[PATCH v14 03/19] function_graph: Pass ftrace_regs to entryfunc
From: Masami Hiramatsu (Google)
Date: Thu Sep 12 2024 - 11:09:27 EST
From: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Pass ftrace_regs to the fgraph_ops::entryfunc(). If ftrace_regs is not
available, it passes a NULL instead. User callback function can access
some registers (including return address) via this ftrace_regs.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
---
Changes in v11:
- Update for the latest for-next branch.
Changes in v8:
- Just pass ftrace_regs to the handler instead of adding a new
entryregfunc.
- Update riscv ftrace_graph_func().
Changes in v3:
- Update for new multiple fgraph.
---
arch/arm64/kernel/ftrace.c | 20 +++++++++++-
arch/loongarch/kernel/ftrace_dyn.c | 10 +++++-
arch/powerpc/kernel/trace/ftrace.c | 2 +
arch/powerpc/kernel/trace/ftrace_64_pg.c | 10 ++++--
arch/riscv/kernel/ftrace.c | 17 ++++++++++
arch/x86/kernel/ftrace.c | 50 +++++++++++++++++++++---------
include/linux/ftrace.h | 18 ++++++++---
kernel/trace/fgraph.c | 23 ++++++++------
kernel/trace/ftrace.c | 3 +-
kernel/trace/trace.h | 3 +-
kernel/trace/trace_functions_graph.c | 3 +-
kernel/trace/trace_irqsoff.c | 3 +-
kernel/trace/trace_sched_wakeup.c | 3 +-
kernel/trace/trace_selftest.c | 8 +++--
14 files changed, 128 insertions(+), 45 deletions(-)
diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
index a650f5e11fc5..bc647b725e6a 100644
--- a/arch/arm64/kernel/ftrace.c
+++ b/arch/arm64/kernel/ftrace.c
@@ -481,7 +481,25 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct ftrace_regs *fregs)
{
- prepare_ftrace_return(ip, &fregs->lr, fregs->fp);
+ unsigned long return_hooker = (unsigned long)&return_to_handler;
+ unsigned long frame_pointer = fregs->fp;
+ unsigned long *parent = &fregs->lr;
+ unsigned long old;
+
+ if (unlikely(atomic_read(¤t->tracing_graph_pause)))
+ return;
+
+ /*
+ * Note:
+ * No protection against faulting at *parent, which may be seen
+ * on other archs. It's unlikely on AArch64.
+ */
+ old = *parent;
+
+ if (!function_graph_enter_regs(old, ip, frame_pointer,
+ (void *)frame_pointer, fregs)) {
+ *parent = return_hooker;
+ }
}
#else
/*
diff --git a/arch/loongarch/kernel/ftrace_dyn.c b/arch/loongarch/kernel/ftrace_dyn.c
index bff058317062..966e0f7f7aca 100644
--- a/arch/loongarch/kernel/ftrace_dyn.c
+++ b/arch/loongarch/kernel/ftrace_dyn.c
@@ -243,8 +243,16 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
{
struct pt_regs *regs = &fregs->regs;
unsigned long *parent = (unsigned long *)®s->regs[1];
+ unsigned long return_hooker = (unsigned long)&return_to_handler;
+ unsigned long old;
+
+ if (unlikely(atomic_read(¤t->tracing_graph_pause)))
+ return;
+
+ old = *parent;
- prepare_ftrace_return(ip, (unsigned long *)parent);
+ if (!function_graph_enter_regs(old, ip, 0, parent, fregs))
+ *parent = return_hooker;
}
#else
static int ftrace_modify_graph_caller(bool enable)
diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c
index d8d6b4fd9a14..a1a0e0b57662 100644
--- a/arch/powerpc/kernel/trace/ftrace.c
+++ b/arch/powerpc/kernel/trace/ftrace.c
@@ -434,7 +434,7 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
if (bit < 0)
goto out;
- if (!function_graph_enter(parent_ip, ip, 0, (unsigned long *)sp))
+ if (!function_graph_enter_regs(parent_ip, ip, 0, (unsigned long *)sp, fregs))
parent_ip = ppc_function_entry(return_to_handler);
ftrace_test_recursion_unlock(bit);
diff --git a/arch/powerpc/kernel/trace/ftrace_64_pg.c b/arch/powerpc/kernel/trace/ftrace_64_pg.c
index 12fab1803bcf..4ae9eeb1c8f1 100644
--- a/arch/powerpc/kernel/trace/ftrace_64_pg.c
+++ b/arch/powerpc/kernel/trace/ftrace_64_pg.c
@@ -800,7 +800,8 @@ int ftrace_disable_ftrace_graph_caller(void)
* in current thread info. Return the address we want to divert to.
