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 <[email protected]>
Signed-off-by: Christophe Leroy <[email protected]>
Acked-by: Masami Hiramatsu <[email protected]>
---
v2: Added missing prototypes in linux/kprobes.h
---
include/linux/kprobes.h | 3 +++
kernel/kprobes.c | 14 ++++++++++++--
2 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 1883a4a9f16a..02d4020615a7 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -409,6 +409,9 @@ void dump_kprobe(struct kprobe *kp);
void *alloc_insn_page(void);
void free_insn_page(void *page);
+void *alloc_optinsn_page(void);
+void free_optinsn_page(void *page);
+
int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
char *sym);
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
Commit 51c9c0843993 ("powerpc/kprobes: Implement Optprobes")
implemented a powerpc specific version of optinsn in order
to workaround the 32Mb limitation for direct branches.
Instead of implementing a dedicated powerpc version, use the
common optinsn and override the allocation and freeing functions.
This also indirectly remove the CLANG warning about
is_kprobe_ppc_optinsn_slot() not being use, and the powerpc will
now benefit from commit 5b485629ba0d ("kprobes, extable: Identify
kprobes trampolines as kernel text area")
Suggested-by: Masami Hiramatsu <[email protected]>
Signed-off-by: Christophe Leroy <[email protected]>
Acked-by: Masami Hiramatsu <[email protected]>
---
v2: no change
---
arch/powerpc/kernel/optprobes.c | 23 +++++------------------
1 file changed, 5 insertions(+), 18 deletions(-)
diff --git a/arch/powerpc/kernel/optprobes.c b/arch/powerpc/kernel/optprobes.c
index cdf87086fa33..a370190cd02a 100644
--- a/arch/powerpc/kernel/optprobes.c
+++ b/arch/powerpc/kernel/optprobes.c
@@ -31,11 +31,9 @@
#define TMPL_END_IDX \
(optprobe_template_end - optprobe_template_entry)
-DEFINE_INSN_CACHE_OPS(ppc_optinsn);
-
static bool insn_page_in_use;
-static void *__ppc_alloc_insn_page(void)
+void *alloc_optinsn_page(void)
{
if (insn_page_in_use)
return NULL;
@@ -43,20 +41,11 @@ static void *__ppc_alloc_insn_page(void)
return &optinsn_slot;
}
-static void __ppc_free_insn_page(void *page __maybe_unused)
+void free_optinsn_page(void *page)
{
insn_page_in_use = false;
}
-struct kprobe_insn_cache kprobe_ppc_optinsn_slots = {
- .mutex = __MUTEX_INITIALIZER(kprobe_ppc_optinsn_slots.mutex),
- .pages = LIST_HEAD_INIT(kprobe_ppc_optinsn_slots.pages),
- /* insn_size initialized later */
- .alloc = __ppc_alloc_insn_page,
- .free = __ppc_free_insn_page,
- .nr_garbage = 0,
-};
-
/*
* Check if we can optimize this probe. Returns NIP post-emulation if this can
* be optimized and 0 otherwise.
@@ -136,7 +125,7 @@ NOKPROBE_SYMBOL(optimized_callback);
void arch_remove_optimized_kprobe(struct optimized_kprobe *op)
{
if (op->optinsn.insn) {
- free_ppc_optinsn_slot(op->optinsn.insn, 1);
+ free_optinsn_slot(op->optinsn.insn, 1);
op->optinsn.insn = NULL;
}
}
@@ -203,14 +192,12 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)
unsigned long nip, size;
int rc, i;
- kprobe_ppc_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
-
nip = can_optimize(p);
if (!nip)
return -EILSEQ;
/* Allocate instruction slot for detour buffer */
- buff = get_ppc_optinsn_slot();
+ buff = get_optinsn_slot();
if (!buff)
return -ENOMEM;
@@ -297,7 +284,7 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)
return 0;
error:
- free_ppc_optinsn_slot(buff, 0);
+ free_optinsn_slot(buff, 0);
return -ERANGE;
}
--
2.25.0
Christophe Leroy wrote:
> 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.
^^^^^^^^^
overridden - courtesy of checkpatch.
>
> Suggested-by: Masami Hiramatsu <[email protected]>
> Signed-off-by: Christophe Leroy <[email protected]>
> Acked-by: Masami Hiramatsu <[email protected]>
> ---
> v2: Added missing prototypes in linux/kprobes.h
> ---
> include/linux/kprobes.h | 3 +++
> kernel/kprobes.c | 14 ++++++++++++--
> 2 files changed, 15 insertions(+), 2 deletions(-)
LGTM. For the series:
Reviewed-by: Naveen N. Rao <[email protected]>
- Naveen
On Thu, 13 May 2021 09:07:51 +0000 (UTC), Christophe Leroy wrote:
> 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.
Applied to powerpc/next.
[1/2] kprobes: Allow architectures to override optinsn page allocation
https://git.kernel.org/powerpc/c/7ee3e97e00a3893e354c3993c3f7d9dc127e9c5e
[2/2] powerpc/kprobes: Replace ppc_optinsn by common optinsn
https://git.kernel.org/powerpc/c/b73c8cccd72ac28beaf262fd6ef4b91411fc8335
cheers