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264c03a245
Currently the callback passed to arch_stack_walk() has an argument called reliable passed to it to indicate if the stack entry is reliable, a comment says that this is used by some printk() consumers. However in the current kernel none of the arch_stack_walk() implementations ever set this flag to true and the only callback implementation we have is in the generic stacktrace code which ignores the flag. It therefore appears that this flag is redundant so we can simplify and clarify things by removing it. Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Link: https://lore.kernel.org/r/20200914153409.25097-2-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
376 lines
9.6 KiB
C
376 lines
9.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* kernel/stacktrace.c
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*
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* Stack trace management functions
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*
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* Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
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*/
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#include <linux/sched/task_stack.h>
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#include <linux/sched/debug.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/export.h>
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#include <linux/kallsyms.h>
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#include <linux/stacktrace.h>
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/**
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* stack_trace_print - Print the entries in the stack trace
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* @entries: Pointer to storage array
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* @nr_entries: Number of entries in the storage array
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* @spaces: Number of leading spaces to print
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*/
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void stack_trace_print(const unsigned long *entries, unsigned int nr_entries,
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int spaces)
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{
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unsigned int i;
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if (WARN_ON(!entries))
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return;
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for (i = 0; i < nr_entries; i++)
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printk("%*c%pS\n", 1 + spaces, ' ', (void *)entries[i]);
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}
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EXPORT_SYMBOL_GPL(stack_trace_print);
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/**
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* stack_trace_snprint - Print the entries in the stack trace into a buffer
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* @buf: Pointer to the print buffer
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* @size: Size of the print buffer
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* @entries: Pointer to storage array
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* @nr_entries: Number of entries in the storage array
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* @spaces: Number of leading spaces to print
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*
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* Return: Number of bytes printed.
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*/
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int stack_trace_snprint(char *buf, size_t size, const unsigned long *entries,
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unsigned int nr_entries, int spaces)
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{
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unsigned int generated, i, total = 0;
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if (WARN_ON(!entries))
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return 0;
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for (i = 0; i < nr_entries && size; i++) {
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generated = snprintf(buf, size, "%*c%pS\n", 1 + spaces, ' ',
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(void *)entries[i]);
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total += generated;
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if (generated >= size) {
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buf += size;
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size = 0;
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} else {
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buf += generated;
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size -= generated;
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}
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}
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return total;
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}
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EXPORT_SYMBOL_GPL(stack_trace_snprint);
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#ifdef CONFIG_ARCH_STACKWALK
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struct stacktrace_cookie {
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unsigned long *store;
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unsigned int size;
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unsigned int skip;
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unsigned int len;
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};
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static bool stack_trace_consume_entry(void *cookie, unsigned long addr)
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{
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struct stacktrace_cookie *c = cookie;
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if (c->len >= c->size)
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return false;
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if (c->skip > 0) {
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c->skip--;
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return true;
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}
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c->store[c->len++] = addr;
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return c->len < c->size;
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}
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static bool stack_trace_consume_entry_nosched(void *cookie, unsigned long addr)
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{
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if (in_sched_functions(addr))
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return true;
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return stack_trace_consume_entry(cookie, addr);
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}
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/**
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* stack_trace_save - Save a stack trace into a storage array
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* @store: Pointer to storage array
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* @size: Size of the storage array
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* @skipnr: Number of entries to skip at the start of the stack trace
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*
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* Return: Number of trace entries stored.
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*/
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unsigned int stack_trace_save(unsigned long *store, unsigned int size,
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unsigned int skipnr)
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{
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stack_trace_consume_fn consume_entry = stack_trace_consume_entry;
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struct stacktrace_cookie c = {
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.store = store,
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.size = size,
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.skip = skipnr + 1,
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};
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arch_stack_walk(consume_entry, &c, current, NULL);
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return c.len;
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}
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EXPORT_SYMBOL_GPL(stack_trace_save);
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/**
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* stack_trace_save_tsk - Save a task stack trace into a storage array
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* @task: The task to examine
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* @store: Pointer to storage array
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* @size: Size of the storage array
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* @skipnr: Number of entries to skip at the start of the stack trace
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*
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* Return: Number of trace entries stored.
