYREG_BITS	0xfffffffb


extern char _heap_start[];

#ifdef CONFIG_DA_CONSOLE
/* Our early channel based console driver */
extern struct console dash_console;
#endif


const struct machine_desc *machine_desc __initdata;

/*
 * Map a Linux CPU number to a hardware thread ID
 * In SMP this will be setup with the correct mapping at startup; in UP this
 * will map to the HW thread on which we are running.
 */

u8 cpu_2_hwthread_id[NR_CPUS] __read_mostly = {
	[0 ... NR_CPUS-1] = BAD_HWTHREAD_ID
};

EXPORT_SYMBOL_GPL(cpu_2_hwthread_id);

/*
 * Map a hardware thread ID to a Linux CPU number
 * In SMP this will be fleshed out with the correct CPU ID for a particular
 * hardware thread. In UP this will be initialised with the boot CPU ID.
 */

u8 hwthread_id_2_cpu[4] __read_mostly = {
	[0 ... 3] = BAD_CPU_ID
};

/* The relative offset of the MMU mapped memory (from ldlk or bootloader)
 * to the real physical memory.  This is needed as we have to use the
 * physical addresses in the MMU tables (pte entries), and not the virtual
 * addresses.
 * This variable is used in the __pa() and __va() macros, and should
 * probably only be used via them.
 */

unsigned int meta_memoffset;

EXPORT_SYMBOL(meta_memoffset);


static char __initdata *original_cmd_line;

DEFINE_PER_CPU(PTBI, pTBI);

/*
 * Mapping are specified as "CPU_ID:HWTHREAD_ID", e.g.
 *
 *      "hwthread_map=0:1,1:2,2:3,3:0"
 *
 *      Linux CPU ID    HWTHREAD_ID
 *      ---------------------------
 *          0                 1
 *          1                 2
 *          2                 3
 *          3                 0
 */



static int __init parse_hwthread_map(char *p)
{
	int cpu;

	while (*p) {
		cpu = (*p++) - '0';
		if (cpu < 0 || cpu > 9)
			goto err_cpu;

		p++;		/* skip semi-colon */
		cpu_2_hwthread_id[cpu] = (*p++) - '0';
		if (cpu_2_hwthread_id[cpu] >= 4)
			goto err_thread;
		hwthread_id_2_cpu[cpu_2_hwthread_id[cpu]] = cpu;

		if (*p == ',')
			p++;		/* skip comma */
	}

	return 0;
err_cpu:
	pr_err("%s: hwthread_map cpu argument out of range\n", __func__);
	return -EINVAL;
err_thread:
	pr_err("%s: hwthread_map thread argument out of range\n", __func__);
	return -EINVAL;
}

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early_param("hwthread_map", parse_hwthread_map);




void __init dump_machine_table(void)
{
	struct machine_desc *p;
	const char **compat;

	pr_info("Available machine support:\n\tNAME\t\tCOMPATIBLE LIST\n");
	for_each_machine_desc(p) {
		pr_info("\t%s\t[", p->name);
		for (compat = p->dt_compat; compat && *compat; ++compat)
			printk(" '%s'", *compat);
		printk(" ]\n");
	}

	pr_info("\nPlease check your kernel config and/or bootloader.\n");

	hard_processor_halt(HALT_PANIC);
}


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#ifdef CONFIG_METAG_HALT_ON_PANIC



static int metag_panic_event(struct notifier_block *this, unsigned long event,
			     void *ptr)
{
	hard_processor_halt(HALT_PANIC);
	return NOTIFY_DONE;
}


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static struct notifier_block metag_panic_block = {
	metag_panic_event,
	NULL,
	0
};
#endif




void __init setup_arch(char **cmdline_p)
{
	unsigned long start_pfn;
	unsigned long text_start = (unsigned long)(&_stext);
	unsigned long cpu = smp_processor_id();
	unsigned long heap_start, heap_end;
	unsigned long start_pte;
	PTBI _pTBI;
	PTBISEG p_heap;
	int heap_id, i;

	metag_cache_probe();

	metag_da_probe();
#ifdef CONFIG_DA_CONSOLE
	if (metag_da_enabled()) {
		/* An early channel based console driver */
		register_console(&dash_console);
		add_preferred_console("ttyDA", 1, NULL);
	}
#endif

