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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276// SPDX-License-Identifier: GPL-2.0-only/* * 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) * * 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 <linux/sched/debug.h>
#include <asm/arcregs.h>#include <asm/unwind.h>#include <asm/stacktrace.h>#include <asm/switch_to.h>
/*------------------------------------------------------------------------- * Unwinder Iterator *------------------------------------------------------------------------- */
#ifdef CONFIG_ARC_DW2_UNWIND
static intseed_unwind_frame_info(struct task_struct *tsk, struct pt_regs *regs, struct unwind_frame_info *frame_info){ if (regs) { /* * Asynchronous unwinding of intr/exception * - Just uses the pt_regs passed */ 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; } else if (tsk == NULL || tsk == current) { /* * synchronous unwinding (e.g. dump_stack) * - uses current values of SP and friends */ 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 { /* * Asynchronous unwinding of a likely sleeping task * - first ensure it is actually sleeping * - if so, it will be in __switch_to, kernel mode SP of task * is safe-kept and BLINK at a well known location in there */
if (task_is_running(tsk)) return -1;
frame_info->task = tsk;
frame_info->regs.r27 = TSK_K_FP(tsk); frame_info->regs.r28 = TSK_K_ESP(tsk); frame_info->regs.r31 = TSK_K_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 += 60; frame_info->call_frame = 0;
} return 0;}
#endif
notrace noinline unsigned intarc_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, cnt = 0; unsigned int address; struct unwind_frame_info frame_info;
if (seed_unwind_frame_info(tsk, regs, &frame_info)) return 0;
while (1) { address = UNW_PC(&frame_info);
if (!address || !__kernel_text_address(address)) break;
if (consumer_fn(address, arg) == -1) break;
ret = arc_unwind(&frame_info); if (ret) break;
frame_info.regs.r63 = frame_info.regs.r31;
if (cnt++ > 128) { printk("unwinder looping too long, aborting !\n"); return 0; } }
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 * prologue is setup (callee regs saved and then fp set and not other * way around */ pr_warn_once("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 *arg){ const char *loglvl = arg;
printk("%s %pS\n", loglvl, (void *)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 *------------------------------------------------------------------------- */
noinline void show_stacktrace(struct task_struct *tsk, struct pt_regs *regs, const char *loglvl){ printk("%s\nStack Trace:\n", loglvl); arc_unwind_core(tsk, regs, __print_sym, (void *)loglvl);}EXPORT_SYMBOL(show_stacktrace);
/* Expected by sched Code */void show_stack(struct task_struct *tsk, unsigned long *sp, const char *loglvl){ show_stacktrace(tsk, NULL, loglvl);}
/* Another API expected by schedular, shows up in "ps" as Wait Channel * Of course just returning schedule( ) would be pointless so unwind until * the function is not in schedular code */unsigned int __get_wchan(struct task_struct *tsk){ 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){ /* Assumes @tsk is sleeping so unwinds from __switch_to */ arc_unwind_core(tsk, NULL, __collect_all_but_sched, trace);}
void save_stack_trace(struct stack_trace *trace){ /* Pass NULL for task so it unwinds the current call frame */ arc_unwind_core(NULL, NULL, __collect_all, trace);}EXPORT_SYMBOL_GPL(save_stack_trace);#endif