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ftrace: Remove the legacy _ftrace_direct API

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This API relies on a single global ops, used for all direct calls
registered with it. However, to implement arm64 direct calls, we need
each ops to point to a single direct call trampoline.

Link: https://lkml.kernel.org/r/20230321140424.345218-4-revest@chromium.org

Signed-off-by: Florent Revest <revest@chromium.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Florent Revest 2023-03-21 15:04:20 +01:00 committed by Steven Rostedt (Google)
parent 23edf48309
commit 8788ca164e
2 changed files with 0 additions and 425 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
include/linux/ftrace.h
View File

@ -397,14 +397,6 @@ struct ftrace_func_entry {
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
extern int ftrace_direct_func_count;
int register_ftrace_direct(unsigned long ip, unsigned long addr);
int unregister_ftrace_direct(unsigned long ip, unsigned long addr);
int modify_ftrace_direct(unsigned long ip, unsigned long old_addr, unsigned long new_addr);
struct ftrace_direct_func *ftrace_find_direct_func(unsigned long addr);
int ftrace_modify_direct_caller(struct ftrace_func_entry *entry,
struct dyn_ftrace *rec,
unsigned long old_addr,
unsigned long new_addr);
unsigned long ftrace_find_rec_direct(unsigned long ip);
int register_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr);
int unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr,
@ -415,30 +407,6 @@ int modify_ftrace_direct_multi_nolock(struct ftrace_ops *ops, unsigned long addr
#else
struct ftrace_ops;
# define ftrace_direct_func_count 0
static inline int register_ftrace_direct(unsigned long ip, unsigned long addr)
{
return -ENOTSUPP;
}
static inline int unregister_ftrace_direct(unsigned long ip, unsigned long addr)
{
return -ENOTSUPP;
}
static inline int modify_ftrace_direct(unsigned long ip,
unsigned long old_addr, unsigned long new_addr)
{
return -ENOTSUPP;
}
static inline struct ftrace_direct_func *ftrace_find_direct_func(unsigned long addr)
{
return NULL;
}
static inline int ftrace_modify_direct_caller(struct ftrace_func_entry *entry,
struct dyn_ftrace *rec,
unsigned long old_addr,
unsigned long new_addr)
{
return -ENODEV;
}
static inline unsigned long ftrace_find_rec_direct(unsigned long ip)
{
return 0;

