[tip: perf/core] uprobes: Re-order struct uprobe_task to save some space

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The following commit has been merged into the perf/core branch of tip:

Commit-ID:     c554aa9ca976480839af342204e05bb4ce8367d5
Gitweb:        https://git.kernel.org/tip/c554aa9ca976480839af342204e05bb4ce8367d5
Author:        Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
AuthorDate:    Fri, 01 Nov 2024 22:13:33 +01:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Mon, 11 Nov 2024 11:49:48 +01:00

uprobes: Re-order struct uprobe_task to save some space

On x86_64, with allmodconfig, struct uprobe_task is 72 bytes long, with a
hole and some padding.

	/* size: 72, cachelines: 2, members: 7 */
	/* sum members: 64, holes: 1, sum holes: 4 */
	/* padding: 4 */
	/* forced alignments: 1, forced holes: 1, sum forced holes: 4 */
	/* last cacheline: 8 bytes */

Reorder the structure to fill the hole and avoid the padding.

This way, the whole structure fits in a single cacheline and some memory is
saved when it is allocated.

	/* size: 64, cachelines: 1, members: 7 */
	/* forced alignments: 1 */

Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: "Masami Hiramatsu (Google)" <mhiramat@xxxxxxxxxx>
Link: https://lore.kernel.org/r/a9f541d0cedf421f765c77a1fb93d6a979778a88.1730495562.git.christophe.jaillet@xxxxxxxxxx
---
 include/linux/uprobes.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
index 7a051b5..e0a4c20 100644
--- a/include/linux/uprobes.h
+++ b/include/linux/uprobes.h
@@ -121,6 +121,9 @@ struct hprobe {
 struct uprobe_task {
 	enum uprobe_task_state		state;
 
+	unsigned int			depth;
+	struct return_instance		*return_instances;
+
 	union {
 		struct {
 			struct arch_uprobe_task	autask;
@@ -138,9 +141,6 @@ struct uprobe_task {
 	unsigned long			xol_vaddr;
 
 	struct arch_uprobe              *auprobe;
-
-	struct return_instance		*return_instances;
-	unsigned int			depth;
 };
 
 struct return_consumer {




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