From 83da9f3197e50d2e2c5b8b8d8358b6be6e867d7f Mon Sep 17 00:00:00 2001 From: "Lorenzo Stoakes (ARM)" Date: Wed, 23 Sep 2026 18:17:52 +0100 Subject: kallsyms: output binary data to speed output and kallsyms assembly kallsyms generates an assembly file that consists mostly of .byte entries containing compressed names, token strings and name-sorted sequence numbers. For an x86-64 build with 158k symbols that is a 37 MiB .S file which takes 0.57s to assemble each of the two to three times it is built over a kernel build. Each time it is generated it also takes kallsyms a similar amount of time to output it. Avoid this overhead by instead outputting this data as binary and importing it into the assembly using the .incbin directive. Tables that are wider than a byte remain part of the assembly to ensure endianness and relative relocations are performed correctly. With this change, the output assembly file shrinks from 37 MiB to 9.8 MiB, with a 2.6 MiB binary data file alongside it, and the object remains identical. The generated binary file is deleted correctly on build clean along with all other ephemeral data. On an x86-64 system with CONFIG_KALLSYMS_ALL set: before after delta scripts/kallsyms 0.24s 0.18s 0.06s assemble 0.57s 0.16s 0.41s Per kallsyms invocation/assembly, for a total of 0.47s time saving upon invocation. An incremental build on the same system was reduced from 11.15s to 9.65s, indicating a total of 1.5 seconds saved over the build. The kallsyms runs and their assembly are on the serial tail of every build that links vmlinux, no-op builds are unchanged. Whole build, 128-thread Threadripper 9980X, best of N runs: before after delta ------------------------------- x86 defconfig, touch mm/vma.c, gcc 10.6s 9.7s -0.89s (-8%) x86 defconfig, touch mm/vma.c, clang 10.5s 9.3s -1.2s (-11%) x86 defconfig, clean, gcc 31.3s 30.3s -1.0s (-3%) x86 defconfig, clean, clang 33.3s 31.7s -1.6s (-5%) x86 allmodconfig, touch mm/vma.c, gcc 38.7s 37.2s -1.4s (-4%) x86 allmodconfig, touch mm/vma.c, clang 39.1s 36.4s -2.6s (-7%) Assisted-by: LLM Reviewed-by: Kees Cook Signed-off-by: Lorenzo Stoakes (ARM) Link: https://patch.msgid.link/20260923-build-speedup-v4-3-73128809a4a4@kernel.org Signed-off-by: Nathan Chancellor --- scripts/link-vmlinux.sh | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'scripts/link-vmlinux.sh') diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index ab0b8125c8cb..e88604150d2c 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -132,7 +132,7 @@ kallsyms() fi info KSYMS "${2}.S" - scripts/kallsyms ${kallsymopt} "${1}" > "${2}.S" + scripts/kallsyms ${kallsymopt} "${1}" "${2}.bin" > "${2}.S" info AS "${2}.o" ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \ -- cgit v1.2.3 From c2970d8b52d132bf5152fba592205a2204d7be5a Mon Sep 17 00:00:00 2001 From: "Lorenzo Stoakes (ARM)" Date: Wed, 23 Sep 2026 18:17:54 +0100 Subject: kbuild: do not sort nm output where the order is irrelevant Unless instructed otherwise, nm sorts by name. There are places where this is unnecessary - an invocation from scripts/sorttable every vmlinux link, scripts/check-function-names.sh run after every vmlinux.o link, and the x86 VOFFSET and ZOFFSET listings between vmlinux and bzImage. Both GNU nm and llvm-nm accept the same '-p' parameter to disable sorting in these instances, so use that to prevent this unnecessary work. Each nm run on its own, x86-64, median of 5: GNU nm 2.47 llvm-nm 22 before after delta before after delta defconfig sorttable, nm -S vmlinux 0.080s 0.039s -0.041s 0.265s 0.113s -0.152s check-function-names.sh 0.072s 0.033s -0.039s 0.244s 0.102s -0.142s VOFFSET 0.077s 0.034s -0.043s 0.261s 0.113s -0.148s ZOFFSET 0.007s 0.005s -0.002s 0.005s 0.005s 0.000s TOTAL -0.125s -0.442s allmodconfig sorttable, nm -S vmlinux 0.156s 0.063s -0.093s 0.539s 0.223s -0.316s check-function-names.sh 0.149s 0.054s -0.095s 0.537s 0.217s -0.320s VOFFSET 0.146s 0.052s -0.094s 0.524s 0.221s -0.303s ZOFFSET 0.007s 0.005s -0.002s 0.006s 0.004s -0.002s TOTAL -0.284s -0.941s llvm-nm appears to be a lot slower than GNU nm, so these builds naturally improve the most. The four run one after another in the serial tail of every build that links vmlinux so impact kernel builds directly. In an allmodconfig the decompressor is built in parallel while the modules, so only the two before the vmlinux link contribute to build time. The build outputs remain unchanged. Whole build, 128-thread Threadripper 9980X, best of N runs: before after delta --------------------------------- x86 defconfig, touch mm/vma.c, gcc 9.7s 9.5s -0.18s (-2%) x86 defconfig, touch mm/vma.c, clang 9.3s 9.0s -0.27s (-3%) x86 defconfig, clean, gcc 30.3s 30.1s -0.16s (-1%) x86 defconfig, clean, clang 31.7s 31.2s -0.55s (-2%) x86 allmodconfig, touch mm/vma.c, clang 36.4s 35.8s -0.67s (-2%) Assisted-by: LLM Reviewed-by: Nicolas Schier Reviewed-by: Kees Cook Signed-off-by: Lorenzo Stoakes (ARM) Link: https://patch.msgid.link/20260923-build-speedup-v4-5-73128809a4a4@kernel.org Signed-off-by: Nathan Chancellor --- arch/x86/boot/Makefile | 2 +- arch/x86/boot/compressed/Makefile | 2 +- scripts/check-function-names.sh | 3 ++- scripts/link-vmlinux.sh | 2 +- 4 files changed, 5 insertions(+), 4 deletions(-) (limited to 'scripts/link-vmlinux.sh') diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile index 3f9fb3698d66..4a9bce32586d 100644 --- a/arch/x86/boot/Makefile +++ b/arch/x86/boot/Makefile @@ -74,7 +74,7 @@ SETUP_OBJS = $(addprefix $(obj)/,$(setup-y)) sed-zoffset := -e 's/^\([0-9a-fA-F]*\) [a-zA-Z] \(startup_32\|efi.._stub_entry\|efi\(32\)\?_pe_entry\|input_data\|kernel_info\|_end\|_ehead\|_text\|_e\?data\|_e\?sbat\|z_.*\)$$/\#define ZO_\2 0x\1/p' quiet_cmd_zoffset = ZOFFSET $@ - cmd_zoffset = $(NM) $< | sed -n $(sed-zoffset) > $@ + cmd_zoffset = $(NM) -p $< | sed -n $(sed-zoffset) > $@ targets += zoffset.h $(obj)/zoffset.h: $(obj)/compressed/vmlinux FORCE diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index 06934f9691d6..6ec5e031db1d 100644 --- a/arch/x86/boot/compressed/Makefile +++ b/arch/x86/boot/compressed/Makefile @@ -76,7 +76,7 @@ HOST_EXTRACFLAGS += -I$(srctree)/tools/include sed-voffset := -e 's/^\([0-9a-fA-F]*\) [ABbCDGRSTtVW] \(_text\|__start_rodata\|_sinittext\|__inittext_end\|__bss_start\|_end\)$$/\#define VO_\2 _AC(0x\1,UL)/p' quiet_cmd_voffset = VOFFSET $@ - cmd_voffset = $(NM) $< | sed -n $(sed-voffset) > $@ + cmd_voffset = $(NM) -p $< | sed -n $(sed-voffset) > $@ targets += ../voffset.h diff --git a/scripts/check-function-names.sh b/scripts/check-function-names.sh index 08071133e5a5..94883e690627 100755 --- a/scripts/check-function-names.sh +++ b/scripts/check-function-names.sh @@ -13,7 +13,8 @@ if [ ! -f "$objfile" ]; then exit 1 fi -bad_symbols=$(${NM:-nm} "$objfile" | awk '$2 ~ /^[TtWw]$/ {print $3}' | grep -E '^(startup|exit|split|unlikely|hot|unknown)(\.|$)') +bad_symbols=$(${NM:-nm} -p "$objfile" | awk '$2 ~ /^[TtWw]$/ {print $3}' | + grep -E '^(startup|exit|split|unlikely|hot|unknown)(\.|$)') if [ -n "$bad_symbols" ]; then echo "$bad_symbols" | while read -r sym; do diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index e88604150d2c..970ca10f8fa9 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -161,7 +161,7 @@ mksysmap() sorttable() { - ${NM} -S ${1} > .tmp_vmlinux.nm-sort + ${NM} -p -S ${1} > .tmp_vmlinux.nm-sort ${objtree}/scripts/sorttable -s .tmp_vmlinux.nm-sort ${1} } -- cgit v1.2.3 From 8050568e0a46f944117970c3969f9316125bc34d Mon Sep 17 00:00:00 2001 From: "Lorenzo Stoakes (ARM)" Date: Wed, 23 Sep 2026 18:17:55 +0100 Subject: kbuild: only emit vmlinux relocations when required A kernel build consists of more than one linking pass on vmlinux.o and vmlinux, at minimum two, and with CONFIG_KALLSYMS and BTF enabled on x86-64 for example there are 5 such stages. For architectures that build their own relocation tables (x86, riscv, mips, s390), vmlinux is linked with the --emit-relocs parameter specified. However, this is only required on the final vmlinux link. Symbol tables of trial links preceding it don't need