xmon.c

linux-2.6.15.6

/*
 * Routines providing a simple monitor for use on the PowerMac.
 *
 * Copyright (C) 1996-2005 Paul Mackerras.
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 */
#include <linux/config.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/mm.h>
#include <linux/reboot.h>
#include <linux/delay.h>
#include <linux/kallsyms.h>
#include <linux/cpumask.h>
#include <linux/module.h>
#include <linux/sysrq.h>
#include <linux/interrupt.h>

#include <asm/ptrace.h>
#include <asm/string.h>
#include <asm/prom.h>
#include <asm/machdep.h>
#include <asm/xmon.h>
#ifdef CONFIG_PMAC_BACKLIGHT
#include <asm/backlight.h>
#endif
#include <asm/processor.h>
#include <asm/pgtable.h>
#include <asm/mmu.h>
#include <asm/mmu_context.h>
#include <asm/cputable.h>
#include <asm/rtas.h>
#include <asm/sstep.h>
#include <asm/bug.h>

#ifdef CONFIG_PPC64
#include <asm/hvcall.h>
#include <asm/paca.h>
#endif

#include "nonstdio.h"

#define scanhex	xmon_scanhex
#define skipbl	xmon_skipbl

#ifdef CONFIG_SMP
cpumask_t cpus_in_xmon = CPU_MASK_NONE;
static unsigned long xmon_taken = 1;
static int xmon_owner;
static int xmon_gate;
#endif /* CONFIG_SMP */

static unsigned long in_xmon = 0;

static unsigned long adrs;
static int size = 1;
#define MAX_DUMP (128 * 1024)
static unsigned long ndump = 64;
static unsigned long nidump = 16;
static unsigned long ncsum = 4096;
static int termch;
static char tmpstr[128];

#define JMP_BUF_LEN	23
static long bus_error_jmp[JMP_BUF_LEN];
static int catch_memory_errors;
static long *xmon_fault_jmp[NR_CPUS];
#define setjmp xmon_setjmp
#define longjmp xmon_longjmp

/* Breakpoint stuff */
struct bpt {
	unsigned long	address;
	unsigned int	instr[2];
	atomic_t	ref_count;
	int		enabled;
	unsigned long	pad;
};

/* Bits in bpt.enabled */
#define BP_IABR_TE	1		/* IABR translation enabled */
#define BP_IABR		2
#define BP_TRAP		8
#define BP_DABR		0x10

#define NBPTS	256
static struct bpt bpts[NBPTS];
static struct bpt dabr;
static struct bpt *iabr;
static unsigned bpinstr = 0x7fe00008;	/* trap */

#define BP_NUM(bp)	((bp) - bpts + 1)

/* Prototypes */
static int cmds(struct pt_regs *);
static int mread(unsigned long, void *, int);
static int mwrite(unsigned long, void *, int);
static int handle_fault(struct pt_regs *);
static void byterev(unsigned char *, int);
static void memex(void);
static int bsesc(void);
static void dump(void);
static void prdump(unsigned long, long);
static int ppc_inst_dump(unsigned long, long, int);
void print_address(unsigned long);
static void backtrace(struct pt_regs *);
static void excprint(struct pt_regs *);
static void prregs(struct pt_regs *);
static void memops(int);
static void memlocate(void);
static void memzcan(void);
static void memdiffs(unsigned char *, unsigned char *, unsigned, unsigned);
int skipbl(void);
int scanhex(unsigned long *valp);
static void scannl(void);
static int hexdigit(int);
void getstring(char *, int);
static void flush_input(void);
static int inchar(void);
static void take_input(char *);
static unsigned long read_spr(int);
static void write_spr(int, unsigned long);
static void super_regs(void);
static void remove_bpts(void);
static void insert_bpts(void);
static void remove_cpu_bpts(void);
static void insert_cpu_bpts(void);
static struct bpt *at_breakpoint(unsigned long pc);
static struct bpt *in_breakpoint_table(unsigned long pc, unsigned long *offp);
static int  do_step(struct pt_regs *);
static void bpt_cmds(void);
static void cacheflush(void);
static int  cpu_cmd(void);
static void csum(void);
static void bootcmds(void);
static void proccall(void);
void dump_segments(void);
static void symbol_lookup(void);
static void xmon_print_symbol(unsigned long address, const char *mid,
			      const char *after);
static const char *getvecname(unsigned long vec);

extern int print_insn_powerpc(unsigned long, unsigned long, int);

extern void xmon_enter(void);
extern void xmon_leave(void);

extern long setjmp(long *);
extern void longjmp(long *, long);
extern void xmon_save_regs(struct pt_regs *);

#ifdef CONFIG_PPC64
#define REG		"%.16lx"
#define REGS_PER_LINE	4
#define LAST_VOLATILE	13
#else
#define REG		"%.8lx"
#define REGS_PER_LINE	8
#define LAST_VOLATILE	12
#endif

