diff options
| author | Steven Rostedt <srostedt@redhat.com> | 2009-02-11 12:45:49 -0800 |
|---|---|---|
| committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2009-02-23 10:48:54 +1100 |
| commit | bb7253403f7a4670a128e4c080fd8ea1bd4d5029 (patch) | |
| tree | f2ee8c966035a67be77fad922ada4c4d52a53be9 /arch/powerpc/kernel/entry_64.S | |
| parent | 465428884765b43d642a967915e16c6c7cacbe8e (diff) | |
powerpc64, ftrace: save toc only on modules for function graph
The TOCS used by modules are different than the one used by
the core kernel code. The function graph tracer must save and
restore the TOC whenever it traces a module call. But this
is an added overhead to burden the majority of core kernel
code being traced.
Benjamin Herrenschmidt suggested in testing the entry of
the call to tell if it is a core kernel function or a module.
He recommended using the REGION_ID() macro to perform this test.
This patch implements Benjamin's idea, and uses a different
return_to_handler routine dependent on if the entry is a core
kernel function or not. The module version saves the TOC, where as
the core kernel version does not.
Geoff Lavand tested on PS3.
Tested-by: Geoff Levand <geoffrey.levand@am.sony.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/kernel/entry_64.S')
| -rw-r--r-- | arch/powerpc/kernel/entry_64.S | 27 |
1 files changed, 26 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index 9f61fd61f27..abfc3233047 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -971,6 +971,28 @@ _GLOBAL(ftrace_graph_caller) _GLOBAL(return_to_handler) /* need to save return values */ + std r4, -24(r1) + std r3, -16(r1) + std r31, -8(r1) + mr r31, r1 + stdu r1, -112(r1) + + bl .ftrace_return_to_handler + nop + + /* return value has real return address */ + mtlr r3 + + ld r1, 0(r1) + ld r4, -24(r1) + ld r3, -16(r1) + ld r31, -8(r1) + + /* Jump back to real return address */ + blr + +_GLOBAL(mod_return_to_handler) + /* need to save return values */ std r4, -32(r1) std r3, -24(r1) /* save TOC */ @@ -979,7 +1001,10 @@ _GLOBAL(return_to_handler) mr r31, r1 stdu r1, -112(r1) - /* update the TOC */ + /* + * We are in a module using the module's TOC. + * Switch to our TOC to run inside the core kernel. + */ LOAD_REG_IMMEDIATE(r4,ftrace_return_to_handler) ld r2, 8(r4) |