	/* try interpreting the argument as a device tree */
	machine_desc = setup_machine_fdt(original_cmd_line);
	/* if it doesn't look like a device tree it must be a command line */
	if (!machine_desc) {
#ifdef CONFIG_METAG_BUILTIN_DTB
		/* try the embedded device tree */
		machine_desc = setup_machine_fdt(__dtb_start);
		if (!machine_desc)
			panic("Invalid embedded device tree.");
#else
		/* use the default machine description */
		machine_desc = default_machine_desc();
#endif
#ifndef CONFIG_CMDLINE_FORCE
		/* append the bootloader cmdline to any builtin fdt cmdline */
		if (boot_command_line[0] && original_cmd_line[0])
			strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
		strlcat(boot_command_line, original_cmd_line,
			COMMAND_LINE_SIZE);
#endif
	}
	setup_meta_clocks(machine_desc->clocks);

	*cmdline_p = boot_command_line;
	parse_early_param();

	/*
         * Make sure we don't alias in dcache or icache
         */
	check_for_cache_aliasing(cpu);


#ifdef CONFIG_METAG_HALT_ON_PANIC
	atomic_notifier_chain_register(&panic_notifier_list,
				       &metag_panic_block);
#endif

#ifdef CONFIG_DUMMY_CONSOLE
	conswitchp = &dummy_con;
#endif

	if (!(__core_reg_get(TXSTATUS) & TXSTATUS_PSTAT_BIT))
		panic("Privilege must be enabled for this thread.");

	_pTBI = __TBI(TBID_ISTAT_BIT);

	per_cpu(pTBI, cpu) = _pTBI;

	if (!per_cpu(pTBI, cpu))
		panic("No TBI found!");

	/*
         * Initialize all interrupt vectors to our copy of __TBIUnExpXXX,
         * rather than the version from the bootloader. This makes call
         * stacks easier to understand and may allow us to unmap the
         * bootloader at some point.
         */
	for (i = 0; i <= TBID_SIGNUM_MAX; i++)
		_pTBI->fnSigs[i] = __TBIUnExpXXX;

	/* A Meta requirement is that the kernel is loaded (virtually)
         * at the PAGE_OFFSET.
         */
	if (PAGE_OFFSET != text_start)
		panic("Kernel not loaded at PAGE_OFFSET (%#x) but at %#lx.",
		      PAGE_OFFSET, text_start);

	start_pte = mmu_read_second_level_page(text_start);

	/*
         * Kernel pages should have the PRIV bit set by the bootloader.
         */
	if (!(start_pte & _PAGE_KERNEL))
		panic("kernel pte does not have PRIV set");

	/*
         * See __pa and __va in include/asm/page.h.
         * This value is negative when running in local space but the
         * calculations work anyway.
         */
	meta_memoffset = text_start - (start_pte & PAGE_MASK);

	/* Now lets look at the heap space */
	heap_id = (__TBIThreadId() & TBID_THREAD_BITS)
		+ TBID_SEG(0, TBID_SEGSCOPE_LOCAL, TBID_SEGTYPE_HEAP);

	p_heap = __TBIFindSeg(NULL, heap_id);

	if (!p_heap)
		panic("Could not find heap from TBI!");

	/* The heap begins at the first full page after the kernel data. */
	heap_start = (unsigned long) &_heap_start;

	/* The heap ends at the end of the heap segment specified with
         * ldlk.
         */
	if (is_global_space(text_start)) {
		pr_debug("WARNING: running in global space!\n");
		heap_end = (unsigned long)p_heap->pGAddr + p_heap->Bytes;
	} else {
		heap_end = (unsigned long)p_heap->pLAddr + p_heap->Bytes;
	}

	ROOT_DEV = Root_RAM0;

	/* init_mm is the mm struct used for the first task.  It is then
         * cloned for all other tasks spawned from that task.
         *
         * Note - we are using the virtual addresses here.
         */
	init_mm.start_code = (unsigned long)(&_stext);
	init_mm.end_code = (unsigned long)(&_etext);
	init_mm.end_data = (unsigned long)(&_edata);
	init_mm.brk = (unsigned long)heap_start;

	min_low_pfn = PFN_UP(__pa(text_start));
	max_low_pfn = PFN_DOWN(__pa(heap_end));

	pfn_base = min_low_pfn;

