289 lines
6.9 KiB
C
289 lines
6.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
|
|
/*
|
|
* Stack trace utility functions etc.
|
|
*
|
|
* Copyright 2008 Christoph Hellwig, IBM Corp.
|
|
* Copyright 2018 SUSE Linux GmbH
|
|
* Copyright 2018 Nick Piggin, Michael Ellerman, IBM Corp.
|
|
*/
|
|
|
|
#include <linux/delay.h>
|
|
#include <linux/export.h>
|
|
#include <linux/kallsyms.h>
|
|
#include <linux/module.h>
|
|
#include <linux/nmi.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/sched/debug.h>
|
|
#include <linux/sched/task_stack.h>
|
|
#include <linux/stacktrace.h>
|
|
#include <asm/ptrace.h>
|
|
#include <asm/processor.h>
|
|
#include <linux/ftrace.h>
|
|
#include <linux/delay.h>
|
|
#include <asm/kprobes.h>
|
|
|
|
#include <asm/paca.h>
|
|
|
|
/*
|
|
* Save stack-backtrace addresses into a stack_trace buffer.
|
|
*/
|
|
static void save_context_stack(struct stack_trace *trace, unsigned long sp,
|
|
struct task_struct *tsk, int savesched)
|
|
{
|
|
for (;;) {
|
|
unsigned long *stack = (unsigned long *) sp;
|
|
unsigned long newsp, ip;
|
|
|
|
if (!validate_sp(sp, tsk, STACK_FRAME_OVERHEAD))
|
|
return;
|
|
|
|
newsp = stack[0];
|
|
ip = stack[STACK_FRAME_LR_SAVE];
|
|
|
|
if (savesched || !in_sched_functions(ip)) {
|
|
if (!trace->skip)
|
|
trace->entries[trace->nr_entries++] = ip;
|
|
else
|
|
trace->skip--;
|
|
}
|
|
|
|
if (trace->nr_entries >= trace->max_entries)
|
|
return;
|
|
|
|
sp = newsp;
|
|
}
|
|
}
|
|
|
|
void save_stack_trace(struct stack_trace *trace)
|
|
{
|
|
unsigned long sp;
|
|
|
|
sp = current_stack_pointer();
|
|
|
|
save_context_stack(trace, sp, current, 1);
|
|
}
|
|
EXPORT_SYMBOL_GPL(save_stack_trace);
|
|
|
|
void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
|
|
{
|
|
unsigned long sp;
|
|
|
|
if (!try_get_task_stack(tsk))
|
|
return;
|
|
|
|
if (tsk == current)
|
|
sp = current_stack_pointer();
|
|
else
|
|
sp = tsk->thread.ksp;
|
|
|
|
save_context_stack(trace, sp, tsk, 0);
|
|
|
|
put_task_stack(tsk);
|
|
}
|
|
EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
|
|
|
|
void
|
|
save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
|
|
{
|
|
save_context_stack(trace, regs->gpr[1], current, 0);
|
|
}
|
|
EXPORT_SYMBOL_GPL(save_stack_trace_regs);
|
|
|
|
#ifdef CONFIG_HAVE_RELIABLE_STACKTRACE
|
|
/*
|
|
* This function returns an error if it detects any unreliable features of the
|
|
* stack. Otherwise it guarantees that the stack trace is reliable.
|
|
*
|
|
* If the task is not 'current', the caller *must* ensure the task is inactive.
|
|
*/
|
|
static int __save_stack_trace_tsk_reliable(struct task_struct *tsk,
|
|
struct stack_trace *trace)
|
|
{
|
|
unsigned long sp;
|
|
unsigned long newsp;
|
|
unsigned long stack_page = (unsigned long)task_stack_page(tsk);
|
|
unsigned long stack_end;
|
|
int graph_idx = 0;
|
|
bool firstframe;
|
|
|
|
stack_end = stack_page + THREAD_SIZE;
|
|
if (!is_idle_task(tsk)) {
|
|
/*
|
|
* For user tasks, this is the SP value loaded on
|
|
* kernel entry, see "PACAKSAVE(r13)" in _switch() and
|
|
* system_call_common()/EXCEPTION_PROLOG_COMMON().
|
|
*
|
|
* Likewise for non-swapper kernel threads,
|
|
* this also happens to be the top of the stack
|
|
* as setup by copy_thread().
|
|
*
|
|
* Note that stack backlinks are not properly setup by
|
|
* copy_thread() and thus, a forked task() will have
|
|
* an unreliable stack trace until it's been
|
|
* _switch()'ed to for the first time.
|
|
*/
|
|
stack_end -= STACK_FRAME_OVERHEAD + sizeof(struct pt_regs);
|
|
} else {
|
|
/*
|
|
* idle tasks have a custom stack layout,
|
|
* c.f. cpu_idle_thread_init().