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*/
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unsigned int stack_trace_save_tsk(struct task_struct *tsk, unsigned long *store,
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unsigned int size, unsigned int skipnr)
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{
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stack_trace_consume_fn consume_entry = stack_trace_consume_entry_nosched;
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struct stacktrace_cookie c = {
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.store = store,
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.size = size,
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/* skip this function if they are tracing us */
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.skip = skipnr + (current == tsk),
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};
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if (!try_get_task_stack(tsk))
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return 0;
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arch_stack_walk(consume_entry, &c, tsk, NULL);
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put_task_stack(tsk);
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return c.len;
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}
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/**
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* stack_trace_save_regs - Save a stack trace based on pt_regs into a storage array
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* @regs: Pointer to pt_regs to examine
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* @store: Pointer to storage array
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* @size: Size of the storage array
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* @skipnr: Number of entries to skip at the start of the stack trace
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*
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* Return: Number of trace entries stored.
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*/
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unsigned int stack_trace_save_regs(struct pt_regs *regs, unsigned long *store,
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unsigned int size, unsigned int skipnr)
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{
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stack_trace_consume_fn consume_entry = stack_trace_consume_entry;
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struct stacktrace_cookie c = {
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.store = store,
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.size = size,
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.skip = skipnr,
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};
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arch_stack_walk(consume_entry, &c, current, regs);
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return c.len;
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}
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#ifdef CONFIG_HAVE_RELIABLE_STACKTRACE
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/**
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* stack_trace_save_tsk_reliable - Save task stack with verification
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* @tsk: Pointer to the task to examine
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* @store: Pointer to storage array
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* @size: Size of the storage array
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*
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* Return: An error if it detects any unreliable features of the
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* stack. Otherwise it guarantees that the stack trace is
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* reliable and returns the number of entries stored.
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*
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* If the task is not 'current', the caller *must* ensure the task is inactive.
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*/
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int stack_trace_save_tsk_reliable(struct task_struct *tsk, unsigned long *store,
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unsigned int size)
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{
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stack_trace_consume_fn consume_entry = stack_trace_consume_entry;
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struct stacktrace_cookie c = {
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.store = store,
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.size = size,
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};
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int ret;
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/*
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* If the task doesn't have a stack (e.g., a zombie), the stack is
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* "reliably" empty.
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*/
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if (!try_get_task_stack(tsk))
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return 0;
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ret = arch_stack_walk_reliable(consume_entry, &c, tsk);
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put_task_stack(tsk);
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return ret ? ret : c.len;
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}
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#endif
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#ifdef CONFIG_USER_STACKTRACE_SUPPORT
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/**
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* stack_trace_save_user - Save a user space stack trace into a storage array
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* @store: Pointer to storage array
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* @size: Size of the storage array
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*
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* Return: Number of trace entries stored.
