ftrace: Synchronize the initialization of ftrace_opsgrafted

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 <rostedt@goodmis.org>

1 files changed, 471 insertions, 0 deletions

diff --git a/tools/perf/util/genelf.c b/tools/perf/util/genelf.c
new file mode 100644
index 000000000..14882def9
--- /dev/null
+++ b/tools/perf/util/genelf.c
@@ -0,0 +1,471 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * genelf.c
+ * Copyright (C) 2014, Google, Inc
+ *
+ * Contributed by:
+ * 	Stephane Eranian <eranian@gmail.com>
+ */
+
+#include <sys/types.h>
+#include <stddef.h>
+#include <libelf.h>
+#include <string.h>
+#include <stdlib.h>
+#include <inttypes.h>
+#include <err.h>
+#ifdef HAVE_LIBDW_SUPPORT
+#include <dwarf.h>
+#endif
+
+#include "blake2s.h"
+#include "genelf.h"
+#include "../util/jitdump.h"
+#include <linux/compiler.h>
+
+#ifndef NT_GNU_BUILD_ID
+#define NT_GNU_BUILD_ID 3
+#endif
+
+typedef struct {
+  unsigned int namesz;  /* Size of entry's owner string */
+  unsigned int descsz;  /* Size of the note descriptor */
+  unsigned int type;    /* Interpretation of the descriptor */
+  char         name[0]; /* Start of the name+desc data */
+} Elf_Note;
+
+static char shd_string_table[] = {
+	0,
+	'.', 't', 'e', 'x', 't', 0,			/*  1 */
+	'.', 's', 'h', 's', 't', 'r', 't', 'a', 'b', 0, /*  7 */
+	'.', 's', 'y', 'm', 't', 'a', 'b', 0,		/* 17 */
+	'.', 's', 't', 'r', 't', 'a', 'b', 0,		/* 25 */
+	'.', 'n', 'o', 't', 'e', '.', 'g', 'n', 'u', '.', 'b', 'u', 'i', 'l', 'd', '-', 'i', 'd', 0, /* 33 */
+	'.', 'd', 'e', 'b', 'u', 'g', '_', 'l', 'i', 'n', 'e', 0, /* 52 */
+	'.', 'd', 'e', 'b', 'u', 'g', '_', 'i', 'n', 'f', 'o', 0, /* 64 */
+	'.', 'd', 'e', 'b', 'u', 'g', '_', 'a', 'b', 'b', 'r', 'e', 'v', 0, /* 76 */
+	'.', 'e', 'h', '_', 'f', 'r', 'a', 'm', 'e', '_', 'h', 'd', 'r', 0, /* 90 */
+	'.', 'e', 'h', '_', 'f', 'r', 'a', 'm', 'e', 0, /* 104 */
+};
+
+static struct buildid_note {
+	Elf_Note desc;		/* descsz: size of build-id, must be multiple of 4 */
+	char	 name[4];	/* GNU\0 */
+	u8	 build_id[20];
+} bnote;
+
+static Elf_Sym symtab[]={
+	/* symbol 0 MUST be the undefined symbol */
+	{ .st_name  = 0, /* index in sym_string table */
+	  .st_info  = ELF_ST_TYPE(STT_NOTYPE),
+	  .st_shndx = 0, /* for now */
+	  .st_value = 0x0,
+	  .st_other = ELF_ST_VIS(STV_DEFAULT),
+	  .st_size  = 0,
+	},
+	{ .st_name  = 1, /* index in sym_string table */
+	  .st_info  = ELF_ST_BIND(STB_LOCAL) | ELF_ST_TYPE(STT_FUNC),
+	  .st_shndx = 1,
+	  .st_value = 0, /* for now */
+	  .st_other = ELF_ST_VIS(STV_DEFAULT),
+	  .st_size  = 0, /* for now */
+	}
+};
+
+static int
+jit_add_eh_frame_info(Elf *e, void* unwinding, uint64_t unwinding_header_size,
+		      uint64_t unwinding_size, uint64_t base_offset)
+{
+	Elf_Data *d;
+	Elf_Scn *scn;
+	Elf_Shdr *shdr;
+	uint64_t unwinding_table_size = unwinding_size - unwinding_header_size;
+
+	/*
+	 * setup eh_frame section
+	 */
+	scn = elf_newscn(e);
+	if (!scn) {
+		warnx("cannot create section");
+		return -1;
+	}
+
+	d = elf_newdata(scn);
+	if (!d) {
+		warnx("cannot get new data");
+		return -1;
+	}
+
+	d->d_align = 8;
+	d->d_off = 0LL;
+	d->d_buf = unwinding;
+	d->d_type = ELF_T_BYTE;
+	d->d_size = unwinding_table_size;
+	d->d_version = EV_CURRENT;
+
+	shdr = elf_getshdr(scn);
+	if (!shdr) {
+		warnx("cannot get section header");
+		return -1;
+	}
+
+	shdr->sh_name = 104;
+	shdr->sh_type = SHT_PROGBITS;
+	shdr->sh_addr = base_offset;
+	shdr->sh_flags = SHF_ALLOC;
+	shdr->sh_entsize = 0;
+
+	/*
+	 * setup eh_frame_hdr section
+	 */
+	scn = elf_newscn(e);
+	if (!scn) {
+		warnx("cannot create section");
+		return -1;
+	}
+
+	d = elf_newdata(scn);
+	if (!d) {
+		warnx("cannot get new data");
+		return -1;
+	}
+
+	d->d_align = 4;
+	d->d_off = 0LL;
+	d->d_buf = unwinding + unwinding_table_size;
+	d->d_type = ELF_T_BYTE;
+	d->d_size = unwinding_header_size;
