* [for-next][PATCH 1/5] sorttable: Move ELF parsing into scripts/elf-parse.[ch]
2025-10-27 20:13 [for-next][PATCH 0/5] tracing: Detect unused tracepoints for v6.19 Steven Rostedt
@ 2025-10-27 20:13 ` Steven Rostedt
2025-10-27 20:13 ` [for-next][PATCH 2/5] tracing: Add a tracepoint verification check at build time Steven Rostedt
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Steven Rostedt @ 2025-10-27 20:13 UTC (permalink / raw)
To: linux-kernel
Cc: Masami Hiramatsu, Mark Rutland, Mathieu Desnoyers, Andrew Morton,
Arnd Bergmann, Masahiro Yamada, Nathan Chancellor, Nicolas Schier,
Nick Desaulniers, Catalin Marinas, Linus Torvalds, Randy Dunlap,
Stephen Rothwell
From: Steven Rostedt <rostedt@goodmis.org>
In order to share the elf parsing that is in sorttable.c so that other
programs could use the same code, move it into elf-parse.c and
elf-parse.h.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nicolas Schier <nicolas.schier@linux.dev>
Cc: Nick Desaulniers <nick.desaulniers+lkml@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Link: https://lore.kernel.org/20251022004452.752298788@kernel.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
scripts/Makefile | 3 +
scripts/elf-parse.c | 198 ++++++++++++++++++
scripts/elf-parse.h | 305 ++++++++++++++++++++++++++++
scripts/sorttable.c | 477 ++++----------------------------------------
4 files changed, 540 insertions(+), 443 deletions(-)
create mode 100644 scripts/elf-parse.c
create mode 100644 scripts/elf-parse.h
diff --git a/scripts/Makefile b/scripts/Makefile
index 46f860529df5..f19624b3ed92 100644
--- a/scripts/Makefile
+++ b/scripts/Makefile
@@ -12,6 +12,8 @@ hostprogs-always-$(CONFIG_SYSTEM_EXTRA_CERTIFICATE) += insert-sys-cert
hostprogs-always-$(CONFIG_RUST_KERNEL_DOCTESTS) += rustdoc_test_builder
hostprogs-always-$(CONFIG_RUST_KERNEL_DOCTESTS) += rustdoc_test_gen
+sorttable-objs := sorttable.o elf-parse.o
+
ifneq ($(or $(CONFIG_X86_64),$(CONFIG_X86_32)),)
always-$(CONFIG_RUST) += target.json
filechk_rust_target = $< < include/config/auto.conf
@@ -25,6 +27,7 @@ generate_rust_target-rust := y
rustdoc_test_builder-rust := y
rustdoc_test_gen-rust := y
+HOSTCFLAGS_elf-parse.o = -I$(srctree)/tools/include
HOSTCFLAGS_sorttable.o = -I$(srctree)/tools/include
HOSTLDLIBS_sorttable = -lpthread
HOSTCFLAGS_asn1_compiler.o = -I$(srctree)/include
diff --git a/scripts/elf-parse.c b/scripts/elf-parse.c
new file mode 100644
index 000000000000..99869ff91a8c
--- /dev/null
+++ b/scripts/elf-parse.c
@@ -0,0 +1,198 @@
+#include <sys/types.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include "elf-parse.h"
+
+struct elf_funcs elf_parser;
+
+/*
+ * Get the whole file as a programming convenience in order to avoid
+ * malloc+lseek+read+free of many pieces. If successful, then mmap
+ * avoids copying unused pieces; else just read the whole file.
+ * Open for both read and write.
+ */
+static void *map_file(char const *fname, size_t *size)
+{
+ int fd;
+ struct stat sb;
+ void *addr = NULL;
+
+ fd = open(fname, O_RDWR);
+ if (fd < 0) {
+ perror(fname);
+ return NULL;
+ }
+ if (fstat(fd, &sb) < 0) {
+ perror(fname);
+ goto out;
+ }
+ if (!S_ISREG(sb.st_mode)) {
+ fprintf(stderr, "not a regular file: %s\n", fname);
+ goto out;
+ }
+
+ addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
+ if (addr == MAP_FAILED) {
+ fprintf(stderr, "Could not mmap file: %s\n", fname);
+ goto out;
+ }
+
+ *size = sb.st_size;
+
+out:
+ close(fd);
+ return addr;
+}
+
+static int elf_parse(const char *fname, void *addr, uint32_t types)
+{
+ Elf_Ehdr *ehdr = addr;
+ uint16_t type;
+
+ switch (ehdr->e32.e_ident[EI_DATA]) {
+ case ELFDATA2LSB:
+ elf_parser.r = rle;
+ elf_parser.r2 = r2le;
+ elf_parser.r8 = r8le;
+ elf_parser.w = wle;
+ elf_parser.w8 = w8le;
+ break;
+ case ELFDATA2MSB:
+ elf_parser.r = rbe;
+ elf_parser.r2 = r2be;
+ elf_parser.r8 = r8be;
+ elf_parser.w = wbe;
+ elf_parser.w8 = w8be;
+ break;
+ default:
+ fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
+ ehdr->e32.e_ident[EI_DATA], fname);
+ return -1;
+ }
+
+ if (memcmp(ELFMAG, ehdr->e32.e_ident, SELFMAG) != 0 ||
+ ehdr->e32.e_ident[EI_VERSION] != EV_CURRENT) {
+ fprintf(stderr, "unrecognized ELF file %s\n", fname);
+ return -1;
+ }
+
+ type = elf_parser.r2(&ehdr->e32.e_type);
+ if (!((1 << type) & types)) {
+ fprintf(stderr, "Invalid ELF type file %s\n", fname);
+ return -1;
+ }
+
+ switch (ehdr->e32.e_ident[EI_CLASS]) {
+ case ELFCLASS32: {
+ elf_parser.ehdr_shoff = ehdr32_shoff;
+ elf_parser.ehdr_shentsize = ehdr32_shentsize;
+ elf_parser.ehdr_shstrndx = ehdr32_shstrndx;
+ elf_parser.ehdr_shnum = ehdr32_shnum;
+ elf_parser.shdr_addr = shdr32_addr;
+ elf_parser.shdr_offset = shdr32_offset;
+ elf_parser.shdr_link = shdr32_link;
+ elf_parser.shdr_size = shdr32_size;
+ elf_parser.shdr_name = shdr32_name;
+ elf_parser.shdr_type = shdr32_type;
+ elf_parser.shdr_entsize = shdr32_entsize;
+ elf_parser.sym_type = sym32_type;
+ elf_parser.sym_name = sym32_name;
+ elf_parser.sym_value = sym32_value;
+ elf_parser.sym_shndx = sym32_shndx;
+ elf_parser.rela_offset = rela32_offset;
+ elf_parser.rela_info = rela32_info;
+ elf_parser.rela_addend = rela32_addend;
+ elf_parser.rela_write_addend = rela32_write_addend;
+
+ if (elf_parser.r2(&ehdr->e32.e_ehsize) != sizeof(Elf32_Ehdr) ||
+ elf_parser.r2(&ehdr->e32.e_shentsize) != sizeof(Elf32_Shdr)) {
+ fprintf(stderr,
+ "unrecognized ET_EXEC/ET_DYN file: %s\n", fname);
+ return -1;
+ }
+
+ }
+ break;
+ case ELFCLASS64: {
+ elf_parser.ehdr_shoff = ehdr64_shoff;
+ elf_parser.ehdr_shentsize = ehdr64_shentsize;
+ elf_parser.ehdr_shstrndx = ehdr64_shstrndx;
+ elf_parser.ehdr_shnum = ehdr64_shnum;
+ elf_parser.shdr_addr = shdr64_addr;
+ elf_parser.shdr_offset = shdr64_offset;
+ elf_parser.shdr_link = shdr64_link;
+ elf_parser.shdr_size = shdr64_size;
+ elf_parser.shdr_name = shdr64_name;
+ elf_parser.shdr_type = shdr64_type;
+ elf_parser.shdr_entsize = shdr64_entsize;
+ elf_parser.sym_type = sym64_type;
+ elf_parser.sym_name = sym64_name;
+ elf_parser.sym_value = sym64_value;
+ elf_parser.sym_shndx = sym64_shndx;
