linux-kernel - [PATCH 5.16 0372/1039] bpf, arm64: Use emit_addr_mov_i64() for BPF_PSEUDO

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Date:   Mon, 24 Jan 2022 19:36:01 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Hou Tao <houtao1@...wei.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.16 0372/1039] bpf, arm64: Use emit_addr_mov_i64() for BPF_PSEUDO_FUNC

From: Hou Tao <houtao1@...wei.com>

[ Upstream commit e4a41c2c1fa916547e63440c73a51a5eb06247af ]

The following error is reported when running "./test_progs -t for_each"
under arm64:

  bpf_jit: multi-func JIT bug 58 != 56
  [...]
  JIT doesn't support bpf-to-bpf calls

The root cause is the size of BPF_PSEUDO_FUNC instruction increases
from 2 to 3 after the address of called bpf-function is settled and
there are two bpf-to-bpf calls in test_pkt_access. The generated
instructions are shown below:

  0x48:  21 00 C0 D2    movz x1, #0x1, lsl #32
  0x4c:  21 00 80 F2    movk x1, #0x1

  0x48:  E1 3F C0 92    movn x1, #0x1ff, lsl #32
  0x4c:  41 FE A2 F2    movk x1, #0x17f2, lsl #16
  0x50:  81 70 9F F2    movk x1, #0xfb84

Fixing it by using emit_addr_mov_i64() for BPF_PSEUDO_FUNC, so
the size of jited image will not change.

Fixes: 69c087ba6225 ("bpf: Add bpf_for_each_map_elem() helper")
Signed-off-by: Hou Tao <houtao1@...wei.com>
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Link: https://lore.kernel.org/bpf/20211231151018.3781550-1-houtao1@huawei.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/arm64/net/bpf_jit_comp.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index 3a8a7140a9bfb..c2d95aa1d294c 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -791,7 +791,10 @@ emit_cond_jmp:
 		u64 imm64;
 
 		imm64 = (u64)insn1.imm << 32 | (u32)imm;
-		emit_a64_mov_i64(dst, imm64, ctx);
+		if (bpf_pseudo_func(insn))
+			emit_addr_mov_i64(dst, imm64, ctx);
+		else
+			emit_a64_mov_i64(dst, imm64, ctx);
 
 		return 1;
 	}
-- 
2.34.1