it because they already check that System.map matches kallsyms symbols on each build. GNU ld is slow at emitting relocation tables, so this results in a reduction in build time. Whole build, 128-thread Threadripper 9980X, best of N runs: before after delta ------------------------------- x86 defconfig, touch mm/vma.c, gcc 9.5s 9.1s -0.42s (-4%) x86 defconfig, clean, gcc 30.1s 29.5s -0.59s (-2%) x86 allmodconfig, touch mm/vma.c, gcc 37.2s 35.8s -1.4s (-4%) Note that this has little impact on LLVM ld which performs this operation more efficiently. Assisted-by: LLM Reviewed-by: Nicolas Schier Reviewed-by: Kees Cook Signed-off-by: Lorenzo Stoakes (ARM) Link: https://patch.msgid.link/20260923-build-speedup-v4-6-73128809a4a4@kernel.org Signed-off-by: Nathan Chancellor --- Makefile | 3 ++- scripts/link-vmlinux.sh | 5 +++++ 2 files changed, 7 insertions(+), 1 deletion(-) (limited to 'scripts/link-vmlinux.sh') diff --git a/Makefile b/Makefile index f6745d723f6d..ab3ba78376f7 100644 --- a/Makefile +++ b/Makefile @@ -1265,8 +1265,9 @@ ifdef CONFIG_LD_ORPHAN_WARN LDFLAGS_vmlinux += --orphan-handling=$(CONFIG_LD_ORPHAN_WARN_LEVEL) endif +# --emit-relocs is added by scripts/link-vmlinux.sh, for the final link only. ifneq ($(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS),) -LDFLAGS_vmlinux += --emit-relocs --discard-none +LDFLAGS_vmlinux += --discard-none endif # Align the architecture of userspace programs with the kernel diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index 970ca10f8fa9..ed5ff97c0667 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -96,6 +96,11 @@ vmlinux_link() ldflags="${ldflags} ${wl}--strip-debug" fi + # Only the final link actually requires the relocations. + if [ "${output}" = "${VMLINUX}" ] && is_enabled CONFIG_ARCH_VMLINUX_NEEDS_RELOCS; then + ldflags="${ldflags} ${wl}--emit-relocs" + fi + if [ -n "${generate_map}" ]; then ldflags="${ldflags} ${wl}-Map=vmlinux.map" fi -- cgit v1.2.3 From 531980b4b17e916f5955bcc53a188827624f5a0f Mon Sep 17 00:00:00 2001 From: "Lorenzo Stoakes (ARM)" Date: Wed, 23 Sep 2026 18:17:57 +0100 Subject: kallsyms: reimplement mksysmap in C mksysmap is a sed script consisting of 30 patterns which link-vmlinux.sh uses to generate *.syms files, and which kallsyms is then called against to generate *.kallsyms files, with the final vmlinux build ultimately generating System.map. For an x86-64 allmodconfig build, this involves three nm runs over a 250 MiB file and half a million lines written and read each time - 0.5s per pass for llvm-nm, and 0.2s for GNU nm, with parsing on top of that. This is unnecessary, instead have kallsyms simply read the ELF file directly making use of the existing elf-parse library in scripts/. This changes kallsyms such that its input is no longer the output from nm, but rather an ELF file. However, if the input file is empty, it outputs an empty table, which retains the same behaviour on first pass that the build system expects. System.map is byte-identical to nm | mksysmap for GNU nm and llvm-nm on two x86 configurations each, and for llvm-nm on arm64, arm, s390 and loongarch defconfigs, so are the kallsyms tables of every pass. Relinking vmlinux, link steps included: before after allmodconfig clang 9.1s 7.9s allmodconfig gcc 7.8s 7.6s defconfig clang 3.7s 3.0s defconfig gcc 3.5s 3.4s Whole build, 128-thread Threadripper 9980X, best of N runs: before after delta ------------------------------- x86 defconfig, touch mm/vma.c, gcc 9.1s 8.6s -0.43s (-5%) x86 defconfig, touch mm/vma.c, clang 9.0s 8.0s -1.1s (-12%) x86 defconfig, clean, gcc 29.5s 28.9s -0.64s (-2%) x86 defconfig, clean, clang 31.2s 29.8s -1.4s (-5%) x86 allmodconfig, touch mm/vma.c, gcc 35.8s 35.0s -0.77s (-2%) x86 allmodconfig, touch mm/vma.c, clang 35.8s 33.7s -2.0s (-6%) Assisted-by: LLM Signed-off-by: Lorenzo Stoakes (ARM) Link: https://patch.msgid.link/20260923-build-speedup-v4-8-73128809a4a4@kernel.org Signed-off-by: Nathan Chancellor --- scripts/Makefile | 5 +- scripts/kallsyms-sysmap.c | 248 ++++++++++++++++++++++++++++++++++++++++++++++ scripts/kallsyms.c | 162 +++++++++++++++++------------- scripts/kallsyms.h | 44 ++++++++ scripts/link-vmlinux.sh | 15 +-- scripts/mksysmap | 94 ------------------ 6 files changed, 395 insertions(+), 173 deletions(-) create mode 100644 scripts/kallsyms-sysmap.c create mode 100644 scripts/kallsyms.h delete mode 100755 scripts/mksysmap (limited to 'scripts/link-vmlinux.sh') diff --git a/scripts/Makefile b/scripts/Makefile index 3434a82a119f..38d58b0a37e6 100644 --- a/scripts/Makefile +++ b/scripts/Makefile @@ -3,7 +3,7 @@ # scripts contains sources for various helper programs used throughout # the kernel for the build process. -hostprogs-always-$(CONFIG_KALLSYMS) += kallsyms +hostprogs-always-y += kallsyms hostprogs-always-$(BUILD_C_RECORDMCOUNT) += recordmcount hostprogs-always-$(CONFIG_BUILDTIME_TABLE_SORT) += sorttable hostprogs-always-$(CONFIG_ASN1) += asn1_compiler @@ -13,6 +13,7 @@ hostprogs-always-$(CONFIG_RUST_KERNEL_DOCTESTS) += rustdoc_test_builder hostprogs-always-$(CONFIG_RUST_KERNEL_DOCTESTS) += rustdoc_test_gen hostprogs-always-$(CONFIG_TRACEPOINTS) += tracepoint-update +kallsyms-objs := kallsyms.o kallsyms-sysmap.o elf-parse.o sorttable-objs := sorttable.o elf-parse.o tracepoint-update-objs := tracepoint-update.o elf-parse.o @@ -30,6 +31,8 @@ rustdoc_test_builder-rust := y rustdoc_test_gen-rust := y HOSTCFLAGS_tracepoint-update.o = -I$(srctree)/tools/include +HOSTCFLAGS_kallsyms.o = -I$(srctree)/tools/include +HOSTCFLAGS_kallsyms-sysmap.o = -I$(srctree)/tools/include HOSTCFLAGS_elf-parse.o = -I$(srctree)/tools/include HOSTCFLAGS_sorttable.o = -I$(srctree)/tools/include HOSTLDLIBS_sorttable = -lpthread diff --git a/scripts/kallsyms-sysmap.c b/scripts/kallsyms-sysmap.c new file mode 100644 index 000000000000..a482968eba51 --- /dev/null +++ b/scripts/kallsyms-sysmap.c @@ -0,0 +1,248 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Obtain symbols from vmlinux for usage by kallsyms. Replaces mksysmap. + * + * To retain compatibility, it provides the same output as nm, only faster. + */ + +#include +#include +#include +#include +#include + +#include "elf-parse.h" +#include "kallsyms.h" + +/* + * What mksysmap dropped from System.map, by name: symbols that are not needed + * there, or not suitable for kallsyms. + */ +static const char *const sysmap_omit_prefixes[] = { + /* local symbols for ARM, MIPS, etc. */ + "$", + /* local labels, .LBB, .Ltmpxxx, .L__unnamed_xx, .LASANPC, etc. */ + ".L", + /* arm64 EFI stub namespace */ + "__efistub_", + /* arm64 local symbols in PIE namespace */ + "__pi_$", + "__pi_.L", + /* arm64 local symbols in non-VHE KVM namespace */ + "__kvm_nvhe_$", + "__kvm_nvhe_.L", + /* CFI type identifiers */ + "__kcfi_typeid_", + "__kvm_nvhe___kcfi_typeid_", + "__pi___kcfi_typeid_", + /* CRC from modversions */ + "__crc_", + /* EXPORT_SYMBOL (symbol name) */ + "__kstrtab_", + /* EXPORT_SYMBOL (namespace) */ + "__kstrtabns_", + /* MODULE_DEVICE_TABLE (symbol name) */ + "__mod_device_table__", +}; + +static const char *const sysmap_omit_suffixes[] = { + /* arm */ + "_from_arm", + "_from_thumb", + "_veneer", +}; + +static const char *const sysmap_omit_names[] = { + /* for LoongArch? */ + "L0", + /* ppc */ + "_SDA_BASE_", + "_SDA2_BASE_", +}; + +/* Symbols that contain the pattern anywhere are dropped. */ +static const char *const sysmap_omit_patterns[] = { + /* ppc stub */ + ".long_branch.", + ".plt_branch.", +}; + +/* __*Thunk_: the linker's range extension thunks on arm. */ +static bool is_range_thunk(const char *name) +{ + const char *p; + + if (!string_starts_with(name, "__")) + return false; + for (p = name + 2; isalnum((unsigned char)*p); p++) + ; + return p - name >= 7 && *p == '_' && strncmp(p - 5, "Thunk", 5) == 0; +} + +/* __UNIQUE_ID_modinfo_: the MODULE_INFO() strings of built-in code. */ +static bool is_modinfo_id(const char *name) +{ + static const char prefix[] = "__UNIQUE_ID_modinfo_"; + const char *p; + + if (!string_starts_with(name, prefix)) + return false; + for (p = name + strlen(prefix); isdigit((unsigned char)*p); p++) + ; + return !