Release 4.14 arch/parisc/kernel/unwind.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Kernel unwinding support
 *
 * (c) 2002-2004 Randolph Chung <tausq@debian.org>
 *
 * Derived partially from the IA64 implementation. The PA-RISC
 * Runtime Architecture Document is also a useful reference to
 * understand what is happening here
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/kallsyms.h>
#include <linux/sort.h>
#include <linux/sched.h>

#include <linux/uaccess.h>
#include <asm/assembly.h>
#include <asm/asm-offsets.h>
#include <asm/ptrace.h>

#include <asm/unwind.h>

/* #define DEBUG 1 */
#ifdef DEBUG

#define dbg(x...) printk(x)
#else

#define dbg(x...)
#endif


#define KERNEL_START (KERNEL_BINARY_TEXT_START)

extern struct unwind_table_entry __start___unwind[];
extern struct unwind_table_entry __stop___unwind[];

static DEFINE_SPINLOCK(unwind_lock);
/*
 * the kernel unwind block is not dynamically allocated so that
 * we can call unwind_init as early in the bootup process as 
 * possible (before the slab allocator is initialized)
 */

static struct unwind_table kernel_unwind_table __read_mostly;
static LIST_HEAD(unwind_tables);


static inline const struct unwind_table_entry *

find_unwind_entry_in_table(const struct unwind_table *table, unsigned long addr)
{
	const struct unwind_table_entry *e = NULL;
	unsigned long lo, hi, mid;

	lo = 0; 
	hi = table->length - 1; 
	
	while (lo <= hi) {
		mid = (hi - lo) / 2 + lo;
		e = &table->table[mid];
		if (addr < e->region_start)
			hi = mid - 1;
		else if (addr > e->region_end)
			lo = mid + 1;
		else
			return e;
	}

	return NULL;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Matthew Wilcox
114
100.00%
2
100.00%
Total
114
100.00%
2
100.00%


static const struct unwind_table_entry *

find_unwind_entry(unsigned long addr)
{
	struct unwind_table *table;
	const struct unwind_table_entry *e = NULL;

	if (addr >= kernel_unwind_table.start && 
	    addr <= kernel_unwind_table.end)
		e = find_unwind_entry_in_table(&kernel_unwind_table, addr);
	else {
		unsigned long flags;

		spin_lock_irqsave(&unwind_lock, flags);
		list_for_each_entry(table, &unwind_tables, list) {
			if (addr >= table->start && 
			    addr <= table->end)
				e = find_unwind_entry_in_table(table, addr);
			if (e) {
				/* Move-to-front to exploit common traces */
				list_move(&table->list, &unwind_tables);
				break;
			}
		}
		spin_unlock_irqrestore(&unwind_lock, flags);
	}

	return e;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Matthew Wilcox
92
71.88%
2
50.00%
Mikulas Patocka
22
17.19%
1
25.00%
Phil Carmody
14
10.94%
1
25.00%
Total
128
100.00%
4
100.00%


static void

unwind_table_init(struct unwind_table *table, const char *name,
		  unsigned long base_addr, unsigned long gp,
		  void *table_start, void *table_end)
{
	struct unwind_table_entry *start = table_start;
	struct unwind_table_entry *end = 
		(struct unwind_table_entry *)table_end - 1;

	table->name = name;
	table->base_addr = base_addr;
	table->gp = gp;
	table->start = base_addr + start->region_start;
	table->end = base_addr + end->region_end;
	table->table = (struct unwind_table_entry *)table_start;
	table->length = end - start + 1;
	INIT_LIST_HEAD(&table->list);

	for (; start <= end; start++) {
		if (start < end && 
		    start->region_end > (start+1)->region_start) {
			printk("WARNING: Out of order unwind entry! %p and %p\n", start, start+1);
		}

		start->region_start += base_addr;
		start->region_end += base_addr;
	}
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Matthew Wilcox
175
100.00%
4
100.00%
Total
175
100.00%
4
100.00%



static int cmp_unwind_table_entry(const void *a, const void *b)
{
	return ((const struct unwind_table_entry *)a)->region_start
	     - ((const struct unwind_table_entry *)b)->region_start;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Helge Deller
41
100.00%
1
100.00%
Total
41
100.00%
1
100.00%


