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From: Tony Ambardar <tony.ambardar@gmail.com>
To: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>
Cc: Tony Ambardar <Tony.Ambardar@gmail.com>,
	netdev@vger.kernel.org, bpf@vger.kernel.org,
	linux-arch@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>
Subject: [PATCH bpf v1 2/3] bpf: prevent .BTF section elimination
Date: Sat, 19 Sep 2020 22:01:34 -0700	[thread overview]
Message-ID: <a635b5d3e2da044e7b51ec1315e8910fbce0083f.1600417359.git.Tony.Ambardar@gmail.com> (raw)
In-Reply-To: <cover.1600417359.git.Tony.Ambardar@gmail.com>

Systems with memory or disk constraints often reduce the kernel footprint
by configuring LD_DEAD_CODE_DATA_ELIMINATION. However, this can result in
removal of any BTF information.

Use the KEEP() macro to preserve the BTF data as done with other important
sections, while still allowing for smaller kernels.

Fixes: 90ceddcb4950 ("bpf: Support llvm-objcopy for vmlinux BTF")

Signed-off-by: Tony Ambardar <Tony.Ambardar@gmail.com>
---
 include/asm-generic/vmlinux.lds.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 5430febd34be..7636bc71c71f 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -661,7 +661,7 @@
 #define BTF								\
 	.BTF : AT(ADDR(.BTF) - LOAD_OFFSET) {				\
 		__start_BTF = .;					\
-		*(.BTF)							\
+		KEEP(*(.BTF))						\
 		__stop_BTF = .;						\
 	}								\
 	. = ALIGN(4);							\
-- 
2.25.1


  parent reply	other threads:[~2020-09-20  5:02 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-20  5:01 [PATCH bpf v1 0/3] fix BTF usage on embedded systems Tony Ambardar
2020-09-20  5:01 ` [PATCH bpf v1 1/3] bpf: fix sysfs export of empty BTF section Tony Ambardar
2020-09-21 15:44   ` John Fastabend
2020-09-21 19:21   ` Andrii Nakryiko
2020-09-20  5:01 ` Tony Ambardar [this message]
2020-09-21 15:45   ` [PATCH bpf v1 2/3] bpf: prevent .BTF section elimination John Fastabend
2020-09-20  5:01 ` [PATCH bpf v1 3/3] libbpf: fix native endian assumption when parsing BTF Tony Ambardar
2020-09-21 15:46   ` John Fastabend
2020-09-21 19:24 ` [PATCH bpf v1 0/3] fix BTF usage on embedded systems Andrii Nakryiko
2020-09-21 20:52 ` Daniel Borkmann

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