#define GETWORD(v)	(((v)[0] << 24) + ((v)[1] << 16) + ((v)[2] << 8) + (v)[3])

#define isxdigit(c)	(('0' <= (c) && (c) <= '9') \
			 || ('a' <= (c) && (c) <= 'f') \
			 || ('A' <= (c) && (c) <= 'F'))
#define isalnum(c)	(('0' <= (c) && (c) <= '9') \
			 || ('a' <= (c) && (c) <= 'z') \
			 || ('A' <= (c) && (c) <= 'Z'))
#define isspace(c)	(c == ' ' || c == '\t' || c == 10 || c == 13 || c == 0)

static char *help_string = "\
Commands:\n\
  b	show breakpoints\n\
  bd	set data breakpoint\n\
  bi	set instruction breakpoint\n\
  bc	clear breakpoint\n"
#ifdef CONFIG_SMP
  "\
  c	print cpus stopped in xmon\n\
  c#	try to switch to cpu number h (in hex)\n"
#endif
  "\
  C	checksum\n\
  d	dump bytes\n\
  di	dump instructions\n\
  df	dump float values\n\
  dd	dump double values\n\
  e	print exception information\n\
  f	flush cache\n\
  la	lookup symbol+offset of specified address\n\
  ls	lookup address of specified symbol\n\
  m	examine/change memory\n\
  mm	move a block of memory\n\
  ms	set a block of memory\n\
  md	compare two blocks of memory\n\
  ml	locate a block of memory\n\
  mz	zero a block of memory\n\
  mi	show information about memory allocation\n\
  p 	call a procedure\n\
  r	print registers\n\
  s	single step\n\
  S	print special registers\n\
  t	print backtrace\n\
  x	exit monitor and recover\n\
  X	exit monitor and dont recover\n"
#ifdef CONFIG_PPC64
"  u	dump segment table or SLB\n"
#endif
#ifdef CONFIG_PPC_STD_MMU_32
"  u	dump segment registers\n"
#endif
"  ?	help\n"
"  zr	reboot\n\
  zh	halt\n"
;

static struct pt_regs *xmon_regs;

static inline void sync(void)
{
	asm volatile("sync; isync");
}

static inline void store_inst(void *p)
{
	asm volatile ("dcbst 0,%0; sync; icbi 0,%0; isync" : : "r" (p));
}

static inline void cflush(void *p)
{
	asm volatile ("dcbf 0,%0; icbi 0,%0" : : "r" (p));
}

static inline void cinval(void *p)
{
	asm volatile ("dcbi 0,%0; icbi 0,%0" : : "r" (p));
}

/*
 * Disable surveillance (the service processor watchdog function)
 * while we are in xmon.
 * XXX we should re-enable it when we leave. :)
 */
#define SURVEILLANCE_TOKEN	9000

static inline void disable_surveillance(void)
{
#ifdef CONFIG_PPC_PSERIES
	/* Since this can't be a module, args should end up below 4GB. */
	static struct rtas_args args;

	/*
	 * At this point we have got all the cpus we can into
	 * xmon, so there is hopefully no other cpu calling RTAS
	 * at the moment, even though we don't take rtas.lock.
	 * If we did try to take rtas.lock there would be a
	 * real possibility of deadlock.
	 */
	args.token = rtas_token("set-indicator");
	if (args.token == RTAS_UNKNOWN_SERVICE)
		return;
	args.nargs = 3;
	args.nret = 1;
	args.rets = &args.args[3];
	args.args[0] = SURVEILLANCE_TOKEN;
	args.args[1] = 0;
	args.args[2] = 0;
	enter_rtas(__pa(&args));
#endif /* CONFIG_PPC_PSERIES */
}

#ifdef CONFIG_SMP
static int xmon_speaker;

static void get_output_lock(void)
{
	int me = smp_processor_id() + 0x100;
	int last_speaker = 0, prev;
	long timeout;

	if (xmon_speaker == me)
		return;
	for (;;) {
		if (xmon_speaker == 0) {
			last_speaker = cmpxchg(&xmon_speaker, 0, me);
			if (last_speaker == 0)
				return;
		}
		timeout = 10000000;
		while (xmon_speaker == last_speaker) {
			if (--timeout > 0)
				continue;
			/* hostile takeover */
			prev = cmpxchg(&xmon_speaker, last_speaker, me);
			if (prev == last_speaker)
				return;
			break;
		}
	}
}

static void release_output_lock(void)
{
	xmon_speaker = 0;
}
#endif

int xmon_core(struct pt_regs *regs, int fromipi)
{
	int cmd = 0;
	unsigned long msr;
	struct bpt *bp;
	long recurse_jmp[JMP_BUF_LEN];
	unsigned long offset;
#ifdef CONFIG_SMP
	int cpu;
	int secondary;
	unsigned long timeout;
#endif

	msr = mfmsr();
	mtmsr(msr & ~MSR_EE);	/* disable interrupts */

	bp = in_breakpoint_table(regs->nip, &offset);
	if (bp != NULL) {
		regs->nip = bp->address + offset;
		atomic_dec(&bp->ref_count);
	}

	remove_cpu_bpts();

