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ftrace: Add return address pointer to ftrace_ret_stack

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Storing this value will help prevent unwinders from getting out of sync
with the function graph tracer ret_stack.  Now instead of needing a
stateful iterator, they can compare the return address pointer to find
the right ret_stack entry.

Note that an array of 50 ftrace_ret_stack structs is allocated for every
task.  So when an arch implements this, it will add either 200 or 400
bytes of memory usage per task (depending on whether it's a 32-bit or
64-bit platform).

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nilay Vaish <nilayvaish@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/a95cfcc39e8f26b89a430c56926af0bb217bc0a1.1471607358.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Josh Poimboeuf 2016-08-19 06:52:57 -05:00 committed by Ingo Molnar
parent daa460a88c
commit 9a7c348ba6
15 changed files with 34 additions and 15 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

11
Documentation/trace/ftrace-design.txt
View file

@ -203,6 +203,17 @@ along to ftrace_push_return_trace() instead of a stub value of 0.
Similarly, when you call ftrace_return_to_handler(), pass it the frame pointer.
HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
--------------------------------
An arch may pass in a pointer to the return address on the stack. This
prevents potential stack unwinding issues where the unwinder gets out of
sync with ret_stack and the wrong addresses are reported by
ftrace_graph_ret_addr().
Adding support for it is easy: just define the macro in asm/ftrace.h and
pass the return address pointer as the 'retp' argument to
ftrace_push_return_trace().
HAVE_FTRACE_NMI_ENTER
---------------------

2
arch/arm/kernel/ftrace.c
View file

@ -218,7 +218,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
}
err = ftrace_push_return_trace(old, self_addr, &trace.depth,
frame_pointer);
frame_pointer, NULL);
if (err == -EBUSY) {
*parent = old;
return;

2
arch/arm64/kernel/ftrace.c
View file

@ -138,7 +138,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
return;
err = ftrace_push_return_trace(old, self_addr, &trace.depth,
frame_pointer);
frame_pointer, NULL);
if (err == -EBUSY)
return;
else

2
arch/blackfin/kernel/ftrace.c
View file

@ -107,7 +107,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
return;
if (ftrace_push_return_trace(*parent, self_addr, &trace.depth,
frame_pointer) == -EBUSY)
frame_pointer, NULL) == -EBUSY)
return;
trace.func = self_addr;

2
arch/microblaze/kernel/ftrace.c
View file

@ -63,7 +63,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
return;
}
err = ftrace_push_return_trace(old, self_addr, &trace.depth, 0);
err = ftrace_push_return_trace(old, self_addr, &trace.depth, 0, NULL);
if (err == -EBUSY) {
*parent = old;
return;

4
arch/mips/kernel/ftrace.c
View file

@ -382,8 +382,8 @@ void prepare_ftrace_return(unsigned long *parent_ra_addr, unsigned long self_ra,
if (unlikely(faulted))
goto out;
if (ftrace_push_return_trace(old_parent_ra, self_ra, &trace.depth, fp)
== -EBUSY) {
if (ftrace_push_return_trace(old_parent_ra, self_ra, &trace.depth, fp,
NULL) == -EBUSY) {
*parent_ra_addr = old_parent_ra;
return;
}

2
arch/parisc/kernel/ftrace.c
View file

@ -48,7 +48,7 @@ static void __hot prepare_ftrace_return(unsigned long *parent,
return;
if (ftrace_push_return_trace(old, self_addr, &trace.depth,
0 ) == -EBUSY)
0, NULL) == -EBUSY)
return;
/* activate parisc_return_to_handler() as return point */

3
arch/powerpc/kernel/ftrace.c
View file

@ -593,7 +593,8 @@ unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip)
if (!ftrace_graph_entry(&trace))
goto out;
if (ftrace_push_return_trace(parent, ip, &trace.depth, 0) == -EBUSY)
if (ftrace_push_return_trace(parent, ip, &trace.depth, 0,
NULL) == -EBUSY)
goto out;
parent = return_hooker;

3
arch/s390/kernel/ftrace.c
View file

@ -209,7 +209,8 @@ unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip)
/* Only trace if the calling function expects to. */
if (!ftrace_graph_entry(&trace))
goto out;
if (ftrace_push_return_trace(parent, ip, &trace.depth, 0) == -EBUSY)
if (ftrace_push_return_trace(parent, ip, &trace.depth, 0,
NULL) == -EBUSY)
goto out;
parent = (unsigned long) return_to_handler;
out:

2
arch/sh/kernel/ftrace.c
View file

@ -382,7 +382,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
return;
}
err = ftrace_push_return_trace(old, self_addr, &trace.depth, 0);
err = ftrace_push_return_trace(old, self_addr, &trace.depth, 0, NULL);
if (err == -EBUSY) {
__raw_writel(old, parent);
return;

2
arch/sparc/kernel/ftrace.c
View file

@ -131,7 +131,7 @@ unsigned long prepare_ftrace_return(unsigned long parent,
return parent + 8UL;
if (ftrace_push_return_trace(parent, self_addr, &trace.depth,
frame_pointer) == -EBUSY)
frame_pointer, NULL) == -EBUSY)
return parent + 8UL;
trace.func = self_addr;

2
arch/tile/kernel/ftrace.c
View file

@ -184,7 +184,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
*parent = return_hooker;
err = ftrace_push_return_trace(old, self_addr, &trace.depth,
frame_pointer);
frame_pointer, NULL);
if (err == -EBUSY) {
*parent = old;
return;

2
arch/x86/kernel/ftrace.c
View file

@ -1029,7 +1029,7 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
}
if (ftrace_push_return_trace(old, self_addr, &trace.depth,
frame_pointer) == -EBUSY) {
frame_pointer, NULL) == -EBUSY) {
*parent = old;
return;
}

5
include/linux/ftrace.h
View file

@ -798,6 +798,9 @@ struct ftrace_ret_stack {
#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
unsigned long fp;
#endif
#ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
unsigned long *retp;
#endif
};
/*
@ -809,7 +812,7 @@ extern void return_to_handler(void);
extern int
ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
unsigned long frame_pointer);
unsigned long frame_pointer, unsigned long *retp);
/*
* Sometimes we don't want to trace a function with the function

5
kernel/trace/trace_functions_graph.c
View file

@ -119,7 +119,7 @@ print_graph_duration(struct trace_array *tr, unsigned long long duration,
/* Add a function return address to the trace stack on thread info.*/
int
ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
unsigned long frame_pointer)
unsigned long frame_pointer, unsigned long *retp)
{
unsigned long long calltime;
int index;
@ -173,6 +173,9 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
current->ret_stack[index].subtime = 0;
#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
current->ret_stack[index].fp = frame_pointer;
#endif
#ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
current->ret_stack[index].retp = retp;
#endif
*depth = current->curr_ret_stack;