|
|
*/
|
|
stack_end -= STACK_FRAME_OVERHEAD;
|
|
}
|
|
|
|
if (tsk == current)
|
|
sp = current_stack_pointer();
|
|
else
|
|
sp = tsk->thread.ksp;
|
|
|
|
if (sp < stack_page + sizeof(struct thread_struct) ||
|
|
sp > stack_end - STACK_FRAME_MIN_SIZE) {
|
|
return -EINVAL;
|
|
}
|
|
|
|
for (firstframe = true; sp != stack_end;
|
|
firstframe = false, sp = newsp) {
|
|
unsigned long *stack = (unsigned long *) sp;
|
|
unsigned long ip;
|
|
|
|
/* sanity check: ABI requires SP to be aligned 16 bytes. */
|
|
if (sp & 0xF)
|
|
return -EINVAL;
|
|
|
|
newsp = stack[0];
|
|
/* Stack grows downwards; unwinder may only go up. */
|
|
if (newsp <= sp)
|
|
return -EINVAL;
|
|
|
|
if (newsp != stack_end &&
|
|
newsp > stack_end - STACK_FRAME_MIN_SIZE) {
|
|
return -EINVAL; /* invalid backlink, too far up. */
|
|
}
|
|
|
|
/*
|
|
* We can only trust the bottom frame's backlink, the
|
|
* rest of the frame may be uninitialized, continue to
|
|
* the next.
|
|
*/
|
|
if (firstframe)
|
|
continue;
|
|
|
|
/* Mark stacktraces with exception frames as unreliable. */
|
|
if (sp <= stack_end - STACK_INT_FRAME_SIZE &&
|
|
stack[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) {
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* Examine the saved LR: it must point into kernel code. */
|
|
ip = stack[STACK_FRAME_LR_SAVE];
|
|
if (!__kernel_text_address(ip))
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* FIXME: IMHO these tests do not belong in
|
|
* arch-dependent code, they are generic.
|
|
*/
|
|
ip = ftrace_graph_ret_addr(tsk, &graph_idx, ip, stack);
|
|
#ifdef CONFIG_KPROBES
|
|
/*
|
|
* Mark stacktraces with kretprobed functions on them
|
|
* as unreliable.
|
|
*/
|
|
if (ip == (unsigned long)kretprobe_trampoline)
|
|
return -EINVAL;
|
|
#endif
|
|
|
|
if (trace->nr_entries >= trace->max_entries)
|
|
return -E2BIG;
|
|
if (!trace->skip)
|
|
trace->entries[trace->nr_entries++] = ip;
|
|
else
|
|
trace->skip--;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
int save_stack_trace_tsk_reliable(struct task_struct *tsk,
|
|
struct stack_trace *trace)
|
|
{
|
|
int ret;
|
|
|
|
/*
|
|
* If the task doesn't have a stack (e.g., a zombie), the stack is
|
|
* "reliably" empty.
|
|
*/
|
|
if (!try_get_task_stack(tsk))
|
|
return 0;
|
|
|
|
ret = __save_stack_trace_tsk_reliable(tsk, trace);
|
|
|
|
put_task_stack(tsk);
|
|
|
|
return ret;
|
|
}
|
|
#endif /* CONFIG_HAVE_RELIABLE_STACKTRACE */
|
|
|
|
#if defined(CONFIG_PPC_BOOK3S_64) && defined(CONFIG_NMI_IPI)
|
|
static void handle_backtrace_ipi(struct pt_regs *regs)
|
|
{
|
|
nmi_cpu_backtrace(regs);
|
|
}
|
|
|
|
static void raise_backtrace_ipi(cpumask_t *mask)
|
|
{
|
|
struct paca_struct *p;
|
|
unsigned int cpu;
|
|
u64 delay_us;
|
|
|
|
for_each_cpu(cpu, mask) {
|
|
if (cpu == smp_processor_id()) {
|
|
handle_backtrace_ipi(NULL);
|
|
continue;
|
|
}
|
|
|
|
delay_us = 5 * USEC_PER_SEC;
|
|
|
|
if (smp_send_safe_nmi_ipi(cpu, handle_backtrace_ipi, delay_us)) {
|
|
// Now wait up to 5s for the other CPU to do its backtrace
|
|
while (cpumask_test_cpu(cpu, mask) && delay_us) {
|
|
udelay(1);
|
|
delay_us--;
|
|
}
|
|
|
|
// Other CPU cleared itself from the mask
|
|
if (delay_us)
|
|
continue;
|
|
}
|
|
|
|
p = paca_ptrs[cpu];
|
|
|
|
cpumask_clear_cpu(cpu, mask);
|
|
|
|
pr_warn("CPU %d didn't respond to backtrace IPI, inspecting paca.\n", cpu);
|
|
if (!virt_addr_valid(p)) {
|
|
pr_warn("paca pointer appears corrupt? (%px)\n", p);
|
|
continue;
|
|
}
|
|
|
|
pr_warn("irq_soft_mask: 0x%02x in_mce: %d in_nmi: %d",
|
|
p->irq_soft_mask, p->in_mce, p->in_nmi);
|
|
|
|
if (virt_addr_valid(p->__current))
|
|
pr_cont(" current: %d (%s)\n", p->__current->pid,
|
|
p->__current->comm);
|
|
else
|
|
pr_cont(" current pointer corrupt? (%px)\n", p->__current);
|
|
|
|
pr_warn("Back trace of paca->saved_r1 (0x%016llx) (possibly stale):\n", p->saved_r1);
|
|
show_stack(p->__current, (unsigned long *)p->saved_r1);
|
|
}
|
|
}
|
|
|
|
void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
|
|
{
|
|
nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace_ipi);
|
|
}
|
|
EXPORT_SYMBOL(arch_trigger_cpumask_backtrace);
|
|
#endif /* defined(CONFIG_PPC_BOOK3S_64) && defined(CONFIG_NMI_IPI) */
|