diff options
Diffstat (limited to 'arch/arc/kernel/stacktrace.c')
| -rw-r--r-- | arch/arc/kernel/stacktrace.c | 215 |
1 files changed, 213 insertions, 2 deletions
diff --git a/arch/arc/kernel/stacktrace.c b/arch/arc/kernel/stacktrace.c index b9d1646..a63ff84 100644 --- a/arch/arc/kernel/stacktrace.c +++ b/arch/arc/kernel/stacktrace.c @@ -1,13 +1,206 @@ /* + * stacktrace.c : stacktracing APIs needed by rest of kernel + * (wrappers over ARC dwarf based unwinder) + * * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. + * + * vineetg: aug 2009 + * -Implemented CONFIG_STACKTRACE APIs, primarily save_stack_trace_tsk( ) + * for displaying task's kernel mode call stack in /proc/<pid>/stack + * -Iterator based approach to have single copy of unwinding core and APIs + * needing unwinding, implement the logic in iterator regarding: + * = which frame onwards to start capture + * = which frame to stop capturing (wchan) + * = specifics of data structs where trace is saved(CONFIG_STACKTRACE etc) + * + * vineetg: March 2009 + * -Implemented correct versions of thread_saved_pc() and get_wchan() + * + * rajeshwarr: 2008 + * -Initial implementation */ #include <linux/ptrace.h> #include <linux/export.h> +#include <linux/stacktrace.h> +#include <linux/kallsyms.h> +#include <asm/arcregs.h> +#include <asm/unwind.h> +#include <asm/switch_to.h> + +/*------------------------------------------------------------------------- + * Unwinder Iterator + *------------------------------------------------------------------------- + */ + +#ifdef CONFIG_ARC_DW2_UNWIND + +static void seed_unwind_frame_info(struct task_struct *tsk, + struct pt_regs *regs, + struct unwind_frame_info *frame_info) +{ + if (tsk == NULL && regs == NULL) { + unsigned long fp, sp, blink, ret; + frame_info->task = current; + + __asm__ __volatile__( + "mov %0,r27\n\t" + "mov %1,r28\n\t" + "mov %2,r31\n\t" + "mov %3,r63\n\t" + : "=r"(fp), "=r"(sp), "=r"(blink), "=r"(ret) + ); + + frame_info->regs.r27 = fp; + frame_info->regs.r28 = sp; + frame_info->regs.r31 = blink; + frame_info->regs.r63 = ret; + frame_info->call_frame = 0; + } else if (regs == NULL) { + + frame_info->task = tsk; + + frame_info->regs.r27 = KSTK_FP(tsk); + frame_info->regs.r28 = KSTK_ESP(tsk); + frame_info->regs.r31 = KSTK_BLINK(tsk); + frame_info->regs.r63 = (unsigned int)__switch_to; + + /* In the prologue of __switch_to, first FP is saved on stack + * and then SP is copied to FP. Dwarf assumes cfa as FP based + * but we didn't save FP. The value retrieved above is FP's + * state in previous frame. + * As a work around for this, we unwind from __switch_to start + * and adjust SP accordingly. The other limitation is that + * __switch_to macro is dwarf rules are not generated for inline + * assembly code + */ + frame_info->regs.r27 = 0; + frame_info->regs.r28 += 64; + frame_info->call_frame = 0; + + } else { + frame_info->task = tsk; + + frame_info->regs.r27 = regs->fp; + frame_info->regs.r28 = regs->sp; + frame_info->regs.r31 = regs->blink; + frame_info->regs.r63 = regs->ret; + frame_info->call_frame = 0; + } +} + +#endif + +static noinline unsigned int +arc_unwind_core(struct task_struct *tsk, struct pt_regs *regs, + int (*consumer_fn) (unsigned int, void *), void *arg) +{ +#ifdef CONFIG_ARC_DW2_UNWIND + int ret = 0; + unsigned int address; + struct unwind_frame_info frame_info; + + seed_unwind_frame_info(tsk, regs, &frame_info); + + while (1) { + address = UNW_PC(&frame_info); + + if (address && __kernel_text_address(address)) { + if (consumer_fn(address, arg) == -1) + break; + } + + ret = arc_unwind(&frame_info); + + if (ret == 0) { + frame_info.regs.r63 = frame_info.regs.r31; + continue; + } else { + break; + } + } + + return address; /* return the last address it saw */ +#else + /* On ARC, only Dward based unwinder works. fp based backtracing is + * not possible (-fno-omit-frame-pointer) because of the way function + * prelogue is setup (callee regs saved and then fp set and not other + * way around + */ + pr_warn("CONFIG_ARC_DW2_UNWIND needs to be enabled\n"); + return 0; + +#endif +} + +/*------------------------------------------------------------------------- + * callbacks called by unwinder iterator to implement kernel APIs + * + * The callback can return -1 to force the iterator to stop, which by default + * keeps going till the bottom-most frame. + *------------------------------------------------------------------------- + */ + +/* Call-back which plugs into unwinding core to dump the stack in + * case of panic/OOPs/BUG etc + */ +static int __print_sym(unsigned int address, void *unused) +{ + __print_symbol(" %s\n", address); + return 0; +} + +#ifdef CONFIG_STACKTRACE + +/* Call-back which plugs into unwinding core to capture the + * traces needed by kernel on /proc/<pid>/stack + */ +static int __collect_all(unsigned int address, void *arg) +{ + struct stack_trace *trace = arg; + + if (trace->skip > 0) + trace->skip--; + else + trace->entries[trace->nr_entries++] = address; + + if (trace->nr_entries >= trace->max_entries) + return -1; + + return 0; +} + +static int __collect_all_but_sched(unsigned int address, void *arg) +{ + struct stack_trace *trace = arg; + + if (in_sched_functions(address)) + return 0; + + if (trace->skip > 0) + trace->skip--; + else + trace->entries[trace->nr_entries++] = address; + + if (trace->nr_entries >= trace->max_entries) + return -1; + + return 0; +} + +#endif + +static int __get_first_nonsched(unsigned int address, void *unused) +{ + if (in_sched_functions(address)) + return 0; + + return -1; +} /*------------------------------------------------------------------------- * APIs expected by various kernel sub-systems @@ -16,7 +209,8 @@ noinline void show_stacktrace(struct task_struct *tsk, struct pt_regs *regs) { - pr_info("\nStack Trace: NOT Available\n"); + pr_info("\nStack Trace:\n"); + arc_unwind_core(tsk, regs, __print_sym, NULL); } EXPORT_SYMBOL(show_stacktrace); @@ -39,5 +233,22 @@ EXPORT_SYMBOL(dump_stack); */ unsigned int get_wchan(struct task_struct *tsk) { - return 0; + return arc_unwind_core(tsk, NULL, __get_first_nonsched, NULL); +} + +#ifdef CONFIG_STACKTRACE + +/* + * API required by CONFIG_STACKTRACE, CONFIG_LATENCYTOP. + * A typical use is when /proc/<pid>/stack is queried by userland + */ +void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) +{ + arc_unwind_core(tsk, NULL, __collect_all_but_sched, trace); +} + +void save_stack_trace(struct stack_trace *trace) +{ + arc_unwind_core(current, NULL, __collect_all, trace); } +#endif |