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Merge patch series "RISC-V: Disable DWARF5 with known broken LLVM versions"

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Nathan Chancellor <nathan@kernel.org> says:

This series disables DWARF5 for LLVM versions where it is known to be
broken due to linker relaxation.

* b4-shazam-merge:
  lib/Kconfig.debug: Update AS_HAS_NON_CONST_LEB128 comment and name
  riscv: Restrict DWARF5 when building with LLVM to known working versions
  riscv: Hoist linker relaxation disabling logic into Kconfig

Link: bbc0f99f3b
Link: https://lore.kernel.org/r/20231205-riscv-restrict-dwarf5-llvm-v2-0-aedf00a382ac@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Palmer Dabbelt 2024-01-17 18:08:30 -08:00
commit 448857ec53
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3 changed files with 22 additions and 8 deletions
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14
arch/riscv/Kconfig
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@ -183,6 +183,20 @@ config HAVE_SHADOW_CALL_STACK
# https://github.com/riscv-non-isa/riscv-elf-psabi-doc/commit/a484e843e6eeb51f0cb7b8819e50da6d2444d769
depends on $(ld-option,--no-relax-gp)
config RISCV_USE_LINKER_RELAXATION
def_bool y
# 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

4
arch/riscv/Makefile
View File

@ -43,8 +43,7 @@ else
KBUILD_LDFLAGS += -melf32lriscv
endif
ifeq ($(CONFIG_LD_IS_LLD),y)
ifeq ($(call test-lt, $(CONFIG_LLD_VERSION), 150000),y)
ifndef CONFIG_RISCV_USE_LINKER_RELAXATION
KBUILD_CFLAGS += -mno-relax
KBUILD_AFLAGS += -mno-relax
ifndef CONFIG_AS_IS_LLVM
@ -52,7 +51,6 @@ ifndef CONFIG_AS_IS_LLVM
KBUILD_AFLAGS += -Wa,-mno-relax
endif
endif
endif
ifeq ($(CONFIG_SHADOW_CALL_STACK),y)
KBUILD_LDFLAGS += --no-relax-gp

12
lib/Kconfig.debug
View File

@ -231,9 +231,10 @@ config DEBUG_INFO
in the "Debug information" choice below, indicating that debug
information will be generated for build targets.
# Clang is known to generate .{s,u}leb128 with symbol deltas with DWARF5, which
# some targets may not support: https://sourceware.org/bugzilla/show_bug.cgi?id=27215
config AS_HAS_NON_CONST_LEB128
# Clang generates .uleb128 with label differences for DWARF v5, a feature that
# older binutils ports do not support when utilizing RISC-V style linker
# relaxation: https://sourceware.org/bugzilla/show_bug.cgi?id=27215
config AS_HAS_NON_CONST_ULEB128
def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:)
choice
@ -258,7 +259,7 @@ config DEBUG_INFO_NONE
config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
bool "Rely on the toolchain's implicit default DWARF version"
select DEBUG_INFO
depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128)
depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128)
help
The implicit default version of DWARF debug info produced by a
toolchain changes over time.
@ -282,7 +283,8 @@ config DEBUG_INFO_DWARF4
config DEBUG_INFO_DWARF5
bool "Generate DWARF Version 5 debuginfo"
select DEBUG_INFO
depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128)
depends on !ARCH_HAS_BROKEN_DWARF5
depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128)
help
Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc
5.0+ accepts the -gdwarf-5 flag but only had partial support for some