Commit 3486bedd authored by Song Liu's avatar Song Liu Committed by Alexei Starovoitov
Browse files

bpf: Use bytes instead of pages for bpf_jit_[charge|uncharge]_modmem 



This enables sub-page memory charge and allocation.

Signed-off-by: default avatarSong Liu <songliubraving@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220204185742.271030-3-song@kernel.org
parent fac54e2b

include/linux/bpf.h

+2 −2
Original line number Diff line number Diff line
@@ -846,8 +846,8 @@ void bpf_image_ksym_add(void *data, struct bpf_ksym *ksym); 
void bpf_image_ksym_del(struct bpf_ksym *ksym);

void bpf_ksym_add(struct bpf_ksym *ksym);

void bpf_ksym_del(struct bpf_ksym *ksym);

int bpf_jit_charge_modmem(u32 pages);

void bpf_jit_uncharge_modmem(u32 pages);

int bpf_jit_charge_modmem(u32 size);

void bpf_jit_uncharge_modmem(u32 size);

bool bpf_prog_has_trampoline(const struct bpf_prog *prog);

#else

static inline int bpf_trampoline_link_prog(struct bpf_prog *prog,

kernel/bpf/core.c

+8 −9
Original line number Diff line number Diff line
@@ -833,12 +833,11 @@ static int __init bpf_jit_charge_init(void) 
}

pure_initcall(bpf_jit_charge_init);



int bpf_jit_charge_modmem(u32 pages)

int bpf_jit_charge_modmem(u32 size)

{

	if (atomic_long_add_return(pages, &bpf_jit_current) >

	    (bpf_jit_limit >> PAGE_SHIFT)) {

	if (atomic_long_add_return(size, &bpf_jit_current) > bpf_jit_limit) {

		if (!bpf_capable()) {

			atomic_long_sub(pages, &bpf_jit_current);

			atomic_long_sub(size, &bpf_jit_current);

			return -EPERM;

		}

	}
@@ -846,9 +845,9 @@ int bpf_jit_charge_modmem(u32 pages) 
	return 0;

}



void bpf_jit_uncharge_modmem(u32 pages)

void bpf_jit_uncharge_modmem(u32 size)

{

	atomic_long_sub(pages, &bpf_jit_current);

	atomic_long_sub(size, &bpf_jit_current);

}



void *__weak bpf_jit_alloc_exec(unsigned long size)
@@ -879,11 +878,11 @@ bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, 
	size = round_up(proglen + sizeof(*hdr) + 128, PAGE_SIZE);

	pages = size / PAGE_SIZE;



	if (bpf_jit_charge_modmem(pages))

	if (bpf_jit_charge_modmem(size))

		return NULL;

	hdr = bpf_jit_alloc_exec(size);

	if (!hdr) {

		bpf_jit_uncharge_modmem(pages);

		bpf_jit_uncharge_modmem(size);

		return NULL;

	}
@@ -906,7 +905,7 @@ void bpf_jit_binary_free(struct bpf_binary_header *hdr) 
	u32 pages = hdr->pages;



	bpf_jit_free_exec(hdr);

	bpf_jit_uncharge_modmem(pages);

	bpf_jit_uncharge_modmem(pages << PAGE_SHIFT);

}



/* This symbol is only overridden by archs that have different

kernel/bpf/trampoline.c

+3 −3
Original line number Diff line number Diff line
@@ -213,7 +213,7 @@ static void __bpf_tramp_image_put_deferred(struct work_struct *work) 
	im = container_of(work, struct bpf_tramp_image, work);

	bpf_image_ksym_del(&im->ksym);

	bpf_jit_free_exec(im->image);

	bpf_jit_uncharge_modmem(1);

	bpf_jit_uncharge_modmem(PAGE_SIZE);

	percpu_ref_exit(&im->pcref);

	kfree_rcu(im, rcu);

}
@@ -310,7 +310,7 @@ static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key, u32 idx) 
	if (!im)

		goto out;



	err = bpf_jit_charge_modmem(1);

	err = bpf_jit_charge_modmem(PAGE_SIZE);

	if (err)

		goto out_free_im;
@@ -332,7 +332,7 @@ static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key, u32 idx) 
out_free_image:

	bpf_jit_free_exec(im->image);

out_uncharge:

	bpf_jit_uncharge_modmem(1);

	bpf_jit_uncharge_modmem(PAGE_SIZE);

out_free_im:

	kfree(im);

out: