In an effort to enable -Wcast-function-type in the top-level Makefile to
support Control Flow Integrity builds, remove all the function callback
casts.
To do this, use the ftrace_ops_list_func function as a wrapper when the
arch not supports ftrace ops instead of the use of a function cast.
Signed-off-by: Oscar Carter <[email protected]>
---
kernel/trace/ftrace.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index c163c3531faf..ed1efc0e3a25 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -119,13 +119,12 @@ struct ftrace_ops __rcu *ftrace_ops_list __read_mostly = &ftrace_list_end;
ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub;
struct ftrace_ops global_ops;
-#if ARCH_SUPPORTS_FTRACE_OPS
static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct pt_regs *regs);
-#else
+
+#if !ARCH_SUPPORTS_FTRACE_OPS
/* See comment below, where ftrace_ops_list_func is defined */
static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip);
-#define ftrace_ops_list_func ((ftrace_func_t)ftrace_ops_no_ops)
#endif
static inline void ftrace_ops_init(struct ftrace_ops *ops)
@@ -6860,6 +6859,12 @@ static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
}
NOKPROBE_SYMBOL(ftrace_ops_list_func);
#else
+static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
+ struct ftrace_ops *op, struct pt_regs *regs)
+{
+ ftrace_ops_no_ops(ip, parent_ip);
+}
+
static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip)
{
__ftrace_ops_list_func(ip, parent_ip, NULL, NULL);
--
2.20.1
On Sun, 14 Jun 2020 09:01:54 +0200
Oscar Carter <[email protected]> wrote:
> In an effort to enable -Wcast-function-type in the top-level Makefile to
> support Control Flow Integrity builds, remove all the function callback
> casts.
>
> To do this, use the ftrace_ops_list_func function as a wrapper when the
> arch not supports ftrace ops instead of the use of a function cast.
>
We need more tricker than this.
> Signed-off-by: Oscar Carter <[email protected]>
> ---
> kernel/trace/ftrace.c | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index c163c3531faf..ed1efc0e3a25 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -119,13 +119,12 @@ struct ftrace_ops __rcu *ftrace_ops_list __read_mostly = &ftrace_list_end;
> ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub;
> struct ftrace_ops global_ops;
>
> -#if ARCH_SUPPORTS_FTRACE_OPS
> static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
> struct ftrace_ops *op, struct pt_regs *regs);
> -#else
> +
> +#if !ARCH_SUPPORTS_FTRACE_OPS
> /* See comment below, where ftrace_ops_list_func is defined */
> static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip);
> -#define ftrace_ops_list_func ((ftrace_func_t)ftrace_ops_no_ops)
The reason for the typecast is because this gets called from asm with only two parameters.
> #endif
>
> static inline void ftrace_ops_init(struct ftrace_ops *ops)
> @@ -6860,6 +6859,12 @@ static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
> }
> NOKPROBE_SYMBOL(ftrace_ops_list_func);
> #else
> +static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
> + struct ftrace_ops *op, struct pt_regs *regs)
> +{
> + ftrace_ops_no_ops(ip, parent_ip);
> +}
> +
> static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip)
> {
> __ftrace_ops_list_func(ip, parent_ip, NULL, NULL);
> --
> 2.20.1
On Mon, 15 Jun 2020 16:17:38 -0400
Steven Rostedt <[email protected]> wrote:
> On Sun, 14 Jun 2020 09:01:54 +0200
> Oscar Carter <[email protected]> wrote:
>
> > In an effort to enable -Wcast-function-type in the top-level Makefile to
> > support Control Flow Integrity builds, remove all the function callback
> > casts.
> >
> > To do this, use the ftrace_ops_list_func function as a wrapper when the
> > arch not supports ftrace ops instead of the use of a function cast.
> >
>
> We need more tricker than this.
>
> > Signed-off-by: Oscar Carter <[email protected]>
> > ---
> > kernel/trace/ftrace.c | 11 ++++++++---
> > 1 file changed, 8 insertions(+), 3 deletions(-)
> >
> > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> > index c163c3531faf..ed1efc0e3a25 100644
> > --- a/kernel/trace/ftrace.c
> > +++ b/kernel/trace/ftrace.c
> > @@ -119,13 +119,12 @@ struct ftrace_ops __rcu *ftrace_ops_list __read_mostly = &ftrace_list_end;
> > ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub;
> > struct ftrace_ops global_ops;
> >
> > -#if ARCH_SUPPORTS_FTRACE_OPS
> > static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
> > struct ftrace_ops *op, struct pt_regs *regs);
> > -#else
> > +
> > +#if !ARCH_SUPPORTS_FTRACE_OPS
> > /* See comment below, where ftrace_ops_list_func is defined */
> > static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip);
> > -#define ftrace_ops_list_func ((ftrace_func_t)ftrace_ops_no_ops)
>
> The reason for the typecast is because this gets called from asm with only two parameters.
