From 1e37392cccdea94da635e3c6d16b21865806f619 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Wed, 14 Jul 2021 11:43:54 +0200 Subject: [PATCH] bpf: Enable BPF_TRAMP_F_IP_ARG for trampolines with call_get_func_ip Enabling BPF_TRAMP_F_IP_ARG for trampolines that actually need it. The BPF_TRAMP_F_IP_ARG adds extra 3 instructions to trampoline code and is used only by programs with bpf_get_func_ip helper, which is added in following patch and sets call_get_func_ip bit. This patch ensures that BPF_TRAMP_F_IP_ARG flag is used only for trampolines that have programs with call_get_func_ip set. Signed-off-by: Jiri Olsa Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20210714094400.396467-3-jolsa@kernel.org --- include/linux/filter.h | 3 ++- kernel/bpf/trampoline.c | 12 +++++++++--- 2 files changed, 11 insertions(+), 4 deletions(-) diff --git a/include/linux/filter.h b/include/linux/filter.h index 472f97074da0..ba36989f711a 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -559,7 +559,8 @@ struct bpf_prog { kprobe_override:1, /* Do we override a kprobe? */ has_callchain_buf:1, /* callchain buffer allocated? */ enforce_expected_attach_type:1, /* Enforce expected_attach_type checking at attach time */ - call_get_stack:1; /* Do we call bpf_get_stack() or bpf_get_stackid() */ + call_get_stack:1, /* Do we call bpf_get_stack() or bpf_get_stackid() */ + call_get_func_ip:1; /* Do we call get_func_ip() */ enum bpf_prog_type type; /* Type of BPF program */ enum bpf_attach_type expected_attach_type; /* For some prog types */ u32 len; /* Number of filter blocks */ diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index 28a3630c48ee..b2535acfe9db 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -172,7 +172,7 @@ static int register_fentry(struct bpf_trampoline *tr, void *new_addr) } static struct bpf_tramp_progs * -bpf_trampoline_get_progs(const struct bpf_trampoline *tr, int *total) +bpf_trampoline_get_progs(const struct bpf_trampoline *tr, int *total, bool *ip_arg) { const struct bpf_prog_aux *aux; struct bpf_tramp_progs *tprogs; @@ -189,8 +189,10 @@ bpf_trampoline_get_progs(const struct bpf_trampoline *tr, int *total) *total += tr->progs_cnt[kind]; progs = tprogs[kind].progs; - hlist_for_each_entry(aux, &tr->progs_hlist[kind], tramp_hlist) + hlist_for_each_entry(aux, &tr->progs_hlist[kind], tramp_hlist) { + *ip_arg |= aux->prog->call_get_func_ip; *progs++ = aux->prog; + } } return tprogs; } @@ -333,9 +335,10 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr) struct bpf_tramp_image *im; struct bpf_tramp_progs *tprogs; u32 flags = BPF_TRAMP_F_RESTORE_REGS; + bool ip_arg = false; int err, total; - tprogs = bpf_trampoline_get_progs(tr, &total); + tprogs = bpf_trampoline_get_progs(tr, &total, &ip_arg); if (IS_ERR(tprogs)) return PTR_ERR(tprogs); @@ -357,6 +360,9 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr) tprogs[BPF_TRAMP_MODIFY_RETURN].nr_progs) flags = BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_SKIP_FRAME; + if (ip_arg) + flags |= BPF_TRAMP_F_IP_ARG; + err = arch_prepare_bpf_trampoline(im, im->image, im->image + PAGE_SIZE, &tr->func.model, flags, tprogs, tr->func.addr); -- 2.11.0