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AJvYcCXgQqRcvBx7jWJWzzP0+APmKtZ11n5rkqj9n54qVsQjJAVni5ak8G/5O9LjasqxggPvxbTaSGCUAPIM8MeCF2LQgLJJ X-Gm-Message-State: AOJu0Yx0zUgAjRpJ+TEImtV4Bsxt6YeOY+TNLr34vY2gS4ZxETmqmmX8 YTatqBh6tGGPn0oiiJ3QLaQbcj2/49aCkEL3FV8fK7P+q6nvYmAon4ymoeQ5BLtZIQ== X-Google-Smtp-Source: AGHT+IHL+1mRyxkztlcgl4k+NAL+OM/Frr4qWCn9roU7Mv8Py49mJym9LFBgZymIb9Pc/5Z/SlNcADA= X-Received: from sdf.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5935]) (user=sdf job=sendgmr) by 2002:a05:6a00:17a9:b0:6e6:9a3c:3748 with SMTP id s41-20020a056a0017a900b006e69a3c3748mr102635pfg.0.1710446293477; Thu, 14 Mar 2024 12:58:13 -0700 (PDT) Date: Thu, 14 Mar 2024 12:58:12 -0700 In-Reply-To: <20240314103153.2489252-1-ben.dooks@codethink.co.uk> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240314103153.2489252-1-ben.dooks@codethink.co.uk> Message-ID: Subject: Re: [PATCH] bpf: remove trunctaiton warning in BPF_LD_IMM64_RAW From: Stanislav Fomichev To: Ben Dooks Cc: ast@kernel.org, daniel@iogearbox.net, bpf@vger.kernel.org Content-Type: text/plain; charset="utf-8" On 03/14, Ben Dooks wrote: > When building W=1, the following warningds get generated by lib/test_bpf.c > due to the BPF_LD_IMM64_RAW() truncating a 64bit to 32bit value without > a specific mask to do so. > > lib/test_bpf.c:6441:25: warning: cast truncates bits from constant value (ffffffff0000 becomes ffff0000) > lib/test_bpf.c:6442:25: warning: cast truncates bits from constant value (ffffffff0000 becomes ffff0000) > lib/test_bpf.c:6473:25: warning: cast truncates bits from constant value (123456789abcdef becomes 89abcdef) > lib/test_bpf.c:6489:25: warning: cast truncates bits from constant value (123456789abcdef becomes 89abcdef) > lib/test_bpf.c:6490:25: warning: cast truncates bits from constant value (123456780a0c0e0 becomes 80a0c0e0) > lib/test_bpf.c:6599:25: warning: cast truncates bits from constant value (123456789abcdef becomes 89abcdef) > lib/test_bpf.c:6637:25: warning: cast truncates bits from constant value (ffffffff0000 becomes ffff0000) > > (more warnings truncated) > > Signed-off-by: Ben Dooks I wonder how many other places (in the kernel) we have where we silently cast u64 to u32.. Surprised that's the only warning you get :-) Acked-by: Stanislav Fomichev