diff options
| -rw-r--r-- | Makefile | 21 | ||||
| -rw-r--r-- | include/asm-generic/vmlinux.lds.h | 1 | ||||
| -rw-r--r-- | include/linux/tracepoint.h | 11 | ||||
| -rw-r--r-- | scripts/Makefile | 3 | ||||
| -rwxr-xr-x | scripts/link-vmlinux.sh | 7 | ||||
| -rw-r--r-- | scripts/tracepoint-update.c | 232 |
6 files changed, 275 insertions, 0 deletions
@@ -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 @@ -222,6 +222,15 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) } /* + * 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 * structure. Force alignment to the same alignment as the section start. @@ -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; +} |