static void

unwind_table_sort(struct unwind_table_entry *start,
		  struct unwind_table_entry *finish)
{
	sort(start, finish - start, sizeof(struct unwind_table_entry),
	     cmp_unwind_table_entry, NULL);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Matthew Wilcox
21
60.00%
2
66.67%
Helge Deller
14
40.00%
1
33.33%
Total
35
100.00%
3
100.00%


struct unwind_table *

unwind_table_add(const char *name, unsigned long base_addr, 
		 unsigned long gp,
                 void *start, void *end)
{
	struct unwind_table *table;
	unsigned long flags;
	struct unwind_table_entry *s = (struct unwind_table_entry *)start;
	struct unwind_table_entry *e = (struct unwind_table_entry *)end;

	unwind_table_sort(s, e);

	table = kmalloc(sizeof(struct unwind_table), GFP_USER);
	if (table == NULL)
		return NULL;
	unwind_table_init(table, name, base_addr, gp, start, end);
	spin_lock_irqsave(&unwind_lock, flags);
	list_add_tail(&table->list, &unwind_tables);
	spin_unlock_irqrestore(&unwind_lock, flags);

	return table;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Matthew Wilcox
135
100.00%
3
100.00%
Total
135
100.00%
3
100.00%



void unwind_table_remove(struct unwind_table *table)
{
	unsigned long flags;

	spin_lock_irqsave(&unwind_lock, flags);
	list_del(&table->list);
	spin_unlock_irqrestore(&unwind_lock, flags);

	kfree(table);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Matthew Wilcox
43
100.00%
2
100.00%
Total
43
100.00%
2
100.00%

/* Called from setup_arch to import the kernel unwind info */


int __init unwind_init(void)
{
	long start, stop;
	register unsigned long gp __asm__ ("r27");

	start = (long)&__start___unwind[0];
	stop = (long)&__stop___unwind[0];

	printk("unwind_init: start = 0x%lx, end = 0x%lx, entries = %lu\n", 
	    start, stop,
	    (stop - start) / sizeof(struct unwind_table_entry));

	unwind_table_init(&kernel_unwind_table, "kernel", KERNEL_START,
			  gp, 
			  &__start___unwind[0], &__stop___unwind[0]);
#if 0
	{
                int i;
                for (i = 0; i < 10; i++)
                {
                        printk("region 0x%x-0x%x\n", 
                                __start___unwind[i].region_start, 
                                __start___unwind[i].region_end);
                }
        }
#endif
	return 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Matthew Wilcox
97
98.98%
1
50.00%
Helge Deller
1
1.02%
1
50.00%
Total
98
100.00%
2
100.00%

#ifdef CONFIG_64BIT

#define get_func_addr(fptr) fptr[2]
#else

#define get_func_addr(fptr) fptr[0]
#endif



static int unwind_special(struct unwind_frame_info *info, unsigned long pc, int frame_size)
{
	extern void handle_interruption(int, struct pt_regs *);
	static unsigned long *hi = (unsigned long *)&handle_interruption;

	if (pc == get_func_addr(hi)) {
		struct pt_regs *regs = (struct pt_regs *)(info->sp - frame_size - PT_SZ_ALGN);
		dbg("Unwinding through handle_interruption()\n");
		info->prev_sp = regs->gr[30];
		info->prev_ip = regs->iaoq[0];

		return 1;
	}

	return 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Randolph Chung
105
98.13%
1
50.00%
Kyle McMartin
2
1.87%
1
50.00%
Total
107
100.00%
2
100.00%



static void unwind_frame_regs(struct unwind_frame_info *info)
{
	const struct unwind_table_entry *e;
	unsigned long npc;
	unsigned int insn;
	long frame_size = 0;
	int looking_for_rp, rpoffset = 0;

	e = find_unwind_entry(info->ip);
	if (e == NULL) {
		unsigned long sp;

		dbg("Cannot find unwind entry for 0x%lx; forced unwinding\n", info->ip);

#ifdef CONFIG_KALLSYMS
		/* Handle some frequent special cases.... */
		{
			char symname[KSYM_NAME_LEN];
			char *modname;

			kallsyms_lookup(info->ip, NULL, NULL, &modname,
				symname);

			dbg("info->ip = 0x%lx, name = %s\n", info->ip, symname);

			if (strcmp(symname, "_switch_to_ret") == 0) {
				info->prev_sp = info->sp - CALLEE_SAVE_FRAME_SIZE;
				info->prev_ip = *(unsigned long *)(info->prev_sp - RP_OFFSET);
				dbg("_switch_to_ret @ %lx - setting "
				    "prev_sp=%lx prev_ip=%lx\n", 
				    info->ip, info->prev_sp, 
				    info->prev_ip);
				return;
			} else if (strcmp(symname, "ret_from_kernel_thread") == 0 ||
				   strcmp(symname, "syscall_exit") == 0) {
				info->prev_ip = info->prev_sp = 0;
				return;
			}
		}
#endif

