From: Quentin Monnet <quentin.monnet@netronome.com>
To: Daniel Borkmann <daniel@iogearbox.net>,
Alexei Starovoitov <ast@kernel.org>
Cc: netdev@vger.kernel.org, oss-drivers@netronome.com,
Quentin Monnet <quentin.monnet@netronome.com>
Subject: [PATCH bpf-next 09/12] nfp: bpf: fix return address from register-saving subroutine to callee
Date: Sun, 7 Oct 2018 12:56:55 +0100 [thread overview]
Message-ID: <1538913418-16039-10-git-send-email-quentin.monnet@netronome.com> (raw)
In-Reply-To: <1538913418-16039-1-git-send-email-quentin.monnet@netronome.com>
On performing a BPF-to-BPF call, we first jump to a subroutine that
pushes callee-saved registers (R6~R9) to the stack, and from there we
goes to the start of the callee next. In order to do so, the caller must
pass to the subroutine the address of the NFP instruction to jump to at
the end of that subroutine. This cannot be reliably implemented when
translated the caller, as we do not always know the start offset of the
callee yet.
This patch implement the required fixup step for passing the start
offset in the callee via the register used by the subroutine to hold its
return address.
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
---
drivers/net/ethernet/netronome/nfp/bpf/jit.c | 28 +++++++++++++++++++++++++++-
1 file changed, 27 insertions(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/netronome/nfp/bpf/jit.c b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
index e8b03d8f54f7..74423d3e714d 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/jit.c
+++ b/drivers/net/ethernet/netronome/nfp/bpf/jit.c
@@ -3340,10 +3340,25 @@ static const instr_cb_t instr_cb[256] = {
};
/* --- Assembler logic --- */
+static int
+nfp_fixup_immed_relo(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
+ struct nfp_insn_meta *jmp_dst, u32 br_idx)
+{
+ if (immed_get_value(nfp_prog->prog[br_idx + 1])) {
+ pr_err("BUG: failed to fix up callee register saving\n");
+ return -EINVAL;
+ }
+
+ immed_set_value(&nfp_prog->prog[br_idx + 1], jmp_dst->off);
+
+ return 0;
+}
+
static int nfp_fixup_branches(struct nfp_prog *nfp_prog)
{
struct nfp_insn_meta *meta, *jmp_dst;
u32 idx, br_idx;
+ int err;
list_for_each_entry(meta, &nfp_prog->insns, l) {
if (meta->skip)
@@ -3380,7 +3395,7 @@ static int nfp_fixup_branches(struct nfp_prog *nfp_prog)
/* Leave special branches for later */
if (FIELD_GET(OP_RELO_TYPE, nfp_prog->prog[br_idx]) !=
- RELO_BR_REL)
+ RELO_BR_REL && !is_mbpf_pseudo_call(meta))
continue;
if (!meta->jmp_dst) {
@@ -3395,6 +3410,17 @@ static int nfp_fixup_branches(struct nfp_prog *nfp_prog)
return -ELOOP;
}
+ if (is_mbpf_pseudo_call(meta)) {
+ err = nfp_fixup_immed_relo(nfp_prog, meta,
+ jmp_dst, br_idx);
+ if (err)
+ return err;
+ }
+
+ if (FIELD_GET(OP_RELO_TYPE, nfp_prog->prog[br_idx]) !=
+ RELO_BR_REL)
+ continue;
+
for (idx = meta->off; idx <= br_idx; idx++) {
if (!nfp_is_br(nfp_prog->prog[idx]))
continue;
--
2.7.4
next prev parent reply other threads:[~2018-10-07 19:04 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-07 11:56 [PATCH bpf-next 00/12] nfp: bpf: add support for BPF-to-BPF function calls Quentin Monnet
2018-10-07 11:56 ` [PATCH bpf-next 01/12] bpf: add verifier callback to get stack usage info for offloaded progs Quentin Monnet
2018-10-07 11:56 ` [PATCH bpf-next 02/12] nfp: bpf: rename nfp_prog->stack_depth as nfp_prog->stack_frame_depth Quentin Monnet
2018-10-07 11:56 ` [PATCH bpf-next 03/12] nfp: bpf: copy eBPF subprograms information from kernel verifier Quentin Monnet
2018-10-07 11:56 ` [PATCH bpf-next 04/12] nfp: bpf: ignore helper-related checks for BPF calls in nfp verifier Quentin Monnet
2018-10-07 11:56 ` [PATCH bpf-next 05/12] nfp: bpf: account for BPF-to-BPF calls when preparing nfp JIT Quentin Monnet
2018-10-07 11:56 ` [PATCH bpf-next 06/12] nfp: bpf: add main logics for BPF-to-BPF calls support in nfp driver Quentin Monnet
2018-10-07 11:56 ` [PATCH bpf-next 07/12] nfp: bpf: account for additional stack usage when checking stack limit Quentin Monnet
2018-10-07 11:56 ` [PATCH bpf-next 08/12] nfp: bpf: update fixup function for BPF-to-BPF calls support Quentin Monnet
2018-10-07 11:56 ` Quentin Monnet [this message]
2018-10-07 11:56 ` [PATCH bpf-next 10/12] nfp: bpf: optimise save/restore for R6~R9 based on register usage Quentin Monnet
2018-10-07 11:56 ` [PATCH bpf-next 11/12] nfp: bpf: support pointers to other stack frames for BPF-to-BPF calls Quentin Monnet
2018-10-07 11:56 ` [PATCH bpf-next 12/12] bpf: allow offload of programs with BPF-to-BPF function calls Quentin Monnet
2018-10-08 8:36 ` [PATCH bpf-next 00/12] nfp: bpf: add support for " Daniel Borkmann
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