+ elf_parser.rela_offset = rela64_offset;
+ elf_parser.rela_info = rela64_info;
+ elf_parser.rela_addend = rela64_addend;
+ elf_parser.rela_write_addend = rela64_write_addend;
+
+ if (elf_parser.r2(&ehdr->e64.e_ehsize) != sizeof(Elf64_Ehdr) ||
+ elf_parser.r2(&ehdr->e64.e_shentsize) != sizeof(Elf64_Shdr)) {
+ fprintf(stderr,
+ "unrecognized ET_EXEC/ET_DYN file: %s\n",
+ fname);
+ return -1;
+ }
+
+ }
+ break;
+ default:
+ fprintf(stderr, "unrecognized ELF class %d %s\n",
+ ehdr->e32.e_ident[EI_CLASS], fname);
+ return -1;
+ }
+ return 0;
+}
+
+int elf_map_machine(void *addr)
+{
+ Elf_Ehdr *ehdr = addr;
+
+ return elf_parser.r2(&ehdr->e32.e_machine);
+}
+
+int elf_map_long_size(void *addr)
+{
+ Elf_Ehdr *ehdr = addr;
+
+ return ehdr->e32.e_ident[EI_CLASS] == ELFCLASS32 ? 4 : 8;
+}
+
+void *elf_map(char const *fname, size_t *size, uint32_t types)
+{
+ void *addr;
+ int ret;
+
+ addr = map_file(fname, size);
+ if (!addr)
+ return NULL;
+
+ ret = elf_parse(fname, addr, types);
+ if (ret < 0) {
+ elf_unmap(addr, *size);
+ return NULL;
+ }
+
+ return addr;
+}
+
+void elf_unmap(void *addr, size_t size)
+{
+ munmap(addr, size);
+}
diff --git a/scripts/elf-parse.h b/scripts/elf-parse.h
new file mode 100644
index 000000000000..f4411e03069d
--- /dev/null
+++ b/scripts/elf-parse.h
@@ -0,0 +1,305 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef _SCRIPTS_ELF_PARSE_H
+#define _SCRIPTS_ELF_PARSE_H
+
+#include <elf.h>
+
+#include <tools/be_byteshift.h>
+#include <tools/le_byteshift.h>
+
+typedef union {
+ Elf32_Ehdr e32;
+ Elf64_Ehdr e64;
+} Elf_Ehdr;
+
+typedef union {
+ Elf32_Shdr e32;
+ Elf64_Shdr e64;
+} Elf_Shdr;
+
+typedef union {
+ Elf32_Sym e32;
+ Elf64_Sym e64;
+} Elf_Sym;
+
+typedef union {
+ Elf32_Rela e32;
+ Elf64_Rela e64;
+} Elf_Rela;
+
+struct elf_funcs {
+ int (*compare_extable)(const void *a, const void *b);
+ uint64_t (*ehdr_shoff)(Elf_Ehdr *ehdr);
+ uint16_t (*ehdr_shstrndx)(Elf_Ehdr *ehdr);
+ uint16_t (*ehdr_shentsize)(Elf_Ehdr *ehdr);
+ uint16_t (*ehdr_shnum)(Elf_Ehdr *ehdr);
+ uint64_t (*shdr_addr)(Elf_Shdr *shdr);
+ uint64_t (*shdr_offset)(Elf_Shdr *shdr);
+ uint64_t (*shdr_size)(Elf_Shdr *shdr);
+ uint64_t (*shdr_entsize)(Elf_Shdr *shdr);
+ uint32_t (*shdr_link)(Elf_Shdr *shdr);
+ uint32_t (*shdr_name)(Elf_Shdr *shdr);
+ uint32_t (*shdr_type)(Elf_Shdr *shdr);
+ uint8_t (*sym_type)(Elf_Sym *sym);
+ uint32_t (*sym_name)(Elf_Sym *sym);
+ uint64_t (*sym_value)(Elf_Sym *sym);
+ uint16_t (*sym_shndx)(Elf_Sym *sym);
+ uint64_t (*rela_offset)(Elf_Rela *rela);
+ uint64_t (*rela_info)(Elf_Rela *rela);
+ uint64_t (*rela_addend)(Elf_Rela *rela);
+ void (*rela_write_addend)(Elf_Rela *rela, uint64_t val);
+ uint32_t (*r)(const uint32_t *);
+ uint16_t (*r2)(const uint16_t *);
+ uint64_t (*r8)(const uint64_t *);
+ void (*w)(uint32_t, uint32_t *);
+ void (*w8)(uint64_t, uint64_t *);
+};
+
+extern struct elf_funcs elf_parser;
+
+static inline uint64_t ehdr64_shoff(Elf_Ehdr *ehdr)
+{
+ return elf_parser.r8(&ehdr->e64.e_shoff);
+}
+
+static inline uint64_t ehdr32_shoff(Elf_Ehdr *ehdr)
+{
+ return elf_parser.r(&ehdr->e32.e_shoff);
+}
+
+static inline uint64_t ehdr_shoff(Elf_Ehdr *ehdr)
+{
+ return elf_parser.ehdr_shoff(ehdr);
+}
+
+#define EHDR_HALF(fn_name) \
+static inline uint16_t ehdr64_##fn_name(Elf_Ehdr *ehdr) \
+{ \
+ return elf_parser.r2(&ehdr->e64.e_##fn_name); \
+} \
+ \
+static inline uint16_t ehdr32_##fn_name(Elf_Ehdr *ehdr) \
+{ \
+ return elf_parser.r2(&ehdr->e32.e_##fn_name); \
+} \
+ \
+static inline uint16_t ehdr_##fn_name(Elf_Ehdr *ehdr) \
+{ \
+ return elf_parser.ehdr_##fn_name(ehdr); \
+}
+
+EHDR_HALF(shentsize)
+EHDR_HALF(shstrndx)
+EHDR_HALF(shnum)
+
+#define SHDR_WORD(fn_name) \
+static inline uint32_t shdr64_##fn_name(Elf_Shdr *shdr) \
+{ \
+ return elf_parser.r(&shdr->e64.sh_##fn_name); \
+} \
+ \
+static inline uint32_t shdr32_##fn_name(Elf_Shdr *shdr) \
+{ \
+ return elf_parser.r(&shdr->e32.sh_##fn_name); \
+} \
+ \
+static inline uint32_t shdr_##fn_name(Elf_Shdr *shdr) \
+{ \
+ return elf_parser.shdr_##fn_name(shdr); \
+}
+
+#define SHDR_ADDR(fn_name) \
+static inline uint64_t shdr64_##fn_name(Elf_Shdr *shdr) \
+{ \
+ return elf_parser.r8(&shdr->e64.sh_##fn_name); \
+} \
+ \
+static inline uint64_t shdr32_##fn_name(Elf_Shdr *shdr) \
+{ \
+ return elf_parser.r(&shdr->e32.sh_##fn_name); \
+} \
+ \
+static inline uint64_t shdr_##fn_name(Elf_Shdr *shdr) \
+{ \
+ return elf_parser.shdr_##fn_name(shdr); \
+}
+
+#define SHDR_WORD(fn_name) \
+static inline uint32_t shdr64_##fn_name(Elf_Shdr *shdr) \
+{ \
+ return elf_parser.r(&shdr->e64.sh_##fn_name); \
+} \
+ \
+static inline uint32_t shdr32_##fn_name(Elf_Shdr *shdr) \
+{ \
+ return elf_parser.r(&shdr->e32.sh_##fn_name); \
+} \
+static inline uint32_t shdr_##fn_name(Elf_Shdr *shdr) \
+{ \
+ return elf_parser.shdr_##fn_name(shdr); \
+}
+
+SHDR_ADDR(addr)
+SHDR_ADDR(offset)
+SHDR_ADDR(size)
+SHDR_ADDR(entsize)
+
+SHDR_WORD(link)
+SHDR_WORD(name)
+SHDR_WORD(type)
+
+#define SYM_ADDR(fn_name) \
+static inline uint64_t sym64_##fn_name(Elf_Sym *sym) \
+{ \
+ return elf_parser.r8(&sym->e64.st_##fn_name); \
+} \
+ \
+static inline uint64_t sym32_##fn_name(Elf_Sym *sym) \
+{ \
+ return elf_parser.r(&sym->e32.st_##fn_name); \
+} \
+ \
+static inline uint64_t sym_##fn_name(Elf_Sym *sym) \
+{ \
+ return elf_parser.sym_##fn_name(sym); \
+}
+
+#define SYM_WORD(fn_name) \
+static inline uint32_t sym64_##fn_name(Elf_Sym *sym) \
+{ \
+ return elf_parser.r(&sym->e64.st_##fn_name); \
+} \
+ \
+static inline uint32_t sym32_##fn_name(Elf_Sym *sym) \
+{ \
+ return elf_parser.r(&sym->e32.st_##fn_name); \
+} \
+ \
+static inline uint32_t sym_##fn_name(Elf_Sym *sym) \
+{ \
+ return elf_parser.sym_##fn_name(sym); \
+}
+
+#define SYM_HALF(fn_name) \
+static inline uint16_t sym64_##fn_name(Elf_Sym *sym) \
+{ \
+ return elf_parser.r2(&sym->e64.st_##fn_name); \
+} \
+ \
+static inline uint16_t sym32_##fn_name(Elf_Sym *sym) \
+{ \
+ return elf_parser.r2(&sym->e32.st_##fn_name); \
+} \
+ \
+static inline uint16_t sym_##fn_name(Elf_Sym *sym) \
+{ \
+ return elf_parser.sym_##fn_name(sym); \
+}
+
