Update the graph tracer examples to cover the new frame pointer semantics
(in terms of passing it along). Move the HAVE_FUNCTION_GRAPH_FP_TEST docs
out of the Kconfig, into the right place, and expand on the details.
Signed-off-by: Mike Frysinger <[email protected]>
---
Documentation/trace/ftrace-design.txt | 26 +++++++++++++++++++++++---
kernel/trace/Kconfig | 4 +---
2 files changed, 24 insertions(+), 6 deletions(-)
diff --git a/Documentation/trace/ftrace-design.txt b/Documentation/trace/ftrace-design.txt
index 239f14b..6a5a579 100644
--- a/Documentation/trace/ftrace-design.txt
+++ b/Documentation/trace/ftrace-design.txt
@@ -1,5 +1,6 @@
function tracer guts
====================
+ By Mike Frysinger
Introduction
------------
@@ -173,14 +174,16 @@ void ftrace_graph_caller(void)
unsigned long *frompc = &...;
unsigned long selfpc = <return address> - MCOUNT_INSN_SIZE;
- prepare_ftrace_return(frompc, selfpc);
+ /* passing frame pointer up is optional -- see below */
+ prepare_ftrace_return(frompc, selfpc, frame_pointer);
/* restore all state needed by the ABI */
}
#endif
-For information on how to implement prepare_ftrace_return(), simply look at
-the x86 version. The only architecture-specific piece in it is the setup of
+For information on how to implement prepare_ftrace_return(), simply look at the
+x86 version (the frame pointer passing is optional; see the next section for
+more information). The only architecture-specific piece in it is the setup of
the fault recovery table (the asm(...) code). The rest should be the same
across architectures.
@@ -205,6 +208,23 @@ void return_to_handler(void)
#endif
+HAVE_FUNCTION_GRAPH_FP_TEST
+---------------------------
+
+An arch may pass in a unique value (frame pointer) to both the entering and
+exiting of a function. On exit, the value is compared and if it does not
+match, then it will panic the kernel. This is largely a sanity check for bad
+code generation with gcc. If gcc for your port sanely updates the frame
+pointer under different opitmization levels, then ignore this option.
+
+However, adding support for it isn't terribly difficult. In your assembly code
+that calls prepare_ftrace_return(), pass the frame pointer as the 3rd argument.
+Then in the C version of that function, do what the x86 port does and pass it
+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_FTRACE_NMI_ENTER
---------------------
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 6c22d8a..60e2ce0 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -27,9 +27,7 @@ config HAVE_FUNCTION_GRAPH_TRACER
config HAVE_FUNCTION_GRAPH_FP_TEST
bool
help
- An arch may pass in a unique value (frame pointer) to both the
- entering and exiting of a function. On exit, the value is compared
- and if it does not match, then it will panic the kernel.
+ See Documentation/trace/ftrace-design.txt
config HAVE_FUNCTION_TRACE_MCOUNT_TEST
bool
--
1.6.6.1
On Fri, 2010-01-22 at 08:12 -0500, Mike Frysinger wrote:
> Update the graph tracer examples to cover the new frame pointer semantics
> (in terms of passing it along). Move the HAVE_FUNCTION_GRAPH_FP_TEST docs
> out of the Kconfig, into the right place, and expand on the details.
>
> Signed-off-by: Mike Frysinger <[email protected]>
Thanks! I'll queue this up for 34. and maybe 33 if there's a fix that is
needed. Not sure if Doc only changes can still make 33, if so, I may
send this patch by itself.
-- Steve
> ---
> Documentation/trace/ftrace-design.txt | 26 +++++++++++++++++++++++---
> kernel/trace/Kconfig | 4 +---
> 2 files changed, 24 insertions(+), 6 deletions(-)
>
> diff --git a/Documentation/trace/ftrace-design.txt b/Documentation/trace/ftrace-design.txt
> index 239f14b..6a5a579 100644
> --- a/Documentation/trace/ftrace-design.txt
> +++ b/Documentation/trace/ftrace-design.txt
> @@ -1,5 +1,6 @@
> function tracer guts
> ====================
> + By Mike Frysinger
>
> Introduction
> ------------
> @@ -173,14 +174,16 @@ void ftrace_graph_caller(void)
>
> unsigned long *frompc = &...;
> unsigned long selfpc = <return address> - MCOUNT_INSN_SIZE;
> - prepare_ftrace_return(frompc, selfpc);
> + /* passing frame pointer up is optional -- see below */
> + prepare_ftrace_return(frompc, selfpc, frame_pointer);
>
> /* restore all state needed by the ABI */
> }
> #endif
>
> -For information on how to implement prepare_ftrace_return(), simply look at
> -the x86 version. The only architecture-specific piece in it is the setup of
> +For information on how to implement prepare_ftrace_return(), simply look at the
> +x86 version (the frame pointer passing is optional; see the next section for
> +more information). The only architecture-specific piece in it is the setup of
> the fault recovery table (the asm(...) code). The rest should be the same
> across architectures.
