From: Xu Kuohai <xukuohai@huaweicloud.com>
To: bpf@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-riscv@lists.infradead.org
Cc: "Ivan Babrou" <ivan@cloudflare.com>,
"Alexei Starovoitov" <ast@kernel.org>,
"Andrii Nakryiko" <andrii@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Björn Töpel" <bjorn@kernel.org>, "Pu Lehui" <pulehui@huawei.com>
Subject: [PATCH bpf-next 1/2] bpf, arm64: Fix incorrect runtime stats
Date: Tue, 16 Apr 2024 14:42:07 +0800 [thread overview]
Message-ID: <20240416064208.2919073-2-xukuohai@huaweicloud.com> (raw)
In-Reply-To: <20240416064208.2919073-1-xukuohai@huaweicloud.com>
From: Xu Kuohai <xukuohai@huawei.com>
When __bpf_prog_enter() returns zero, the arm64 register x20 that stores
prog start time is not assigned to zero, causing incorrect runtime stats.
To fix it, assign the return value of bpf_prog_enter() to x20 register
immediately upon its return.
Fixes: efc9909fdce0 ("bpf, arm64: Add bpf trampoline for arm64")
Reported-by: Ivan Babrou <ivan@cloudflare.com>
Tested-by: Ivan Babrou <ivan@cloudflare.com>
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
---
arch/arm64/net/bpf_jit_comp.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index 76b91f36c729..cf9a9ebb4cda 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -1905,15 +1905,15 @@ static void invoke_bpf_prog(struct jit_ctx *ctx, struct bpf_tramp_link *l,
emit_call(enter_prog, ctx);
+ /* save return value to callee saved register x20 */
+ emit(A64_MOV(1, A64_R(20), A64_R(0)), ctx);
+
/* if (__bpf_prog_enter(prog) == 0)
* goto skip_exec_of_prog;
*/
branch = ctx->image + ctx->idx;
emit(A64_NOP, ctx);
- /* save return value to callee saved register x20 */
- emit(A64_MOV(1, A64_R(20), A64_R(0)), ctx);
-
emit(A64_ADD_I(1, A64_R(0), A64_SP, args_off), ctx);
if (!p->jited)
emit_addr_mov_i64(A64_R(1), (const u64)p->insnsi, ctx);
--
2.40.1
next prev parent reply other threads:[~2024-04-16 6:39 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-16 6:42 [PATCH bpf-next 0/2] Fix incorrect bpf runtime stats for arm64 and riscv64 Xu Kuohai
2024-04-16 6:42 ` Xu Kuohai [this message]
2024-04-16 6:42 ` [PATCH bpf-next 2/2] riscv, bpf: Fix incorrect runtime stats Xu Kuohai
2024-04-16 9:35 ` Pu Lehui
2024-04-16 14:09 ` Björn Töpel
2024-04-16 15:30 ` [PATCH bpf-next 0/2] Fix incorrect bpf runtime stats for arm64 and riscv64 patchwork-bot+netdevbpf
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