[ Some how hit a short cut key that sent this before I was finished! :-p ]
As I was saying. This typecast is being paranoid, as archs will call
the ftrace_ops_list_func directly, and only pass in two parameters.
Now one way around this is to instead of having the typecast, I could
use linker magic to create another function that I can define without
the typecast to get the same effect. Similar to what I did in commit:
46f9469247c6f ("ftrace: Rename ftrace_graph_stub to ftrace_stub_graph")
-- Steve
>
> > #endif
> >
> > static inline void ftrace_ops_init(struct ftrace_ops *ops)
> > @@ -6860,6 +6859,12 @@ static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
> > }
> > NOKPROBE_SYMBOL(ftrace_ops_list_func);
> > #else
> > +static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
> > + struct ftrace_ops *op, struct pt_regs *regs)
> > +{
> > + ftrace_ops_no_ops(ip, parent_ip);
> > +}
> > +
> > static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip)
> > {
> > __ftrace_ops_list_func(ip, parent_ip, NULL, NULL);
> > --
> > 2.20.1
>
On Mon, 15 Jun 2020 16:22:45 -0400
Steven Rostedt <[email protected]> wrote:
> As I was saying. This typecast is being paranoid, as archs will call
> the ftrace_ops_list_func directly, and only pass in two parameters.
>
> Now one way around this is to instead of having the typecast, I could
> use linker magic to create another function that I can define without
> the typecast to get the same effect. Similar to what I did in commit:
>
> 46f9469247c6f ("ftrace: Rename ftrace_graph_stub to ftrace_stub_graph")
Would something like this work for you?
-- Steve
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index db600ef218d7..120babd9ba44 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -145,13 +145,18 @@
* Need to also make ftrace_stub_graph point to ftrace_stub
* so that the same stub location may have different protocols
* and not mess up with C verifiers.
+ *
+ * ftrace_ops_list_func will be defined as arch_ftrace_ops_list_func
+ * as some archs will have a different prototype for that function
+ * but ftrace_ops_list_func() will have a single prototype.
*/
#define MCOUNT_REC() . = ALIGN(8); \
__start_mcount_loc = .; \
KEEP(*(__mcount_loc)) \
KEEP(*(__patchable_function_entries)) \
__stop_mcount_loc = .; \
- ftrace_stub_graph = ftrace_stub;
+ ftrace_stub_graph = ftrace_stub; \
+ ftrace_ops_list_func = arch_ftrace_ops_list_func;
#else
# ifdef CONFIG_FUNCTION_TRACER
# define MCOUNT_REC() ftrace_stub_graph = ftrace_stub;
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index f060838e9cbb..b775d399026e 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -119,14 +119,9 @@ struct ftrace_ops __rcu *ftrace_ops_list __read_mostly = &ftrace_list_end;
ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub;
struct ftrace_ops global_ops;
-#if ARCH_SUPPORTS_FTRACE_OPS
-static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
- struct ftrace_ops *op, struct pt_regs *regs);
-#else
-/* See comment below, where ftrace_ops_list_func is defined */
-static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip);
-#define ftrace_ops_list_func ((ftrace_func_t)ftrace_ops_no_ops)
-#endif
+/* Defined by vmlinux.lds.h see the commment above arch_ftrace_ops_list_func for details */
+void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
+ struct ftrace_ops *op, struct pt_regs *regs);
static inline void ftrace_ops_init(struct ftrace_ops *ops)
{
@@ -6859,21 +6854,23 @@ __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
* Note, CONFIG_DYNAMIC_FTRACE_WITH_REGS expects a full regs to be saved.
* An architecture can pass partial regs with ftrace_ops and still
* set the ARCH_SUPPORTS_FTRACE_OPS.
+ *
+ * In vmlinux.lds.h, ftrace_ops_list_func() is defined to be
+ * arch_ftrace_ops_list_func.