>
> @@ -205,6 +208,23 @@ void return_to_handler(void)
> #endif
>
>
> +HAVE_FUNCTION_GRAPH_FP_TEST
> +---------------------------
> +
> +An arch may pass in a unique value (frame pointer) to both the entering and
> +exiting of a function. On exit, the value is compared and if it does not
> +match, then it will panic the kernel. This is largely a sanity check for bad
> +code generation with gcc. If gcc for your port sanely updates the frame
> +pointer under different opitmization levels, then ignore this option.
> +
> +However, adding support for it isn't terribly difficult. In your assembly code
> +that calls prepare_ftrace_return(), pass the frame pointer as the 3rd argument.
> +Then in the C version of that function, do what the x86 port does and pass it
> +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_FTRACE_NMI_ENTER
> ---------------------
>
> diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
> index 6c22d8a..60e2ce0 100644
> --- a/kernel/trace/Kconfig
> +++ b/kernel/trace/Kconfig
> @@ -27,9 +27,7 @@ config HAVE_FUNCTION_GRAPH_TRACER
> config HAVE_FUNCTION_GRAPH_FP_TEST
> bool
> help
> - An arch may pass in a unique value (frame pointer) to both the
> - entering and exiting of a function. On exit, the value is compared
> - and if it does not match, then it will panic the kernel.
> + See Documentation/trace/ftrace-design.txt
>
> config HAVE_FUNCTION_TRACE_MCOUNT_TEST
> bool
Commit-ID: 03688970347bfea32823953a7ce5886d1713205f
Gitweb: http://git.kernel.org/tip/03688970347bfea32823953a7ce5886d1713205f
Author: Mike Frysinger <[email protected]>
AuthorDate: Fri, 22 Jan 2010 08:12:47 -0500
Committer: Steven Rostedt <[email protected]>
CommitDate: Tue, 26 Jan 2010 17:00:39 -0500
tracing/documentation: Cover new frame pointer semantics
Update the graph tracer examples to cover the new frame pointer semantics
(in terms of passing it along). Move the HAVE_FUNCTION_GRAPH_FP_TEST docs
out of the Kconfig, into the right place, and expand on the details.
Signed-off-by: Mike Frysinger <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>
---
Documentation/trace/ftrace-design.txt | 26 +++++++++++++++++++++++---
kernel/trace/Kconfig | 4 +---
2 files changed, 24 insertions(+), 6 deletions(-)
diff --git a/Documentation/trace/ftrace-design.txt b/Documentation/trace/ftrace-design.txt
index 239f14b..6a5a579 100644
--- a/Documentation/trace/ftrace-design.txt
+++ b/Documentation/trace/ftrace-design.txt
@@ -1,5 +1,6 @@
function tracer guts
====================
+ By Mike Frysinger
Introduction
------------
@@ -173,14 +174,16 @@ void ftrace_graph_caller(void)
unsigned long *frompc = &...;
unsigned long selfpc = <return address> - MCOUNT_INSN_SIZE;
- prepare_ftrace_return(frompc, selfpc);
+ /* passing frame pointer up is optional -- see below */
+ prepare_ftrace_return(frompc, selfpc, frame_pointer);
/* restore all state needed by the ABI */
}
#endif
-For information on how to implement prepare_ftrace_return(), simply look at
-the x86 version. The only architecture-specific piece in it is the setup of
+For information on how to implement prepare_ftrace_return(), simply look at the
+x86 version (the frame pointer passing is optional; see the next section for
+more information). The only architecture-specific piece in it is the setup of
the fault recovery table (the asm(...) code). The rest should be the same
across architectures.
@@ -205,6 +208,23 @@ void return_to_handler(void)
#endif
+HAVE_FUNCTION_GRAPH_FP_TEST
+---------------------------
+
+An arch may pass in a unique value (frame pointer) to both the entering and
+exiting of a function. On exit, the value is compared and if it does not
+match, then it will panic the kernel. This is largely a sanity check for bad
+code generation with gcc. If gcc for your port sanely updates the frame
+pointer under different opitmization levels, then ignore this option.
+
+However, adding support for it isn't terribly difficult. In your assembly code
+that calls prepare_ftrace_return(), pass the frame pointer as the 3rd argument.
+Then in the C version of that function, do what the x86 port does and pass it
+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_FTRACE_NMI_ENTER
---------------------
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 6c22d8a..60e2ce0 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -27,9 +27,7 @@ config HAVE_FUNCTION_GRAPH_TRACER
config HAVE_FUNCTION_GRAPH_FP_TEST
bool
help
- An arch may pass in a unique value (frame pointer) to both the
- entering and exiting of a function. On exit, the value is compared
- and if it does not match, then it will panic the kernel.
+ See Documentation/trace/ftrace-design.txt
config HAVE_FUNCTION_TRACE_MCOUNT_TEST
bool