*/
static unsigned long
-__prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long sp)
+__prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long sp,
+ struct ftrace_regs *fregs)
{
unsigned long return_hooker;
int bit;
@@ -817,7 +818,7 @@ __prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long sp
return_hooker = ppc_function_entry(return_to_handler);
- if (!function_graph_enter(parent, ip, 0, (unsigned long *)sp))
+ if (!function_graph_enter_regs(parent, ip, 0, (unsigned long *)sp, fregs))
parent = return_hooker;
ftrace_test_recursion_unlock(bit);
@@ -829,13 +830,14 @@ __prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long sp
void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct ftrace_regs *fregs)
{
- fregs->regs.link = __prepare_ftrace_return(parent_ip, ip, fregs->regs.gpr[1]);
+ fregs->regs.link = __prepare_ftrace_return(parent_ip, ip,
+ fregs->regs.gpr[1], fregs);
}
#else
unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip,
unsigned long sp)
{
- return __prepare_ftrace_return(parent, ip, sp);
+ return __prepare_ftrace_return(parent, ip, sp, NULL);
}
#endif
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
diff --git a/arch/riscv/kernel/ftrace.c b/arch/riscv/kernel/ftrace.c
index 4b95c574fd04..f5c3b5a752b0 100644
--- a/arch/riscv/kernel/ftrace.c
+++ b/arch/riscv/kernel/ftrace.c
@@ -214,7 +214,22 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct ftrace_regs *fregs)
{
- prepare_ftrace_return(&fregs->ra, ip, fregs->s0);
+ unsigned long return_hooker = (unsigned long)&return_to_handler;
+ unsigned long frame_pointer = fregs->s0;
+ unsigned long *parent = &fregs->ra;
+ unsigned long old;
+
+ if (unlikely(atomic_read(¤t->tracing_graph_pause)))
+ return;
+
+ /*
+ * We don't suffer access faults, so no extra fault-recovery assembly
+ * is needed here.
+ */
+ old = *parent;
+
+ if (!function_graph_enter_regs(old, ip, frame_pointer, parent, fregs))
+ *parent = return_hooker;
}
#else /* CONFIG_DYNAMIC_FTRACE_WITH_ARGS */
extern void ftrace_graph_call(void);
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 8da0e66ca22d..decf4c11dcf3 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -605,16 +605,8 @@ int ftrace_disable_ftrace_graph_caller(void)
}
#endif /* CONFIG_DYNAMIC_FTRACE && !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */
-/*
- * Hook the return address and push it in the stack of return addrs
- * in current thread info.
- */
-void prepare_ftrace_return(unsigned long ip, unsigned long *parent,
- unsigned long frame_pointer)
+static inline bool skip_ftrace_return(void)
{
- unsigned long return_hooker = (unsigned long)&return_to_handler;
- int bit;
-
/*
* When resuming from suspend-to-ram, this function can be indirectly
* called from early CPU startup code while the CPU is in real mode,
@@ -624,13 +616,28 @@ void prepare_ftrace_return(unsigned long ip, unsigned long *parent,
* This check isn't as accurate as virt_addr_valid(), but it should be
* good enough for this purpose, and it's fast.
*/
- if (unlikely((long)__builtin_frame_address(0) >= 0))
- return;
+ if ((long)__builtin_frame_address(0) >= 0)
+ return true;
- if (unlikely(ftrace_graph_is_dead()))
- return;
+ if (ftrace_graph_is_dead())
+ return true;
+
+ if (atomic_read(¤t->tracing_graph_pause))
+ return true;
+ return false;
+}
+
+/*
+ * Hook the return address and push it in the stack of return addrs
+ * in current thread info.