*/
#if ARCH_SUPPORTS_FTRACE_OPS
-static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
- struct ftrace_ops *op, struct pt_regs *regs)
+void arch_ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
+ struct ftrace_ops *op, struct pt_regs *regs)
{
__ftrace_ops_list_func(ip, parent_ip, NULL, regs);
}
-NOKPROBE_SYMBOL(ftrace_ops_list_func);
#else
-static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip)
+void arch_ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip)
{
__ftrace_ops_list_func(ip, parent_ip, NULL, NULL);
}
-NOKPROBE_SYMBOL(ftrace_ops_no_ops);
#endif
+NOKPROBE_SYMBOL(arch_ftrace_ops_list_func);
/*
* If there's only one function registered but it does not support
On Wed, Jun 17, 2020 at 04:28:00PM -0400, Steven Rostedt wrote:
> On Mon, 15 Jun 2020 16:22:45 -0400
> Steven Rostedt <[email protected]> wrote:
>
> > As I was saying. This typecast is being paranoid, as archs will call
> > the ftrace_ops_list_func directly, and only pass in two parameters.
> >
> > Now one way around this is to instead of having the typecast, I could
> > use linker magic to create another function that I can define without
> > the typecast to get the same effect. Similar to what I did in commit:
> >
> > 46f9469247c6f ("ftrace: Rename ftrace_graph_stub to ftrace_stub_graph")
>
> Would something like this work for you?
>
> -- Steve
>
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index db600ef218d7..120babd9ba44 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -145,13 +145,18 @@
> * Need to also make ftrace_stub_graph point to ftrace_stub
> * so that the same stub location may have different protocols
> * and not mess up with C verifiers.
> + *
> + * ftrace_ops_list_func will be defined as arch_ftrace_ops_list_func
> + * as some archs will have a different prototype for that function
> + * but ftrace_ops_list_func() will have a single prototype.
> */
> #define MCOUNT_REC() . = ALIGN(8); \
> __start_mcount_loc = .; \
> KEEP(*(__mcount_loc)) \
> KEEP(*(__patchable_function_entries)) \
> __stop_mcount_loc = .; \
> - ftrace_stub_graph = ftrace_stub;
> + ftrace_stub_graph = ftrace_stub; \
> + ftrace_ops_list_func = arch_ftrace_ops_list_func;
> #else
> # ifdef CONFIG_FUNCTION_TRACER
> # define MCOUNT_REC() ftrace_stub_graph = ftrace_stub;
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index f060838e9cbb..b775d399026e 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -119,14 +119,9 @@ struct ftrace_ops __rcu *ftrace_ops_list __read_mostly = &ftrace_list_end;
> ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub;
> struct ftrace_ops global_ops;
>
> -#if ARCH_SUPPORTS_FTRACE_OPS
> -static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
> - struct ftrace_ops *op, struct pt_regs *regs);
> -#else
> -/* See comment below, where ftrace_ops_list_func is defined */
> -static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip);
> -#define ftrace_ops_list_func ((ftrace_func_t)ftrace_ops_no_ops)
> -#endif
> +/* Defined by vmlinux.lds.h see the commment above arch_ftrace_ops_list_func for details */
> +void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
> + struct ftrace_ops *op, struct pt_regs *regs);
>
> static inline void ftrace_ops_init(struct ftrace_ops *ops)
> {
> @@ -6859,21 +6854,23 @@ __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
> * Note, CONFIG_DYNAMIC_FTRACE_WITH_REGS expects a full regs to be saved.
> * An architecture can pass partial regs with ftrace_ops and still
> * set the ARCH_SUPPORTS_FTRACE_OPS.
> + *
> + * In vmlinux.lds.h, ftrace_ops_list_func() is defined to be
> + * arch_ftrace_ops_list_func.
> */
> #if ARCH_SUPPORTS_FTRACE_OPS
> -static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
> - struct ftrace_ops *op, struct pt_regs *regs)
> +void arch_ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
> + struct ftrace_ops *op, struct pt_regs *regs)
> {
> __ftrace_ops_list_func(ip, parent_ip, NULL, regs);
> }
> -NOKPROBE_SYMBOL(ftrace_ops_list_func);
> #else
> -static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip)
> +void arch_ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip)
> {
> __ftrace_ops_list_func(ip, parent_ip, NULL, NULL);
> }
> -NOKPROBE_SYMBOL(ftrace_ops_no_ops);
> #endif
> +NOKPROBE_SYMBOL(arch_ftrace_ops_list_func);
>
> /*
> * If there's only one function registered but it does not support
Thanks for your work and the proper patch sent [1].
I will follow the thread to see if I can help.
[1] https://lore.kernel.org/lkml/[email protected]/
Regards,
Oscar Carter