		/* Since we are doing the unwinding blind, we don't know if
                   we are adjusting the stack correctly or extracting the rp
                   correctly. The rp is checked to see if it belongs to the
                   kernel text section, if not we assume we don't have a 
                   correct stack frame and we continue to unwind the stack.
                   This is not quite correct, and will fail for loadable
                   modules. */
		sp = info->sp & ~63;
		do {
			unsigned long tmp;

			info->prev_sp = sp - 64;
			info->prev_ip = 0;

			/* The stack is at the end inside the thread_union
                         * struct. If we reach data, we have reached the
                         * beginning of the stack and should stop unwinding. */
			if (info->prev_sp >= (unsigned long) task_thread_info(info->t) &&
			    info->prev_sp < ((unsigned long) task_thread_info(info->t)
						+ THREAD_SZ_ALGN)) {
				info->prev_sp = 0;
				break;
			}

			if (get_user(tmp, (unsigned long *)(info->prev_sp - RP_OFFSET))) 
				break;
			info->prev_ip = tmp;
			sp = info->prev_sp;
		} while (!kernel_text_address(info->prev_ip));

		info->rp = 0;

		dbg("analyzing func @ %lx with no unwind info, setting "
		    "prev_sp=%lx prev_ip=%lx\n", info->ip, 
		    info->prev_sp, info->prev_ip);
	} else {
		dbg("e->start = 0x%x, e->end = 0x%x, Save_SP = %d, "
		    "Save_RP = %d, Millicode = %d size = %u\n", 
		    e->region_start, e->region_end, e->Save_SP, e->Save_RP, 
		    e->Millicode, e->Total_frame_size);

		looking_for_rp = e->Save_RP;

		for (npc = e->region_start; 
		     (frame_size < (e->Total_frame_size << 3) || 
		      looking_for_rp) && 
		     npc < info->ip; 
		     npc += 4) {

			insn = *(unsigned int *)npc;

			if ((insn & 0xffffc001) == 0x37de0000 ||
			    (insn & 0xffe00001) == 0x6fc00000) {
				/* ldo X(sp), sp, or stwm X,D(sp) */
				frame_size += (insn & 0x3fff) >> 1;
				dbg("analyzing func @ %lx, insn=%08x @ "
				    "%lx, frame_size = %ld\n", info->ip,
				    insn, npc, frame_size);
			} else if ((insn & 0xffe00009) == 0x73c00008) {
				/* std,ma X,D(sp) */
				frame_size += ((insn >> 4) & 0x3ff) << 3;
				dbg("analyzing func @ %lx, insn=%08x @ "
				    "%lx, frame_size = %ld\n", info->ip,
				    insn, npc, frame_size);
			} else if (insn == 0x6bc23fd9) { 
				/* stw rp,-20(sp) */
				rpoffset = 20;
				looking_for_rp = 0;
				dbg("analyzing func @ %lx, insn=stw rp,"
				    "-20(sp) @ %lx\n", info->ip, npc);
			} else if (insn == 0x0fc212c1) {
				/* std rp,-16(sr0,sp) */
				rpoffset = 16;
				looking_for_rp = 0;
				dbg("analyzing func @ %lx, insn=std rp,"
				    "-16(sp) @ %lx\n", info->ip, npc);
			}
		}

		if (frame_size > e->Total_frame_size << 3)
			frame_size = e->Total_frame_size << 3;

		if (!unwind_special(info, e->region_start, frame_size)) {
			info->prev_sp = info->sp - frame_size;
			if (e->Millicode)
				info->rp = info->r31;
			else if (rpoffset)
				info->rp = *(unsigned long *)(info->prev_sp - rpoffset);
			info->prev_ip = info->rp;
			info->rp = 0;
		}

		dbg("analyzing func @ %lx, setting prev_sp=%lx "
		    "prev_ip=%lx npc=%lx\n", info->ip, info->prev_sp, 
		    info->prev_ip, npc);
	}
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Matthew Wilcox
605
86.43%
4
40.00%
Helge Deller
50
7.14%
2
20.00%
Mikulas Patocka
21
3.00%
1
10.00%
Randolph Chung
16
2.29%
1
10.00%
Kyle McMartin
6
0.86%
1
10.00%
Alexey Dobriyan
2
0.29%
1
10.00%
Total
700
100.00%
10
100.00%



