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bpf: Add initial poke descriptor table for jit images

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Add initial poke table data structures and management to the BPF
prog that can later be used by JITs. Also add an instance of poke
specific data for tail call maps; plan for later work is to extend
this also for BPF static keys.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/1db285ec2ea4207ee0455b3f8e191a4fc58b9ade.1574452833.git.daniel@iogearbox.net
This commit is contained in:
Daniel Borkmann
2019-11-22 21:07:57 +01:00
committed by Alexei Starovoitov
parent 2beee5f574
commit a66886fe6c
3 changed files with 64 additions and 0 deletions
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34
kernel/bpf/core.c
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@@ -256,6 +256,7 @@ void __bpf_prog_free(struct bpf_prog *fp)
{
if (fp->aux) {
free_percpu(fp->aux->stats);
kfree(fp->aux->poke_tab);
kfree(fp->aux);
}
vfree(fp);
@@ -756,6 +757,39 @@ int bpf_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
return ret;
}
int bpf_jit_add_poke_descriptor(struct bpf_prog *prog,
struct bpf_jit_poke_descriptor *poke)
{
struct bpf_jit_poke_descriptor *tab = prog->aux->poke_tab;
static const u32 poke_tab_max = 1024;
u32 slot = prog->aux->size_poke_tab;
u32 size = slot + 1;
if (size > poke_tab_max)
return -ENOSPC;
if (poke->ip || poke->ip_stable || poke->adj_off)
return -EINVAL;
switch (poke->reason) {
case BPF_POKE_REASON_TAIL_CALL:
if (!poke->tail_call.map)
return -EINVAL;
break;
default:
return -EINVAL;
}
tab = krealloc(tab, size * sizeof(*poke), GFP_KERNEL);
if (!tab)
return -ENOMEM;
memcpy(&tab[slot], poke, sizeof(*poke));
prog->aux->size_poke_tab = size;
prog->aux->poke_tab = tab;
return slot;
}
static atomic_long_t bpf_jit_current;
/* Can be overridden by an arch's JIT compiler if it has a custom,