#ifdef CONFIG_SMP
	cpu = smp_processor_id();
	if (cpu_isset(cpu, cpus_in_xmon)) {
		get_output_lock();
		excprint(regs);
		printf("cpu 0x%x: Exception %lx %s in xmon, "
		       "returning to main loop\n",
		       cpu, regs->trap, getvecname(TRAP(regs)));
		release_output_lock();
		longjmp(xmon_fault_jmp[cpu], 1);
	}

	if (setjmp(recurse_jmp) != 0) {
		if (!in_xmon || !xmon_gate) {
			get_output_lock();
			printf("xmon: WARNING: bad recursive fault "
			       "on cpu 0x%x\n", cpu);
			release_output_lock();
			goto waiting;
		}
		secondary = !(xmon_taken && cpu == xmon_owner);
		goto cmdloop;
	}

	xmon_fault_jmp[cpu] = recurse_jmp;
	cpu_set(cpu, cpus_in_xmon);

	bp = NULL;
	if ((regs->msr & (MSR_IR|MSR_PR|MSR_SF)) == (MSR_IR|MSR_SF))
		bp = at_breakpoint(regs->nip);
	if (bp || (regs->msr & MSR_RI) == 0)
		fromipi = 0;

	if (!fromipi) {
		get_output_lock();
		excprint(regs);
		if (bp) {
			printf("cpu 0x%x stopped at breakpoint 0x%x (",
			       cpu, BP_NUM(bp));
			xmon_print_symbol(regs->nip, " ", ")\n");
		}
		if ((regs->msr & MSR_RI) == 0)
			printf("WARNING: exception is not recoverable, "
			       "can't continue\n");
		release_output_lock();
	}

 waiting:
	secondary = 1;
	while (secondary && !xmon_gate) {
		if (in_xmon == 0) {
			if (fromipi)
				goto leave;
			secondary = test_and_set_bit(0, &in_xmon);
		}
		barrier();
	}

	if (!secondary && !xmon_gate) {
		/* we are the first cpu to come in */
		/* interrupt other cpu(s) */
		int ncpus = num_online_cpus();

		xmon_owner = cpu;
		mb();
		if (ncpus > 1) {
			smp_send_debugger_break(MSG_ALL_BUT_SELF);
			/* wait for other cpus to come in */
			for (timeout = 100000000; timeout != 0; --timeout) {
				if (cpus_weight(cpus_in_xmon) >= ncpus)
					break;
				barrier();
			}
		}
		remove_bpts();
		disable_surveillance();
		/* for breakpoint or single step, print the current instr. */
		if (bp || TRAP(regs) == 0xd00)
			ppc_inst_dump(regs->nip, 1, 0);
		printf("enter ? for help\n");
		mb();
		xmon_gate = 1;
		barrier();
	}

 cmdloop:
	while (in_xmon) {
		if (secondary) {
			if (cpu == xmon_owner) {
				if (!test_and_set_bit(0, &xmon_taken)) {
					secondary = 0;
					continue;
				}
				/* missed it */
				while (cpu == xmon_owner)
					barrier();
			}
			barrier();
		} else {
			cmd = cmds(regs);
			if (cmd != 0) {
				/* exiting xmon */
				insert_bpts();
				xmon_gate = 0;
				wmb();
				in_xmon = 0;
				break;
			}
			/* have switched to some other cpu */
			secondary = 1;
		}
	}
 leave:
	cpu_clear(cpu, cpus_in_xmon);
	xmon_fault_jmp[cpu] = NULL;

#else
	/* UP is simple... */
	if (in_xmon) {
		printf("Exception %lx %s in xmon, returning to main loop\n",
		       regs->trap, getvecname(TRAP(regs)));
		longjmp(xmon_fault_jmp[0], 1);
	}
	if (setjmp(recurse_jmp) == 0) {
		xmon_fault_jmp[0] = recurse_jmp;
		in_xmon = 1;

		excprint(regs);
		bp = at_breakpoint(regs->nip);
		if (bp) {
			printf("Stopped at breakpoint %x (", BP_NUM(bp));
			xmon_print_symbol(regs->nip, " ", ")\n");
		}
		if ((regs->msr & MSR_RI) == 0)
			printf("WARNING: exception is not recoverable, "
			       "can't continue\n");
		remove_bpts();
		disable_surveillance();
		/* for breakpoint or single step, print the current instr. */
		if (bp || TRAP(regs) == 0xd00)
			ppc_inst_dump(regs->nip, 1, 0);
		printf("enter ? for help\n");
	}

