From cf71b174d3464c7dc22f86f25d629a8d9d5c3519 Mon Sep 17 00:00:00 2001 From: Maciej Fijalkowski Date: Wed, 16 Sep 2020 23:10:06 +0200 Subject: [PATCH] bpf: rename poke descriptor's 'ip' member to 'tailcall_target' Reflect the actual purpose of poke->ip and rename it to poke->tailcall_target so that it will not the be confused with another poke target that will be introduced in next commit. While at it, do the same thing with poke->ip_stable - rename it to poke->tailcall_target_stable. Signed-off-by: Maciej Fijalkowski Signed-off-by: Alexei Starovoitov --- arch/x86/net/bpf_jit_comp.c | 20 +++++++++++--------- include/linux/bpf.h | 4 ++-- kernel/bpf/arraymap.c | 17 +++++++++-------- kernel/bpf/core.c | 3 ++- 4 files changed, 24 insertions(+), 20 deletions(-) diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 6fb8c9435980..7b0ff169c9a0 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -434,7 +434,7 @@ static void emit_bpf_tail_call_direct(struct bpf_jit_poke_descriptor *poke, EMIT3(0x83, 0xC0, 0x01); /* add eax, 1 */ EMIT2_off32(0x89, 0x85, -36 - MAX_BPF_STACK); /* mov dword ptr [rbp -548], eax */ - poke->ip = image + (addr - X86_PATCH_SIZE); + poke->tailcall_target = image + (addr - X86_PATCH_SIZE); poke->adj_off = PROLOGUE_SIZE; memcpy(prog, ideal_nops[NOP_ATOMIC5], X86_PATCH_SIZE); @@ -453,7 +453,7 @@ static void bpf_tail_call_direct_fixup(struct bpf_prog *prog) for (i = 0; i < prog->aux->size_poke_tab; i++) { poke = &prog->aux->poke_tab[i]; - WARN_ON_ONCE(READ_ONCE(poke->ip_stable)); + WARN_ON_ONCE(READ_ONCE(poke->tailcall_target_stable)); if (poke->reason != BPF_POKE_REASON_TAIL_CALL) continue; @@ -464,18 +464,20 @@ static void bpf_tail_call_direct_fixup(struct bpf_prog *prog) if (target) { /* Plain memcpy is used when image is not live yet * and still not locked as read-only. Once poke - * location is active (poke->ip_stable), any parallel - * bpf_arch_text_poke() might occur still on the - * read-write image until we finally locked it as - * read-only. Both modifications on the given image - * are under text_mutex to avoid interference. + * location is active (poke->tailcall_target_stable), + * any parallel bpf_arch_text_poke() might occur + * still on the read-write image until we finally + * locked it as read-only. Both modifications on + * the given image are under text_mutex to avoid + * interference. */ - ret = __bpf_arch_text_poke(poke->ip, BPF_MOD_JUMP, NULL, + ret = __bpf_arch_text_poke(poke->tailcall_target, + BPF_MOD_JUMP, NULL, (u8 *)target->bpf_func + poke->adj_off, false); BUG_ON(ret < 0); } - WRITE_ONCE(poke->ip_stable, true); + WRITE_ONCE(poke->tailcall_target_stable, true); mutex_unlock(&array->aux->poke_mutex); } } diff --git a/include/linux/bpf.h b/include/linux/bpf.h index a23e5eb728c8..f3790c9cf542 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -697,14 +697,14 @@ enum bpf_jit_poke_reason { /* Descriptor of pokes pointing /into/ the JITed image. */ struct bpf_jit_poke_descriptor { - void *ip; + void *tailcall_target; union { struct { struct bpf_map *map; u32 key; } tail_call; }; - bool ip_stable; + bool tailcall_target_stable; u8 adj_off; u16 reason; u32 insn_idx; diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index e046fb7d17cd..60abf7fe12de 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -918,12 +918,13 @@ static void prog_array_map_poke_run(struct bpf_map *map, u32 key, * there could be danger of use after free otherwise. * 2) Initially when we start tracking aux, the program * is not JITed yet and also does not have a kallsyms - * entry. We skip these as poke->ip_stable is not - * active yet. The JIT will do the final fixup before - * setting it stable. The various poke->ip_stable are - * successively activated, so tail call updates can - * arrive from here while JIT is still finishing its - * final fixup for non-activated poke entries. + * entry. We skip these as poke->tailcall_target_stable + * is not active yet. The JIT will do the final fixup + * before setting it stable. The various + * poke->tailcall_target_stable are successively + * activated, so tail call updates can arrive from here + * while JIT is still finishing its final fixup for + * non-activated poke entries. * 3) On program teardown, the program's kallsym entry gets * removed out of RCU callback, but we can only untrack * from sleepable context, therefore bpf_arch_text_poke() @@ -940,7 +941,7 @@ static void prog_array_map_poke_run(struct bpf_map *map, u32 key, * 5) Any other error happening below from bpf_arch_text_poke() * is a unexpected bug. */ - if (!READ_ONCE(poke->ip_stable)) + if (!READ_ONCE(poke->tailcall_target_stable)) continue; if (poke->reason != BPF_POKE_REASON_TAIL_CALL) continue; @@ -948,7 +949,7 @@ static void prog_array_map_poke_run(struct bpf_map *map, u32 key, poke->tail_call.key != key) continue; - ret = bpf_arch_text_poke(poke->ip, BPF_MOD_JUMP, + ret = bpf_arch_text_poke(poke->tailcall_target, BPF_MOD_JUMP, old ? (u8 *)old->bpf_func + poke->adj_off : NULL, new ? (u8 *)new->bpf_func + diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 2a20c2833996..2e00ac028d38 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -775,7 +775,8 @@ int bpf_jit_add_poke_descriptor(struct bpf_prog *prog, if (size > poke_tab_max) return -ENOSPC; - if (poke->ip || poke->ip_stable || poke->adj_off) + if (poke->tailcall_target || poke->tailcall_target_stable || + poke->adj_off) return -EINVAL; switch (poke->reason) {