diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/tile/include/asm/processor.h | 2 | ||||
| -rw-r--r-- | arch/tile/kernel/stack.c | 30 |
2 files changed, 30 insertions, 2 deletions
diff --git a/arch/tile/include/asm/processor.h b/arch/tile/include/asm/processor.h index cda27243fb09..fed1c044fec8 100644 --- a/arch/tile/include/asm/processor.h +++ b/arch/tile/include/asm/processor.h @@ -110,6 +110,8 @@ struct thread_struct { unsigned long long interrupt_mask; /* User interrupt-control 0 state */ unsigned long intctrl_0; + /* Is this task currently doing a backtrace? */ + bool in_backtrace; #if CHIP_HAS_PROC_STATUS_SPR() /* Any other miscellaneous processor state bits */ unsigned long proc_status; diff --git a/arch/tile/kernel/stack.c b/arch/tile/kernel/stack.c index af8dfc9665f6..c972689231ef 100644 --- a/arch/tile/kernel/stack.c +++ b/arch/tile/kernel/stack.c @@ -103,8 +103,7 @@ static struct pt_regs *valid_fault_handler(struct KBacktraceIterator* kbt) if (kbt->verbose) pr_err(" <%s while in kernel mode>\n", fault); } else if (EX1_PL(p->ex1) == USER_PL && - p->pc < PAGE_OFFSET && - p->sp < PAGE_OFFSET) { + p->sp < PAGE_OFFSET && p->sp != 0) { if (kbt->verbose) pr_err(" <%s while in user mode>\n", fault); } else if (kbt->verbose) { @@ -352,6 +351,26 @@ static void describe_addr(struct KBacktraceIterator *kbt, } /* + * Avoid possible crash recursion during backtrace. If it happens, it + * makes it easy to lose the actual root cause of the failure, so we + * put a simple guard on all the backtrace loops. + */ +static bool start_backtrace(void) +{ + if (current->thread.in_backtrace) { + pr_err("Backtrace requested while in backtrace!\n"); + return false; + } + current->thread.in_backtrace = true; + return true; +} + +static void end_backtrace(void) +{ + current->thread.in_backtrace = false; +} + +/* * This method wraps the backtracer's more generic support. * It is only invoked from the architecture-specific code; show_stack() * and dump_stack() (in entry.S) are architecture-independent entry points. @@ -361,6 +380,8 @@ void tile_show_stack(struct KBacktraceIterator *kbt, int headers) int i; int have_mmap_sem = 0; + if (!start_backtrace()) + return; if (headers) { /* * Add a blank line since if we are called from panic(), @@ -402,6 +423,7 @@ void tile_show_stack(struct KBacktraceIterator *kbt, int headers) pr_err("Stack dump complete\n"); if (have_mmap_sem) up_read(&kbt->task->mm->mmap_sem); + end_backtrace(); } EXPORT_SYMBOL(tile_show_stack); @@ -463,6 +485,8 @@ void save_stack_trace_tsk(struct task_struct *task, struct stack_trace *trace) int skip = trace->skip; int i = 0; + if (!start_backtrace()) + goto done; if (task == NULL || task == current) KBacktraceIterator_init_current(&kbt); else @@ -476,6 +500,8 @@ void save_stack_trace_tsk(struct task_struct *task, struct stack_trace *trace) break; trace->entries[i++] = kbt.it.pc; } + end_backtrace(); +done: trace->nr_entries = i; } EXPORT_SYMBOL(save_stack_trace_tsk); |