[PATCH] fgraph: Separate size of ret_stack from PAGE_SIZE

From: Steven Rostedt
Date: Sat Oct 19 2024 - 15:30:04 EST


From: Steven Rostedt <rostedt@xxxxxxxxxxx>

The ret_stack (shadow stack used by function graph infrastructure) is
currently defined as PAGE_SIZE. But some architectures which have 64K
PAGE_SIZE, this is way overkill. Also there's an effort to allow the
PAGE_SIZE to be defined at boot up.

Hard code it for now to 4096. In the future, this size may change and even
be dependent on specific architectures.

Link: https://lore.kernel.org/all/e5067bb8-0fcd-4739-9bca-0e872037d5a1@xxxxxxx/

Suggested-by: Ryan Roberts <ryan.roberts@xxxxxxx>
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
---
kernel/trace/fgraph.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index ee829d65f301..51e81b299a0d 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -153,7 +153,7 @@ enum {
* SHADOW_STACK_OFFSET: The size in long words of the shadow stack
* SHADOW_STACK_MAX_OFFSET: The max offset of the stack for a new frame to be added
*/
-#define SHADOW_STACK_SIZE (PAGE_SIZE)
+#define SHADOW_STACK_SIZE (4096)
#define SHADOW_STACK_OFFSET (SHADOW_STACK_SIZE / sizeof(long))
/* Leave on a buffer at the end */
#define SHADOW_STACK_MAX_OFFSET \
--
2.45.2