	/* Round max_pfn up to a 4Mb boundary. The free_bootmem_node()
         * call later makes sure to keep the rounded up pages marked reserved.
         */
	max_pfn = max_low_pfn + ((1 << MAX_ORDER) - 1);
	max_pfn &= ~((1 << MAX_ORDER) - 1);

	start_pfn = PFN_UP(__pa(heap_start));

	if (min_low_pfn & ((1 << MAX_ORDER) - 1)) {
		/* Theoretically, we could expand the space that the
                 * bootmem allocator covers - much as we do for the
                 * 'high' address, and then tell the bootmem system
                 * that the lowest chunk is 'not available'.  Right
                 * now it is just much easier to constrain the
                 * user to always MAX_ORDER align their kernel space.
                 */

		panic("Kernel must be %d byte aligned, currently at %#lx.",
		      1 << (MAX_ORDER + PAGE_SHIFT),
		      min_low_pfn << PAGE_SHIFT);
	}

#ifdef CONFIG_HIGHMEM
	highstart_pfn = highend_pfn = max_pfn;
	high_memory = (void *) __va(PFN_PHYS(highstart_pfn));
#else
	high_memory = (void *)__va(PFN_PHYS(max_pfn));
#endif

	paging_init(heap_end);

	setup_priv();

	/* Setup the boot cpu's mapping. The rest will be setup below. */
	cpu_2_hwthread_id[smp_processor_id()] = hard_processor_id();
	hwthread_id_2_cpu[hard_processor_id()] = smp_processor_id();

	unflatten_and_copy_device_tree();

#ifdef CONFIG_SMP
	smp_init_cpus();
#endif

	if (machine_desc->init_early)
		machine_desc->init_early();
}


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static int __init customize_machine(void)
{
	/* customizes platform devices, or adds new ones */
	if (machine_desc->init_machine)
		machine_desc->init_machine();

	return 0;
}

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arch_initcall(customize_machine);




static int __init init_machine_late(void)
{
	if (machine_desc->init_late)
		machine_desc->init_late();
	return 0;
}

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late_initcall(init_machine_late);

#ifdef CONFIG_PROC_FS
/*
 *      Get CPU information for use by the procfs.
 */



static const char *get_cpu_capabilities(unsigned int txenable)
{
#ifdef CONFIG_METAG_META21
	/* See CORE_ID in META HTP.GP TRM - Architecture Overview 2.1.238 */
	int coreid = metag_in32(METAC_CORE_ID);
	unsigned int dsp_type = (coreid >> 3) & 7;
	unsigned int fpu_type = (coreid >> 7) & 3;

	switch (dsp_type | fpu_type << 3) {
	case (0x00): return "EDSP";
	case (0x01): return "DSP";
	case (0x08): return "EDSP+LFPU";
	case (0x09): return "DSP+LFPU";
	case (0x10): return "EDSP+FPU";
	case (0x11): return "DSP+FPU";
	}
	return "UNKNOWN";

#else
	if (!(txenable & TXENABLE_CLASS_BITS))
		return "DSP";
	else
		return "";
#endif
}


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static int show_cpuinfo(struct seq_file *m, void *v)
{
	const char *cpu;
	unsigned int txenable, thread_id, major, minor;
	unsigned long clockfreq = get_coreclock();
#ifdef CONFIG_SMP
	int i;
	unsigned long lpj;
#endif

	cpu = "META";

	txenable = __core_reg_get(TXENABLE);
	major = (txenable & TXENABLE_MAJOR_REV_BITS) >> TXENABLE_MAJOR_REV_S;
	minor = (txenable & TXENABLE_MINOR_REV_BITS) >> TXENABLE_MINOR_REV_S;
	thread_id = (txenable >> 8) & 0x3;