void unwind_frame_init(struct unwind_frame_info *info, struct task_struct *t, 
		       struct pt_regs *regs)
{
	memset(info, 0, sizeof(struct unwind_frame_info));
	info->t = t;
	info->sp = regs->gr[30];
	info->ip = regs->iaoq[0];
	info->rp = regs->gr[2];
	info->r31 = regs->gr[31];

	dbg("(%d) Start unwind from sp=%08lx ip=%08lx\n", 
	    t ? (int)t->pid : -1, info->sp, info->ip);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Matthew Wilcox
108
100.00%
4
100.00%
Total
108
100.00%
4
100.00%



void unwind_frame_init_from_blocked_task(struct unwind_frame_info *info, struct task_struct *t)
{
	struct pt_regs *r = &t->thread.regs;
	struct pt_regs *r2;

	r2 = kmalloc(sizeof(struct pt_regs), GFP_ATOMIC);
	if (!r2)
		return;
	*r2 = *r;
	r2->gr[30] = r->ksp;
	r2->iaoq[0] = r->kpc;
	unwind_frame_init(info, t, r2);
	kfree(r2);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Matthew Wilcox
92
98.92%
3
75.00%
Helge Deller
1
1.08%
1
25.00%
Total
93
100.00%
4
100.00%



void unwind_frame_init_running(struct unwind_frame_info *info, struct pt_regs *regs)
{
	unwind_frame_init(info, current, regs);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Matthew Wilcox
24
100.00%
2
100.00%
Total
24
100.00%
2
100.00%



int unwind_once(struct unwind_frame_info *next_frame)
{
	unwind_frame_regs(next_frame);

	if (next_frame->prev_sp == 0 ||
	    next_frame->prev_ip == 0)
		return -1;

	next_frame->sp = next_frame->prev_sp;
	next_frame->ip = next_frame->prev_ip;
	next_frame->prev_sp = 0;
	next_frame->prev_ip = 0;

	dbg("(%d) Continue unwind to sp=%08lx ip=%08lx\n", 
	    next_frame->t ? (int)next_frame->t->pid : -1, 
	    next_frame->sp, next_frame->ip);

	return 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Matthew Wilcox
93
100.00%
2
100.00%
Total
93
100.00%
2
100.00%



int unwind_to_user(struct unwind_frame_info *info)
{
	int ret;
	
	do {
		ret = unwind_once(info);
	} while (!ret && !(info->ip & 3));

	return ret;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Matthew Wilcox
41
100.00%
1
100.00%
Total
41
100.00%
1
100.00%



unsigned long return_address(unsigned int level)
{
	struct unwind_frame_info info;
	struct pt_regs r;
	unsigned long sp;

	/* initialize unwind info */
	asm volatile ("copy %%r30, %0" : "=r"(sp));
	memset(&r, 0, sizeof(struct pt_regs));
	r.iaoq[0] = (unsigned long) current_text_addr();
	r.gr[2] = (unsigned long) __builtin_return_address(0);
	r.gr[30] = sp;
	unwind_frame_init(&info, current, &r);

	/* unwind stack */
	++level;
	do {
		if (unwind_once(&info) < 0 || info.ip == 0)
			return 0;
		if (!kernel_text_address(info.ip))
			return 0;
	} while (info.ip && level--);

	return info.ip;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Helge Deller
144
100.00%
2
100.00%
Total
144
100.00%
2
100.00%

Overall Contributors
Person
Tokens
Prop
Commits
CommitProp
Matthew Wilcox
1714
78.02%
5
22.73%
Helge Deller
263
11.97%
8
36.36%
Randolph Chung
151
6.87%
2
9.09%
Mikulas Patocka
43
1.96%
1
4.55%
Phil Carmody
14
0.64%
1
4.55%
Kyle McMartin
8
0.36%
2
9.09%
Alexey Dobriyan
2
0.09%
1
4.55%
Linus Torvalds
1
0.05%
1
4.55%
Greg Kroah-Hartman
1
0.05%
1
4.55%
Total
2197
100.00%
22
100.00%
Directory: arch/parisc/kernel

Information contained on this website is for historical information purposes only and does not indicate or represent copyright ownership.