linux-kernel - [PATCH v2] arm64: Handle .ARM.attributes section in linker scripts

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Message-Id: <20250204-arm64-handle-arm-attributes-in-linker-script-v2-1-d684097f5554@kernel.org>
Date: Tue, 04 Feb 2025 10:48:55 -0700
From: Nathan Chancellor <nathan@...nel.org>
To: Catalin Marinas <catalin.marinas@....com>, 
 Will Deacon <will@...nel.org>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 llvm@...ts.linux.dev, stable@...r.kernel.org, 
 Nathan Chancellor <nathan@...nel.org>
Subject: [PATCH v2] arm64: Handle .ARM.attributes section in linker scripts

A recent LLVM commit [1] started generating an .ARM.attributes section
similar to the one that exists for 32-bit, which results in orphan
section warnings (or errors if CONFIG_WERROR is enabled) from the linker
because it is not handled in the arm64 linker scripts.

  ld.lld: error: arch/arm64/kernel/vdso/vgettimeofday.o:(.ARM.attributes) is being placed in '.ARM.attributes'
  ld.lld: error: arch/arm64/kernel/vdso/vgetrandom.o:(.ARM.attributes) is being placed in '.ARM.attributes'

  ld.lld: error: vmlinux.a(lib/vsprintf.o):(.ARM.attributes) is being placed in '.ARM.attributes'
  ld.lld: error: vmlinux.a(lib/win_minmax.o):(.ARM.attributes) is being placed in '.ARM.attributes'
  ld.lld: error: vmlinux.a(lib/xarray.o):(.ARM.attributes) is being placed in '.ARM.attributes'

Discard the new sections in the necessary linker scripts to resolve the
warnings, as the kernel and vDSO do not need to retain it, similar to
the .note.gnu.property section.

Cc: stable@...r.kernel.org
Fixes: b3e5d80d0c48 ("arm64/build: Warn on orphan section placement")
Link: https://github.com/llvm/llvm-project/commit/ee99c4d4845db66c4daa2373352133f4b237c942 [1]
Signed-off-by: Nathan Chancellor <nathan@...nel.org>
---
Changes in v2:
- Discard the section instead of adding it to the final artifacts to
  mirror the .note.gnu.property section handling (Will).
- Link to v1: https://lore.kernel.org/r/20250124-arm64-handle-arm-attributes-in-linker-script-v1-1-74135b6cf349@kernel.org
---
 arch/arm64/kernel/vdso/vdso.lds.S | 1 +
 arch/arm64/kernel/vmlinux.lds.S   | 1 +
 2 files changed, 2 insertions(+)

diff --git a/arch/arm64/kernel/vdso/vdso.lds.S b/arch/arm64/kernel/vdso/vdso.lds.S
index 4ec32e86a8da..8095fef66209 100644
--- a/arch/arm64/kernel/vdso/vdso.lds.S
+++ b/arch/arm64/kernel/vdso/vdso.lds.S
@@ -80,6 +80,7 @@ SECTIONS
 		*(.data .data.* .gnu.linkonce.d.* .sdata*)
 		*(.bss .sbss .dynbss .dynsbss)
 		*(.eh_frame .eh_frame_hdr)
+		*(.ARM.attributes)
 	}
 }
 
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index f84c71f04d9e..e73326bd3ff7 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -162,6 +162,7 @@ SECTIONS
 	/DISCARD/ : {
 		*(.interp .dynamic)
 		*(.dynsym .dynstr .hash .gnu.hash)
+		*(.ARM.attributes)
 	}
 
 	. = KIMAGE_VADDR;

---
base-commit: 1dd3393696efba1598aa7692939bba99d0cffae3
change-id: 20250123-arm64-handle-arm-attributes-in-linker-script-82aee25313ac

Best regards,
-- 
Nathan Chancellor <nathan@...nel.org>