+static inline uint8_t sym64_type(Elf_Sym *sym)
+{
+ return ELF64_ST_TYPE(sym->e64.st_info);
+}
+
+static inline uint8_t sym32_type(Elf_Sym *sym)
+{
+ return ELF32_ST_TYPE(sym->e32.st_info);
+}
+
+static inline uint8_t sym_type(Elf_Sym *sym)
+{
+ return elf_parser.sym_type(sym);
+}
+
+SYM_ADDR(value)
+SYM_WORD(name)
+SYM_HALF(shndx)
+
+#define __maybe_unused __attribute__((__unused__))
+
+#define RELA_ADDR(fn_name) \
+static inline uint64_t rela64_##fn_name(Elf_Rela *rela) \
+{ \
+ return elf_parser.r8((uint64_t *)&rela->e64.r_##fn_name); \
+} \
+ \
+static inline uint64_t rela32_##fn_name(Elf_Rela *rela) \
+{ \
+ return elf_parser.r((uint32_t *)&rela->e32.r_##fn_name); \
+} \
+ \
+static inline uint64_t __maybe_unused rela_##fn_name(Elf_Rela *rela) \
+{ \
+ return elf_parser.rela_##fn_name(rela); \
+}
+
+RELA_ADDR(offset)
+RELA_ADDR(info)
+RELA_ADDR(addend)
+
+static inline void rela64_write_addend(Elf_Rela *rela, uint64_t val)
+{
+ elf_parser.w8(val, (uint64_t *)&rela->e64.r_addend);
+}
+
+static inline void rela32_write_addend(Elf_Rela *rela, uint64_t val)
+{
+ elf_parser.w(val, (uint32_t *)&rela->e32.r_addend);
+}
+
+static inline uint32_t rbe(const uint32_t *x)
+{
+ return get_unaligned_be32(x);
+}
+
+static inline uint16_t r2be(const uint16_t *x)
+{
+ return get_unaligned_be16(x);
+}
+
+static inline uint64_t r8be(const uint64_t *x)
+{
+ return get_unaligned_be64(x);
+}
+
+static inline uint32_t rle(const uint32_t *x)
+{
+ return get_unaligned_le32(x);
+}
+
+static inline uint16_t r2le(const uint16_t *x)
+{
+ return get_unaligned_le16(x);
+}
+
+static inline uint64_t r8le(const uint64_t *x)
+{
+ return get_unaligned_le64(x);
+}
+
+static inline void wbe(uint32_t val, uint32_t *x)
+{
+ put_unaligned_be32(val, x);
+}
+
+static inline void wle(uint32_t val, uint32_t *x)
+{
+ put_unaligned_le32(val, x);
+}
+
+static inline void w8be(uint64_t val, uint64_t *x)
+{
+ put_unaligned_be64(val, x);
+}
+
+static inline void w8le(uint64_t val, uint64_t *x)
+{
+ put_unaligned_le64(val, x);
+}
+
+void *elf_map(char const *fname, size_t *size, uint32_t types);
+void elf_unmap(void *addr, size_t size);
+int elf_map_machine(void *addr);
+int elf_map_long_size(void *addr);
+
+#endif /* _SCRIPTS_ELF_PARSE_H */
diff --git a/scripts/sorttable.c b/scripts/sorttable.c
index deed676bfe38..e8ed11c680c6 100644
--- a/scripts/sorttable.c
+++ b/scripts/sorttable.c
@@ -21,10 +21,8 @@
*/
#include <sys/types.h>
-#include <sys/mman.h>
#include <sys/stat.h>
#include <getopt.h>
-#include <elf.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
@@ -34,8 +32,7 @@
#include <errno.h>
#include <pthread.h>
-#include <tools/be_byteshift.h>
-#include <tools/le_byteshift.h>
+#include "elf-parse.h"
#ifndef EM_ARCOMPACT
#define EM_ARCOMPACT 93
@@ -65,335 +62,8 @@
#define EM_LOONGARCH 258
#endif
-typedef union {
- Elf32_Ehdr e32;
- Elf64_Ehdr e64;
-} Elf_Ehdr;
-
-typedef union {
- Elf32_Shdr e32;
- Elf64_Shdr e64;
-} Elf_Shdr;
-
-typedef union {
- Elf32_Sym e32;
- Elf64_Sym e64;
-} Elf_Sym;
-
-typedef union {
- Elf32_Rela e32;
- Elf64_Rela e64;
-} Elf_Rela;
-
-static uint32_t (*r)(const uint32_t *);
-static uint16_t (*r2)(const uint16_t *);
-static uint64_t (*r8)(const uint64_t *);
-static void (*w)(uint32_t, uint32_t *);
-static void (*w8)(uint64_t, uint64_t *);
typedef void (*table_sort_t)(char *, int);
-static struct elf_funcs {
- int (*compare_extable)(const void *a, const void *b);
- uint64_t (*ehdr_shoff)(Elf_Ehdr *ehdr);
- uint16_t (*ehdr_shstrndx)(Elf_Ehdr *ehdr);
- uint16_t (*ehdr_shentsize)(Elf_Ehdr *ehdr);
- uint16_t (*ehdr_shnum)(Elf_Ehdr *ehdr);
- uint64_t (*shdr_addr)(Elf_Shdr *shdr);
- uint64_t (*shdr_offset)(Elf_Shdr *shdr);
- uint64_t (*shdr_size)(Elf_Shdr *shdr);
- uint64_t (*shdr_entsize)(Elf_Shdr *shdr);
- uint32_t (*shdr_link)(Elf_Shdr *shdr);
- uint32_t (*shdr_name)(Elf_Shdr *shdr);
- uint32_t (*shdr_type)(Elf_Shdr *shdr);
- uint8_t (*sym_type)(Elf_Sym *sym);
- uint32_t (*sym_name)(Elf_Sym *sym);
- uint64_t (*sym_value)(Elf_Sym *sym);
- uint16_t (*sym_shndx)(Elf_Sym *sym);
- uint64_t (*rela_offset)(Elf_Rela *rela);
- uint64_t (*rela_info)(Elf_Rela *rela);
- uint64_t (*rela_addend)(Elf_Rela *rela);
- void (*rela_write_addend)(Elf_Rela *rela, uint64_t val);
-} e;
-
-static uint64_t ehdr64_shoff(Elf_Ehdr *ehdr)
-{
- return r8(&ehdr->e64.e_shoff);
-}
-
-static uint64_t ehdr32_shoff(Elf_Ehdr *ehdr)
-{
- return r(&ehdr->e32.e_shoff);
-}
-
-static uint64_t ehdr_shoff(Elf_Ehdr *ehdr)
-{
- return e.ehdr_shoff(ehdr);
-}
-
-#define EHDR_HALF(fn_name) \
-static uint16_t ehdr64_##fn_name(Elf_Ehdr *ehdr) \
-{ \
- return r2(&ehdr->e64.e_##fn_name); \
-} \
- \
-static uint16_t ehdr32_##fn_name(Elf_Ehdr *ehdr) \
-{ \
- return r2(&ehdr->e32.e_##fn_name); \
-} \
- \
-static uint16_t ehdr_##fn_name(Elf_Ehdr *ehdr) \
-{ \
- return e.ehdr_##fn_name(ehdr); \
-}
-
-EHDR_HALF(shentsize)
-EHDR_HALF(shstrndx)
-EHDR_HALF(shnum)
-
-#define SHDR_WORD(fn_name) \
-static uint32_t shdr64_##fn_name(Elf_Shdr *shdr) \
-{ \
- return r(&shdr->e64.sh_##fn_name); \
-} \
- \
-static uint32_t shdr32_##fn_name(Elf_Shdr *shdr) \
-{ \
- return r(&shdr->e32.sh_##fn_name); \
-} \
- \
-static uint32_t shdr_##fn_name(Elf_Shdr *shdr) \
-{ \
- return e.shdr_##fn_name(shdr); \
-}
-
-#define SHDR_ADDR(fn_name) \
-static uint64_t shdr64_##fn_name(Elf_Shdr *shdr) \
-{ \
- return r8(&shdr->e64.sh_##fn_name); \
-} \
- \
-static uint64_t shdr32_##fn_name(Elf_Shdr *shdr) \
-{ \
- return r(&shdr->e32.sh_##fn_name); \
-} \
- \
-static uint64_t shdr_##fn_name(Elf_Shdr *shdr) \
-{ \
- return e.shdr_##fn_name(shdr); \
-}
-
-#define SHDR_WORD(fn_name) \
-static uint32_t shdr64_##fn_name(Elf_Shdr *shdr) \
-{ \
- return r(&shdr->e64.sh_##fn_name); \
-} \
- \
-static uint32_t shdr32_##fn_name(Elf_Shdr *shdr) \
-{ \
- return r(&shdr->e32.sh_##fn_name); \
-} \
-static uint32_t shdr_##fn_name(Elf_Shdr *shdr) \
-{ \
- return e.shdr_##fn_name(shdr); \
-}
-
-SHDR_ADDR(addr)
-SHDR_ADDR(offset)
-SHDR_ADDR(size)
-SHDR_ADDR(entsize)
-
-SHDR_WORD(link)
-SHDR_WORD(name)
-SHDR_WORD(type)
-
-#define SYM_ADDR(fn_name) \
