From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- tools/lib/symbol/Build | 1 + tools/lib/symbol/Makefile | 114 ++++++++++++++++++++++++++++++++++++++++++++ tools/lib/symbol/kallsyms.c | 81 +++++++++++++++++++++++++++++++ tools/lib/symbol/kallsyms.h | 29 +++++++++++ 4 files changed, 225 insertions(+) create mode 100644 tools/lib/symbol/Build create mode 100644 tools/lib/symbol/Makefile create mode 100644 tools/lib/symbol/kallsyms.c create mode 100644 tools/lib/symbol/kallsyms.h (limited to 'tools/lib/symbol') diff --git a/tools/lib/symbol/Build b/tools/lib/symbol/Build new file mode 100644 index 000000000..9b9a9c78d --- /dev/null +++ b/tools/lib/symbol/Build @@ -0,0 +1 @@ +libsymbol-y += kallsyms.o diff --git a/tools/lib/symbol/Makefile b/tools/lib/symbol/Makefile new file mode 100644 index 000000000..d692abe8a --- /dev/null +++ b/tools/lib/symbol/Makefile @@ -0,0 +1,114 @@ +# SPDX-License-Identifier: GPL-2.0 +include ../../scripts/Makefile.include +include ../../scripts/utilities.mak # QUIET_CLEAN + +ifeq ($(srctree),) +srctree := $(patsubst %/,%,$(dir $(CURDIR))) +srctree := $(patsubst %/,%,$(dir $(srctree))) +srctree := $(patsubst %/,%,$(dir $(srctree))) +#$(info Determined 'srctree' to be $(srctree)) +endif + +MAKEFLAGS += --no-print-directory + +INSTALL = install + + +# Use DESTDIR for installing into a different root directory. +# This is useful for building a package. The program will be +# installed in this directory as if it was the root directory. +# Then the build tool can move it later. +DESTDIR ?= +DESTDIR_SQ = '$(subst ','\'',$(DESTDIR))' + +LIBFILE = $(OUTPUT)libsymbol.a + +CFLAGS := $(EXTRA_WARNINGS) $(EXTRA_CFLAGS) +CFLAGS += -ggdb3 -Wall -Wextra -std=gnu11 -U_FORTIFY_SOURCE -fPIC + +ifeq ($(DEBUG),0) + CFLAGS += -O3 +endif + +ifeq ($(DEBUG),0) + CFLAGS += -D_FORTIFY_SOURCE +endif + +# Treat warnings as errors unless directed not to +ifneq ($(WERROR),0) + CFLAGS += -Werror +endif + +CFLAGS += -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 + +CFLAGS += -I$(srctree)/tools/lib +CFLAGS += -I$(srctree)/tools/include + +RM = rm -f + +SYMBOL_IN := $(OUTPUT)libsymbol-in.o + +ifeq ($(LP64), 1) + libdir_relative = lib64 +else + libdir_relative = lib +endif + +prefix ?= +libdir = $(prefix)/$(libdir_relative) + +# Shell quotes +libdir_SQ = $(subst ','\'',$(libdir)) + +all: + +export srctree OUTPUT CC LD CFLAGS V +include $(srctree)/tools/build/Makefile.include +include $(srctree)/tools/scripts/Makefile.include + +all: fixdep $(LIBFILE) + +$(SYMBOL_IN): FORCE + @$(MAKE) $(build)=libsymbol + +$(LIBFILE): $(SYMBOL_IN) + $(QUIET_AR)$(RM) $@ && $(AR) rcs $@ $(SYMBOL_IN) + +define do_install_mkdir + if [ ! -d '$(DESTDIR_SQ)$1' ]; then \ + $(INSTALL) -d -m 755 '$(DESTDIR_SQ)$1'; \ + fi +endef + +define do_install + if [ ! -d '$2' ]; then \ + $(INSTALL) -d -m 755 '$2'; \ + fi; \ + $(INSTALL) $1 $(if $3,-m $3,) '$2' +endef + +install_lib: $(LIBFILE) + $(call QUIET_INSTALL, $(LIBFILE)) \ + $(call do_install_mkdir,$(libdir_SQ)); \ + cp -fpR $(LIBFILE) $(DESTDIR)$(libdir_SQ) + +HDRS := kallsyms.h +INSTALL_HDRS_PFX := $(DESTDIR)$(prefix)/include/symbol +INSTALL_HDRS := $(addprefix $(INSTALL_HDRS_PFX)/, $(HDRS)) + +$(INSTALL_HDRS): $(INSTALL_HDRS_PFX)/%.h: %.h + $(call QUIET_INSTALL, $@) \ + $(call do_install,$<,$(INSTALL_HDRS_PFX)/,644) + +install_headers: $(INSTALL_HDRS) + $(call QUIET_INSTALL, libsymbol_headers) + +install: install_lib install_headers + +clean: + $(call QUIET_CLEAN, libsymbol) $(RM) $(LIBFILE); \ + find $(or $(OUTPUT),.) -name \*.o -or -name \*.o.cmd -or -name \*.o.d | xargs $(RM) + +FORCE: + +.PHONY: clean FORCE diff --git a/tools/lib/symbol/kallsyms.c b/tools/lib/symbol/kallsyms.c new file mode 100644 index 000000000..d64bd9cc8 --- /dev/null +++ b/tools/lib/symbol/kallsyms.c @@ -0,0 +1,81 @@ +// SPDX-License-Identifier: GPL-2.0 +#include "symbol/kallsyms.h" +#include "api/io.h" +#include +#include +#include + +u8 kallsyms2elf_type(char type) +{ + type = tolower(type); + return (type == 't' || type == 'w') ? STT_FUNC : STT_OBJECT; +} + +bool kallsyms__is_function(char symbol_type) +{ + symbol_type = toupper(symbol_type); + return symbol_type == 'T' || symbol_type == 'W'; +} + +static void read_to_eol(struct io *io) +{ + int ch; + + for (;;) { + ch = io__get_char(io); + if (ch < 0 || ch == '\n') + return; + } +} + +int kallsyms__parse(const char *filename, void *arg, + int (*process_symbol)(void *arg, const char *name, + char type, u64 start)) +{ + struct io io; + char bf[BUFSIZ]; + int err; + + io.fd = open(filename, O_RDONLY, 0); + + if (io.fd < 0) + return -1; + + io__init(&io, io.fd, bf, sizeof(bf)); + + err = 0; + while (!io.eof) { + __u64 start; + int ch; + size_t i; + char symbol_type; + char symbol_name[KSYM_NAME_LEN + 1]; + + if (io__get_hex(&io, &start) != ' ') { + read_to_eol(&io); + continue; + } + symbol_type = io__get_char(&io); + if (io__get_char(&io) != ' ') { + read_to_eol(&io); + continue; + } + for (i = 0; i < KSYM_NAME_LEN; i++) { + ch = io__get_char(&io); + if (ch < 0 || ch == '\n') + break; + symbol_name[i] = ch; + } + symbol_name[i] = '\0'; + + if (i == KSYM_NAME_LEN) + read_to_eol(&io); + + err = process_symbol(arg, symbol_name, symbol_type, start); + if (err) + break; + } + + close(io.fd); + return err; +} diff --git a/tools/lib/symbol/kallsyms.h b/tools/lib/symbol/kallsyms.h new file mode 100644 index 000000000..542f9b059 --- /dev/null +++ b/tools/lib/symbol/kallsyms.h @@ -0,0 +1,29 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __TOOLS_KALLSYMS_H_ +#define __TOOLS_KALLSYMS_H_ 1 + +#include +#include +#include + +#ifndef KSYM_NAME_LEN +#define KSYM_NAME_LEN 512 +#endif + +static inline u8 kallsyms2elf_binding(char type) +{ + if (type == 'W') + return STB_WEAK; + + return isupper(type) ? STB_GLOBAL : STB_LOCAL; +} + +u8 kallsyms2elf_type(char type); + +bool kallsyms__is_function(char symbol_type); + +int kallsyms__parse(const char *filename, void *arg, + int (*process_symbol)(void *arg, const char *name, + char type, u64 start)); + +#endif /* __TOOLS_KALLSYMS_H_ */ -- cgit v1.3.1