diff options
Diffstat (limited to 'kernel/kgdb.c')
| -rw-r--r-- | kernel/kgdb.c | 205 |
1 files changed, 103 insertions, 102 deletions
diff --git a/kernel/kgdb.c b/kernel/kgdb.c index 761fdd2b3034..11f3515ca83f 100644 --- a/kernel/kgdb.c +++ b/kernel/kgdb.c @@ -69,9 +69,16 @@ struct kgdb_state { struct pt_regs *linux_regs; }; +/* Exception state values */ +#define DCPU_WANT_MASTER 0x1 /* Waiting to become a master kgdb cpu */ +#define DCPU_NEXT_MASTER 0x2 /* Transition from one master cpu to another */ +#define DCPU_IS_SLAVE 0x4 /* Slave cpu enter exception */ +#define DCPU_SSTEP 0x8 /* CPU is single stepping */ + static struct debuggerinfo_struct { void *debuggerinfo; struct task_struct *task; + int exception_state; } kgdb_info[NR_CPUS]; /** @@ -391,27 +398,22 @@ int kgdb_mem2hex(char *mem, char *buf, int count) /* * Copy the binary array pointed to by buf into mem. Fix $, #, and - * 0x7d escaped with 0x7d. Return a pointer to the character after - * the last byte written. + * 0x7d escaped with 0x7d. Return -EFAULT on failure or 0 on success. + * The input buf is overwitten with the result to write to mem. */ static int kgdb_ebin2mem(char *buf, char *mem, int count) { - int err = 0; - char c; + int size = 0; + char *c = buf; while (count-- > 0) { - c = *buf++; - if (c == 0x7d) - c = *buf++ ^ 0x20; - - err = probe_kernel_write(mem, &c, 1); - if (err) - break; - - mem++; + c[size] = *buf++; + if (c[size] == 0x7d) + c[size] = *buf++ ^ 0x20; + size++; } - return err; + return probe_kernel_write(mem, c, size); } /* @@ -563,49 +565,6 @@ static struct task_struct *getthread(struct pt_regs *regs, int tid) } /* - * CPU debug state control: - */ - -#ifdef CONFIG_SMP -static void kgdb_wait(struct pt_regs *regs) -{ - unsigned long flags; - int cpu; - - local_irq_save(flags); - cpu = raw_smp_processor_id(); - kgdb_info[cpu].debuggerinfo = regs; - kgdb_info[cpu].task = current; - /* - * Make sure the above info reaches the primary CPU before - * our cpu_in_kgdb[] flag setting does: - */ - smp_wmb(); - atomic_set(&cpu_in_kgdb[cpu], 1); - - /* Disable any cpu specific hw breakpoints */ - kgdb_disable_hw_debug(regs); - - /* Wait till primary CPU is done with debugging */ - while (atomic_read(&passive_cpu_wait[cpu])) - cpu_relax(); - - kgdb_info[cpu].debuggerinfo = NULL; - kgdb_info[cpu].task = NULL; - - /* fix up hardware debug registers on local cpu */ - if (arch_kgdb_ops.correct_hw_break) - arch_kgdb_ops.correct_hw_break(); - - /* Signal the primary CPU that we are done: */ - atomic_set(&cpu_in_kgdb[cpu], 0); - touch_softlockup_watchdog_sync(); - clocksource_touch_watchdog(); - local_irq_restore(flags); -} -#endif - -/* * Some architectures need cache flushes when we set/clear a * breakpoint: */ @@ -1400,34 +1359,13 @@ static int kgdb_reenter_check(struct kgdb_state *ks) return 1; } -/* - * kgdb_handle_exception() - main entry point from a kernel exception - * - * Locking hierarchy: - * interface locks, if any (begin_session) - * kgdb lock (kgdb_active) - */ -int -kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs) +static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs) { - struct kgdb_state kgdb_var; - struct kgdb_state *ks = &kgdb_var; unsigned long flags; int sstep_tries = 100; int error = 0; int i, cpu; - - ks->cpu = raw_smp_processor_id(); - ks->ex_vector = evector; - ks->signo = signo; - ks->ex_vector = evector; - ks->err_code = ecode; - ks->kgdb_usethreadid = 0; - ks->linux_regs = regs; - - if (kgdb_reenter_check(ks)) - return 0; /* Ouch, double exception ! */ - + int trace_on = 0; acquirelock: /* * Interrupts will be restored by the 'trap return' code, except when @@ -1435,13 +1373,43 @@ acquirelock: */ local_irq_save(flags); - cpu = raw_smp_processor_id(); + cpu = ks->cpu; + kgdb_info[cpu].debuggerinfo = regs; + kgdb_info[cpu].task = current; + /* + * Make sure the above info reaches the primary CPU before + * our cpu_in_kgdb[] flag setting does: + */ + atomic_inc(&cpu_in_kgdb[cpu]); /* - * Acquire the kgdb_active lock: + * CPU will loop if it is a slave or request to become a kgdb + * master cpu and acquire the kgdb_active lock: */ - while (atomic_cmpxchg(&kgdb_active, -1, cpu) != -1) + while (1) { + if (kgdb_info[cpu].exception_state & DCPU_WANT_MASTER) { + if (atomic_cmpxchg(&kgdb_active, -1, cpu) == cpu) + break; + } else if (kgdb_info[cpu].exception_state & DCPU_IS_SLAVE) { + if (!atomic_read(&passive_cpu_wait[cpu])) + goto return_normal; + } else { +return_normal: + /* Return to normal operation by executing any + * hw breakpoint fixup. + */ + if (arch_kgdb_ops.correct_hw_break) + arch_kgdb_ops.correct_hw_break(); + if (trace_on) + tracing_on(); + atomic_dec(&cpu_in_kgdb[cpu]); + touch_softlockup_watchdog_sync(); + clocksource_touch_watchdog(); + local_irq_restore(flags); + return 0; + } cpu_relax(); + } /* * For single stepping, try to only enter on the processor @@ -1475,9 +1443,6 @@ acquirelock: if (kgdb_io_ops->pre_exception) kgdb_io_ops->pre_exception(); - kgdb_info[ks->cpu].debuggerinfo = ks->linux_regs; - kgdb_info[ks->cpu].task = current; - kgdb_disable_hw_debug(ks->linux_regs); /* @@ -1486,15 +1451,9 @@ acquirelock: */ if (!kgdb_single_step) { for (i = 0; i < NR_CPUS; i++) - atomic_set(&passive_cpu_wait[i], 1); + atomic_inc(&passive_cpu_wait[i]); } - /* - * spin_lock code is good enough as a barrier so we don't - * need one here: - */ - atomic_set(&cpu_in_kgdb[ks->cpu], 1); - #ifdef CONFIG_SMP /* Signal the other CPUs to enter kgdb_wait() */ if ((!kgdb_single_step) && kgdb_do_roundup) @@ -1518,6 +1477,9 @@ acquirelock: kgdb_single_step = 0; kgdb_contthread = current; exception_level = 0; + trace_on = tracing_is_on(); + if (trace_on) + tracing_off(); /* Talk to debugger with gdbserial protocol */ error = gdb_serial_stub(ks); @@ -1526,13 +1488,11 @@ acquirelock: if (kgdb_io_ops->post_exception) kgdb_io_ops->post_exception(); - kgdb_info[ks->cpu].debuggerinfo = NULL; - kgdb_info[ks->cpu].task = NULL; - atomic_set(&cpu_in_kgdb[ks->cpu], 0); + atomic_dec(&cpu_in_kgdb[ks->cpu]); if (!kgdb_single_step) { for (i = NR_CPUS-1; i >= 0; i--) - atomic_set(&passive_cpu_wait[i], 0); + atomic_dec(&passive_cpu_wait[i]); /* * Wait till all the CPUs have quit * from the debugger. @@ -1551,6 +1511,8 @@ kgdb_restore: else kgdb_sstep_pid = 0; } + if (trace_on) + tracing_on(); /* Free kgdb_active */ atomic_set(&kgdb_active, -1); touch_softlockup_watchdog_sync(); @@ -1560,13 +1522,52 @@ kgdb_restore: return error; } +/* + * kgdb_handle_exception() - main entry point from a kernel exception + * + * Locking hierarchy: + * interface locks, if any (begin_session) + * kgdb lock (kgdb_active) + */ +int +kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs) +{ + struct kgdb_state kgdb_var; + struct kgdb_state *ks = &kgdb_var; + int ret; + + ks->cpu = raw_smp_processor_id(); + ks->ex_vector = evector; + ks->signo = signo; + ks->ex_vector = evector; + ks->err_code = ecode; + ks->kgdb_usethreadid = 0; + ks->linux_regs = regs; + + if (kgdb_reenter_check(ks)) + return 0; /* Ouch, double exception ! */ + kgdb_info[ks->cpu].exception_state |= DCPU_WANT_MASTER; + ret = kgdb_cpu_enter(ks, regs); + kgdb_info[ks->cpu].exception_state &= ~DCPU_WANT_MASTER; + return ret; +} + int kgdb_nmicallback(int cpu, void *regs) { #ifdef CONFIG_SMP + struct kgdb_state kgdb_var; + struct kgdb_state *ks = &kgdb_var; + + memset(ks, 0, sizeof(struct kgdb_state)); + ks->cpu = cpu; + ks->linux_regs = regs; + if (!atomic_read(&cpu_in_kgdb[cpu]) && - atomic_read(&kgdb_active) != cpu && - atomic_read(&cpu_in_kgdb[atomic_read(&kgdb_active)])) { - kgdb_wait((struct pt_regs *)regs); + atomic_read(&kgdb_active) != -1 && + atomic_read(&kgdb_active) != cpu) { + kgdb_info[cpu].exception_state |= DCPU_IS_SLAVE; + kgdb_cpu_enter(ks, regs); + kgdb_info[cpu].exception_state &= ~DCPU_IS_SLAVE; return 0; } #endif @@ -1742,11 +1743,11 @@ EXPORT_SYMBOL_GPL(kgdb_unregister_io_module); */ void kgdb_breakpoint(void) { - atomic_set(&kgdb_setting_breakpoint, 1); + atomic_inc(&kgdb_setting_breakpoint); wmb(); /* Sync point before breakpoint */ arch_kgdb_breakpoint(); wmb(); /* Sync point after breakpoint */ - atomic_set(&kgdb_setting_breakpoint, 0); + atomic_dec(&kgdb_setting_breakpoint); } EXPORT_SYMBOL_GPL(kgdb_breakpoint); |