-static uint64_t sym64_##fn_name(Elf_Sym *sym) \
-{ \
- return r8(&sym->e64.st_##fn_name); \
-} \
- \
-static uint64_t sym32_##fn_name(Elf_Sym *sym) \
-{ \
- return r(&sym->e32.st_##fn_name); \
-} \
- \
-static uint64_t sym_##fn_name(Elf_Sym *sym) \
-{ \
- return e.sym_##fn_name(sym); \
-}
-
-#define SYM_WORD(fn_name) \
-static uint32_t sym64_##fn_name(Elf_Sym *sym) \
-{ \
- return r(&sym->e64.st_##fn_name); \
-} \
- \
-static uint32_t sym32_##fn_name(Elf_Sym *sym) \
-{ \
- return r(&sym->e32.st_##fn_name); \
-} \
- \
-static uint32_t sym_##fn_name(Elf_Sym *sym) \
-{ \
- return e.sym_##fn_name(sym); \
-}
-
-#define SYM_HALF(fn_name) \
-static uint16_t sym64_##fn_name(Elf_Sym *sym) \
-{ \
- return r2(&sym->e64.st_##fn_name); \
-} \
- \
-static uint16_t sym32_##fn_name(Elf_Sym *sym) \
-{ \
- return r2(&sym->e32.st_##fn_name); \
-} \
- \
-static uint16_t sym_##fn_name(Elf_Sym *sym) \
-{ \
- return e.sym_##fn_name(sym); \
-}
-
-static uint8_t sym64_type(Elf_Sym *sym)
-{
- return ELF64_ST_TYPE(sym->e64.st_info);
-}
-
-static uint8_t sym32_type(Elf_Sym *sym)
-{
- return ELF32_ST_TYPE(sym->e32.st_info);
-}
-
-static uint8_t sym_type(Elf_Sym *sym)
-{
- return e.sym_type(sym);
-}
-
-SYM_ADDR(value)
-SYM_WORD(name)
-SYM_HALF(shndx)
-
-#define __maybe_unused __attribute__((__unused__))
-
-#define RELA_ADDR(fn_name) \
-static uint64_t rela64_##fn_name(Elf_Rela *rela) \
-{ \
- return r8((uint64_t *)&rela->e64.r_##fn_name); \
-} \
- \
-static uint64_t rela32_##fn_name(Elf_Rela *rela) \
-{ \
- return r((uint32_t *)&rela->e32.r_##fn_name); \
-} \
- \
-static uint64_t __maybe_unused rela_##fn_name(Elf_Rela *rela) \
-{ \
- return e.rela_##fn_name(rela); \
-}
-
-RELA_ADDR(offset)
-RELA_ADDR(info)
-RELA_ADDR(addend)
-
-static void rela64_write_addend(Elf_Rela *rela, uint64_t val)
-{
- w8(val, (uint64_t *)&rela->e64.r_addend);
-}
-
-static void rela32_write_addend(Elf_Rela *rela, uint64_t val)
-{
- w(val, (uint32_t *)&rela->e32.r_addend);
-}
-
-/*
- * Get the whole file as a programming convenience in order to avoid
- * malloc+lseek+read+free of many pieces. If successful, then mmap
- * avoids copying unused pieces; else just read the whole file.
- * Open for both read and write.
- */
-static void *mmap_file(char const *fname, size_t *size)
-{
- int fd;
- struct stat sb;
- void *addr = NULL;
-
- fd = open(fname, O_RDWR);
- if (fd < 0) {
- perror(fname);
- return NULL;
- }
- if (fstat(fd, &sb) < 0) {
- perror(fname);
- goto out;
- }
- if (!S_ISREG(sb.st_mode)) {
- fprintf(stderr, "not a regular file: %s\n", fname);
- goto out;
- }
-
- addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
- if (addr == MAP_FAILED) {
- fprintf(stderr, "Could not mmap file: %s\n", fname);
- goto out;
- }
-
- *size = sb.st_size;
-
-out:
- close(fd);
- return addr;
-}
-
-static uint32_t rbe(const uint32_t *x)
-{
- return get_unaligned_be32(x);
-}
-
-static uint16_t r2be(const uint16_t *x)
-{
- return get_unaligned_be16(x);
-}
-
-static uint64_t r8be(const uint64_t *x)
-{
- return get_unaligned_be64(x);
-}
-
-static uint32_t rle(const uint32_t *x)
-{
- return get_unaligned_le32(x);
-}
-
-static uint16_t r2le(const uint16_t *x)
-{
- return get_unaligned_le16(x);
-}
-
-static uint64_t r8le(const uint64_t *x)
-{
- return get_unaligned_le64(x);
-}
-
-static void wbe(uint32_t val, uint32_t *x)
-{
- put_unaligned_be32(val, x);
-}
-
-static void wle(uint32_t val, uint32_t *x)
-{
- put_unaligned_le32(val, x);
-}
-
-static void w8be(uint64_t val, uint64_t *x)
-{
- put_unaligned_be64(val, x);
-}
-
-static void w8le(uint64_t val, uint64_t *x)
-{
- put_unaligned_le64(val, x);
-}
-
/*
* Move reserved section indices SHN_LORESERVE..SHN_HIRESERVE out of
* the way to -256..-1, to avoid conflicting with real section
@@ -415,13 +85,13 @@ static inline unsigned int get_secindex(unsigned int shndx,
return SPECIAL(shndx);
if (shndx != SHN_XINDEX)
return shndx;
- return r(&symtab_shndx_start[sym_offs]);
+ return elf_parser.r(&symtab_shndx_start[sym_offs]);
}
static int compare_extable_32(const void *a, const void *b)
{
- Elf32_Addr av = r(a);
- Elf32_Addr bv = r(b);
+ Elf32_Addr av = elf_parser.r(a);
+ Elf32_Addr bv = elf_parser.r(b);
if (av < bv)
return -1;
@@ -430,18 +100,15 @@ static int compare_extable_32(const void *a, const void *b)
static int compare_extable_64(const void *a, const void *b)
{
- Elf64_Addr av = r8(a);
- Elf64_Addr bv = r8(b);
+ Elf64_Addr av = elf_parser.r8(a);
+ Elf64_Addr bv = elf_parser.r8(b);
if (av < bv)
return -1;
return av > bv;
}
-static int compare_extable(const void *a, const void *b)
-{
- return e.compare_extable(a, b);
-}
+static int (*compare_extable)(const void *a, const void *b);
static inline void *get_index(void *start, int entsize, int index)
{
@@ -577,7 +244,7 @@ static int (*compare_values)(const void *a, const void *b);
/* Only used for sorting mcount table */
static void rela_write_addend(Elf_Rela *rela, uint64_t val)
{
- e.rela_write_addend(rela, val);
+ elf_parser.rela_write_addend(rela, val);
}
struct func_info {
@@ -792,9 +459,9 @@ static int fill_addrs(void *ptr, uint64_t size, void *addrs)
for (; ptr < end; ptr += long_size, addrs += long_size, count++) {
if (long_size == 4)
- *(uint32_t *)ptr = r(addrs);
+ *(uint32_t *)ptr = elf_parser.r(addrs);
else
- *(uint64_t *)ptr = r8(addrs);
+ *(uint64_t *)ptr = elf_parser.r8(addrs);
}
return count;
}
@@ -805,9 +472,9 @@ static void replace_addrs(void *ptr, uint64_t size, void *addrs)
for (; ptr < end; ptr += long_size, addrs += long_size) {
if (long_size == 4)
- w(*(uint32_t *)ptr, addrs);
+ elf_parser.w(*(uint32_t *)ptr, addrs);
else
- w8(*(uint64_t *)ptr, addrs);
+ elf_parser.w8(*(uint64_t *)ptr, addrs);
}
}
@@ -1111,7 +778,7 @@ static int do_sort(Elf_Ehdr *ehdr,
sym_value(sort_needed_sym) - shdr_addr(sort_needed_sec);
/* extable has been sorted, clear the flag */
- w(0, sort_needed_loc);
+ elf_parser.w(0, sort_needed_loc);
rc = 0;
out:
@@ -1155,8 +822,8 @@ static int do_sort(Elf_Ehdr *ehdr,
static int compare_relative_table(const void *a, const void *b)
{
- int32_t av = (int32_t)r(a);
- int32_t bv = (int32_t)r(b);