*p; +} + +static bool sysmap_omits(const char *name, char type) +{ + size_t i; + + /* Absolute, undefined and debugging symbols. */ + if (type == 'a' || type == 'N' || type == 'U' || type == 'w') + return true; + + for (i = 0; i < ARRAY_SIZE(sysmap_omit_prefixes); i++) + if (string_starts_with(name, sysmap_omit_prefixes[i])) + return true; + for (i = 0; i < ARRAY_SIZE(sysmap_omit_suffixes); i++) + if (string_ends_with(name, sysmap_omit_suffixes[i])) + return true; + for (i = 0; i < ARRAY_SIZE(sysmap_omit_names); i++) + if (strcmp(name, sysmap_omit_names[i]) == 0) + return true; + for (i = 0; i < ARRAY_SIZE(sysmap_omit_patterns); i++) + if (strstr(name, sysmap_omit_patterns[i])) + return true; + + return is_range_thunk(name) || is_modinfo_id(name); +} + +/* nm's letter for a symbol defined in a section, as BFD classifies it. */ +static char section_symbol_type(Elf_Shdr *shdr, const char *secname) +{ + static const char *const debug_prefixes[] = { + ".debug", ".zdebug", ".gnu.debuglto_.debug_", + ".gnu.linkonce.wi.", ".line", ".stab", + }; + const uint64_t flags = shdr_flags(shdr); + size_t i; + + if (flags & SHF_EXECINSTR) + return 't'; + if (flags & SHF_ALLOC) { + if (shdr_type(shdr) == SHT_NOBITS) + return 'b'; + return flags & SHF_WRITE ? 'd' : 'r'; + } + for (i = 0; i < ARRAY_SIZE(debug_prefixes); i++) + if (string_starts_with(secname, debug_prefixes[i])) + return 'N'; + if (shdr_type(shdr) != SHT_NOBITS && !(flags & SHF_WRITE)) + return 'n'; + return '?'; +} + +/* The letter nm prints for a symbol, or 0 for one it leaves out. */ +static char elf_symbol_type(const struct elf_file *elf, Elf_Sym *sym) +{ + unsigned int bind = sym_bind(sym), type = sym_type(sym); + unsigned int shndx = sym_shndx(sym); + Elf_Shdr *shdr; + char c; + + if (type == STT_SECTION || type == STT_FILE) + return 0; + if (shndx == SHN_COMMON) + return 'C'; + if (shndx == SHN_UNDEF) { + if (bind == STB_WEAK) + return type == STT_OBJECT ? 'v' : 'w'; + return 'U'; + } + if (type == STT_GNU_IFUNC) + return 'i'; + if (bind == STB_WEAK) + return type == STT_OBJECT ? 'V' : 'W'; + if (bind == STB_GNU_UNIQUE) + return 'u'; + if (bind != STB_GLOBAL && bind != STB_LOCAL) + return '?'; + + if (shndx == SHN_ABS) { + c = 'a'; + } else if (shndx < elf->shnum) { + shdr = elf_section(elf, shndx); + c = section_symbol_type(shdr, elf_section_name(elf, shdr)); + } else { + return '?'; + } + + return bind == STB_GLOBAL ? toupper(c) : c; +} + +/* nm -n order: by address, then by name. */ +static int compare_symbols(const void *a, const void *b) +{ + const struct sysmap_symbol *sa = a, *sb = b; + + if (sa->addr != sb->addr) + return sa->addr < sb->addr ? -1 : 1; + return strcmp(sa->name, sb->name); +} + +/* The symbols "nm -n | mksysmap" would list, in that order. */ +static struct sysmap_symbol *elf_read_symbols(const struct elf_file *elf, + size_t *nr_kept) +{ + struct sysmap_symbol *syms = xmalloc(elf->nr_syms * sizeof(*syms)); + size_t i, n = 0; + + for (i = 1; i < elf->nr_syms; i++) { + Elf_Sym *sym = elf_symbol(elf, i); + const char *name = elf->strtab + sym_name(sym); + char type = elf_symbol_type(elf, sym); + + if (!type || sysmap_omits(name, type)) + continue; + + syms[n].addr = sym_value(sym); + syms[n].name = name; + syms[n].type = type; + n++; + } + + qsort(syms, n, sizeof(*syms), compare_symbols); + *nr_kept = n; + return syms; +} + +struct sysmap *sysmap_read(const char *path) +{ + struct sysmap *map = xcalloc(1, sizeof(*map)); + + /* The names point into the mapping; keep it until the map is freed. */ + if (elf_open_ro(path, (1 << ET_EXEC) | (1 << ET_DYN), &map->elf)) + exit(EXIT_FAILURE); + map->syms = elf_read_symbols(&map->elf, &map->nr_syms); + map->addr_width = elf_map_long_size(map->elf.base) * 2; + + return map; +} + +void sysmap_write(const struct sysmap *map, FILE *out) +{ + size_t i; + + for (i = 0; i < map->nr_syms; i++) { + const struct sysmap_symbol *s = &map->syms[i]; + + fprintf(out, "%0*llx %c %s\n", map->addr_width, s->addr, s->type, + s->name); + } +} + +void sysmap_free(struct sysmap *map) +{ + free(map->syms); + elf_close(&map->elf); + free(map); +} diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c index b615db767b1d..ecb444078c1c 100644 --- a/scripts/kallsyms.c +++ b/scripts/kallsyms.c @@ -5,7 +5,12 @@ * This software may be used and distributed according to the terms * of the GNU General Public License, incorporated herein by reference. * - * Usage: kallsyms [--all-symbols] [--pc-relative] in.map out.bin > out.S + * Usage: kallsyms [--all-symbols] [--pc-relative] [--sysmap=out.map] in out.bin > out.S + * kallsyms --sysmap=out.map in + * + * in is vmlinux; an empty file stands for the first link, which has no + * symbols yet, and gives an empty table. --sysmap also writes the symbols + * in System.map format. * * The byte tables go to out.bin and are pulled into out.S with .incbin; * wider tables stay assembler source for endianness and relocations. @@ -21,7 +26,6 @@ * */ -#include #include #include #include @@ -29,10 +33,10 @@ #include #include #include - +#include #include -#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof(arr[0])) +#include "kallsyms.h" #define KSYM_NAME_LEN 512 @@ -108,11 +112,13 @@ static void sym_arr_free(struct sym_arr *arr) static void usage(void) { - fprintf(stderr, "Usage: kallsyms [--all-symbols] [--pc-relative] in.map out.bin > out.S\n"); + fprintf(stderr, "Usage: kallsyms [--all-symbols] [--pc-relative] [--sysmap=out.map]\n" + " in out.bin > out.S\n" + " kallsyms --sysmap=out.map vmlinux\n"); exit(1); } -static char *sym_name(const struct sym_entry *s) +static char *sym_entry_name(const struct sym_entry *s) { return (char *)s->sym + 1; } @@ -153,37 +159,12 @@ static void check_symbol_range(const char *sym, unsigned long long addr, } } -static struct sym_entry *read_symbol(FILE *in, char **buf, size_t *buf_len) +static struct sym_entry *add_symbol(unsigned long long addr, char type, + const char *name) { - char *name, type, *p; - unsigned long long addr; - size_t len; - ssize_t readlen; + size_t len = strlen(name); struct sym_entry *sym; - errno = 0; - readlen = getline(buf, buf_len, in); - if (readlen < 0) { - if (errno) { - perror("read_symbol"); - exit(EXIT_FAILURE); - } - return NULL; - } - - if ((*buf)[readlen - 1] == '\n') - (*buf)[readlen - 1] = 0; - - addr = strtoull(*buf, &p, 16); - - if (*buf == p || *p++ != ' ' || !isascii((type = *p++)) || *p++ != ' ') { - fprintf(stderr, "line format error\n"); - exit(EXIT_FAILURE); - } - - name = p; - len = strlen(name); - if (len >= KSYM_NAME_LEN) { fprintf(stderr, "Symbol %s too long for kallsyms (%zu >= %d).\n" "Please increase KSYM_NAME_LEN both in kernel and kallsyms.c\n", @@ -208,7 +189,7 @@ static struct sym_entry *read_symbol(FILE *in, char **buf, size_t *buf_len) sym->addr = addr; sym->len = len; sym->sym[0] = type; - strcpy(sym_name(sym), name); + strcpy(sym_entry_name(sym), name); return sym; } @@ -229,14 +210,9 @@ static int symbol_in_range(const struct sym_entry *s, return 0; } -static bool string_starts_with(const char *s, const char *prefix) -{ - return strncmp(s, prefix, strlen(prefix)) == 0; -} - static int symbol_valid(const struct sym_entry *s) { - const char *name = sym_name(s); + const char *name = sym_entry_name(s); /* if --all-symbols is not specified, then symbols outside the text * and inittext sections are discarded */ @@ -286,36 +262,55 @@ static void shrink_table(void) table_cnt = pos; } -static void read_map(const char *in) +static void add_table_entry(struct sym_entry *sym) { - FILE *fp; - struct sym_entry *sym; - char *buf = NULL; - size_t buflen = 0; + sym->seq = table_cnt; - fp = fopen(in, "r"); - if (!fp) { - perror(in); - exit(1); + if (table_cnt >= table_size) { + table_size = table_size ? table_size * 2 : 10000; + table = xrealloc(table, sizeof(*table) * table_size); } - while (!feof(fp)) { - sym = read_symbol(fp, &buf, &buflen); - if (!sym) - continue; + table[table_cnt++] = sym; +} - sym->seq = table_cnt; +static bool