Commit 7ee3e97e authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

kprobes: Allow architectures to override optinsn page allocation 



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
overridden by the architecture.

Suggested-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/40a43d6df1fdf41ade36e9a46e60a4df774ca9f6.1620896780.git.christophe.leroy@csgroup.eu
parent 6fcb5741

include/linux/kprobes.h

+3 −0
Original line number Diff line number Diff line
@@ -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);

kernel/kprobes.c

+12 −2
Original line number Diff line number Diff line
@@ -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 */