+ int32_t av = (int32_t)elf_parser.r(a);
+ int32_t bv = (int32_t)elf_parser.r(b);
if (av < bv)
return -1;
@@ -1175,7 +842,7 @@ static void sort_relative_table(char *extab_image, int image_size)
*/
while (i < image_size) {
uint32_t *loc = (uint32_t *)(extab_image + i);
- w(r(loc) + i, loc);
+ elf_parser.w(elf_parser.r(loc) + i, loc);
i += 4;
}
@@ -1185,7 +852,7 @@ static void sort_relative_table(char *extab_image, int image_size)
i = 0;
while (i < image_size) {
uint32_t *loc = (uint32_t *)(extab_image + i);
- w(r(loc) - i, loc);
+ elf_parser.w(elf_parser.r(loc) - i, loc);
i += 4;
}
}
@@ -1197,8 +864,8 @@ static void sort_relative_table_with_data(char *extab_image, int image_size)
while (i < image_size) {
uint32_t *loc = (uint32_t *)(extab_image + i);
- w(r(loc) + i, loc);
- w(r(loc + 1) + i + 4, loc + 1);
+ elf_parser.w(elf_parser.r(loc) + i, loc);
+ elf_parser.w(elf_parser.r(loc + 1) + i + 4, loc + 1);
/* Don't touch the fixup type or data */
i += sizeof(uint32_t) * 3;
@@ -1210,8 +877,8 @@ static void sort_relative_table_with_data(char *extab_image, int image_size)
while (i < image_size) {
uint32_t *loc = (uint32_t *)(extab_image + i);
- w(r(loc) - i, loc);
- w(r(loc + 1) - (i + 4), loc + 1);
+ elf_parser.w(elf_parser.r(loc) - i, loc);
+ elf_parser.w(elf_parser.r(loc + 1) - (i + 4), loc + 1);
/* Don't touch the fixup type or data */
i += sizeof(uint32_t) * 3;
@@ -1223,35 +890,7 @@ static int do_file(char const *const fname, void *addr)
Elf_Ehdr *ehdr = addr;
table_sort_t custom_sort = NULL;
- switch (ehdr->e32.e_ident[EI_DATA]) {
- case ELFDATA2LSB:
- r = rle;
- r2 = r2le;
- r8 = r8le;
- w = wle;
- w8 = w8le;
- break;
- case ELFDATA2MSB:
- r = rbe;
- r2 = r2be;
- r8 = r8be;
- w = wbe;
- w8 = w8be;
- break;
- default:
- fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
- ehdr->e32.e_ident[EI_DATA], fname);
- return -1;
- }
-
- if (memcmp(ELFMAG, ehdr->e32.e_ident, SELFMAG) != 0 ||
- (r2(&ehdr->e32.e_type) != ET_EXEC && r2(&ehdr->e32.e_type) != ET_DYN) ||
- ehdr->e32.e_ident[EI_VERSION] != EV_CURRENT) {
- fprintf(stderr, "unrecognized ET_EXEC/ET_DYN file %s\n", fname);
- return -1;
- }
-
- switch (r2(&ehdr->e32.e_machine)) {
+ switch (elf_map_machine(ehdr)) {
case EM_AARCH64:
#ifdef MCOUNT_SORT_ENABLED
sort_reloc = true;
@@ -1281,85 +920,37 @@ static int do_file(char const *const fname, void *addr)
break;
default:
fprintf(stderr, "unrecognized e_machine %d %s\n",
- r2(&ehdr->e32.e_machine), fname);
+ elf_parser.r2(&ehdr->e32.e_machine), fname);
return -1;
}
- switch (ehdr->e32.e_ident[EI_CLASS]) {
- case ELFCLASS32: {
- struct elf_funcs efuncs = {
- .compare_extable = compare_extable_32,
- .ehdr_shoff = ehdr32_shoff,
- .ehdr_shentsize = ehdr32_shentsize,
- .ehdr_shstrndx = ehdr32_shstrndx,
- .ehdr_shnum = ehdr32_shnum,
- .shdr_addr = shdr32_addr,
- .shdr_offset = shdr32_offset,
- .shdr_link = shdr32_link,
- .shdr_size = shdr32_size,
- .shdr_name = shdr32_name,
- .shdr_type = shdr32_type,
- .shdr_entsize = shdr32_entsize,
- .sym_type = sym32_type,
- .sym_name = sym32_name,
- .sym_value = sym32_value,
- .sym_shndx = sym32_shndx,
- .rela_offset = rela32_offset,
- .rela_info = rela32_info,
- .rela_addend = rela32_addend,
- .rela_write_addend = rela32_write_addend,
- };
-
- e = efuncs;
+ switch (elf_map_long_size(addr)) {
+ case 4:
+ compare_extable = compare_extable_32,
long_size = 4;
extable_ent_size = 8;
- if (r2(&ehdr->e32.e_ehsize) != sizeof(Elf32_Ehdr) ||
- r2(&ehdr->e32.e_shentsize) != sizeof(Elf32_Shdr)) {
+ if (elf_parser.r2(&ehdr->e32.e_ehsize) != sizeof(Elf32_Ehdr) ||
+ elf_parser.r2(&ehdr->e32.e_shentsize) != sizeof(Elf32_Shdr)) {
fprintf(stderr,
"unrecognized ET_EXEC/ET_DYN file: %s\n", fname);
return -1;
}
- }
break;
- case ELFCLASS64: {
- struct elf_funcs efuncs = {
- .compare_extable = compare_extable_64,
- .ehdr_shoff = ehdr64_shoff,
- .ehdr_shentsize = ehdr64_shentsize,
- .ehdr_shstrndx = ehdr64_shstrndx,
- .ehdr_shnum = ehdr64_shnum,
- .shdr_addr = shdr64_addr,
- .shdr_offset = shdr64_offset,
- .shdr_link = shdr64_link,
- .shdr_size = shdr64_size,
- .shdr_name = shdr64_name,
- .shdr_type = shdr64_type,
- .shdr_entsize = shdr64_entsize,
- .sym_type = sym64_type,
- .sym_name = sym64_name,
- .sym_value = sym64_value,
- .sym_shndx = sym64_shndx,
- .rela_offset = rela64_offset,
- .rela_info = rela64_info,
- .rela_addend = rela64_addend,
- .rela_write_addend = rela64_write_addend,
- };
-
- e = efuncs;
+ case 8:
+ compare_extable = compare_extable_64,
long_size = 8;
extable_ent_size = 16;
- if (r2(&ehdr->e64.e_ehsize) != sizeof(Elf64_Ehdr) ||
- r2(&ehdr->e64.e_shentsize) != sizeof(Elf64_Shdr)) {
+ if (elf_parser.r2(&ehdr->e64.e_ehsize) != sizeof(Elf64_Ehdr) ||
+ elf_parser.r2(&ehdr->e64.e_shentsize) != sizeof(Elf64_Shdr)) {
fprintf(stderr,
"unrecognized ET_EXEC/ET_DYN file: %s\n",
fname);
return -1;
}
- }
break;
default:
fprintf(stderr, "unrecognized ELF class %d %s\n",
@@ -1398,7 +989,7 @@ int main(int argc, char *argv[])
/* Process each file in turn, allowing deep failure. */
for (i = optind; i < argc; i++) {
- addr = mmap_file(argv[i], &size);
+ addr = elf_map(argv[i], &size, (1 << ET_EXEC) | (1 << ET_DYN));
if (!addr) {
++n_error;
continue;
@@ -1407,7 +998,7 @@ int main(int argc, char *argv[])
if (do_file(argv[i], addr))
++n_error;
- munmap(addr, size);
+ elf_unmap(addr, size);
}
return !!n_error;
--
2.51.0
^ permalink raw reply related [flat|nested] 6+ messages in thread* [for-next][PATCH 2/5] tracing: Add a tracepoint verification check at build time
2025-10-27 20:13 [for-next][PATCH 0/5] tracing: Detect unused tracepoints for v6.19 Steven Rostedt
2025-10-27 20:13 ` [for-next][PATCH 1/5] sorttable: Move ELF parsing into scripts/elf-parse.[ch] Steven Rostedt
@ 2025-10-27 20:13 ` Steven Rostedt
2025-10-27 20:13 ` [for-next][PATCH 3/5] tracepoint: Do not warn for unused event that is exported Steven Rostedt
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Steven Rostedt @ 2025-10-27 20:13 UTC (permalink / raw)
To: linux-kernel
Cc: Masami Hiramatsu, Mark Rutland, Mathieu Desnoyers, Andrew Morton,
