arch/powerpc/kernel/kgdb.c

/*
 * PowerPC backend to the KGDB stub.
 *
 * 1998 (c) Michael AK Tesch (tesch@cs.wisc.edu)
 * Copyright (C) 2003 Timesys Corporation.
 * Copyright (C) 2004-2006 MontaVista Software, Inc.
 * PPC64 Mods (C) 2005 Frank Rowand (frowand@mvista.com)
 * PPC32 support restored by Vitaly Wool <vwool@ru.mvista.com> and
 * Sergei Shtylyov <sshtylyov@ru.mvista.com>
 * Copyright (C) 2007-2008 Wind River Systems, Inc.
 *
 * This file is licensed under the terms of the GNU General Public License
 * version 2. This program as licensed "as is" without any warranty of any
 * kind, whether express or implied.
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/kgdb.h>
#include <linux/smp.h>
#include <linux/signal.h>
#include <linux/ptrace.h>
#include <linux/kdebug.h>
#include <asm/current.h>
#include <asm/processor.h>
#include <asm/machdep.h>

/*
 * This table contains the mapping between PowerPC hardware trap types, and
 * signals, which are primarily what GDB understands.  GDB and the kernel
 * don't always agree on values, so we use constants taken from gdb-6.2.
 */
static struct hard_trap_info
{
	unsigned int tt;		/* Trap type code for powerpc */
	unsigned char signo;		/* Signal that we map this trap into */
} hard_trap_info[] = {
	{ 0x0100, 0x02 /* SIGINT */  },		/* system reset */
	{ 0x0200, 0x0b /* SIGSEGV */ },		/* machine check */
	{ 0x0300, 0x0b /* SIGSEGV */ },		/* data access */
	{ 0x0400, 0x0b /* SIGSEGV */ },		/* instruction access */
	{ 0x0500, 0x02 /* SIGINT */  },		/* external interrupt */
	{ 0x0600, 0x0a /* SIGBUS */  },		/* alignment */
	{ 0x0700, 0x05 /* SIGTRAP */ },		/* program check */
	{ 0x0800, 0x08 /* SIGFPE */  },		/* fp unavailable */
	{ 0x0900, 0x0e /* SIGALRM */ },		/* decrementer */
	{ 0x0c00, 0x14 /* SIGCHLD */ },		/* system call */
#if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
	{ 0x2002, 0x05 /* SIGTRAP */ },		/* debug */
#if defined(CONFIG_FSL_BOOKE)
	{ 0x2010, 0x08 /* SIGFPE */  },		/* spe unavailable */
	{ 0x2020, 0x08 /* SIGFPE */  },		/* spe unavailable */
	{ 0x2030, 0x08 /* SIGFPE */  },		/* spe fp data */
	{ 0x2040, 0x08 /* SIGFPE */  },		/* spe fp data */
	{ 0x2050, 0x08 /* SIGFPE */  },		/* spe fp round */
	{ 0x2060, 0x0e /* SIGILL */  },		/* performance monitor */
	{ 0x2900, 0x08 /* SIGFPE */  },		/* apu unavailable */
	{ 0x3100, 0x0e /* SIGALRM */ },		/* fixed interval timer */
	{ 0x3200, 0x02 /* SIGINT */  }, 	/* watchdog */
#else /* ! CONFIG_FSL_BOOKE */
	{ 0x1000, 0x0e /* SIGALRM */ },		/* prog interval timer */
	{ 0x1010, 0x0e /* SIGALRM */ },		/* fixed interval timer */
	{ 0x1020, 0x02 /* SIGINT */  }, 	/* watchdog */
	{ 0x2010, 0x08 /* SIGFPE */  },		/* fp unavailable */
	{ 0x2020, 0x08 /* SIGFPE */  },		/* ap unavailable */
#endif
#else /* ! (defined(CONFIG_40x) || defined(CONFIG_BOOKE)) */
	{ 0x0d00, 0x05 /* SIGTRAP */ },		/* single-step */
#if defined(CONFIG_8xx)
	{ 0x1000, 0x04 /* SIGILL */  },		/* software emulation */
#else /* ! CONFIG_8xx */
	{ 0x0f00, 0x04 /* SIGILL */  },		/* performance monitor */
	{ 0x0f20, 0x08 /* SIGFPE */  },		/* altivec unavailable */
	{ 0x1300, 0x05 /* SIGTRAP */ }, 	/* instruction address break */
#if defined(CONFIG_PPC64)
	{ 0x1200, 0x05 /* SIGILL */  },		/* system error */
	{ 0x1500, 0x04 /* SIGILL */  },		/* soft patch */
	{ 0x1600, 0x04 /* SIGILL */  },		/* maintenance */
	{ 0x1700, 0x08 /* SIGFPE */  },		/* altivec assist */
	{ 0x1800, 0x04 /* SIGILL */  },		/* thermal */
#else /* ! CONFIG_PPC64 */
	{ 0x1400, 0x02 /* SIGINT */  },		/* SMI */
	{ 0x1600, 0x08 /* SIGFPE */  },		/* altivec assist */
	{ 0x1700, 0x04 /* SIGILL */  },		/* TAU */
	{ 0x2000, 0x05 /* SIGTRAP */ },		/* run mode */
#endif
#endif
#endif
	{ 0x0000, 0x00 }			/* Must be last */
};

static int computeSignal(unsigned int tt)
{
	struct hard_trap_info *ht;

	for (ht = hard_trap_info; ht->tt && ht->signo; ht++)
		if (ht->tt == tt)
			return ht->signo;

	return SIGHUP;		/* default for things we don't know about */
}

static int kgdb_call_nmi_hook(struct pt_regs *regs)
{
	kgdb_nmicallback(raw_smp_processor_id(), regs);
	return 0;
}

