From ae84ff9a14a5a8d36a329a30626800155782e617 Mon Sep 17 00:00:00 2001 From: Nathan Chancellor <nathan@kernel.org> Date: Tue, 5 Dec 2023 16:53:51 -0700 Subject: [PATCH] riscv: Restrict DWARF5 when building with LLVM to known working versions LLVM prior to 18.0.0 would generate incorrect debug info for DWARF5 due to linker relaxation, which was worked around in clang by defaulting RISC-V to DWARF4 [1]. Unfortunately, this workaround does not work for the kernel because the DWARF version can be independently changed from the default in Kconfig. Do not allow DWARF5 to be selected for RISC-V when using linker relaxation (ld.lld >= 15.0.0) and a version of LLVM that does not have the fixes (the integrated assembler [2] and ld.lld [3] < 18.0.0) necessary to generate the correct debug info. Link: https://github.com/llvm/llvm-project/commit/bbc0f99f3bc96f1db16f649fc21dd18e5b0918f6 [1] Link: https://github.com/llvm/llvm-project/commit/1df5ea29b43690b6622db2cad7b745607ca4de6a [2] Link: https://github.com/llvm/llvm-project/commit/7ffabb61a5569444b5ac9322e22e5471cc5e4a77 [3] Signed-off-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Fangrui Song <maskray@google.com> Link: https://lore.kernel.org/r/20231205-riscv-restrict-dwarf5-llvm-v2-2-aedf00a382ac@kernel.org Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com> --- arch/riscv/Kconfig | 9 +++++++++ lib/Kconfig.debug | 1 + 2 files changed, 10 insertions(+) diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 72be1d8122a3c..81b473cb47b05 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -186,6 +186,15 @@ config RISCV_USE_LINKER_RELAXATION # https://github.com/llvm/llvm-project/commit/6611d58f5bbcbec77262d392e2923e1d680f6985 depends on !LD_IS_LLD || LLD_VERSION >= 150000 +# https://github.com/llvm/llvm-project/commit/bbc0f99f3bc96f1db16f649fc21dd18e5b0918f6 +config ARCH_HAS_BROKEN_DWARF5 + def_bool y + depends on RISCV_USE_LINKER_RELAXATION + # https://github.com/llvm/llvm-project/commit/1df5ea29b43690b6622db2cad7b745607ca4de6a + depends on AS_IS_LLVM && AS_VERSION < 180000 + # https://github.com/llvm/llvm-project/commit/7ffabb61a5569444b5ac9322e22e5471cc5e4a77 + depends on LD_IS_LLD && LLD_VERSION < 180000 + config ARCH_MMAP_RND_BITS_MIN default 18 if 64BIT default 8 diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index cc7d53d9dc019..a0ebce05a368f 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -282,6 +282,7 @@ config DEBUG_INFO_DWARF4 config DEBUG_INFO_DWARF5 bool "Generate DWARF Version 5 debuginfo" select DEBUG_INFO + depends on !ARCH_HAS_BROKEN_DWARF5 depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128) help Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc -- GitLab