Arnd Bergmann, Masahiro Yamada, Nathan Chancellor, Nicolas Schier,
Nick Desaulniers, Catalin Marinas, Linus Torvalds, Randy Dunlap,
Stephen Rothwell
From: Steven Rostedt <rostedt@goodmis.org>
If a tracepoint is defined via DECLARE_TRACE() or TRACE_EVENT() but never
called (via the trace_<tracepoint>() function), its metadata is still
around in memory and not discarded.
When created via TRACE_EVENT() the situation is worse because the
TRACE_EVENT() creates metadata that can be around 5k per trace event.
Having unused trace events causes several thousand of wasted bytes.
Add a verifier that injects a string of the name of the tracepoint it
calls that is added to the discarded section "__tracepoint_check".
For every builtin tracepoint, its name (which is saved in the in-memory
section "__tracepoint_strings") will have its name also in the
"__tracepoint_check" section if it is used.
Add a new program that is run on build called tracepoint-update. This is
executed on the vmlinux.o before the __tracepoint_check section is
discarded (the section is discarded before vmlinux is created). This
program will create an array of each string in the __tracepoint_check
section and then sort it. Then it will walk the strings in the
__tracepoint_strings section and do a binary search to check if its name
is in the __tracepoint_check section. If it is not, then it is unused and
a warning is printed.
Note, this currently only handles tracepoints that are builtin and not in
modules.
Enabling this currently with a given config produces:
warning: tracepoint 'sched_move_numa' is unused.
warning: tracepoint 'sched_stick_numa' is unused.
warning: tracepoint 'sched_swap_numa' is unused.
warning: tracepoint 'pelt_hw_tp' is unused.
warning: tracepoint 'pelt_irq_tp' is unused.
warning: tracepoint 'rcu_preempt_task' is unused.
warning: tracepoint 'rcu_unlock_preempted_task' is unused.
warning: tracepoint 'xdp_bulk_tx' is unused.
warning: tracepoint 'xdp_redirect_map' is unused.
warning: tracepoint 'xdp_redirect_map_err' is unused.
warning: tracepoint 'vma_mas_szero' is unused.
warning: tracepoint 'vma_store' is unused.
warning: tracepoint 'hugepage_set_pmd' is unused.
warning: tracepoint 'hugepage_set_pud' is unused.
warning: tracepoint 'hugepage_update_pmd' is unused.
warning: tracepoint 'hugepage_update_pud' is unused.
warning: tracepoint 'block_rq_remap' is unused.
warning: tracepoint 'xhci_dbc_handle_event' is unused.
warning: tracepoint 'xhci_dbc_handle_transfer' is unused.
warning: tracepoint 'xhci_dbc_gadget_ep_queue' is unused.
warning: tracepoint 'xhci_dbc_alloc_request' is unused.
warning: tracepoint 'xhci_dbc_free_request' is unused.
warning: tracepoint 'xhci_dbc_queue_request' is unused.
warning: tracepoint 'xhci_dbc_giveback_request' is unused.
warning: tracepoint 'tcp_ao_wrong_maclen' is unused.
warning: tracepoint 'tcp_ao_mismatch' is unused.
warning: tracepoint 'tcp_ao_key_not_found' is unused.
warning: tracepoint 'tcp_ao_rnext_request' is unused.
warning: tracepoint 'tcp_ao_synack_no_key' is unused.
warning: tracepoint 'tcp_ao_snd_sne_update' is unused.
warning: tracepoint 'tcp_ao_rcv_sne_update' is unused.
Some of the above is totally unused but others are not used due to their
"trace_" functions being inside configs, in which case, the defined
tracepoints should also be inside those same configs. Others are
architecture specific but defined in generic code, where they should
either be moved to the architecture or be surrounded by #ifdef for the
architectures they are for.
This tool could be updated to process modules in the future.
I'd like to thank Mathieu Desnoyers for suggesting using strings instead
of pointers, as using pointers in vmlinux.o required handling relocations
and it required implementing almost a full feature linker to do so.
To enable this check, run the build with: make UT=1
Note, when all the existing unused tracepoints are removed from the build,
the "UT=1" will be removed and this will always be enabled when
tracepoints are configured to warn on any new tracepoints. The reason this
isn't always enabled now is because it will introduce a lot of warnings
for the current unused tracepoints, and all bisects would end at this
commit for those warnings.
Link: https://lore.kernel.org/all/20250528114549.4d8a5e03@gandalf.local.home/
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nicolas Schier <nicolas.schier@linux.dev>
Cc: Nick Desaulniers <nick.desaulniers+lkml@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Link: https://lore.kernel.org/20251022004452.920728129@kernel.org
Suggested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> # for using strings instead of pointers
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
Makefile | 21 +++
include/asm-generic/vmlinux.lds.h | 1 +
include/linux/tracepoint.h | 11 ++
scripts/Makefile | 3 +
scripts/link-vmlinux.sh | 7 +
scripts/tracepoint-update.c | 232 ++++++++++++++++++++++++++++++
6 files changed, 275 insertions(+)
create mode 100644 scripts/tracepoint-update.c
diff --git a/Makefile b/Makefile
index d14824792227..9823c20c4278 100644
--- a/Makefile
+++ b/Makefile
@@ -810,6 +810,25 @@ ifdef CONFIG_FUNCTION_TRACER
CC_FLAGS_FTRACE := -pg
endif
+ifdef CONFIG_TRACEPOINTS
+# To check for unused tracepoints (tracepoints that are defined but never
+# called), run with:
+#
+# make UT=1
+#
+# Each unused tracepoints can take up to 5KB of memory in the running kernel.
+# It is best to remove any that are not used.
+#
+# This command line option will be removed when all current unused
+# tracepoints are removed.
+
+ifeq ("$(origin UT)", "command line")
+ WARN_ON_UNUSED_TRACEPOINTS := $(UT)
+endif
+endif # CONFIG_TRACEPOINTS
+
+export WARN_ON_UNUSED_TRACEPOINTS
+
include $(srctree)/arch/$(SRCARCH)/Makefile
ifdef need-config
@@ -1772,6 +1791,8 @@ help:
@echo ' c: extra checks in the configuration stage (Kconfig)'
@echo ' e: warnings are being treated as errors'
@echo ' Multiple levels can be combined with W=12 or W=123'
+ @echo ' make UT=1 [targets] Warn if a tracepoint is defined but not used.'
