From 4f001a21080ff2e2f0e1c3692f5e119aedbb3bc1 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Wed, 5 Oct 2022 01:29:03 +0900 Subject: [PATCH 1/8] Kconfig.debug: simplify the dependency of DEBUG_INFO_DWARF4/5 Commit c0a5c81ca9be ("Kconfig.debug: drop GCC 5+ version check for DWARF5") could have cleaned up the code a bit more. "CC_IS_CLANG &&" is unneeded. No functional change is intended. Signed-off-by: Masahiro Yamada Reviewed-by: Nathan Chancellor --- lib/Kconfig.debug | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 3761118d1879ae..72f01edec00e4f 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -264,7 +264,7 @@ config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT config DEBUG_INFO_DWARF4 bool "Generate DWARF Version 4 debuginfo" select DEBUG_INFO - depends on !CC_IS_CLANG || (CC_IS_CLANG && (AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502))) + depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502) help Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2 if using clang without clang's integrated assembler, and gdb 7.0+. @@ -276,7 +276,7 @@ config DEBUG_INFO_DWARF4 config DEBUG_INFO_DWARF5 bool "Generate DWARF Version 5 debuginfo" select DEBUG_INFO - depends on !CC_IS_CLANG || (CC_IS_CLANG && (AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502))) + depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502) 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 From bb1435f3f575b5213eaf27434efa3971f51c01de Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Wed, 5 Oct 2022 01:29:04 +0900 Subject: [PATCH 2/8] Kconfig.debug: add toolchain checks for DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT does not give explicit -gdwarf-* flag. The actual DWARF version is up to the toolchain. The combination of GCC and GAS works fine, and Clang with the integrated assembler is good too. The combination of Clang and GAS is tricky, but at least, the -g flag works for Clang <=13, which defaults to DWARF v4. Clang 14 switched its default to DWARF v5. Now, CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT has the same issue as addressed by commit 98cd6f521f10 ("Kconfig: allow explicit opt in to DWARF v5"). CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y for Clang >= 14 and GAS < 2.35 produces a ton of errors like follows: /tmp/main-c2741c.s: Assembler messages: /tmp/main-c2741c.s:109: Error: junk at end of line, first unrecognized character is `"' /tmp/main-c2741c.s:109: Error: file number less than one Add 'depends on' to check toolchains. Signed-off-by: Masahiro Yamada Reviewed-by: Nathan Chancellor --- lib/Kconfig.debug | 1 + 1 file changed, 1 insertion(+) diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 72f01edec00e4f..db8d9271cabf5e 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -253,6 +253,7 @@ 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) help The implicit default version of DWARF debug info produced by a toolchain changes over time. From fc8c2d8ff20651f887e574767533d1176e3a479c Mon Sep 17 00:00:00 2001 From: Zack Rusin Date: Thu, 6 Oct 2022 10:33:19 -0400 Subject: [PATCH 3/8] kbuild: Stop including vmlinux.bz2 in the rpm's vmlinux.bz2 was added to the rpm packages in 2009 in the fc370ecfdb37 ("kbuild: add vmlinux to kernel rpm") but seemingly hasn't been used since. Originally this should have been split up in a seperate debugging package because it massively increases the size of the generated rpm's e.g. kernel rpm built using binrpm-pkg on Fedora 36 default 5.19.8 kernel config and localmodconfig is ~255MB with vmlinux.bz2 and only ~65MB without it. Make the kernel built rpms about 4x smaller by not including the unused vmlinux.bz2 in them. Signed-off-by: Zack Rusin Signed-off-by: Masahiro Yamada --- scripts/package/mkspec | 2 -- 1 file changed, 2 deletions(-) diff --git a/scripts/package/mkspec b/scripts/package/mkspec index c920c1b18e7ada..70392fd2fd29c1 100755 --- a/scripts/package/mkspec +++ b/scripts/package/mkspec @@ -97,8 +97,6 @@ $M $MAKE %{?_smp_mflags} INSTALL_MOD_PATH=%{buildroot} modules_install $MAKE %{?