[PATCH 1/2] kprobes: Allow architectures to override optinsn page allocation

From: Christophe Leroy
Date: Wed May 12 2021 - 10:29:30 EST


Some architectures like powerpc require a non standard
allocation of optinsn page, because module pages are
too far from the kernel for direct branches.

Define weak alloc_optinsn_page() and free_optinsn_page(), that
fall back on alloc_insn_page() and free_insn_page() when not
overriden by the architecture.

Suggested-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
kernel/kprobes.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 745f08fdd7a6..8c0a6fdef771 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -321,11 +321,21 @@ int kprobe_cache_get_kallsym(struct kprobe_insn_cache *c, unsigned int *symnum,
}

#ifdef CONFIG_OPTPROBES
+void __weak *alloc_optinsn_page(void)
+{
+ return alloc_insn_page();
+}
+
+void __weak free_optinsn_page(void *page)
+{
+ free_insn_page(page);
+}
+
/* For optimized_kprobe buffer */
struct kprobe_insn_cache kprobe_optinsn_slots = {
.mutex = __MUTEX_INITIALIZER(kprobe_optinsn_slots.mutex),
- .alloc = alloc_insn_page,
- .free = free_insn_page,
+ .alloc = alloc_optinsn_page,
+ .free = free_optinsn_page,
.sym = KPROBE_OPTINSN_PAGE_SYM,
.pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages),
/* .insn_size is initialized later */
--
2.25.0