diff options
| author | Anton Blanchard <anton@samba.org> | 2014-09-17 17:07:04 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2014-11-10 09:59:28 +1100 |
| commit | b3c18725a0eb7ea2458e9ae3b7e5a477f52e361f (patch) | |
| tree | faecb26b2ba42de9abe84471f02d8230f81a2b06 /arch/powerpc/kernel/entry_32.S | |
| parent | 7d56c65a6ff9065c459fc63c509950d8ea66e00c (diff) | |
powerpc/ftrace: simplify prepare_ftrace_return
Instead of passing in the stack address of the link register
to be modified, just pass in the old value and return the
new value and rely on ftrace_graph_caller to do the
modification.
This removes the exception handling around the stack update -
it isn't needed and we weren't consistent about it. Later on
we would do an unprotected modification:
if (!ftrace_graph_entry(&trace)) {
*parent = old;
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/kernel/entry_32.S')
| -rw-r--r-- | arch/powerpc/kernel/entry_32.S | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S index 22b45a4955c..ad837d8a26d 100644 --- a/arch/powerpc/kernel/entry_32.S +++ b/arch/powerpc/kernel/entry_32.S @@ -1424,12 +1424,18 @@ _GLOBAL(ftrace_graph_caller) lwz r4, 44(r1) subi r4, r4, MCOUNT_INSN_SIZE - /* get the parent address */ - addi r3, r1, 52 + /* Grab the LR out of the caller stack frame */ + lwz r3,52(r1) bl prepare_ftrace_return nop + /* + * prepare_ftrace_return gives us the address we divert to. + * Change the LR in the callers stack frame to this. + */ + stw r3,52(r1) + MCOUNT_RESTORE_FRAME /* old link register ends up in ctr reg */ bctr |