2019-06-07 12:00:20

by Geert Uytterhoeven

Subject: [PATCH] MIPS: ftrace: Reword prepare_ftrace_return() comment block

Improve the comment block for prepare_ftrace_return().

Signed-off-by: Geert Uytterhoeven <[email protected]>
---
arch/mips/kernel/ftrace.c | 23 ++++++++++++-----------
1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/arch/mips/kernel/ftrace.c b/arch/mips/kernel/ftrace.c
index 4b5e1f2bfbcea85f..2625232bfe526a84 100644
--- a/arch/mips/kernel/ftrace.c
+++ b/arch/mips/kernel/ftrace.c
@@ -333,20 +333,21 @@ void prepare_ftrace_return(unsigned long *parent_ra_addr, unsigned long self_ra,
return;

/*
- * "parent_ra_addr" is the stack address saved the return address of
- * the caller of _mcount.
+ * "parent_ra_addr" is the stack address where the return address of
+ * the caller of _mcount is saved.
*
- * if the gcc < 4.5, a leaf function does not save the return address
- * in the stack address, so, we "emulate" one in _mcount's stack space,
- * and hijack it directly, but for a non-leaf function, it save the
- * return address to the its own stack space, we can not hijack it
- * directly, but need to find the real stack address,
- * ftrace_get_parent_addr() does it!
+ * If gcc < 4.5, a leaf function does not save the return address
+ * in the stack address, so we "emulate" one in _mcount's stack space,
+ * and hijack it directly.
+ * For a non-leaf function, it does save the return address to its own
+ * stack space, so we can not hijack it directly, but need to find the
+ * real stack address, which is done by ftrace_get_parent_addr().
*
- * if gcc>= 4.5, with the new -mmcount-ra-address option, for a
+ * If gcc >= 4.5, with the new -mmcount-ra-address option, for a
* non-leaf function, the location of the return address will be saved
- * to $12 for us, and for a leaf function, only put a zero into $12. we
- * do it in ftrace_graph_caller of mcount.S.
+ * to $12 for us.
+ * For a leaf function, it just puts a zero into $12, so we handle
+ * it in ftrace_graph_caller() of mcount.S.
*/

/* old_parent_ra = *parent_ra_addr; */
--
2.17.1

2019-06-12 05:13:13

by Paul Burton

Subject: Re: [PATCH] MIPS: ftrace: Reword prepare_ftrace_return() comment block

Hello,

Geert Uytterhoeven wrote:
> Improve the comment block for prepare_ftrace_return().
>
> Signed-off-by: Geert Uytterhoeven <[email protected]>

Applied to mips-next.

Thanks,
Paul

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