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*/
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unsigned int stack_trace_save_user(unsigned long *store, unsigned int size)
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{
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stack_trace_consume_fn consume_entry = stack_trace_consume_entry;
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struct stacktrace_cookie c = {
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.store = store,
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.size = size,
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};
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mm_segment_t fs;
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/* Trace user stack if not a kernel thread */
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if (current->flags & PF_KTHREAD)
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return 0;
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fs = force_uaccess_begin();
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arch_stack_walk_user(consume_entry, &c, task_pt_regs(current));
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force_uaccess_end(fs);
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return c.len;
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}
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#endif
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#else /* CONFIG_ARCH_STACKWALK */
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/*
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* Architectures that do not implement save_stack_trace_*()
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* get these weak aliases and once-per-bootup warnings
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* (whenever this facility is utilized - for example by procfs):
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*/
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__weak void
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save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
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{
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WARN_ONCE(1, KERN_INFO "save_stack_trace_tsk() not implemented yet.\n");
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}
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__weak void
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save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
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{
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WARN_ONCE(1, KERN_INFO "save_stack_trace_regs() not implemented yet.\n");
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}
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/**
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* stack_trace_save - Save a stack trace into a storage array
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* @store: Pointer to storage array
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* @size: Size of the storage array
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* @skipnr: Number of entries to skip at the start of the stack trace
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*
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* Return: Number of trace entries stored
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*/
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unsigned int stack_trace_save(unsigned long *store, unsigned int size,
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unsigned int skipnr)
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{
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struct stack_trace trace = {
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.entries = store,
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.max_entries = size,
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.skip = skipnr + 1,
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};
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save_stack_trace(&trace);
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return trace.nr_entries;
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}
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EXPORT_SYMBOL_GPL(stack_trace_save);
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/**
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* stack_trace_save_tsk - Save a task stack trace into a storage array
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* @task: The task to examine
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* @store: Pointer to storage array
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* @size: Size of the storage array
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* @skipnr: Number of entries to skip at the start of the stack trace
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*
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* Return: Number of trace entries stored
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*/
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unsigned int stack_trace_save_tsk(struct task_struct *task,
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unsigned long *store, unsigned int size,
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unsigned int skipnr)
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{
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struct stack_trace trace = {
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.entries = store,
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.max_entries = size,
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/* skip this function if they are tracing us */
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.skip = skipnr + (current == task),
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};
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save_stack_trace_tsk(task, &trace);
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return trace.nr_entries;
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}
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/**
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* stack_trace_save_regs - Save a stack trace based on pt_regs into a storage array
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* @regs: Pointer to pt_regs to examine
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* @store: Pointer to storage array
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* @size: Size of the storage array
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* @skipnr: Number of entries to skip at the start of the stack trace
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*
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* Return: Number of trace entries stored
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*/
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unsigned int stack_trace_save_regs(struct pt_regs *regs, unsigned long *store,
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unsigned int size, unsigned int skipnr)
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{
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struct stack_trace trace = {
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.entries = store,
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.max_entries = size,
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.skip = skipnr,
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};
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save_stack_trace_regs(regs, &trace);
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return trace.nr_entries;
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}
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#ifdef CONFIG_HAVE_RELIABLE_STACKTRACE
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/**
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* stack_trace_save_tsk_reliable - Save task stack with verification
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* @tsk: Pointer to the task to examine
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* @store: Pointer to storage array
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* @size: Size of the storage array
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*
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* Return: An error if it detects any unreliable features of the
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* stack. Otherwise it guarantees that the stack trace is
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* reliable and returns the number of entries stored.
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*
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* If the task is not 'current', the caller *must* ensure the task is inactive.
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*/
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int stack_trace_save_tsk_reliable(struct task_struct *tsk, unsigned long *store,
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unsigned int size)
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{
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struct stack_trace trace = {
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.entries = store,
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.max_entries = size,
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};
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int ret = save_stack_trace_tsk_reliable(tsk, &trace);
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return ret ? ret : trace.nr_entries;
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}
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#endif
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#ifdef CONFIG_USER_STACKTRACE_SUPPORT
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/**
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* stack_trace_save_user - Save a user space stack trace into a storage array
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* @store: Pointer to storage array
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* @size: Size of the storage array
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*
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* Return: Number of trace entries stored
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*/
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unsigned int stack_trace_save_user(unsigned long *store, unsigned int size)
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{
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struct stack_trace trace = {
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.entries = store,
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.max_entries = size,
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};
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save_stack_trace_user(&trace);
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return trace.nr_entries;
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}
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#endif /* CONFIG_USER_STACKTRACE_SUPPORT */
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#endif /* !CONFIG_ARCH_STACKWALK */
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