+ @echo ' [ This will be removed when all current unused tracepoints are eliminated. ]'
@$(if $(dtstree), \
echo ' make CHECK_DTBS=1 [targets] Check all generated dtb files against schema'; \
echo ' This can be applied both to "dtbs" and to individual "foo.dtb" targets' ; \
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 8a9a2e732a65..c510fb097a8c 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -1048,6 +1048,7 @@ defined(CONFIG_AUTOFDO_CLANG) || defined(CONFIG_PROPELLER_CLANG)
*(.no_trim_symbol) \
/* ld.bfd warns about .gnu.version* even when not emitted */ \
*(.gnu.version*) \
+ *(__tracepoint_check) \
#define DISCARDS \
/DISCARD/ : { \
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 826ce3f8e1f8..1e53d3626c78 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -221,6 +221,15 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
__do_trace_##name(args); \
}
+/*
+ * When a tracepoint is used, it's name is added to the __tracepoint_check
+ * section. This section is only used at build time to make sure all
+ * defined tracepoints are used. It is discarded after the build.
+ */
+# define TRACEPOINT_CHECK(name) \
+ static const char __used __section("__tracepoint_check") __trace_check[] = \
+ #name;
+
/*
* Make sure the alignment of the structure in the __tracepoints section will
* not add unwanted padding between the beginning of the section and the
@@ -270,6 +279,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
__DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto)) \
static inline void __do_trace_##name(proto) \
{ \
+ TRACEPOINT_CHECK(name) \
if (cond) { \
guard(preempt_notrace)(); \
__DO_TRACE_CALL(name, TP_ARGS(args)); \
@@ -289,6 +299,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
__DECLARE_TRACE_COMMON(name, PARAMS(proto), PARAMS(args), PARAMS(data_proto)) \
static inline void __do_trace_##name(proto) \
{ \
+ TRACEPOINT_CHECK(name) \
guard(rcu_tasks_trace)(); \
__DO_TRACE_CALL(name, TP_ARGS(args)); \
} \
diff --git a/scripts/Makefile b/scripts/Makefile
index f19624b3ed92..0941e5ce7b57 100644
--- a/scripts/Makefile
+++ b/scripts/Makefile
@@ -11,8 +11,10 @@ hostprogs-always-$(CONFIG_MODULE_SIG_FORMAT) += sign-file
hostprogs-always-$(CONFIG_SYSTEM_EXTRA_CERTIFICATE) += insert-sys-cert
hostprogs-always-$(CONFIG_RUST_KERNEL_DOCTESTS) += rustdoc_test_builder
hostprogs-always-$(CONFIG_RUST_KERNEL_DOCTESTS) += rustdoc_test_gen
+hostprogs-always-$(CONFIG_TRACEPOINTS) += tracepoint-update
sorttable-objs := sorttable.o elf-parse.o
+tracepoint-update-objs := tracepoint-update.o elf-parse.o
ifneq ($(or $(CONFIG_X86_64),$(CONFIG_X86_32)),)
always-$(CONFIG_RUST) += target.json
@@ -27,6 +29,7 @@ generate_rust_target-rust := y
rustdoc_test_builder-rust := y
rustdoc_test_gen-rust := y
+HOSTCFLAGS_tracepoint-update.o = -I$(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/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 433849ff7529..d304029fa6da 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -208,6 +208,13 @@ kallsymso=
strip_debug=
generate_map=
+# Use "make UT=1" to trigger warnings on unused tracepoints
+case "${WARN_ON_UNUSED_TRACEPOINTS}" in
+*1*)
+ ${objtree}/scripts/tracepoint-update vmlinux.o
+ ;;
+esac
+
if is_enabled CONFIG_KALLSYMS; then
true > .tmp_vmlinux0.syms
kallsyms .tmp_vmlinux0.syms .tmp_vmlinux0.kallsyms
diff --git a/scripts/tracepoint-update.c b/scripts/tracepoint-update.c
new file mode 100644
index 000000000000..6ec30f39d0ad
--- /dev/null
+++ b/scripts/tracepoint-update.c
@@ -0,0 +1,232 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <getopt.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <pthread.h>
+
+#include "elf-parse.h"
+
+static Elf_Shdr *check_data_sec;
+static Elf_Shdr *tracepoint_data_sec;
+
+static inline void *get_index(void *start, int entsize, int index)
+{
+ return start + (entsize * index);
+}
+
+static int compare_strings(const void *a, const void *b)
+{
+ const char *av = *(const char **)a;
+ const char *bv = *(const char **)b;
+
+ return strcmp(av, bv);
+}
+
+struct elf_tracepoint {
+ Elf_Ehdr *ehdr;
+ const char **array;
+ int count;
+};
+
+#define REALLOC_SIZE (1 << 10)
+#define REALLOC_MASK (REALLOC_SIZE - 1)
+
+static int add_string(const char *str, const char ***vals, int *count)
+{
+ const char **array = *vals;
+
+ if (!(*count & REALLOC_MASK)) {
+ int size = (*count) + REALLOC_SIZE;
+
+ array = realloc(array, sizeof(char *) * size);
+ if (!array) {
+ fprintf(stderr, "Failed memory allocation\n");
+ return -1;
+ }
+ *vals = array;
+ }
+
+ array[(*count)++] = str;
+ return 0;
+}
+
+/**
+ * for_each_shdr_str - iterator that reads strings that are in an ELF section.
+ * @len: "int" to hold the length of the current string
+ * @ehdr: A pointer to the ehdr of the ELF file
+ * @sec: The section that has the strings to iterate on
+ *
+ * This is a for loop that iterates over all the nul terminated strings
+ * that are in a given ELF section. The variable "str" will hold
+ * the current string for each iteration and the passed in @len will
+ * contain the strlen() of that string.
+ */
+#define for_each_shdr_str(len, ehdr, sec) \
+ for (const char *str = (void *)(ehdr) + shdr_offset(sec), \
+ *end = str + shdr_size(sec); \
+ len = strlen(str), str < end; \
+ str += (len) + 1)
+
+
+static void make_trace_array(struct elf_tracepoint *etrace)
+{
+ Elf_Ehdr *ehdr = etrace->ehdr;
+ const char **vals = NULL;
+ int count = 0;
+ int len;
+
+ etrace->array = NULL;
+
+ /*
+ * The __tracepoint_check section is filled with strings of the
+ * names of tracepoints (in tracepoint_strings). Create an array
+ * that points to each string and then sort the array.
+ */
+ for_each_shdr_str(len, ehdr, check_data_sec) {
+ if (!len)
+ continue;
+ if (add_string(str, &vals, &count) < 0)
+ return;
+ }
+
+ /* If CONFIG_TRACEPOINT_VERIFY_USED is not set, there's nothing to do */
+ if (!count)
+ return;
+
+ qsort(vals, count, sizeof(char *), compare_strings);
+
+ etrace->array = vals;
+ etrace->count = count;
+}
+
+static int find_event(const char *str, void *array, size_t size)
+{
+ return bsearch(&str, array, size, sizeof(char *), compare_strings) != NULL;
+}
+
+static void check_tracepoints(struct elf_tracepoint *etrace)
+{
+ Elf_Ehdr *ehdr = etrace->ehdr;
+ int len;
+
+ if (!etrace->array)
+ return;
+
+ /*
+ * The __tracepoints_strings section holds all the names of the
+ * defined tracepoints. If any of them are not in the
+ * __tracepoint_check_section it means they are not used.