393
kernel/trace/ftrace.c
View File

@ -2591,20 +2591,6 @@ static void call_direct_funcs(unsigned long ip, unsigned long pip,
arch_ftrace_set_direct_caller(fregs, addr);
}
static struct ftrace_ops direct_ops = {
.func = call_direct_funcs,
.flags = FTRACE_OPS_FL_DIRECT | FTRACE_OPS_FL_SAVE_REGS
| FTRACE_OPS_FL_PERMANENT,
/*
* By declaring the main trampoline as this trampoline
* it will never have one allocated for it. Allocated
* trampolines should not call direct functions.
* The direct_ops should only be called by the builtin
* ftrace_regs_caller trampoline.
*/
.trampoline = FTRACE_REGS_ADDR,
};
#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */
/**
@ -5301,387 +5287,8 @@ struct ftrace_direct_func {
static LIST_HEAD(ftrace_direct_funcs);
/**
* ftrace_find_direct_func - test an address if it is a registered direct caller
* @addr: The address of a registered direct caller
*
* This searches to see if a ftrace direct caller has been registered
* at a specific address, and if so, it returns a descriptor for it.
*
* This can be used by architecture code to see if an address is
* a direct caller (trampoline) attached to a fentry/mcount location.
* This is useful for the function_graph tracer, as it may need to
* do adjustments if it traced a location that also has a direct
* trampoline attached to it.
*/
struct ftrace_direct_func *ftrace_find_direct_func(unsigned long addr)
{
struct ftrace_direct_func *entry;
bool found = false;
/* May be called by fgraph trampoline (protected by rcu tasks) */
list_for_each_entry_rcu(entry, &ftrace_direct_funcs, next) {
if (entry->addr == addr) {
found = true;
break;
}
}
if (found)
return entry;
return NULL;
}
static struct ftrace_direct_func *ftrace_alloc_direct_func(unsigned long addr)
{
struct ftrace_direct_func *direct;
direct = kmalloc(sizeof(*direct), GFP_KERNEL);
if (!direct)
return NULL;
direct->addr = addr;
direct->count = 0;
list_add_rcu(&direct->next, &ftrace_direct_funcs);
ftrace_direct_func_count++;
return direct;
}
static int register_ftrace_function_nolock(struct ftrace_ops *ops);
/**
* register_ftrace_direct - Call a custom trampoline directly
* @ip: The address of the nop at the beginning of a function
* @addr: The address of the trampoline to call at @ip
*
* This is used to connect a direct call from the nop location (@ip)
* at the start of ftrace traced functions. The location that it calls
* (@addr) must be able to handle a direct call, and save the parameters
* of the function being traced, and restore them (or inject new ones
* if needed), before returning.
*
* Returns:
* 0 on success
* -EBUSY - Another direct function is already attached (there can be only one)
* -ENODEV - @ip does not point to a ftrace nop location (or not supported)
* -ENOMEM - There was an allocation failure.
*/
int register_ftrace_direct(unsigned long ip, unsigned long addr)
{
struct ftrace_direct_func *direct;
struct ftrace_func_entry *entry;
struct ftrace_hash *free_hash = NULL;
struct dyn_ftrace *rec;
int ret = -ENODEV;
mutex_lock(&direct_mutex);
ip = ftrace_location(ip);
if (!ip)
goto out_unlock;
/* See if there's a direct function at @ip already */
ret = -EBUSY;
if (ftrace_find_rec_direct(ip))
goto out_unlock;
ret = -ENODEV;
rec = lookup_rec(ip, ip);
if (!rec)
goto out_unlock;
/*
* Check if the rec says it has a direct call but we didn't
* find one earlier?
*/
if (WARN_ON(rec->flags & FTRACE_FL_DIRECT))
goto out_unlock;
/* Make sure the ip points to the exact record */
if (ip != rec->ip) {
ip = rec->ip;
/* Need to check this ip for a direct. */
if (ftrace_find_rec_direct(ip))
goto out_unlock;
}
ret = -ENOMEM;
direct = ftrace_find_direct_func(addr);
if (!direct) {
direct = ftrace_alloc_direct_func(addr);
if (!direct)
goto out_unlock;
}
entry = ftrace_add_rec_direct(ip, addr, &free_hash);
if (!entry)
goto out_unlock;
ret = ftrace_set_filter_ip(&direct_ops, ip, 0, 0);
if (!ret && !(direct_ops.flags & FTRACE_OPS_FL_ENABLED)) {
ret = register_ftrace_function_nolock(&direct_ops);
if (ret)
ftrace_set_filter_ip(&direct_ops, ip, 1, 0);
}
if (ret) {
remove_hash_entry(direct_functions, entry);
kfree(entry);
if (!direct->count) {
list_del_rcu(&direct->next);
synchronize_rcu_tasks();
kfree(direct);
if (free_hash)
free_ftrace_hash(free_hash);
free_hash = NULL;
ftrace_direct_func_count--;
}
} else {
direct->count++;
}
out_unlock:
mutex_unlock(&direct_mutex);
if (free_hash) {
synchronize_rcu_tasks();
free_ftrace_hash(free_hash);
}
return ret;
}
EXPORT_SYMBOL_GPL(register_ftrace_direct);
static struct ftrace_func_entry *find_direct_entry(unsigned long *ip,
struct dyn_ftrace **recp)
{
struct ftrace_func_entry *entry;
struct dyn_ftrace *rec;
rec = lookup_rec(*ip, *ip);
if (!rec)
return NULL;
entry = __ftrace_lookup_ip(direct_functions, rec->ip);
if (!entry) {
WARN_ON(rec->flags & FTRACE_FL_DIRECT);
return NULL;
}
WARN_ON(!(rec->flags & FTRACE_FL_DIRECT));
/* Passed in ip just needs to be on the call site */
*ip = rec->ip;
if (recp)
*recp = rec;
return entry;
}
int unregister_ftrace_direct(unsigned long ip, unsigned long addr)
{
struct ftrace_direct_func *direct;
struct ftrace_func_entry *entry;
struct ftrace_hash *hash;
int ret = -ENODEV;
mutex_lock(&direct_mutex);
