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bpf: add __weak hook for allocating executable memory

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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: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Danny Lin <danny@kdrag0n.dev>
Change-Id: I582794881942bc0b766515861f2232354860536b
This commit is contained in:
Ard Biesheuvel
2018-11-23 23:18:03 +01:00
committed by Bruno Martins
parent f973db0464
commit 90e35adc2c
1 changed files with 12 additions and 2 deletions
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14
kernel/bpf/core.c
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@@ -627,6 +627,16 @@ 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);
}
#if IS_ENABLED(CONFIG_BPF_JIT) && IS_ENABLED(CONFIG_CFI_CLANG) #if IS_ENABLED(CONFIG_BPF_JIT) && IS_ENABLED(CONFIG_CFI_CLANG)
bool __weak arch_bpf_jit_check_func(const struct bpf_prog *prog) 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)) 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;
@@ -677,7 +687,7 @@ 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);
} }