233 строки
6.8 KiB
C
233 строки
6.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef _LINUX_TRACE_RECURSION_H
|
|
#define _LINUX_TRACE_RECURSION_H
|
|
|
|
#include <linux/interrupt.h>
|
|
#include <linux/sched.h>
|
|
|
|
#ifdef CONFIG_TRACING
|
|
|
|
/* Only current can touch trace_recursion */
|
|
|
|
/*
|
|
* For function tracing recursion:
|
|
* The order of these bits are important.
|
|
*
|
|
* When function tracing occurs, the following steps are made:
|
|
* If arch does not support a ftrace feature:
|
|
* call internal function (uses INTERNAL bits) which calls...
|
|
* If callback is registered to the "global" list, the list
|
|
* function is called and recursion checks the GLOBAL bits.
|
|
* then this function calls...
|
|
* The function callback, which can use the FTRACE bits to
|
|
* check for recursion.
|
|
*
|
|
* Now if the arch does not support a feature, and it calls
|
|
* the global list function which calls the ftrace callback
|
|
* all three of these steps will do a recursion protection.
|
|
* There's no reason to do one if the previous caller already
|
|
* did. The recursion that we are protecting against will
|
|
* go through the same steps again.
|
|
*
|
|
* To prevent the multiple recursion checks, if a recursion
|
|
* bit is set that is higher than the MAX bit of the current
|
|
* check, then we know that the check was made by the previous
|
|
* caller, and we can skip the current check.
|
|
*/
|
|
enum {
|
|
/* Function recursion bits */
|
|
TRACE_FTRACE_BIT,
|
|
TRACE_FTRACE_NMI_BIT,
|
|
TRACE_FTRACE_IRQ_BIT,
|
|
TRACE_FTRACE_SIRQ_BIT,
|
|
|
|
/* INTERNAL_BITs must be greater than FTRACE_BITs */
|
|
TRACE_INTERNAL_BIT,
|
|
TRACE_INTERNAL_NMI_BIT,
|
|
TRACE_INTERNAL_IRQ_BIT,
|
|
TRACE_INTERNAL_SIRQ_BIT,
|
|
|
|
TRACE_BRANCH_BIT,
|
|
/*
|
|
* Abuse of the trace_recursion.
|
|
* As we need a way to maintain state if we are tracing the function
|
|
* graph in irq because we want to trace a particular function that
|
|
* was called in irq context but we have irq tracing off. Since this
|
|
* can only be modified by current, we can reuse trace_recursion.
|
|
*/
|
|
TRACE_IRQ_BIT,
|
|
|
|
/* Set if the function is in the set_graph_function file */
|
|
TRACE_GRAPH_BIT,
|
|
|
|
/*
|
|
* In the very unlikely case that an interrupt came in
|
|
* at a start of graph tracing, and we want to trace
|
|
* the function in that interrupt, the depth can be greater
|
|
* than zero, because of the preempted start of a previous
|
|
* trace. In an even more unlikely case, depth could be 2
|
|
* if a softirq interrupted the start of graph tracing,
|
|
* followed by an interrupt preempting a start of graph
|
|
* tracing in the softirq, and depth can even be 3
|
|
* if an NMI came in at the start of an interrupt function
|
|
* that preempted a softirq start of a function that
|
|
* preempted normal context!!!! Luckily, it can't be
|
|
* greater than 3, so the next two bits are a mask
|
|
* of what the depth is when we set TRACE_GRAPH_BIT
|
|
*/
|
|
|
|
TRACE_GRAPH_DEPTH_START_BIT,
|
|
TRACE_GRAPH_DEPTH_END_BIT,
|
|
|
|
/*
|
|
* To implement set_graph_notrace, if this bit is set, we ignore
|
|
* function graph tracing of called functions, until the return
|
|
* function is called to clear it.
|
|
*/
|
|
TRACE_GRAPH_NOTRACE_BIT,
|
|
|
|
/*
|
|
* When transitioning between context, the preempt_count() may
|
|
* not be correct. Allow for a single recursion to cover this case.
