On Wed, 29 Jan 2014 16:09:24 -0500
John David Anglin <dave.anglin@xxxxxxxx> wrote:
> On 1/29/2014 3:44 PM, Helge Deller wrote:
> > Can you try
> > BL ftrace_return_to_handler, %r0
> > (I'm not good in hppa assembly - as you can see if you take a look
> > at this assembly code section :-)).
> >
> BL might not reach on PA 1.1. The PA 2.0 b,l instruction is only
> "long" when the link
> register is %rp and it is used for the return_trampoline.
>
> I would say replace "b" with the following as it will always reach
> target: load32 ftrace_return_to_handler, %r20
> bv %r0(%r20)
>
> %r1 is another register alternative.
Thanks, however, I later found out that this part of the code isn't
used if you set CONFIG_FUNCTION_GRAPH_TRACER=n.
In my config, I've enabled only this :
CONFIG_FTRACE=y
CONFIG_FUNCTION_TRACER=y
Full config can be found here : http://bpaste.net/show/178555/
So far I came up with the attached patch to try to get a booting kernel
but I don't even have the first line being printed, the box HPMC and
reboot.
As far as I understand, compiling with -pg will make each function jump
to _mcount before being actually executed. This is why I tried to make
the _mcount function simply jump back to %rp but this doesn't seem to
be helpful.
What am I missing here ?
GUy
diff --git a/arch/parisc/Kconfig.debug b/arch/parisc/Kconfig.debug
index bc989e5..6d23a1a 100644
--- a/arch/parisc/Kconfig.debug
+++ b/arch/parisc/Kconfig.debug
@@ -1,5 +1,8 @@
menu "Kernel hacking"
+config TRACE_IRQFLAGS_SUPPORT
+ def_bool y
+
source "lib/Kconfig.debug"
config DEBUG_RODATA
diff --git a/arch/parisc/kernel/entry.S b/arch/parisc/kernel/entry.S
index e8f07dd..bdb4d33 100644
--- a/arch/parisc/kernel/entry.S
+++ b/arch/parisc/kernel/entry.S
@@ -1999,11 +1999,15 @@ ENDPROC(syscall_exit)
#ifdef CONFIG_FUNCTION_TRACER
.import ftrace_function_trampoline,code
ENTRY(_mcount)
+ bv %r0(%rp)
+ nop
+ /* not reached */
copy %r3, %arg2
b ftrace_function_trampoline
nop
ENDPROC(_mcount)
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
ENTRY(return_to_handler)
load32 return_trampoline, %rp
copy %ret0, %arg0
@@ -2019,7 +2023,19 @@ return_trampoline:
ftrace_stub:
bv %r0(%rp)
nop
+#else /* CONFIG_FUNCTION_GRAPH_TRACER */
+
+ENTRY(ftrace_stub)
+ bv %r0(%rp)
+ nop
+ENDPROC(ftrace_stub)
+
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
ENDPROC(return_to_handler)
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+
#endif /* CONFIG_FUNCTION_TRACER */
#ifdef CONFIG_IRQSTACKS
diff --git a/arch/parisc/kernel/ftrace.c b/arch/parisc/kernel/ftrace.c
index 5beb97b..8c9f757 100644
--- a/arch/parisc/kernel/ftrace.c
+++ b/arch/parisc/kernel/ftrace.c
@@ -156,7 +156,7 @@ void ftrace_function_trampoline(unsigned long parent,
return;
if (ftrace_trace_function != ftrace_stub) {
- ftrace_trace_function(parent, self_addr);
+ ftrace_trace_function(parent, self_addr, NULL, NULL);
return;
}
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
