f58bd2f4a7
Signed-off-by: superCharge-xsy <xiesongyang@huawei.com> (cherry picked from commit 767848cdce2c8335a84af7d2a2cabe4ceeb7b2de)
48 lines
1.8 KiB
Diff
48 lines
1.8 KiB
Diff
From 0167a883554df812013ae1778724943ed0c8a069 Mon Sep 17 00:00:00 2001
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From: Yonghong Song <yhs@fb.com>
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Date: Mon, 6 Jun 2022 23:26:10 -0700
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Subject: [PATCH] libbpf: Fix an error in 64bit relocation value computation
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Currently, the 64bit relocation value in the instruction
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is computed as follows:
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__u64 imm = insn[0].imm + ((__u64)insn[1].imm << 32)
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Suppose insn[0].imm = -1 (0xffffffff) and insn[1].imm = 1.
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With the above computation, insn[0].imm will first sign-extend
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to 64bit -1 (0xffffffffFFFFFFFF) and then add 0x1FFFFFFFF,
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producing incorrect value 0xFFFFFFFF. The correct value
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should be 0x1FFFFFFFF.
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Changing insn[0].imm to __u32 first will prevent 64bit sign
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extension and fix the issue. Merging high and low 32bit values
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also changed from '+' to '|' to be consistent with other
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similar occurences in kernel and libbpf.
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Acked-by: Andrii Nakryiko <andrii@kernel.org>
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Acked-by: Dave Marchevsky <davemarchevsky@fb.com>
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Signed-off-by: Yonghong Song <yhs@fb.com>
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Link: https://lore.kernel.org/r/20220607062610.3717378-1-yhs@fb.com
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Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Conflict:NA
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Reference:https://github.com/libbpf/libbpf/commit/0167a883554df812013ae1778724943ed0c8a069
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---
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src/relo_core.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/src/relo_core.c b/src/relo_core.c
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index ba4453d..a9216b6 100644
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--- a/src/relo_core.c
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+++ b/src/relo_core.c
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@@ -1027,7 +1027,7 @@ int bpf_core_patch_insn(const char *prog_name, struct bpf_insn *insn,
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return -EINVAL;
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}
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- imm = insn[0].imm + ((__u64)insn[1].imm << 32);
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+ imm = (__u32)insn[0].imm | ((__u64)insn[1].imm << 32);
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if (res->validate && imm != orig_val) {
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pr_warn("prog '%s': relo #%d: unexpected insn #%d (LDIMM64) value: got %llu, exp %u -> %u\n",
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prog_name, relo_idx,
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--
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2.33.0
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