_smp_mflags} INSTALL_HDR_PATH=%{buildroot}/usr headers_install cp System.map %{buildroot}/boot/System.map-$KERNELRELEASE cp .config %{buildroot}/boot/config-$KERNELRELEASE - bzip2 -9 --keep vmlinux - mv vmlinux.bz2 %{buildroot}/boot/vmlinux-$KERNELRELEASE.bz2 $S$M rm -f %{buildroot}/lib/modules/$KERNELRELEASE/build $S$M rm -f %{buildroot}/lib/modules/$KERNELRELEASE/source $S$M mkdir -p %{buildroot}/usr/src/kernels/$KERNELRELEASE From 11df33c36c4b7a04d2674531f2c6178ad8d61572 Mon Sep 17 00:00:00 2001 From: Richard Acayan Date: Mon, 10 Oct 2022 21:38:28 -0400 Subject: [PATCH 4/8] modpost: put modpost options before argument The musl implementation of getopt stops looking for options after the first non-option argument. Put the options before the non-option argument so environments using musl can still build the kernel and modules. Fixes: f73edc8951b2 ("kbuild: unify two modpost invocations") Link: https://git.musl-libc.org/cgit/musl/tree/src/misc/getopt.c?h=dc9285ad1dc19349c407072cc48ba70dab86de45#n44 Signed-off-by: Richard Acayan Signed-off-by: Masahiro Yamada --- scripts/Makefile.modpost | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost index 7740ce3b29e803..8489a3402eb8cb 100644 --- a/scripts/Makefile.modpost +++ b/scripts/Makefile.modpost @@ -119,7 +119,7 @@ quiet_cmd_modpost = MODPOST $@ echo >&2 "WARNING: $(missing-input) is missing."; \ echo >&2 " Modules may not have dependencies or modversions."; \ echo >&2 " You may get many unresolved symbol warnings.";) \ - sed 's/ko$$/o/' $(or $(modorder-if-needed), /dev/null) | $(MODPOST) $(modpost-args) $(vmlinux.o-if-present) -T - + sed 's/ko$$/o/' $(or $(modorder-if-needed), /dev/null) | $(MODPOST) $(modpost-args) -T - $(vmlinux.o-if-present) targets += $(output-symdump) $(output-symdump): $(modorder-if-needed) $(vmlinux.o-if-present) $(moudle.symvers-if-present) $(MODPOST) FORCE From 04518e4c2edc78bc90b4651d50c4aad48d09ac23 Mon Sep 17 00:00:00 2001 From: Guru Das Srinagesh Date: Tue, 11 Oct 2022 12:06:00 -0700 Subject: [PATCH 5/8] scripts/clang-tools: Convert clang-tidy args to list Convert list of clang-tidy arguments to a list for ease of adding to them and extending them as required. Signed-off-by: Guru Das Srinagesh Suggested-by: Nick Desaulniers Reviewed-by: Nick Desaulniers Signed-off-by: Masahiro Yamada --- scripts/clang-tools/run-clang-tools.py | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/scripts/clang-tools/run-clang-tools.py b/scripts/clang-tools/run-clang-tools.py index bb78c9bde55c94..56f2ec8f0f40a7 100755 --- a/scripts/clang-tools/run-clang-tools.py +++ b/scripts/clang-tools/run-clang-tools.py @@ -45,13 +45,14 @@ def init(l, a): def run_analysis(entry): # Disable all checks, then re-enable the ones we want - checks = "-checks=-*," + checks = [] + checks.append("-checks=-*") if args.type == "clang-tidy": - checks += "linuxkernel-*" + checks.append("linuxkernel-*") else: - checks += "clang-analyzer-*" - checks += ",-clang-analyzer-security.insecureAPI.DeprecatedOrUnsafeBufferHandling" - p = subprocess.run(["clang-tidy", "-p", args.path, checks, entry["file"]], + checks.append("clang-analyzer-*") + checks.append("-clang-analyzer-security.insecureAPI.DeprecatedOrUnsafeBufferHandling") + p = subprocess.run(["clang-tidy", "-p", args.path, ",".join(checks), entry["file"]], stdout=subprocess.PIPE, stderr=subprocess.STDOUT, cwd=entry["directory"]) From c67a85bee78db74c6889a5ca645c3763ad23d863 Mon Sep 17 00:00:00 2001 From: Nick Desaulniers Date: Fri, 14 Oct 2022 09:53:02 -0700 Subject: [PATCH 6/8] kbuild: add -fno-discard-value-names to cmd_cc_ll_c When debugging LLVM IR, it can be handy for clang to not discard value names used for local variables and parameters. Compare the generated IR. -fdiscard-value-names: define i32 @core_sys_select(i32 %0, ptr %1, ptr %2, ptr %3, ptr %4) { %6 = alloca i64 %7 = alloca %struct.poll_wqueues %8 = alloca [64 x i32] -fno-discard-value-names: define i32 @core_sys_select(i32 %n, ptr %inp, ptr %outp, ptr %exp, ptr %end_time) { %expire.i = alloca i64 %table.i = alloca %struct.poll_wqueues %stack_fds = alloca [64 x i32] The rule for generating human readable LLVM IR (.ll) is only useful as a debugging feature: $ make LLVM=1 fs/select.ll As Fangrui notes: A LLVM_ENABLE_ASSERTIONS=off build of Clang defaults to -fdiscard-value-names. A LLVM_ENABLE_ASSERTIONS=on build of Clang defaults to -fno-discard-value-names. Explicitly enable -fno-discard-value-names so that the IR always contains value names regardless of whether assertions