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linux/arch/powerpc/kernel/kgdb.c
Balbir Singh 94e3d92359 powerpc: Fix kgdb on little endian ppc64le 
I spent some time trying to use kgdb and debugged my inability to
resume from kgdb_handle_breakpoint(). NIP is not incremented
and that leads to a loop in the debugger.

I've tested this lightly on a virtual instance with KDB enabled.
After the patch, I am able to get the "go" command to work as
expected.

Signed-off-by: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2016-02-18 00:03:26 +11:00

499 lines
15 KiB
C
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/*
* 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/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 */
}
/**
*
* kgdb_skipexception - Bail out of KGDB when we've been triggered.
* @exception: Exception vector number
* @regs: Current &struct pt_regs.
*
* On some architectures we need to skip a breakpoint exception when
* it occurs after a breakpoint has been removed.
*
*/
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 DEFINE_PER_CPU(struct thread_info, kgdb_thread_info);
static int kgdb_singlestep(struct pt_regs *regs)
{
struct thread_info *thread_info, *exception_thread_info;
struct thread_info *backup_current_thread_info =
this_cpu_ptr(&kgdb_thread_info);
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_break_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 = {
#ifdef __LITTLE_ENDIAN__
.gdb_bpt_instr = {0x08, 0x10, 0x82, 0x7d},
#else
.gdb_bpt_instr = {0x7d, 0x82, 0x10, 0x08},
#endif
};
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_break_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_break_match = __debugger_break_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_break_match = kgdb_break_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_break_match = old__debugger_break_match;
__debugger_fault_handler = old__debugger_fault_handler;
}
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