Commit ed2d9e1a authored by Song Liu's avatar Song Liu Committed by Alexei Starovoitov
Browse files

bpf: Use size instead of pages in bpf_binary_header 



This is necessary to charge sub page memory for the BPF program.

Signed-off-by: default avatarSong Liu <songliubraving@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220204185742.271030-4-song@kernel.org
parent 3486bedd

include/linux/filter.h

+3 −3
Original line number Diff line number Diff line
@@ -548,7 +548,7 @@ struct sock_fprog_kern { 
#define BPF_IMAGE_ALIGNMENT 8



struct bpf_binary_header {

	u32 pages;

	u32 size;

	u8 image[] __aligned(BPF_IMAGE_ALIGNMENT);

};
@@ -886,8 +886,8 @@ static inline void bpf_prog_lock_ro(struct bpf_prog *fp) 
static inline void bpf_jit_binary_lock_ro(struct bpf_binary_header *hdr)

{

	set_vm_flush_reset_perms(hdr);

	set_memory_ro((unsigned long)hdr, hdr->pages);

	set_memory_x((unsigned long)hdr, hdr->pages);

	set_memory_ro((unsigned long)hdr, hdr->size >> PAGE_SHIFT);

	set_memory_x((unsigned long)hdr, hdr->size >> PAGE_SHIFT);

}



static inline struct bpf_binary_header *

kernel/bpf/core.c

+5 −6
Original line number Diff line number Diff line
@@ -543,7 +543,7 @@ bpf_prog_ksym_set_addr(struct bpf_prog *prog) 
	WARN_ON_ONCE(!bpf_prog_ebpf_jited(prog));



	prog->aux->ksym.start = (unsigned long) prog->bpf_func;

	prog->aux->ksym.end   = addr + hdr->pages * PAGE_SIZE;

	prog->aux->ksym.end   = addr + hdr->size;

}



static void
@@ -866,7 +866,7 @@ bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, 
		     bpf_jit_fill_hole_t bpf_fill_ill_insns)

{

	struct bpf_binary_header *hdr;

	u32 size, hole, start, pages;

	u32 size, hole, start;



	WARN_ON_ONCE(!is_power_of_2(alignment) ||

		     alignment > BPF_IMAGE_ALIGNMENT);
@@ -876,7 +876,6 @@ bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, 
	 * random section of illegal instructions.

	 */

	size = round_up(proglen + sizeof(*hdr) + 128, PAGE_SIZE);

	pages = size / PAGE_SIZE;



	if (bpf_jit_charge_modmem(size))

		return NULL;
@@ -889,7 +888,7 @@ bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, 
	/* Fill space with illegal/arch-dep instructions. */

	bpf_fill_ill_insns(hdr, size);



	hdr->pages = pages;

	hdr->size = size;

	hole = min_t(unsigned int, size - (proglen + sizeof(*hdr)),

		     PAGE_SIZE - sizeof(*hdr));

	start = (get_random_int() % hole) & ~(alignment - 1);
@@ -902,10 +901,10 @@ bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, 


void bpf_jit_binary_free(struct bpf_binary_header *hdr)

{

	u32 pages = hdr->pages;

	u32 size = hdr->size;



	bpf_jit_free_exec(hdr);

	bpf_jit_uncharge_modmem(pages << PAGE_SHIFT);

	bpf_jit_uncharge_modmem(size);

}



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