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Commit dc002bb6 authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Daniel Borkmann
Browse files

bpf: add __weak hook for allocating executable memory 



By default, BPF uses module_alloc() to allocate executable memory,
but this is not necessary on all arches and potentially undesirable
on some of them.

So break out the module_alloc() and module_memfree() calls into __weak
functions to allow them to be overridden in arch code.

Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 2a95471c

kernel/bpf/core.c

+12 −2
Original line number Original line Diff line number Diff line
@@ -623,6 +623,16 @@ static void bpf_jit_uncharge_modmem(u32 pages) 
	atomic_long_sub(pages, &bpf_jit_current);

	atomic_long_sub(pages, &bpf_jit_current);

}

}





void *__weak bpf_jit_alloc_exec(unsigned long size)

{

	return module_alloc(size);

}



void __weak bpf_jit_free_exec(void *addr)

{

	module_memfree(addr);

}



struct bpf_binary_header *

struct bpf_binary_header *

bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr,

bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr,

		     unsigned int alignment,

		     unsigned int alignment,
@@ -640,7 +650,7 @@ bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, 




	if (bpf_jit_charge_modmem(pages))

	if (bpf_jit_charge_modmem(pages))

		return NULL;

		return NULL;

	hdr = module_alloc(size);

	hdr = bpf_jit_alloc_exec(size);

	if (!hdr) {

	if (!hdr) {

		bpf_jit_uncharge_modmem(pages);

		bpf_jit_uncharge_modmem(pages);

		return NULL;

		return NULL;
@@ -664,7 +674,7 @@ void bpf_jit_binary_free(struct bpf_binary_header *hdr) 
{

{

	u32 pages = hdr->pages;

	u32 pages = hdr->pages;





	module_memfree(hdr);

	bpf_jit_free_exec(hdr);

	bpf_jit_uncharge_modmem(pages);

	bpf_jit_uncharge_modmem(pages);

}

}