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Commit 90e35adc authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Bruno Martins
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>
Signed-off-by: default avatarDanny Lin <danny@kdrag0n.dev>
Change-Id: I582794881942bc0b766515861f2232354860536b
parent f973db04

kernel/bpf/core.c

+12 −2
Original line number Diff line number Diff line
@@ -627,6 +627,16 @@ static void bpf_jit_uncharge_modmem(u32 pages) 
	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);

}



#if IS_ENABLED(CONFIG_BPF_JIT) && IS_ENABLED(CONFIG_CFI_CLANG)

bool __weak arch_bpf_jit_check_func(const struct bpf_prog *prog)

{
@@ -652,7 +662,7 @@ bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, 


	if (bpf_jit_charge_modmem(pages))

		return NULL;

	hdr = module_alloc(size);

	hdr = bpf_jit_alloc_exec(size);

	if (!hdr) {

		bpf_jit_uncharge_modmem(pages);

		return NULL;
@@ -677,7 +687,7 @@ void bpf_jit_binary_free(struct bpf_binary_header *hdr) 
{

	u32 pages = hdr->pages;



	module_memfree(hdr);

	bpf_jit_free_exec(hdr);

	bpf_jit_uncharge_modmem(pages);

}