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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Cc: Andrii Nakryiko <andrii@kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 6.8 149/715] libbpf: fix return value for PERF_EVENT __arg_ctx type fix up check
Date: Sun, 24 Mar 2024 18:25:28 -0400
Message-ID: <20240324223455.1342824-150-sashal@kernel.org>
In-Reply-To: <20240324223455.1342824-1-sashal@kernel.org>
References: <20240324223455.1342824-1-sashal@kernel.org>
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From: Andrii Nakryiko <andrii@kernel.org>

[ Upstream commit d7bc416aa5cc183691287e8f0b1d5b182a7ce9c3 ]

If PERF_EVENT program has __arg_ctx argument with matching
architecture-specific pt_regs/user_pt_regs/user_regs_struct pointer
type, libbpf should still perform type rewrite for old kernels, but not
emit the warning. Fix copy/paste from kernel code where 0 is meant to
signify "no error" condition. For libbpf we need to return "true" to
proceed with type rewrite (which for PERF_EVENT program will be
a canonical `struct bpf_perf_event_data *` type).

Fixes: 9eea8fafe33e ("libbpf: fix __arg_ctx type enforcement for perf_event programs")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240206002243.1439450-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 tools/lib/bpf/libbpf.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 910f72c9e6a49..92bca96587a4a 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -6755,13 +6755,13 @@ static bool need_func_arg_type_fixup(const struct btf *btf, const struct bpf_pro
 	case BPF_PROG_TYPE_PERF_EVENT:
 		if (__builtin_types_compatible_p(bpf_user_pt_regs_t, struct pt_regs) &&
 		    btf_is_struct(t) && strcmp(tname, "pt_regs") == 0)
-			return 0;
+			return true;
 		if (__builtin_types_compatible_p(bpf_user_pt_regs_t, struct user_pt_regs) &&
 		    btf_is_struct(t) && strcmp(tname, "user_pt_regs") == 0)
-			return 0;
+			return true;
 		if (__builtin_types_compatible_p(bpf_user_pt_regs_t, struct user_regs_struct) &&
 		    btf_is_struct(t) && strcmp(tname, "user_regs_struct") == 0)
-			return 0;
+			return true;
 		break;
 	case BPF_PROG_TYPE_RAW_TRACEPOINT:
 	case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
-- 
2.43.0