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Subject[PATCH 6/7] powerpc32, ftrace: port function graph tracer to ppc32, static only
From: Steven Rostedt <rostedt@goodmis.org>

This patch ports the function graph tracer for PowerPC, but only
for static function tracing.

Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
arch/powerpc/Kconfig | 2 +-
arch/powerpc/kernel/entry_32.S | 43 +++++++++++++++++++++++++++++++++++++++-
arch/powerpc/kernel/ftrace.c | 2 +-
3 files changed, 44 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 6e1ee1b..9e4bd20 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -111,7 +111,7 @@ config PPC
select HAVE_FTRACE_MCOUNT_RECORD
select HAVE_DYNAMIC_FTRACE
select HAVE_FUNCTION_TRACER
- select HAVE_FUNCTION_GRAPH_TRACER if PPC64
+ select HAVE_FUNCTION_GRAPH_TRACER if PPC64 || !DYNAMIC_FTRACE
select ARCH_WANT_OPTIONAL_GPIOLIB
select HAVE_IDE
select HAVE_IOREMAP_PROT
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index eb0c13e..9cf7083 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -1199,9 +1199,11 @@ _GLOBAL(_mcount)

mtctr r5
bctrl
-
nop

+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ b ftrace_graph_caller
+#endif
MCOUNT_RESTORE_FRAME

bctr
@@ -1210,4 +1212,43 @@ _GLOBAL(_mcount)
_GLOBAL(ftrace_stub)
blr

+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+_GLOBAL(ftrace_graph_caller)
+ /* load r4 with local address */
+ lwz r4, 44(r1)
+ subi r4, r4, MCOUNT_INSN_SIZE
+
+ /* get the parent address */
+ addi r3, r1, 52
+
+ bl prepare_ftrace_return
+ nop
+
+ MCOUNT_RESTORE_FRAME
+ /* old link register ends up in ctr reg */
+ bctr
+
+_GLOBAL(return_to_handler)
+ /* need to save return values */
+ stwu r1, -32(r1)
+ stw r3, 20(r1)
+ stw r4, 16(r1)
+ stw r31, 12(r1)
+ mr r31, r1
+
+ bl ftrace_return_to_handler
+ nop
+
+ /* return value has real return address */
+ mtlr r3
+
+ lwz r3, 20(r1)
+ lwz r4, 16(r1)
+ lwz r31,12(r1)
+ lwz r1, 0(r1)
+
+ /* Jump back to real return address */
+ blr
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+
#endif /* CONFIG_MCOUNT */
diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c
index 5c6dfa9..dddd99b 100644
--- a/arch/powerpc/kernel/ftrace.c
+++ b/arch/powerpc/kernel/ftrace.c
@@ -603,7 +603,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
"1: " PPC_LL "%[old], 0(%[parent])\n"
"2: " PPC_STL "%[return_hooker], 0(%[parent])\n"
" li %[faulted], 0\n"
- "3:"
+ "3:\n"

".section .fixup, \"ax\"\n"
"4: li %[faulted], 1\n"
--
1.5.6.5
--


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