+ */
+void prepare_ftrace_return(unsigned long ip, unsigned long *parent,
+ unsigned long frame_pointer)
+{
+ unsigned long return_hooker = (unsigned long)&return_to_handler;
+ int bit;
- if (unlikely(atomic_read(¤t->tracing_graph_pause)))
+ if (unlikely(skip_ftrace_return()))
return;
bit = ftrace_test_recursion_trylock(ip, *parent);
@@ -649,8 +656,21 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
{
struct pt_regs *regs = &fregs->regs;
unsigned long *stack = (unsigned long *)kernel_stack_pointer(regs);
+ unsigned long return_hooker = (unsigned long)&return_to_handler;
+ unsigned long *parent = (unsigned long *)stack;
+ int bit;
- prepare_ftrace_return(ip, (unsigned long *)stack, 0);
+ if (unlikely(skip_ftrace_return()))
+ return;
+
+ bit = ftrace_test_recursion_trylock(ip, *parent);
+ if (bit < 0)
+ return;
+
+ if (!function_graph_enter_regs(*parent, ip, 0, parent, fregs))
+ *parent = return_hooker;
+
+ ftrace_test_recursion_unlock(bit);
}
#endif
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index f84fb9635fb0..1fe49a28de2d 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -1063,9 +1063,12 @@ struct fgraph_ops;
typedef void (*trace_func_graph_ret_t)(struct ftrace_graph_ret *,
struct fgraph_ops *); /* return */
typedef int (*trace_func_graph_ent_t)(struct ftrace_graph_ent *,
- struct fgraph_ops *); /* entry */
+ struct fgraph_ops *,
+ struct ftrace_regs *); /* entry */
-extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace, struct fgraph_ops *gops);
+extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace,
+ struct fgraph_ops *gops,
+ struct ftrace_regs *fregs);
bool ftrace_pids_enabled(struct ftrace_ops *ops);
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
@@ -1108,8 +1111,15 @@ struct ftrace_ret_stack {
extern void return_to_handler(void);
extern int
-function_graph_enter(unsigned long ret, unsigned long func,
- unsigned long frame_pointer, unsigned long *retp);
+function_graph_enter_regs(unsigned long ret, unsigned long func,
+ unsigned long frame_pointer, unsigned long *retp,
+ struct ftrace_regs *fregs);
+
+static inline int function_graph_enter(unsigned long ret, unsigned long func,
+ unsigned long fp, unsigned long *retp)
+{
+ return function_graph_enter_regs(ret, func, fp, retp, NULL);
+}
struct ftrace_ret_stack *
ftrace_graph_get_ret_stack(struct task_struct *task, int skip);
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index d7d4fb403f6f..0322c5723748 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -290,7 +290,8 @@ static inline unsigned long make_data_type_val(int idx, int size, int offset)
}
/* ftrace_graph_entry set to this to tell some archs to run function graph */
-static int entry_run(struct ftrace_graph_ent *trace, struct fgraph_ops *ops)
+static int entry_run(struct ftrace_graph_ent *trace, struct fgraph_ops *ops,
+ struct ftrace_regs *fregs)
{
return 0;
}
@@ -484,7 +485,7 @@ int __weak ftrace_disable_ftrace_graph_caller(void)
#endif
int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace,
- struct fgraph_ops *gops)
+ struct fgraph_ops *gops, struct ftrace_regs *fregs)
{
return 0;
}
@@ -612,8 +613,9 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
#endif
/* If the caller does not use ftrace, call this function. */
-int function_graph_enter(unsigned long ret, unsigned long func,
- unsigned long frame_pointer, unsigned long *retp)
+int function_graph_enter_regs(unsigned long ret, unsigned long func,
+ unsigned long frame_pointer, unsigned long *retp,
+ struct ftrace_regs *fregs)
{
struct ftrace_graph_ent trace;
unsigned long bitmap = 0;
@@ -631,7 +633,7 @@ int function_graph_enter(unsigned long ret, unsigned long func,
if (static_branch_likely(&fgraph_do_direct)) {
int save_curr_ret_stack = current->curr_ret_stack;
- if (static_call(fgraph_func)(&trace, fgraph_direct_gops))
+ if (static_call(fgraph_func)(&trace, fgraph_direct_gops, fregs))
bitmap |= BIT(fgraph_direct_gops->idx);
else
/* Clear out any saved storage */
@@ -649,7 +651,7 @@ int function_graph_enter(unsigned long ret, unsigned long func,
save_curr_ret_stack = current->curr_ret_stack;
if (ftrace_ops_test(&gops->ops, func, NULL) &&
- gops->entryfunc(&trace, gops))
+ gops->entryfunc(&trace, gops, fregs))
bitmap |= BIT(i);
else
/* Clear out any saved storage */
@@ -925,7 +927,7 @@ unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
static struct ftrace_ops graph_ops = {
.func = ftrace_graph_func,
- .flags = FTRACE_OPS_GRAPH_STUB,