#ifdef CONFIG_SMP
void kgdb_roundup_cpus(unsigned long flags)
{
	smp_send_debugger_break(MSG_ALL_BUT_SELF);
}
#endif

/* KGDB functions to use existing PowerPC64 hooks. */
static int kgdb_debugger(struct pt_regs *regs)
{
	return !kgdb_handle_exception(1, computeSignal(TRAP(regs)),
				      DIE_OOPS, regs);
}

static int kgdb_handle_breakpoint(struct pt_regs *regs)
{
	if (user_mode(regs))
		return 0;

	if (kgdb_handle_exception(1, SIGTRAP, 0, regs) != 0)
		return 0;

	if (*(u32 *) (regs->nip) == *(u32 *) (&arch_kgdb_ops.gdb_bpt_instr))
		regs->nip += BREAK_INSTR_SIZE;

	return 1;
}

static int kgdb_singlestep(struct pt_regs *regs)
{
	struct thread_info *thread_info, *exception_thread_info;

	if (user_mode(regs))
		return 0;

	/*
	 * On Book E and perhaps other processsors, singlestep is handled on
	 * the critical exception stack.  This causes current_thread_info()
	 * to fail, since it it locates the thread_info by masking off
	 * the low bits of the current stack pointer.  We work around
	 * this issue by copying the thread_info from the kernel stack
	 * before calling kgdb_handle_exception, and copying it back
	 * afterwards.  On most processors the copy is avoided since
	 * exception_thread_info == thread_info.
	 */
	thread_info = (struct thread_info *)(regs->gpr[1] & ~(THREAD_SIZE-1));
	exception_thread_info = current_thread_info();

	if (thread_info != exception_thread_info)
		memcpy(exception_thread_info, thread_info, sizeof *thread_info);

	kgdb_handle_exception(0, SIGTRAP, 0, regs);

	if (thread_info != exception_thread_info)
		memcpy(thread_info, exception_thread_info, sizeof *thread_info);

	return 1;
}

static int kgdb_iabr_match(struct pt_regs *regs)
{
	if (user_mode(regs))
		return 0;

	if (kgdb_handle_exception(0, computeSignal(TRAP(regs)), 0, regs) != 0)
		return 0;
	return 1;
}

static int kgdb_dabr_match(struct pt_regs *regs)
{
	if (user_mode(regs))
		return 0;

	if (kgdb_handle_exception(0, computeSignal(TRAP(regs)), 0, regs) != 0)
		return 0;
	return 1;
}

#define PACK64(ptr, src) do { *(ptr++) = (src); } while (0)

#define PACK32(ptr, src) do {          \
	u32 *ptr32;                   \
	ptr32 = (u32 *)ptr;           \
	*(ptr32++) = (src);           \
	ptr = (unsigned long *)ptr32; \
	} while (0)


void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
{
	unsigned long *ptr = gdb_regs;
	int reg;

	memset(gdb_regs, 0, NUMREGBYTES);

	for (reg = 0; reg < 32; reg++)
		PACK64(ptr, regs->gpr[reg]);

#ifdef CONFIG_FSL_BOOKE
#ifdef CONFIG_SPE
	for (reg = 0; reg < 32; reg++)
		PACK64(ptr, current->thread.evr[reg]);
#else
	ptr += 32;
#endif
#else
	/* fp registers not used by kernel, leave zero */
	ptr += 32 * 8 / sizeof(long);
#endif

	PACK64(ptr, regs->nip);
	PACK64(ptr, regs->msr);
	PACK32(ptr, regs->ccr);
	PACK64(ptr, regs->link);
	PACK64(ptr, regs->ctr);
	PACK32(ptr, regs->xer);

	BUG_ON((unsigned long)ptr >
	       (unsigned long)(((void *)gdb_regs) + NUMREGBYTES));
}

void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
{
	struct pt_regs *regs = (struct pt_regs *)(p->thread.ksp +
						  STACK_FRAME_OVERHEAD);
	unsigned long *ptr = gdb_regs;
	int reg;

	memset(gdb_regs, 0, NUMREGBYTES);

	/* Regs GPR0-2 */
	for (reg = 0; reg < 3; reg++)
		PACK64(ptr, regs->gpr[reg]);

	/* Regs GPR3-13 are caller saved, not in regs->gpr[] */
	ptr += 11;

	/* Regs GPR14-31 */
	for (reg = 14; reg < 32; reg++)
		PACK64(ptr, regs->gpr[reg]);