#ifdef CONFIG_SMP
	for_each_online_cpu(i) {
		lpj = per_cpu(cpu_data, i).loops_per_jiffy;
		txenable = core_reg_read(TXUCT_ID, TXENABLE_REGNUM,
							cpu_2_hwthread_id[i]);

		seq_printf(m, "CPU:\t\t%s %d.%d (thread %d)\n"
			      "Clocking:\t%lu.%1luMHz\n"
			      "BogoMips:\t%lu.%02lu\n"
			      "Calibration:\t%lu loops\n"
			      "Capabilities:\t%s\n\n",
			      cpu, major, minor, i,
			      clockfreq / 1000000, (clockfreq / 100000) % 10,
			      lpj / (500000 / HZ), (lpj / (5000 / HZ)) % 100,
			      lpj,
			      get_cpu_capabilities(txenable));
	}
#else
	seq_printf(m, "CPU:\t\t%s %d.%d (thread %d)\n"
		   "Clocking:\t%lu.%1luMHz\n"
		   "BogoMips:\t%lu.%02lu\n"
		   "Calibration:\t%lu loops\n"
		   "Capabilities:\t%s\n",
		   cpu, major, minor, thread_id,
		   clockfreq / 1000000, (clockfreq / 100000) % 10,
		   loops_per_jiffy / (500000 / HZ),
		   (loops_per_jiffy / (5000 / HZ)) % 100,
		   loops_per_jiffy,
		   get_cpu_capabilities(txenable));
#endif /* CONFIG_SMP */

#ifdef CONFIG_METAG_L2C
	if (meta_l2c_is_present()) {
		seq_printf(m, "L2 cache:\t%s\n"
			      "L2 cache size:\t%d KB\n",
			      meta_l2c_is_enabled() ? "enabled" : "disabled",
			      meta_l2c_size() >> 10);
	}
#endif
	return 0;
}


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static void *c_start(struct seq_file *m, loff_t *pos)
{
	return (void *)(*pos == 0);
}

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

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

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const struct seq_operations cpuinfo_op = {
	.start = c_start,
	.next  = c_next,
	.stop  = c_stop,
	.show  = show_cpuinfo,
};
#endif /* CONFIG_PROC_FS */




void __init metag_start_kernel(char *args)
{
	/* Zero the timer register so timestamps are from the point at
         * which the kernel started running.
         */
	__core_reg_set(TXTIMER, 0);

	/* Clear the bss. */
	memset(__bss_start, 0,
	       (unsigned long)__bss_stop - (unsigned long)__bss_start);

	/* Remember where these are for use in setup_arch */
	original_cmd_line = args;

	current_thread_info()->cpu = hard_processor_id();

	start_kernel();
}


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/**
 * setup_priv() - Set up privilege protection registers.
 *
 * Set up privilege protection registers such as TXPRIVEXT to prevent userland
 * from touching our precious registers and sensitive memory areas.
 */



void setup_priv(void)
{
	unsigned int offset = hard_processor_id() << TXPRIVREG_STRIDE_S;

	__core_reg_set(TXPRIVEXT, PRIV_BITS);

	metag_out32(PRIVSYSR_BITS, T0PRIVSYSR + offset);
	metag_out32(PIOREG_BITS,   T0PIOREG   + offset);
	metag_out32(PSYREG_BITS,   T0PSYREG   + offset);
}


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PTBI pTBI_get(unsigned int cpu)
{
	return per_cpu(pTBI, cpu);
}

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EXPORT_SYMBOL(pTBI_get);

#if defined(CONFIG_METAG_DSP) && defined(CONFIG_METAG_FPU)

static char capabilities[] = "dsp fpu";
#elif defined(CONFIG_METAG_DSP)

static char capabilities[] = "dsp";
#elif defined(CONFIG_METAG_FPU)

static char capabilities[] = "fpu";
#else

static char capabilities[] = "";
#endif


static struct ctl_table caps_kern_table[] = {
	{
		.procname	= "capabilities",
		.data		= capabilities,
		.maxlen		= sizeof(capabilities),
		.mode		= 0444,
		.proc_handler	= proc_dostring,
        },
	{}
};


static struct ctl_table caps_root_table[] = {
	{
		.procname	= "kernel",
		.mode		= 0555,
		.child		= caps_kern_table,
        },
	{}
};




static int __init capabilities_register_sysctl(void)
{
	struct ctl_table_header *caps_table_header;

	caps_table_header = register_sysctl_table(caps_root_table);
	if (!caps_table_header) {
		pr_err("Unable to register CAPABILITIES sysctl\n");
		return -ENOMEM;
	}

	return 0;
}


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core_initcall(capabilities_register_sysctl);

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Directory: arch/metag/kernel



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