diff options
Diffstat (limited to 'scripts')
| -rw-r--r-- | scripts/Makefile.btf | 21 | ||||
| -rw-r--r-- | scripts/Makefile.modfinal | 5 | ||||
| -rw-r--r-- | scripts/Makefile.vmlinux | 2 | ||||
| -rwxr-xr-x | scripts/gen-btf.sh | 147 | ||||
| -rwxr-xr-x | scripts/link-vmlinux.sh | 43 |
5 files changed, 165 insertions, 53 deletions
diff --git a/scripts/Makefile.btf b/scripts/Makefile.btf index db76335dd917..562a04b40e06 100644 --- a/scripts/Makefile.btf +++ b/scripts/Makefile.btf @@ -7,14 +7,7 @@ JOBS := $(patsubst -j%,%,$(filter -j%,$(MAKEFLAGS))) ifeq ($(call test-le, $(pahole-ver), 125),y) -# pahole 1.18 through 1.21 can't handle zero-sized per-CPU vars -ifeq ($(call test-le, $(pahole-ver), 121),y) -pahole-flags-$(call test-ge, $(pahole-ver), 118) += --skip_encoding_btf_vars -endif - -pahole-flags-$(call test-ge, $(pahole-ver), 121) += --btf_gen_floats - -pahole-flags-$(call test-ge, $(pahole-ver), 122) += -j$(JOBS) +pahole-flags-y += --btf_gen_floats -j$(JOBS) pahole-flags-$(call test-ge, $(pahole-ver), 125) += --skip_encoding_btf_inconsistent_proto --btf_gen_optimized @@ -25,13 +18,15 @@ pahole-flags-$(call test-ge, $(pahole-ver), 126) = -j$(JOBS) --btf_features=enc pahole-flags-$(call test-ge, $(pahole-ver), 130) += --btf_features=attributes -ifneq ($(KBUILD_EXTMOD),) -module-pahole-flags-$(call test-ge, $(pahole-ver), 128) += --btf_features=distilled_base -endif - endif pahole-flags-$(CONFIG_PAHOLE_HAS_LANG_EXCLUDE) += --lang_exclude=rust export PAHOLE_FLAGS := $(pahole-flags-y) -export MODULE_PAHOLE_FLAGS := $(module-pahole-flags-y) + +resolve-btfids-flags-y := +resolve-btfids-flags-$(CONFIG_WERROR) += --fatal_warnings +resolve-btfids-flags-$(if $(KBUILD_EXTMOD),y) += --distill_base +resolve-btfids-flags-$(if $(KBUILD_VERBOSE),y) += --verbose + +export RESOLVE_BTFIDS_FLAGS := $(resolve-btfids-flags-y) diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal index 149e12ff5700..adcbcde16a07 100644 --- a/scripts/Makefile.modfinal +++ b/scripts/Makefile.modfinal @@ -42,9 +42,8 @@ quiet_cmd_btf_ko = BTF [M] $@ cmd_btf_ko = \ if [ ! -f $(objtree)/vmlinux ]; then \ printf "Skipping BTF generation for %s due to unavailability of vmlinux\n" $@ 1>&2; \ - else \ - LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J $(PAHOLE_FLAGS) $(MODULE_PAHOLE_FLAGS) --btf_base $(objtree)/vmlinux $@; \ - $(RESOLVE_BTFIDS) -b $(objtree)/vmlinux $@; \ + else \ + $(CONFIG_SHELL) $(srctree)/scripts/gen-btf.sh --btf_base $(objtree)/vmlinux $@; \ fi; # Same as newer-prereqs, but allows to exclude specified extra dependencies diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux index 276c3134a563..fcae1e432d9a 100644 --- a/scripts/Makefile.vmlinux +++ b/scripts/Makefile.vmlinux @@ -71,7 +71,7 @@ targets += vmlinux.unstripped .vmlinux.export.o vmlinux.unstripped: scripts/link-vmlinux.sh vmlinux.o .vmlinux.export.o $(KBUILD_LDS) FORCE +$(call if_changed_dep,link_vmlinux) ifdef CONFIG_DEBUG_INFO_BTF -vmlinux.unstripped: $(RESOLVE_BTFIDS) +vmlinux.unstripped: $(RESOLVE_BTFIDS) $(srctree)/scripts/gen-btf.sh endif ifdef CONFIG_BUILDTIME_TABLE_SORT diff --git a/scripts/gen-btf.sh b/scripts/gen-btf.sh new file mode 100755 index 000000000000..8ca96eb10a69 --- /dev/null +++ b/scripts/gen-btf.sh @@ -0,0 +1,147 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# Copyright (c) 2025 Meta Platforms, Inc. and affiliates. +# +# This script generates BTF data for the provided ELF file. +# +# Kernel BTF generation involves these conceptual steps: +# 1. pahole generates BTF from DWARF data +# 2. resolve_btfids applies kernel-specific btf2btf +# transformations and computes data for .BTF_ids section +# 3. the result gets linked/objcopied into the target binary +# +# How step (3) should be done differs between vmlinux, and +# kernel modules, which is the primary reason for the existence +# of this script. +# +# For modules the script expects vmlinux passed in as --btf_base. +# Generated .BTF, .BTF.base and .BTF_ids sections become embedded +# into the input ELF file with objcopy. +# +# For vmlinux the input file remains unchanged and two files are produced: +# - ${1}.btf.o ready for linking into vmlinux +# - ${1}.BTF_ids with .BTF_ids data blob +# This output is consumed by scripts/link-vmlinux.sh + +set -e + +usage() +{ + echo "Usage: $0 [--btf_base <file>] <target ELF file>" + exit 1 +} + +BTF_BASE="" + +while [ $# -gt 0 ]; do + case "$1" in + --btf_base) + BTF_BASE="$2" + shift 2 + ;; + -*) + echo "Unknown option: $1" >&2 + usage + ;; + *) + break + ;; + esac +done + +if [ $# -ne 1 ]; then + usage +fi + +ELF_FILE="$1" +shift + +is_enabled() { + grep -q "^$1=y" ${objtree}/include/config/auto.conf +} + +case "${KBUILD_VERBOSE}" in +*1*) + set -x + ;; +esac + +gen_btf_data() +{ + btf1="${ELF_FILE}.BTF.1" + ${PAHOLE} -J ${PAHOLE_FLAGS} \ + ${BTF_BASE:+--btf_base ${BTF_BASE}} \ + --btf_encode_detached=${btf1} \ + "${ELF_FILE}" + + ${RESOLVE_BTFIDS} ${RESOLVE_BTFIDS_FLAGS} \ + ${BTF_BASE:+--btf_base ${BTF_BASE}} \ + --btf ${btf1} "${ELF_FILE}" +} + +gen_btf_o() +{ + btf_data=${ELF_FILE}.btf.o + + # Create ${btf_data} which contains just .BTF section but no symbols. Add + # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all + # deletes all symbols including __start_BTF and __stop_BTF, which will + # be redefined in the linker script. + echo "" | ${CC} ${CLANG_FLAGS} ${KBUILD_CPPFLAGS} ${KBUILD_CFLAGS} -fno-lto -c -x c -o ${btf_data} - + ${OBJCOPY} --add-section .BTF=${ELF_FILE}.BTF \ + --set-section-flags .BTF=alloc,readonly ${btf_data} + ${OBJCOPY} --only-section=.BTF --strip-all ${btf_data} + + # Change e_type to ET_REL so that it can be used to link final vmlinux. + # GNU ld 2.35+ and lld do not allow an ET_EXEC input. + if is_enabled CONFIG_CPU_BIG_ENDIAN; then + et_rel='\0\1' + else + et_rel='\1\0' + fi + printf "${et_rel}" | dd of="${btf_data}" conv=notrunc bs=1 seek=16 status=none +} + +embed_btf_data() +{ + ${OBJCOPY} --add-section .BTF=${ELF_FILE}.BTF ${ELF_FILE} + + # a module might not have a .BTF_ids or .BTF.base section + btf_base="${ELF_FILE}.BTF.base" + if [ -f "${btf_base}" ]; then + ${OBJCOPY} --add-section .BTF.base=${btf_base} ${ELF_FILE} + fi + btf_ids="${ELF_FILE}.BTF_ids" + if [ -f "${btf_ids}" ]; then + ${RESOLVE_BTFIDS} --patch_btfids ${btf_ids} ${ELF_FILE} + fi +} + +cleanup() +{ + rm -f "${ELF_FILE}.BTF.1" + rm -f "${ELF_FILE}.BTF" + if [ "${BTFGEN_MODE}" = "module" ]; then + rm -f "${ELF_FILE}.BTF.base" + rm -f "${ELF_FILE}.BTF_ids" + fi +} +trap cleanup EXIT + +BTFGEN_MODE="vmlinux" +if [ -n "${BTF_BASE}" ]; then + BTFGEN_MODE="module" +fi + +gen_btf_data + +case "${BTFGEN_MODE}" in +vmlinux) + gen_btf_o + ;; +module) + embed_btf_data + ;; +esac + +exit 0 diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index 4ab44c73da4d..16d6a048e07c 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -106,34 +106,6 @@ vmlinux_link() ${kallsymso} ${btf_vmlinux_bin_o} ${arch_vmlinux_o} ${ldlibs} } -# generate .BTF typeinfo from DWARF debuginfo -# ${1} - vmlinux image -gen_btf() -{ - local btf_data=${1}.btf.o - - info BTF "${btf_data}" - LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1} - - # Create ${btf_data} which contains just .BTF section but no symbols. Add - # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all - # deletes all symbols including __start_BTF and __stop_BTF, which will - # be redefined in the linker script. Add 2>/dev/null to suppress GNU - # objcopy warnings: "empty loadable segment detected at ..." - ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \ - --strip-all ${1} "${btf_data}" 2>/dev/null - # Change e_type to ET_REL so that it can be used to link final vmlinux. - # GNU ld 2.35+ and lld do not allow an ET_EXEC input. - if is_enabled CONFIG_CPU_BIG_ENDIAN; then - et_rel='\0\1' - else - et_rel='\1\0' - fi - printf "${et_rel}" | dd of="${btf_data}" conv=notrunc bs=1 seek=16 status=none - - btf_vmlinux_bin_o=${btf_data} -} - # Create ${2}.o file with all symbols from the ${1} object file kallsyms() { @@ -205,6 +177,7 @@ if is_enabled CONFIG_ARCH_WANTS_PRE_LINK_VMLINUX; then fi btf_vmlinux_bin_o= +btfids_vmlinux= kallsymso= strip_debug= generate_map= @@ -232,11 +205,14 @@ if is_enabled CONFIG_KALLSYMS || is_enabled CONFIG_DEBUG_INFO_BTF; then fi if is_enabled CONFIG_DEBUG_INFO_BTF; then - if ! gen_btf .tmp_vmlinux1; then + info BTF .tmp_vmlinux1 + if ! ${CONFIG_SHELL} ${srctree}/scripts/gen-btf.sh .tmp_vmlinux1; then echo >&2 "Failed to generate BTF for vmlinux" echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" exit 1 fi + btf_vmlinux_bin_o=.tmp_vmlinux1.btf.o + btfids_vmlinux=.tmp_vmlinux1.BTF_ids fi if is_enabled CONFIG_KALLSYMS; then @@ -289,14 +265,9 @@ fi vmlinux_link "${VMLINUX}" -# fill in BTF IDs if is_enabled CONFIG_DEBUG_INFO_BTF; then - info BTFIDS "${VMLINUX}" - RESOLVE_BTFIDS_ARGS="" - if is_enabled CONFIG_WERROR; then - RESOLVE_BTFIDS_ARGS=" --fatal_warnings " - fi - ${RESOLVE_BTFIDS} ${RESOLVE_BTFIDS_ARGS} "${VMLINUX}" + info BTFIDS ${VMLINUX} + ${RESOLVE_BTFIDS} --patch_btfids ${btfids_vmlinux} ${VMLINUX} fi mksysmap "${VMLINUX}" System.map |