#ifdef CONFIG_FSL_BOOKE
#ifdef CONFIG_SPE
	for (reg = 0; reg < 32; reg++)
		PACK64(ptr, p->thread.evr[reg]);
#else
	ptr += 32;
#endif
#else
	/* fp registers not used by kernel, leave zero */
	ptr += 32 * 8 / sizeof(long);
#endif

	PACK64(ptr, regs->nip);
	PACK64(ptr, regs->msr);
	PACK32(ptr, regs->ccr);
	PACK64(ptr, regs->link);
	PACK64(ptr, regs->ctr);
	PACK32(ptr, regs->xer);

	BUG_ON((unsigned long)ptr >
	       (unsigned long)(((void *)gdb_regs) + NUMREGBYTES));
}

#define UNPACK64(dest, ptr) do { dest = *(ptr++); } while (0)

#define UNPACK32(dest, ptr) do {       \
	u32 *ptr32;                   \
	ptr32 = (u32 *)ptr;           \
	dest = *(ptr32++);            \
	ptr = (unsigned long *)ptr32; \
	} while (0)

void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
{
	unsigned long *ptr = gdb_regs;
	int reg;

	for (reg = 0; reg < 32; reg++)
		UNPACK64(regs->gpr[reg], ptr);

#ifdef CONFIG_FSL_BOOKE
#ifdef CONFIG_SPE
	for (reg = 0; reg < 32; reg++)
		UNPACK64(current->thread.evr[reg], ptr);
#else
	ptr += 32;
#endif
#else
	/* fp registers not used by kernel, leave zero */
	ptr += 32 * 8 / sizeof(int);
#endif

	UNPACK64(regs->nip, ptr);
	UNPACK64(regs->msr, ptr);
	UNPACK32(regs->ccr, ptr);
	UNPACK64(regs->link, ptr);
	UNPACK64(regs->ctr, ptr);
	UNPACK32(regs->xer, ptr);

	BUG_ON((unsigned long)ptr >
	       (unsigned long)(((void *)gdb_regs) + NUMREGBYTES));
}

void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
{
	regs->nip = pc;
}

/*
 * This function does PowerPC specific procesing for interfacing to gdb.
 */
int kgdb_arch_handle_exception(int vector, int signo, int err_code,
			       char *remcom_in_buffer, char *remcom_out_buffer,
			       struct pt_regs *linux_regs)
{
	char *ptr = &remcom_in_buffer[1];
	unsigned long addr;

	switch (remcom_in_buffer[0]) {
		/*
		 * sAA..AA   Step one instruction from AA..AA
		 * This will return an error to gdb ..
		 */
	case 's':
	case 'c':
		/* handle the optional parameter */
		if (kgdb_hex2long(&ptr, &addr))
			linux_regs->nip = addr;

		atomic_set(&kgdb_cpu_doing_single_step, -1);
		/* set the trace bit if we're stepping */
		if (remcom_in_buffer[0] == 's') {
#ifdef CONFIG_PPC_ADV_DEBUG_REGS
			mtspr(SPRN_DBCR0,
			      mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM);
			linux_regs->msr |= MSR_DE;
#else
			linux_regs->msr |= MSR_SE;
#endif
			kgdb_single_step = 1;
			atomic_set(&kgdb_cpu_doing_single_step,
				   raw_smp_processor_id());
		}
		return 0;
	}

	return -1;
}

/*
 * Global data
 */
struct kgdb_arch arch_kgdb_ops = {
	.gdb_bpt_instr = {0x7d, 0x82, 0x10, 0x08},
};

static int kgdb_not_implemented(struct pt_regs *regs)
{
	return 0;
}

static void *old__debugger_ipi;
static void *old__debugger;
static void *old__debugger_bpt;
static void *old__debugger_sstep;
static void *old__debugger_iabr_match;
static void *old__debugger_dabr_match;
static void *old__debugger_fault_handler;

int kgdb_arch_init(void)
{
	old__debugger_ipi = __debugger_ipi;
	old__debugger = __debugger;
	old__debugger_bpt = __debugger_bpt;
	old__debugger_sstep = __debugger_sstep;
	old__debugger_iabr_match = __debugger_iabr_match;
	old__debugger_dabr_match = __debugger_dabr_match;
	old__debugger_fault_handler = __debugger_fault_handler;

	__debugger_ipi = kgdb_call_nmi_hook;
	__debugger = kgdb_debugger;
	__debugger_bpt = kgdb_handle_breakpoint;
	__debugger_sstep = kgdb_singlestep;
	__debugger_iabr_match = kgdb_iabr_match;
	__debugger_dabr_match = kgdb_dabr_match;
	__debugger_fault_handler = kgdb_not_implemented;

	return 0;
}

void kgdb_arch_exit(void)
{
	__debugger_ipi = old__debugger_ipi;
	__debugger = old__debugger;
	__debugger_bpt = old__debugger_bpt;
	__debugger_sstep = old__debugger_sstep;
	__debugger_iabr_match = old__debugger_iabr_match;
	__debugger_dabr_match = old__debugger_dabr_match;
	__debugger_fault_handler = old__debugger_fault_handler;
}