linux/arch/tile/kernel/entry.S
Chris Metcalf 47ad7b9bbe tile: improve stack backtrace
This commit fixes a number of issues with the tile backtrace code.

- Don't try to identify userspace shared object or executable paths
  if we are doing a backtrace from an interrupt; it's not legal,
  and also unlikely to be interesting.  Likewise, don't try to do
  it for other address spaces, since d_path() assumes it is being
  called in "current" context.

- Move "in_backtrace" from thread_struct to thread_info.
  This way we can access it even if our stack thread_info has been
  clobbered, which makes backtracing more robust.

- Avoid using "current" directly when testing for is_sigreturn().
  Since "current" may be corrupt, we're better off using kbt->task
  explicitly to look up the vdso_base for the current task.
  Conveniently, this simplifies the internal APIs (we only need
  one is_sigreturn() function now).

- Avoid bogus "Odd fault" warning when pc/sp/ex1 are all zero,
  as is true for kernel threads above the last frame.

- Hook into Tejun Heo's dump_stack() framework in lib/dump_stack.c.

- Write last entry in save_stack_trace() as ULONG_MAX, not zero,
  since ftrace (at least) relies on finding that marker.

- Implement save_stack_trace_regs() and save_strack_trace_user(),
  and set CONFIG_USER_STACKTRACE_SUPPORT.

Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com>
2015-05-11 11:22:40 -04:00

65 lines
2.1 KiB
ArmAsm

/*
* Copyright 2010 Tilera Corporation. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, version 2.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for
* more details.
*/
#include <linux/linkage.h>
#include <linux/unistd.h>
#include <asm/irqflags.h>
#include <asm/processor.h>
#include <arch/abi.h>
#include <arch/spr_def.h>
#ifdef __tilegx__
#define bnzt bnezt
#endif
STD_ENTRY(current_text_addr)
{ move r0, lr; jrp lr }
STD_ENDPROC(current_text_addr)
STD_ENTRY(KBacktraceIterator_init_current)
{ move r2, lr; lnk r1 }
{ move r4, r52; addli r1, r1, KBacktraceIterator_init_current - . }
{ move r3, sp; j _KBacktraceIterator_init_current }
jrp lr /* keep backtracer happy */
STD_ENDPROC(KBacktraceIterator_init_current)
/* Loop forever on a nap during SMP boot. */
STD_ENTRY(smp_nap)
nap
nop /* avoid provoking the icache prefetch with a jump */
j smp_nap /* we are not architecturally guaranteed not to exit nap */
jrp lr /* clue in the backtracer */
STD_ENDPROC(smp_nap)
/*
* Enable interrupts racelessly and then nap until interrupted.
* Architecturally, we are guaranteed that enabling interrupts via
* mtspr to INTERRUPT_CRITICAL_SECTION only interrupts at the next PC.
* This function's _cpu_idle_nap address is special; see intvec.S.
* When interrupted at _cpu_idle_nap, we bump the PC forward 8, and
* as a result return to the function that called _cpu_idle().
*/
STD_ENTRY(_cpu_idle)
movei r1, 1
IRQ_ENABLE_LOAD(r2, r3)
mtspr INTERRUPT_CRITICAL_SECTION, r1
IRQ_ENABLE_APPLY(r2, r3) /* unmask, but still with ICS set */
mtspr INTERRUPT_CRITICAL_SECTION, zero
.global _cpu_idle_nap
_cpu_idle_nap:
nap
nop /* avoid provoking the icache prefetch with a jump */
jrp lr
STD_ENDPROC(_cpu_idle)