	cmd = cmds(regs);

	insert_bpts();
	in_xmon = 0;
#endif

	if ((regs->msr & (MSR_IR|MSR_PR|MSR_SF)) == (MSR_IR|MSR_SF)) {
		bp = at_breakpoint(regs->nip);
		if (bp != NULL) {
			int stepped = emulate_step(regs, bp->instr[0]);
			if (stepped == 0) {
				regs->nip = (unsigned long) &bp->instr[0];
				atomic_inc(&bp->ref_count);
			} else if (stepped < 0) {
				printf("Couldn't single-step %s instruction\n",
				    (IS_RFID(bp->instr[0])? "rfid": "mtmsrd"));
			}
		}
	}

	insert_cpu_bpts();

	mtmsr(msr);		/* restore interrupt enable */

	return cmd != 'X';
}

int xmon(struct pt_regs *excp)
{
	struct pt_regs regs;

	if (excp == NULL) {
		xmon_save_regs(&regs);
		excp = &regs;
	}
	return xmon_core(excp, 0);
}
EXPORT_SYMBOL(xmon);

irqreturn_t
xmon_irq(int irq, void *d, struct pt_regs *regs)
{
	unsigned long flags;
	local_irq_save(flags);
	printf("Keyboard interrupt\n");
	xmon(regs);
	local_irq_restore(flags);
	return IRQ_HANDLED;
}

int xmon_bpt(struct pt_regs *regs)
{
	struct bpt *bp;
	unsigned long offset;

	if ((regs->msr & (MSR_IR|MSR_PR|MSR_SF)) != (MSR_IR|MSR_SF))
		return 0;

	/* Are we at the trap at bp->instr[1] for some bp? */
	bp = in_breakpoint_table(regs->nip, &offset);
	if (bp != NULL && offset == 4) {
		regs->nip = bp->address + 4;
		atomic_dec(&bp->ref_count);
		return 1;
	}

	/* Are we at a breakpoint? */
	bp = at_breakpoint(regs->nip);
	if (!bp)
		return 0;

	xmon_core(regs, 0);

	return 1;
}

int xmon_sstep(struct pt_regs *regs)
{
	if (user_mode(regs))
		return 0;
	xmon_core(regs, 0);
	return 1;
}

int xmon_dabr_match(struct pt_regs *regs)
{
	if ((regs->msr & (MSR_IR|MSR_PR|MSR_SF)) != (MSR_IR|MSR_SF))
		return 0;
	if (dabr.enabled == 0)
		return 0;
	xmon_core(regs, 0);
	return 1;
}

int xmon_iabr_match(struct pt_regs *regs)
{
	if ((regs->msr & (MSR_IR|MSR_PR|MSR_SF)) != (MSR_IR|MSR_SF))
		return 0;
	if (iabr == 0)
		return 0;
	xmon_core(regs, 0);
	return 1;
}

int xmon_ipi(struct pt_regs *regs)
{
#ifdef CONFIG_SMP
	if (in_xmon && !cpu_isset(smp_processor_id(), cpus_in_xmon))
		xmon_core(regs, 1);
#endif
	return 0;
}

int xmon_fault_handler(struct pt_regs *regs)
{
	struct bpt *bp;
	unsigned long offset;

	if (in_xmon && catch_memory_errors)
		handle_fault(regs);	/* doesn't return */

	if ((regs->msr & (MSR_IR|MSR_PR|MSR_SF)) == (MSR_IR|MSR_SF)) {
		bp = in_breakpoint_table(regs->nip, &offset);
		if (bp != NULL) {
			regs->nip = bp->address + offset;
			atomic_dec(&bp->ref_count);
		}
	}

	return 0;
}

static struct bpt *at_breakpoint(unsigned long pc)
{
	int i;
	struct bpt *bp;

	bp = bpts;
	for (i = 0; i < NBPTS; ++i, ++bp)
		if (bp->enabled && pc == bp->address)
			return bp;
	return NULL;
}

static struct bpt *in_breakpoint_table(unsigned long nip, unsigned long *offp)
{
	unsigned long off;

	off = nip - (unsigned long) bpts;
	if (off >= sizeof(bpts))
		return NULL;
	off %= sizeof(struct bpt);
	if (off != offsetof(struct bpt, instr[0])
	    && off != offsetof(struct bpt, instr[1]))
		return NULL;
	*offp = off - offsetof(struct bpt, instr[0]);
	return (struct bpt *) (nip - off);
}

static struct bpt *new_breakpoint(unsigned long a)