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Subject[PATCH 5.15 046/230] bpf, arm64: Use emit_addr_mov_i64() for BPF_PSEUDO_FUNC
Date
From: Hou Tao <houtao1@huawei.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@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211231151018.3781550-1-houtao1@huawei.com
Signed-off-by: Sasha Levin <sashal@kernel.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 95439bbe5df8..4895b4d7e150 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -788,7 +788,10 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
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;
}
--
2.35.1


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