were enabled or not. Assertions generally are not enabled in releases of clang packaged by distributions. Link: https://github.com/ClangBuiltLinux/linux/issues/1467 Reviewed-by: Nathan Chancellor Reviewed-by: Fangrui Song Signed-off-by: Nick Desaulniers Signed-off-by: Masahiro Yamada --- scripts/Makefile.build | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/scripts/Makefile.build b/scripts/Makefile.build index 22adbf89cb3103..41f3602fc8de75 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -140,7 +140,7 @@ $(obj)/%.symtypes : $(src)/%.c FORCE # LLVM assembly # Generate .ll files from .c quiet_cmd_cc_ll_c = CC $(quiet_modtag) $@ - cmd_cc_ll_c = $(CC) $(c_flags) -emit-llvm -S -o $@ $< + cmd_cc_ll_c = $(CC) $(c_flags) -emit-llvm -S -fno-discard-value-names -o $@ $< $(obj)/%.ll: $(src)/%.c FORCE $(call if_changed_dep,cc_ll_c) From 3753af778dd9d0d5199d6a7d01b0ead33135d095 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Sat, 15 Oct 2022 05:18:11 +0900 Subject: [PATCH 7/8] kbuild: fix single directory build Commit f110e5a250e3 ("kbuild: refactor single builds of *.ko") was wrong. KBUILD_MODULES _is_ needed for single builds. Otherwise, "make foo/bar/baz/" does not build module objects at all. Fixes: f110e5a250e3 ("kbuild: refactor single builds of *.ko") Reported-by: David Sterba Signed-off-by: Masahiro Yamada Tested-by: David Sterba --- Makefile | 2 ++ 1 file changed, 2 insertions(+) diff --git a/Makefile b/Makefile index 85a63a1d29b37e..48a005fc69ca0b 100644 --- a/Makefile +++ b/Makefile @@ -1978,6 +1978,8 @@ endif single-goals := $(addprefix $(build-dir)/, $(single-no-ko)) +KBUILD_MODULES := 1 + endif # Preset locale variables to speed up the build process. Limit locale From 0a6de78cff600cb991f2a1b7ed376935871796a0 Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Fri, 14 Oct 2022 13:42:11 -0700 Subject: [PATCH 8/8] lib/Kconfig.debug: Add check for non-constant .{s,u}leb128 support to DWARF5 When building with a RISC-V kernel with DWARF5 debug info using clang and the GNU assembler, several instances of the following error appear: /tmp/vgettimeofday-48aa35.s:2963: Error: non-constant .uleb128 is not supported Dumping the .s file reveals these .uleb128 directives come from .debug_loc and .debug_ranges: .Ldebug_loc0: .byte 4 # DW_LLE_offset_pair .uleb128 .Lfunc_begin0-.Lfunc_begin0 # starting offset .uleb128 .Ltmp1-.Lfunc_begin0 # ending offset .byte 1 # Loc expr size .byte 90 # DW_OP_reg10 .byte 0 # DW_LLE_end_of_list .Ldebug_ranges0: .byte 4 # DW_RLE_offset_pair .uleb128 .Ltmp6-.Lfunc_begin0 # starting offset .uleb128 .Ltmp27-.Lfunc_begin0 # ending offset .byte 4 # DW_RLE_offset_pair .uleb128 .Ltmp28-.Lfunc_begin0 # starting offset .uleb128 .Ltmp30-.Lfunc_begin0 # ending offset .byte 0 # DW_RLE_end_of_list There is an outstanding binutils issue to support a non-constant operand to .sleb128 and .uleb128 in GAS for RISC-V but there does not appear to be any movement on it, due to concerns over how it would work with linker relaxation. To avoid these build errors, prevent DWARF5 from being selected when using clang and an assembler that does not have support for these symbol deltas, which can be easily checked in Kconfig with as-instr plus the small test program from the dwz test suite from the binutils issue. Link: https://sourceware.org/bugzilla/show_bug.cgi?id=27215 Link: https://github.com/ClangBuiltLinux/linux/issues/1719 Signed-off-by: Nathan Chancellor Reviewed-by: Nick Desaulniers Signed-off-by: Masahiro Yamada --- lib/Kconfig.debug | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index db8d9271cabf5e..5c1c635758951c 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -231,6 +231,11 @@ 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 + def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:) + choice prompt "Debug information" depends on DEBUG_KERNEL @@ -253,7 +258,7 @@ 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) + depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128) help The implicit default version of DWARF debug info produced by a toolchain changes over time. @@ -277,7 +282,7 @@ 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) + 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 5.0+ accepts the -gdwarf-5 flag but only had partial support for some