ip = ftrace_location(ip);
if (!ip)
goto out_unlock;
entry = find_direct_entry(&ip, NULL);
if (!entry)
goto out_unlock;
hash = direct_ops.func_hash->filter_hash;
if (hash->count == 1)
unregister_ftrace_function(&direct_ops);
ret = ftrace_set_filter_ip(&direct_ops, ip, 1, 0);
WARN_ON(ret);
remove_hash_entry(direct_functions, entry);
direct = ftrace_find_direct_func(addr);
if (!WARN_ON(!direct)) {
/* This is the good path (see the ! before WARN) */
direct->count--;
WARN_ON(direct->count < 0);
if (!direct->count) {
list_del_rcu(&direct->next);
synchronize_rcu_tasks();
kfree(direct);
kfree(entry);
ftrace_direct_func_count--;
}
}
out_unlock:
mutex_unlock(&direct_mutex);
return ret;
}
EXPORT_SYMBOL_GPL(unregister_ftrace_direct);
static struct ftrace_ops stub_ops = {
.func = ftrace_stub,
};
/**
* ftrace_modify_direct_caller - modify ftrace nop directly
* @entry: The ftrace hash entry of the direct helper for @rec
* @rec: The record representing the function site to patch
* @old_addr: The location that the site at @rec->ip currently calls
* @new_addr: The location that the site at @rec->ip should call
*
* An architecture may overwrite this function to optimize the
* changing of the direct callback on an ftrace nop location.
* This is called with the ftrace_lock mutex held, and no other
* ftrace callbacks are on the associated record (@rec). Thus,
* it is safe to modify the ftrace record, where it should be
* currently calling @old_addr directly, to call @new_addr.
*
* This is called with direct_mutex locked.
*
* Safety checks should be made to make sure that the code at
* @rec->ip is currently calling @old_addr. And this must
* also update entry->direct to @new_addr.
*/
int __weak ftrace_modify_direct_caller(struct ftrace_func_entry *entry,
struct dyn_ftrace *rec,
unsigned long old_addr,
unsigned long new_addr)
{
unsigned long ip = rec->ip;
int ret;
lockdep_assert_held(&direct_mutex);
/*
* The ftrace_lock was used to determine if the record
* had more than one registered user to it. If it did,
* we needed to prevent that from changing to do the quick
* switch. But if it did not (only a direct caller was attached)
* then this function is called. But this function can deal
* with attached callers to the rec that we care about, and
* since this function uses standard ftrace calls that take
* the ftrace_lock mutex, we need to release it.
*/
mutex_unlock(&ftrace_lock);
/*
* By setting a stub function at the same address, we force
* the code to call the iterator and the direct_ops helper.
* This means that @ip does not call the direct call, and
* we can simply modify it.
*/
ret = ftrace_set_filter_ip(&stub_ops, ip, 0, 0);
if (ret)
goto out_lock;
ret = register_ftrace_function_nolock(&stub_ops);
if (ret) {
ftrace_set_filter_ip(&stub_ops, ip, 1, 0);
goto out_lock;
}
entry->direct = new_addr;
/*
* By removing the stub, we put back the direct call, calling
* the @new_addr.
*/
unregister_ftrace_function(&stub_ops);
ftrace_set_filter_ip(&stub_ops, ip, 1, 0);
out_lock:
mutex_lock(&ftrace_lock);
return ret;
}
/**
* modify_ftrace_direct - Modify an existing direct call to call something else
* @ip: The instruction pointer to modify
* @old_addr: The address that the current @ip calls directly
* @new_addr: The address that the @ip should call
*
* This modifies a ftrace direct caller at an instruction pointer without
* having to disable it first. The direct call will switch over to the
* @new_addr without missing anything.
*
* Returns: zero on success. Non zero on error, which includes:
* -ENODEV : the @ip given has no direct caller attached
* -EINVAL : the @old_addr does not match the current direct caller
*/
int modify_ftrace_direct(unsigned long ip,
unsigned long old_addr, unsigned long new_addr)
{
struct ftrace_direct_func *direct, *new_direct = NULL;
struct ftrace_func_entry *entry;
struct dyn_ftrace *rec;
int ret = -ENODEV;
mutex_lock(&direct_mutex);
mutex_lock(&ftrace_lock);
ip = ftrace_location(ip);
if (!ip)
goto out_unlock;
entry = find_direct_entry(&ip, &rec);
if (!entry)
goto out_unlock;
ret = -EINVAL;
if (entry->direct != old_addr)
goto out_unlock;
direct = ftrace_find_direct_func(old_addr);
if (WARN_ON(!direct))
goto out_unlock;
if (direct->count > 1) {
ret = -ENOMEM;
new_direct = ftrace_alloc_direct_func(new_addr);
if (!new_direct)
goto out_unlock;
direct->count--;
new_direct->count++;
} else {
direct->addr = new_addr;
}
/*
* If there's no other ftrace callback on the rec->ip location,
* then it can be changed directly by the architecture.
* If there is another caller, then we just need to change the
* direct caller helper to point to @new_addr.
*/
if (ftrace_rec_count(rec) == 1) {
ret = ftrace_modify_direct_caller(entry, rec, old_addr, new_addr);
} else {
entry->direct = new_addr;
ret = 0;
}
if (unlikely(ret && new_direct)) {
direct->count++;
list_del_rcu(&new_direct->next);
synchronize_rcu_tasks();
kfree(new_direct);
ftrace_direct_func_count--;
}
out_unlock:
mutex_unlock(&ftrace_lock);
mutex_unlock(&direct_mutex);
return ret;
}
EXPORT_SYMBOL_GPL(modify_ftrace_direct);
#define MULTI_FLAGS (FTRACE_OPS_FL_DIRECT | FTRACE_OPS_FL_SAVE_REGS)
static int check_direct_multi(struct ftrace_ops *ops)