file_is_empty(const char *path) +{ + struct stat st; - if (table_cnt >= table_size) { - table_size += 10000; - table = xrealloc(table, sizeof(*table) * table_size); - } + if (stat(path, &st)) { + perror(path); + exit(EXIT_FAILURE); + } + + return st.st_size == 0; +} + +/* + * Read the symbols from vmlinux, writing System.map if asked to. The first + * link has no symbols yet: an empty file gives an empty table. + */ +static void read_elf(const char *path, FILE *sysmap_out) +{ + struct sysmap *map; + size_t i; + + if (file_is_empty(path)) + return; + + map = sysmap_read(path); + if (sysmap_out) + sysmap_write(map, sysmap_out); + + for (i = 0; i < map->nr_syms; i++) { + const struct sysmap_symbol *s = &map->syms[i]; + struct sym_entry *sym = add_symbol(s->addr, s->type, s->name); - table[table_cnt++] = sym; + if (sym) + add_table_entry(sym); } - free(buf); - fclose(fp); + sysmap_free(map); } static void output_label(const char *label) @@ -378,7 +373,7 @@ static int compare_names(const void *a, const void *b) const struct sym_entry *sa = *(const struct sym_entry **)a; const struct sym_entry *sb = *(const struct sym_entry **)b; - ret = strcmp(sym_name(sa), sym_name(sb)); + ret = strcmp(sym_entry_name(sa), sym_entry_name(sb)); if (!ret) { if (sa->addr > sb->addr) return 1; @@ -756,7 +751,7 @@ static void optimize_token_table(void) /* guess for "linker script provide" symbol */ static int may_be_linker_script_provide_symbol(const struct sym_entry *se) { - const char *symbol = sym_name(se); + const char *symbol = sym_entry_name(se); int len = se->len - 1; if (len < 8) @@ -813,8 +808,8 @@ static int compare_symbols(const void *a, const void *b) return wa - wb; /* sort by the number of prefix underscores */ - wa = strspn(sym_name(sa), "_"); - wb = strspn(sym_name(sb), "_"); + wa = strspn(sym_entry_name(sa), "_"); + wb = strspn(sym_entry_name(sb), "_"); if (wa != wb) return wa - wb; @@ -829,13 +824,14 @@ static void sort_symbols(void) int main(int argc, char **argv) { - const char *out_bin_name; - FILE *out_bin_file; + const char *in, *sysmap = NULL, *out_bin_name; + FILE *sysmap_out = NULL, *out_bin_file; while (1) { static const struct option long_options[] = { {"all-symbols", no_argument, &all_symbols, 1}, {"pc-relative", no_argument, &pc_relative, 1}, + {"sysmap", required_argument, NULL, 's'}, {}, }; @@ -843,13 +839,33 @@ int main(int argc, char **argv) if (c == -1) break; - if (c != 0) + if (c == 's') + sysmap = optarg; + else if (c != 0) usage(); } - if (optind + 2 != argc) + if (optind + 2 != argc && !(sysmap && optind + 1 == argc)) usage(); + in = argv[optind]; + if (sysmap) { + sysmap_out = fopen(sysmap, "w"); + if (!sysmap_out) { + perror(sysmap); + exit(EXIT_FAILURE); + } + } + + if (optind + 1 == argc) { + read_elf(in, sysmap_out); + if (ferror(sysmap_out) || fclose(sysmap_out)) { + perror(sysmap); + exit(EXIT_FAILURE); + } + return 0; + } + out_bin_name = argv[optind + 1]; out_bin_file = fopen(out_bin_name, "w"); if (!out_bin_file) { @@ -857,7 +873,11 @@ int main(int argc, char **argv) exit(EXIT_FAILURE); } - read_map(argv[optind]); + read_elf(in, sysmap_out); + if (sysmap_out && (ferror(sysmap_out) || fclose(sysmap_out))) { + perror(sysmap); + exit(EXIT_FAILURE); + } shrink_table(); sort_symbols(); optimize_token_table(); diff --git a/scripts/kallsyms.h b/scripts/kallsyms.h new file mode 100644 index 000000000000..4b2801ba6285 --- /dev/null +++ b/scripts/kallsyms.h @@ -0,0 +1,44 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef KALLSYMS_H +#define KALLSYMS_H + +#include +#include +#include +#include + +#include +#include "elf-parse.h" + +static inline bool string_starts_with(const char *s, const char *prefix) +{ + return strncmp(s, prefix, strlen(prefix)) == 0; +} + +static inline bool string_ends_with(const char *s, const char *suffix) +{ + size_t len = strlen(s), suffix_len = strlen(suffix); + + return len >= suffix_len && strcmp(s + len - suffix_len, suffix) == 0; +} + +/* A symbol as nm lists it. */ +struct sysmap_symbol { + unsigned long