kgdb.c

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/*
 * PowerPC backend to the KGDB stub.
 *
 * 1998 (c) Michael AK Tesch ([email protected])
 * Copyright (C) 2003 Timesys Corporation.
 * Copyright (C) 2004-2006 MontaVista Software, Inc.
 * PPC64 Mods (C) 2005 Frank Rowand ([email protected])
 * PPC32 support restored by Vitaly Wool <[email protected]> and
 * Sergei Shtylyov <[email protected]>
 * 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>
#include <asm/debug.h>
#include <linux/slab.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 */
}

int kgdb_skipexception(int exception, struct pt_regs *regs)
{
    return kgdb_isremovedbreak(regs->nip);
}

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();
}
#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;
    struct thread_info *backup_current_thread_info = \
        (struct thread_info *)kmalloc(sizeof(struct thread_info), GFP_KERNEL);

    if (user_mode(regs))
        return 0;

    /*
     * On Book E and perhaps other processors, 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) {
        /* Save the original current_thread_info. */
        memcpy(backup_current_thread_info, exception_thread_info, sizeof *thread_info);
        memcpy(exception_thread_info, thread_info, sizeof *thread_info);
    }

    kgdb_handle_exception(0, SIGTRAP, 0, regs);

    if (thread_info != exception_thread_info)
        /* Restore current_thread_info lastly. */
        memcpy(exception_thread_info, backup_current_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 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 GDB_SIZEOF_REG sizeof(unsigned long)
#define GDB_SIZEOF_REG_U32 sizeof(u32)

#ifdef CONFIG_FSL_BOOKE
#define GDB_SIZEOF_FLOAT_REG sizeof(unsigned long)
#else
#define GDB_SIZEOF_FLOAT_REG sizeof(u64)
#endif

struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
{
    { "r0", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[0]) },
    { "r1", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[1]) },
    { "r2", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[2]) },
    { "r3", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[3]) },
    { "r4", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[4]) },
    { "r5", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[5]) },
    { "r6", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[6]) },
    { "r7", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[7]) },
    { "r8", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[8]) },
    { "r9", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[9]) },
    { "r10", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[10]) },
    { "r11", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[11]) },
    { "r12", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[12]) },
    { "r13", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[13]) },
    { "r14", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[14]) },
    { "r15", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[15]) },
    { "r16", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[16]) },
    { "r17", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[17]) },
    { "r18", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[18]) },
    { "r19", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[19]) },
    { "r20", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[20]) },
    { "r21", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[21]) },
    { "r22", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[22]) },
    { "r23", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[23]) },
    { "r24", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[24]) },
    { "r25", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[25]) },
    { "r26", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[26]) },
    { "r27", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[27]) },
    { "r28", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[28]) },
    { "r29", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[29]) },
    { "r30", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[30]) },
    { "r31", GDB_SIZEOF_REG, offsetof(struct pt_regs, gpr[31]) },

    { "f0", GDB_SIZEOF_FLOAT_REG, 0 },
    { "f1", GDB_SIZEOF_FLOAT_REG, 1 },
    { "f2", GDB_SIZEOF_FLOAT_REG, 2 },
    { "f3", GDB_SIZEOF_FLOAT_REG, 3 },
    { "f4", GDB_SIZEOF_FLOAT_REG, 4 },
    { "f5", GDB_SIZEOF_FLOAT_REG, 5 },
    { "f6", GDB_SIZEOF_FLOAT_REG, 6 },
    { "f7", GDB_SIZEOF_FLOAT_REG, 7 },
    { "f8", GDB_SIZEOF_FLOAT_REG, 8 },
    { "f9", GDB_SIZEOF_FLOAT_REG, 9 },
    { "f10", GDB_SIZEOF_FLOAT_REG, 10 },
    { "f11", GDB_SIZEOF_FLOAT_REG, 11 },
    { "f12", GDB_SIZEOF_FLOAT_REG, 12 },
    { "f13", GDB_SIZEOF_FLOAT_REG, 13 },
    { "f14", GDB_SIZEOF_FLOAT_REG, 14 },
    { "f15", GDB_SIZEOF_FLOAT_REG, 15 },
    { "f16", GDB_SIZEOF_FLOAT_REG, 16 },
    { "f17", GDB_SIZEOF_FLOAT_REG, 17 },
    { "f18", GDB_SIZEOF_FLOAT_REG, 18 },
    { "f19", GDB_SIZEOF_FLOAT_REG, 19 },
    { "f20", GDB_SIZEOF_FLOAT_REG, 20 },
    { "f21", GDB_SIZEOF_FLOAT_REG, 21 },
    { "f22", GDB_SIZEOF_FLOAT_REG, 22 },
    { "f23", GDB_SIZEOF_FLOAT_REG, 23 },
    { "f24", GDB_SIZEOF_FLOAT_REG, 24 },
    { "f25", GDB_SIZEOF_FLOAT_REG, 25 },
    { "f26", GDB_SIZEOF_FLOAT_REG, 26 },
    { "f27", GDB_SIZEOF_FLOAT_REG, 27 },
    { "f28", GDB_SIZEOF_FLOAT_REG, 28 },
    { "f29", GDB_SIZEOF_FLOAT_REG, 29 },
    { "f30", GDB_SIZEOF_FLOAT_REG, 30 },
    { "f31", GDB_SIZEOF_FLOAT_REG, 31 },

    { "pc", GDB_SIZEOF_REG, offsetof(struct pt_regs, nip) },
    { "msr", GDB_SIZEOF_REG, offsetof(struct pt_regs, msr) },
    { "cr", GDB_SIZEOF_REG_U32, offsetof(struct pt_regs, ccr) },
    { "lr", GDB_SIZEOF_REG, offsetof(struct pt_regs, link) },
    { "ctr", GDB_SIZEOF_REG_U32, offsetof(struct pt_regs, ctr) },
    { "xer", GDB_SIZEOF_REG, offsetof(struct pt_regs, xer) },
};

char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
{
    if (regno >= DBG_MAX_REG_NUM || regno < 0)
        return NULL;

    if (regno < 32 || regno >= 64)
        /* First 0 -> 31 gpr registers*/
        /* pc, msr, ls... registers 64 -> 69 */
        memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
                dbg_reg_def[regno].size);

    if (regno >= 32 && regno < 64) {
        /* FP registers 32 -> 63 */
#if defined(CONFIG_FSL_BOOKE) && defined(CONFIG_SPE)
        if (current)
            memcpy(mem, &current->thread.evr[regno-32],
                    dbg_reg_def[regno].size);
#else
        /* fp registers not used by kernel, leave zero */
        memset(mem, 0, dbg_reg_def[regno].size);
#endif
    }

    return dbg_reg_def[regno].name;
}

int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
{
    if (regno >= DBG_MAX_REG_NUM || regno < 0)
        return -EINVAL;

    if (regno < 32 || regno >= 64)
        /* First 0 -> 31 gpr registers*/
        /* pc, msr, ls... registers 64 -> 69 */
        memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
                dbg_reg_def[regno].size);

    if (regno >= 32 && regno < 64) {
        /* FP registers 32 -> 63 */
#if defined(CONFIG_FSL_BOOKE) && defined(CONFIG_SPE)
        memcpy(&current->thread.evr[regno-32], mem,
                dbg_reg_def[regno].size);
#else
        /* fp registers not used by kernel, leave zero */
        return 0;
#endif
    }

    return 0;
}

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
            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;
}