|
|
*/
|
|
TRACE_TRANSITION_BIT,
|
|
|
|
/* Used to prevent recursion recording from recursing. */
|
|
TRACE_RECORD_RECURSION_BIT,
|
|
};
|
|
|
|
#define trace_recursion_set(bit) do { (current)->trace_recursion |= (1<<(bit)); } while (0)
|
|
#define trace_recursion_clear(bit) do { (current)->trace_recursion &= ~(1<<(bit)); } while (0)
|
|
#define trace_recursion_test(bit) ((current)->trace_recursion & (1<<(bit)))
|
|
|
|
#define trace_recursion_depth() \
|
|
(((current)->trace_recursion >> TRACE_GRAPH_DEPTH_START_BIT) & 3)
|
|
#define trace_recursion_set_depth(depth) \
|
|
do { \
|
|
current->trace_recursion &= \
|
|
~(3 << TRACE_GRAPH_DEPTH_START_BIT); \
|
|
current->trace_recursion |= \
|
|
((depth) & 3) << TRACE_GRAPH_DEPTH_START_BIT; \
|
|
} while (0)
|
|
|
|
#define TRACE_CONTEXT_BITS 4
|
|
|
|
#define TRACE_FTRACE_START TRACE_FTRACE_BIT
|
|
#define TRACE_FTRACE_MAX ((1 << (TRACE_FTRACE_START + TRACE_CONTEXT_BITS)) - 1)
|
|
|
|
#define TRACE_LIST_START TRACE_INTERNAL_BIT
|
|
#define TRACE_LIST_MAX ((1 << (TRACE_LIST_START + TRACE_CONTEXT_BITS)) - 1)
|
|
|
|
#define TRACE_CONTEXT_MASK TRACE_LIST_MAX
|
|
|
|
/*
|
|
* Used for setting context
|
|
* NMI = 0
|
|
* IRQ = 1
|
|
* SOFTIRQ = 2
|
|
* NORMAL = 3
|
|
*/
|
|
enum {
|
|
TRACE_CTX_NMI,
|
|
TRACE_CTX_IRQ,
|
|
TRACE_CTX_SOFTIRQ,
|
|
TRACE_CTX_NORMAL,
|
|
};
|
|
|
|
static __always_inline int trace_get_context_bit(void)
|
|
{
|
|
unsigned long pc = preempt_count();
|
|
|
|
if (!(pc & (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET)))
|
|
return TRACE_CTX_NORMAL;
|
|
else
|
|
return pc & NMI_MASK ? TRACE_CTX_NMI :
|
|
pc & HARDIRQ_MASK ? TRACE_CTX_IRQ : TRACE_CTX_SOFTIRQ;
|
|
}
|
|
|
|
#ifdef CONFIG_FTRACE_RECORD_RECURSION
|
|
extern void ftrace_record_recursion(unsigned long ip, unsigned long parent_ip);
|
|
# define do_ftrace_record_recursion(ip, pip) \
|
|
do { \
|
|
if (!trace_recursion_test(TRACE_RECORD_RECURSION_BIT)) { \
|
|
trace_recursion_set(TRACE_RECORD_RECURSION_BIT); \
|
|
ftrace_record_recursion(ip, pip); \
|
|
trace_recursion_clear(TRACE_RECORD_RECURSION_BIT); \
|
|
} \
|
|
} while (0)
|
|
#else
|
|
# define do_ftrace_record_recursion(ip, pip) do { } while (0)
|
|
#endif
|
|
|
|
static __always_inline int trace_test_and_set_recursion(unsigned long ip, unsigned long pip,
|
|
int start, int max)
|
|
{
|
|
unsigned int val = READ_ONCE(current->trace_recursion);
|
|
int bit;
|
|
|
|
/* A previous recursion check was made */
|
|
if ((val & TRACE_CONTEXT_MASK) > max)
|
|
return 0;
|
|
|
|
bit = trace_get_context_bit() + start;
|
|
if (unlikely(val & (1 << bit))) {
|
|
/*
|
|
* It could be that preempt_count has not been updated during
|
|
* a switch between contexts. Allow for a single recursion.
|
|
*/
|
|
bit = TRACE_TRANSITION_BIT;
|
|
if (val & (1 << bit)) {
|
|
do_ftrace_record_recursion(ip, pip);
|
|
return -1;
|
|
}
|
|
} else {
|
|
/* Normal check passed, clear the transition to allow it again */
|
|
val &= ~(1 << TRACE_TRANSITION_BIT);
|
|
}
|
|
|
|
val |= 1 << bit;
|
|
current->trace_recursion = val;
|
|
barrier();
|
|
|
|
return bit + 1;
|
|
}
|
|
|
|
static __always_inline void trace_clear_recursion(int bit)
|
|
{
|
|
if (!bit)
|
|
return;
|
|
|
|
barrier();
|
|
bit--;
|
|
trace_recursion_clear(bit);
|
|
}
|
|
|
|
/**
|
|
* ftrace_test_recursion_trylock - tests for recursion in same context
|
|
*
|
|
* Use this for ftrace callbacks. This will detect if the function
|
|
* tracing recursed in the same context (normal vs interrupt),
|
|
*
|
|
* Returns: -1 if a recursion happened.
|
|
* >= 0 if no recursion
|
|
*/
|
|
static __always_inline int ftrace_test_recursion_trylock(unsigned long ip,
|
|
unsigned long parent_ip)
|
|
{
|
|
return trace_test_and_set_recursion(ip, parent_ip, TRACE_FTRACE_START, TRACE_FTRACE_MAX);
|
|
}
|
|
|
|
/**
|
|
* ftrace_test_recursion_unlock - called when function callback is complete
|
|
* @bit: The return of a successful ftrace_test_recursion_trylock()
|
|
*
|
|
* This is used at the end of a ftrace callback.
|
|
*/
|
|
static __always_inline void ftrace_test_recursion_unlock(int bit)
|
|
{
|
|
trace_clear_recursion(bit);
|
|
}
|
|
|
|
#endif /* CONFIG_TRACING */
|
|
#endif /* _LINUX_TRACE_RECURSION_H */
|