+ */
+ for_each_shdr_str(len, ehdr, tracepoint_data_sec) {
+ if (!len)
+ continue;
+ if (!find_event(str, etrace->array, etrace->count)) {
+ fprintf(stderr, "warning: tracepoint '%s' is unused.\n", str);
+ }
+ }
+
+ free(etrace->array);
+}
+
+static void *tracepoint_check(struct elf_tracepoint *etrace)
+{
+ make_trace_array(etrace);
+ check_tracepoints(etrace);
+
+ return NULL;
+}
+
+static int process_tracepoints(void *addr, char const *const fname)
+{
+ struct elf_tracepoint etrace = {0};
+ Elf_Ehdr *ehdr = addr;
+ Elf_Shdr *shdr_start;
+ Elf_Shdr *string_sec;
+ const char *secstrings;
+ unsigned int shnum;
+ unsigned int shstrndx;
+ int shentsize;
+ int idx;
+ int done = 2;
+
+ shdr_start = (Elf_Shdr *)((char *)ehdr + ehdr_shoff(ehdr));
+ shentsize = ehdr_shentsize(ehdr);
+
+ shstrndx = ehdr_shstrndx(ehdr);
+ if (shstrndx == SHN_XINDEX)
+ shstrndx = shdr_link(shdr_start);
+ string_sec = get_index(shdr_start, shentsize, shstrndx);
+ secstrings = (const char *)ehdr + shdr_offset(string_sec);
+
+ shnum = ehdr_shnum(ehdr);
+ if (shnum == SHN_UNDEF)
+ shnum = shdr_size(shdr_start);
+
+ for (int i = 0; done && i < shnum; i++) {
+ Elf_Shdr *shdr = get_index(shdr_start, shentsize, i);
+
+ idx = shdr_name(shdr);
+
+ /* locate the __tracepoint_check in vmlinux */
+ if (!strcmp(secstrings + idx, "__tracepoint_check")) {
+ check_data_sec = shdr;
+ done--;
+ }
+
+ /* locate the __tracepoints_ptrs section in vmlinux */
+ if (!strcmp(secstrings + idx, "__tracepoints_strings")) {
+ tracepoint_data_sec = shdr;
+ done--;
+ }
+ }
+
+ if (!check_data_sec) {
+ fprintf(stderr, "no __tracepoint_check in file: %s\n", fname);
+ return -1;
+ }
+
+ if (!tracepoint_data_sec) {
+ fprintf(stderr, "no __tracepoint_strings in file: %s\n", fname);
+ return -1;
+ }
+
+ etrace.ehdr = ehdr;
+ tracepoint_check(&etrace);
+ return 0;
+}
+
+int main(int argc, char *argv[])
+{
+ int n_error = 0;
+ size_t size = 0;
+ void *addr = NULL;
+
+ if (argc < 2) {
+ fprintf(stderr, "usage: tracepoint-update vmlinux...\n");
+ return 0;
+ }
+
+ /* Process each file in turn, allowing deep failure. */
+ for (int i = 1; i < argc; i++) {
+ addr = elf_map(argv[i], &size, 1 << ET_REL);
+ if (!addr) {
+ ++n_error;
+ continue;
+ }
+
+ if (process_tracepoints(addr, argv[i]))
+ ++n_error;
+
+ elf_unmap(addr, size);
+ }
+
+ return !!n_error;
+}
--
2.51.0
^ permalink raw reply related [flat|nested] 6+ messages in thread* [for-next][PATCH 4/5] tracing: Allow tracepoint-update.c to work with modules
2025-10-27 20:13 [for-next][PATCH 0/5] tracing: Detect unused tracepoints for v6.19 Steven Rostedt
` (2 preceding siblings ...)
2025-10-27 20:13 ` [for-next][PATCH 3/5] tracepoint: Do not warn for unused event that is exported Steven Rostedt
@ 2025-10-27 20:13 ` Steven Rostedt
2025-10-27 20:13 ` [for-next][PATCH 5/5] tracing: Add warnings for unused tracepoints for modules Steven Rostedt
4 siblings, 0 replies; 6+ messages in thread
From: Steven Rostedt @ 2025-10-27 20:13 UTC (permalink / raw)
To: linux-kernel
Cc: Masami Hiramatsu, Mark Rutland, Mathieu Desnoyers, Andrew Morton,
Arnd Bergmann, Masahiro Yamada, Nathan Chancellor, Nicolas Schier,
Nick Desaulniers, Catalin Marinas, Linus Torvalds, Randy Dunlap,
Stephen Rothwell
From: Steven Rostedt <rostedt@goodmis.org>
In order for tracepoint-update.c to work with modules, it cannot error out
if both "__tracepoint_check" and "__tracepoints_strings" are not found.
When enabled, the vmlinux.o may be required to have both, but modules only
have these sections if they have tracepoints. Modules without tracepoints
will not have either. They should not fail to build because of that.
If one section exists the other one should too. Note, if a module defines
a tracepoint but doesn't use any, it can cause this to fail.
Add a new "--module" parameter to tracepoint-update to be used when
running on module code. It will not error out if this is set and both
sections are missing. If this is set, and only the "__tracepoint_check"
section is missing, it means the module has defined tracepoints but none
of them are used. In that case, it prints a warning that the module has
only unused tracepoints and exits normally to not fail the build.
If the "__tracepoint_check" section exists but not the
"__tracepoint_strings", then that is an error and should fail the build.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nicolas Schier <nicolas.schier@linux.dev>
Cc: Nick Desaulniers <nick.desaulniers+lkml@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Link: https://lore.kernel.org/20251022004453.255696445@kernel.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
scripts/tracepoint-update.c | 45 ++++++++++++++++++++++++++++++-------
1 file changed, 37 insertions(+), 8 deletions(-)
diff --git a/scripts/tracepoint-update.c b/scripts/tracepoint-update.c
index 6ec30f39d0ad..7f7d90df14ce 100644
--- a/scripts/tracepoint-update.c
+++ b/scripts/tracepoint-update.c
@@ -112,7 +112,7 @@ static int find_event(const char *str, void *array, size_t size)
return bsearch(&str, array, size, sizeof(char *), compare_strings) != NULL;
}
-static void check_tracepoints(struct elf_tracepoint *etrace)
+static void check_tracepoints(struct elf_tracepoint *etrace, const char *fname)
{
Elf_Ehdr *ehdr = etrace->ehdr;
int len;
@@ -129,22 +129,26 @@ static void check_tracepoints(struct elf_tracepoint *etrace)
if (!len)
continue;
if (!find_event(str, etrace->array, etrace->count)) {
- fprintf(stderr, "warning: tracepoint '%s' is unused.\n", str);
+ fprintf(stderr, "warning: tracepoint '%s' is unused", str);
+ if (fname)
+ fprintf(stderr, " in module %s\n", fname);
+ else
+ fprintf(stderr, "\n");
}
}
free(etrace->array);
}
-static void *tracepoint_check(struct elf_tracepoint *etrace)
+static void *tracepoint_check(struct elf_tracepoint *etrace, const char *fname)
{
make_trace_array(etrace);
- check_tracepoints(etrace);
+ check_tracepoints(etrace, fname);
return NULL;
}
-static int process_tracepoints(void *addr, char const *const fname)
+static int process_tracepoints(bool mod, void *addr, const char *fname)
{
struct elf_tracepoint etrace = {0};
Elf_Ehdr *ehdr = addr;
@@ -188,7 +192,19 @@ static int process_tracepoints(void *addr, char const *const fname)
}
}
+ /*
+ * Modules may not have either section. But if it has one section,
+ * it should have both of them.
+ */
+ if (mod && !check_data_sec && !tracepoint_data_sec)
+ return 0;
+
if (!check_data_sec) {
+ if (mod) {
+ fprintf(stderr, "warning: Module %s has only unused tracepoints\n", fname);
+ /* Do not fail build */
+ return 0;
+ }
fprintf(stderr, "no __tracepoint_check in file: %s\n", fname);
return -1;
}
@@ -198,8 +214,11 @@ static int process_tracepoints(void *addr, char const *const fname)
return -1;
}
+ if (!mod)
+ fname = NULL;
+
etrace.ehdr = ehdr;
- tracepoint_check(&etrace);
+ tracepoint_check(&etrace, fname);
return 0;
}
@@ -208,9 +227,19 @@ int main(int argc, char *argv[])
int n_error = 0;
size_t size = 0;
void *addr = NULL;
+ bool mod = false;
+
+ if (argc > 1 && strcmp(argv[1], "--module") == 0) {
+ mod = true;
+ argc--;
+ argv++;
+ }
if (argc < 2) {
- fprintf(stderr, "usage: tracepoint-update vmlinux...\n");
+ if (mod)
+ fprintf(stderr, "usage: tracepoint-update --module module...\n");
+ else
+ fprintf(stderr, "usage: tracepoint-update vmlinux...\n");
return 0;
}
@@ -222,7 +251,7 @@ int main(int argc, char *argv[])
continue;
}
- if (process_tracepoints(addr, argv[i]))
+ if (process_tracepoints(mod, addr, argv[i]))
++n_error;
elf_unmap(addr, size);
--
2.51.0
^ permalink raw reply related [flat|nested] 6+ messages in thread