+ .flags = FTRACE_OPS_GRAPH_STUB | FTRACE_OPS_FL_SAVE_ARGS,
#ifdef FTRACE_GRAPH_TRAMP_ADDR
.trampoline = FTRACE_GRAPH_TRAMP_ADDR,
/* trampoline_size is only needed for dynamically allocated tramps */
@@ -935,7 +937,8 @@ static struct ftrace_ops graph_ops = {
void fgraph_init_ops(struct ftrace_ops *dst_ops,
struct ftrace_ops *src_ops)
{
- dst_ops->flags = FTRACE_OPS_FL_PID | FTRACE_OPS_GRAPH_STUB;
+ dst_ops->flags = FTRACE_OPS_FL_PID | FTRACE_OPS_GRAPH_STUB |
+ FTRACE_OPS_FL_SAVE_ARGS;
#ifdef CONFIG_DYNAMIC_FTRACE
if (src_ops) {
@@ -1119,7 +1122,7 @@ void ftrace_graph_exit_task(struct task_struct *t)
#ifdef CONFIG_DYNAMIC_FTRACE
static int fgraph_pid_func(struct ftrace_graph_ent *trace,
- struct fgraph_ops *gops)
+ struct fgraph_ops *gops, struct ftrace_regs *fregs)
{
struct trace_array *tr = gops->ops.private;
int pid;
@@ -1133,7 +1136,7 @@ static int fgraph_pid_func(struct ftrace_graph_ent *trace,
return 0;
}
- return gops->saved_func(trace, gops);
+ return gops->saved_func(trace, gops, fregs);
}
void fgraph_update_pid_func(void)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 4c28dd177ca6..775040a9f541 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -821,7 +821,8 @@ void ftrace_graph_graph_time_control(bool enable)
}
static int profile_graph_entry(struct ftrace_graph_ent *trace,
- struct fgraph_ops *gops)
+ struct fgraph_ops *gops,
+ struct ftrace_regs *fregs)
{
struct ftrace_ret_stack *ret_stack;
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index bd3e3069300e..28d8ad5e31e6 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -683,7 +683,8 @@ void trace_default_header(struct seq_file *m);
void print_trace_header(struct seq_file *m, struct trace_iterator *iter);
void trace_graph_return(struct ftrace_graph_ret *trace, struct fgraph_ops *gops);
-int trace_graph_entry(struct ftrace_graph_ent *trace, struct fgraph_ops *gops);
+int trace_graph_entry(struct ftrace_graph_ent *trace, struct fgraph_ops *gops,
+ struct ftrace_regs *fregs);
void tracing_start_cmdline_record(void);
void tracing_stop_cmdline_record(void);
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 13d0387ac6a6..b9785fc919c9 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -128,7 +128,8 @@ static inline int ftrace_graph_ignore_irqs(void)
}
int trace_graph_entry(struct ftrace_graph_ent *trace,
- struct fgraph_ops *gops)
+ struct fgraph_ops *gops,
+ struct ftrace_regs *fregs)
{
unsigned long *task_var = fgraph_get_task_var(gops);
struct trace_array *tr = gops->private;
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index fce064e20570..ad739d76fc86 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -176,7 +176,8 @@ static int irqsoff_display_graph(struct trace_array *tr, int set)
}
static int irqsoff_graph_entry(struct ftrace_graph_ent *trace,
- struct fgraph_ops *gops)
+ struct fgraph_ops *gops,
+ struct ftrace_regs *fregs)
{
struct trace_array *tr = irqsoff_trace;
struct trace_array_cpu *data;
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index 130ca7e7787e..23360a2700de 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -113,7 +113,8 @@ static int wakeup_display_graph(struct trace_array *tr, int set)
}
static int wakeup_graph_entry(struct ftrace_graph_ent *trace,
- struct fgraph_ops *gops)
+ struct fgraph_ops *gops,
+ struct ftrace_regs *fregs)
{
struct trace_array *tr = wakeup_trace;
struct trace_array_cpu *data;
diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index c4ad7cd7e778..89067f02094a 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -773,7 +773,8 @@ struct fgraph_fixture {
};
static __init int store_entry(struct ftrace_graph_ent *trace,
- struct fgraph_ops *gops)
+ struct fgraph_ops *gops,
+ struct ftrace_regs *fregs)
{
struct fgraph_fixture *fixture = container_of(gops, struct fgraph_fixture, gops);
const char *type = fixture->store_type_name;
@@ -1024,7 +1025,8 @@ static unsigned int graph_hang_thresh;
/* Wrap the real function entry probe to avoid possible hanging */
static int trace_graph_entry_watchdog(struct ftrace_graph_ent *trace,
- struct fgraph_ops *gops)
+ struct fgraph_ops *gops,
+ struct ftrace_regs *fregs)
{
/* This is harmlessly racy, we want to approximately detect a hang */
if (unlikely(++graph_hang_thresh > GRAPH_MAX_FUNC_TEST)) {
@@ -1038,7 +1040,7 @@ static int trace_graph_entry_watchdog(struct ftrace_graph_ent *trace,
return 0;
}
- return trace_graph_entry(trace, gops);
+ return trace_graph_entry(trace, gops, fregs);
}
static struct fgraph_ops fgraph_ops __initdata = {