long addr; + const char *name; + char type; +}; + +/* The symbols of an ELF file that System.map lists, in its order. */ +struct sysmap { + struct sysmap_symbol *syms; + size_t nr_syms; + int addr_width; /* hex digits of an address */ + struct elf_file elf; /* the mapping the names point into */ +}; + +struct sysmap *sysmap_read(const char *path); +void sysmap_write(const struct sysmap *map, FILE *out); +void sysmap_free(struct sysmap *map); + +#endif /* KALLSYMS_H */ diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index ed5ff97c0667..c520741f85c2 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -123,11 +123,15 @@ kallsymso_changed() ! cmp -s "${kallsymso_prev}.sym" "${kallsymso}.sym" } -# Create ${2}.o file with all symbols from the ${1} object file +# Create ${2}.o with the kallsyms tables for ${1} (the vmlinux, or an empty +# listing for the first pass); list the symbols used in ${3} if given. kallsyms() { local kallsymopt; + if [ -n "${3:-}" ]; then + kallsymopt="--sysmap=${3}" + fi if is_enabled CONFIG_KALLSYMS_ALL; then kallsymopt="${kallsymopt} --all-symbols" fi @@ -150,18 +154,15 @@ kallsyms() # Perform kallsyms for the given temporary vmlinux. sysmap_and_kallsyms() { - mksysmap "${1}" "${1}.syms" - kallsyms "${1}.syms" "${1}.kallsyms" - + kallsyms "${1}" "${1}.kallsyms" "${1}.syms" kallsyms_sysmap=${1}.syms } # Create map file with all symbols from ${1} -# See mksymap for additional details mksysmap() { - info NM ${2} - ${NM} -n "${1}" | sed -f "${srctree}/scripts/mksysmap" > "${2}" + info SYSMAP ${2} + scripts/kallsyms --sysmap="${2}" "${1}" } sorttable() diff --git a/scripts/mksysmap b/scripts/mksysmap deleted file mode 100755 index 856b26ba2ac0..000000000000 --- a/scripts/mksysmap +++ /dev/null @@ -1,94 +0,0 @@ -#!/bin/sed -f -# SPDX-License-Identifier: GPL-2.0-only -# -# sed script to filter out symbols that are not needed for System.map, -# or not suitable for kallsyms. The input should be 'nm -n '. -# -# System.map is used by module-init tools and some debugging -# tools to retrieve the actual addresses of symbols in the kernel. -# -# readprofile starts reading symbols when _stext is found, and -# continue until it finds a symbol which is not either of 'T', 't', -# 'W' or 'w'. -# -# --------------------------------------------------------------------------- -# Ignored symbol types -# - -# a: local absolute symbols -# N: debugging symbols -# U: undefined global symbols -# w: local weak symbols -/ [aNUw] /d - -# --------------------------------------------------------------------------- -# Ignored prefixes -# (do not forget a space before each pattern) - -# local symbols for ARM, MIPS, etc. -/ \$/d - -# local labels, .LBB, .Ltmpxxx, .L__unnamed_xx, .LASANPC, etc. -/ \.L/d - -# arm64 EFI stub namespace -/ __efistub_/d - -# arm64 local symbols in PIE namespace -/ __pi_\$/d -/ __pi_\.L/d - -# arm64 local symbols in non-VHE KVM namespace -/ __kvm_nvhe_\$/d -/ __kvm_nvhe_\.L/d - -# lld arm/aarch64/mips thunks -/ __[[:alnum:]]*Thunk_/d - -# CFI type identifiers -/ __kcfi_typeid_/d -/ __kvm_nvhe___kcfi_typeid_/d -/ __pi___kcfi_typeid_/d - -# CRC from modversions -/ __crc_/d - -# EXPORT_SYMBOL (symbol name) -/ __kstrtab_/d - -# EXPORT_SYMBOL (namespace) -/ __kstrtabns_/d - -# MODULE_DEVICE_TABLE (symbol name) -/ __mod_device_table__/d - -# --------------------------------------------------------------------------- -# Ignored suffixes -# (do not forget '$' after each pattern) - -# arm -/_from_arm$/d -/_from_thumb$/d -/_veneer$/d - -# --------------------------------------------------------------------------- -# Ignored symbols (exact match) -# (do not forget a space before and '$' after each pattern) - -# for LoongArch? -/ L0$/d - -# ppc -/ _SDA_BASE_$/d -/ _SDA2_BASE_$/d - -# MODULE_INFO() -/ __UNIQUE_ID_modinfo_[0-9]*$/d - -# --------------------------------------------------------------------------- -# Ignored patterns -# (symbols that contain the pattern are ignored) - -# ppc stub -/\.long_branch\./d -/\.plt_branch\./d -- cgit v1.2.3