+	d->d_version = EV_CURRENT;
+
+	shdr = elf_getshdr(scn);
+	if (!shdr) {
+		warnx("cannot get section header");
+		return -1;
+	}
+
+	shdr->sh_name = 90;
+	shdr->sh_type = SHT_PROGBITS;
+	shdr->sh_addr = base_offset + unwinding_table_size;
+	shdr->sh_flags = SHF_ALLOC;
+	shdr->sh_entsize = 0;
+
+	return 0;
+}
+
+enum {
+	TAG_CODE = 0,
+	TAG_SYMTAB = 1,
+	TAG_STRSYM = 2,
+};
+
+/*
+ * Update the hash using the given data, also prepending a (tag, len) prefix to
+ * ensure that distinct input tuples reliably result in distinct hashes.
+ */
+static void blake2s_update_tagged(struct blake2s_ctx *ctx, int tag,
+				  const void *data, size_t len)
+{
+	u64 prefix = ((u64)tag << 56) | len;
+
+	blake2s_update(ctx, (const u8 *)&prefix, sizeof(prefix));
+	blake2s_update(ctx, data, len);
+}
+
+/*
+ * fd: file descriptor open for writing for the output file
+ * load_addr: code load address (could be zero)
+ * sym: function name (for native code - used as the symbol)
+ * code: the native code
+ * csize: the code size in bytes
+ */
+int
+jit_write_elf(int fd, uint64_t load_addr __maybe_unused, const char *sym,
+	      const void *code, int csize,
+	      void *debug __maybe_unused, int nr_debug_entries __maybe_unused,
+	      void *unwinding, uint64_t unwinding_header_size, uint64_t unwinding_size)
+{
+	Elf *e;
+	Elf_Data *d;
+	Elf_Scn *scn;
+	Elf_Ehdr *ehdr;
+	Elf_Phdr *phdr;
+	Elf_Shdr *shdr;
+	uint64_t eh_frame_base_offset;
+	char *strsym = NULL;
+	struct blake2s_ctx ctx;
+	int symlen;
+	int retval = -1;
+
+	if (elf_version(EV_CURRENT) == EV_NONE) {
+		warnx("ELF initialization failed");
+		return -1;
+	}
+
+	e = elf_begin(fd, ELF_C_WRITE, NULL);
+	if (!e) {
+		warnx("elf_begin failed");
+		goto error;
+	}
+
+	/*
+	 * setup ELF header
+	 */
+	ehdr = elf_newehdr(e);
+	if (!ehdr) {
+		warnx("cannot get ehdr");
+		goto error;
+	}
+
+	ehdr->e_ident[EI_DATA] = GEN_ELF_ENDIAN;
+	ehdr->e_ident[EI_CLASS] = GEN_ELF_CLASS;
+	ehdr->e_machine = GEN_ELF_ARCH;
+	ehdr->e_type = ET_DYN;
+	ehdr->e_entry = GEN_ELF_TEXT_OFFSET;
+	ehdr->e_version = EV_CURRENT;
+	ehdr->e_shstrndx= unwinding ? 4 : 2; /* shdr index for section name */
+
+	/*
+	 * setup program header
+	 */
+	phdr = elf_newphdr(e, 1);
+	phdr[0].p_type = PT_LOAD;
+	phdr[0].p_offset = GEN_ELF_TEXT_OFFSET;
+	phdr[0].p_vaddr = GEN_ELF_TEXT_OFFSET;
+	phdr[0].p_paddr = GEN_ELF_TEXT_OFFSET;
+	phdr[0].p_filesz = csize;
+	phdr[0].p_memsz = csize;
+	phdr[0].p_flags = PF_X | PF_R;
+	phdr[0].p_align = 8;
+
+	/*
+	 * setup text section
+	 */
+	scn = elf_newscn(e);
+	if (!scn) {
+		warnx("cannot create section");
+		goto error;
+	}
+
+	d = elf_newdata(scn);
+	if (!d) {
+		warnx("cannot get new data");
+		goto error;
+	}
+
+	d->d_align = 16;
+	d->d_off = 0LL;
+	d->d_buf = (void *)code;
+	d->d_type = ELF_T_BYTE;
+	d->d_size = csize;
+	d->d_version = EV_CURRENT;
+
+	shdr = elf_getshdr(scn);
+	if (!shdr) {
+		warnx("cannot get section header");
+		goto error;
+	}
+
+	shdr->sh_name = 1;
+	shdr->sh_type = SHT_PROGBITS;
+	shdr->sh_addr = GEN_ELF_TEXT_OFFSET;
+	shdr->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
+	shdr->sh_entsize = 0;
+
+	blake2s_init(&ctx, sizeof(bnote.build_id));
+	blake2s_update_tagged(&ctx, TAG_CODE, code, csize);
+
+	/*
+	 * Setup .eh_frame_hdr and .eh_frame
+	 */
+	if (unwinding) {
+		eh_frame_base_offset = ALIGN_8(GEN_ELF_TEXT_OFFSET + csize);
+		retval = jit_add_eh_frame_info(e, unwinding,
+					       unwinding_header_size, unwinding_size,
+					       eh_frame_base_offset);
+		if (retval)
+			goto error;
+		retval = -1;
+	}
+
+	/*
+	 * setup section headers string table
+	 */
+	scn = elf_newscn(e);
+	if (!scn) {
+		warnx("cannot create section");
+		goto error;
+	}
+
+	d = elf_newdata(scn);
+	if (!d) {
+		warnx("cannot get new data");
+		goto error;
+	}
+
+	d->d_align = 1;
+	d->d_off = 0LL;
+	d->d_buf = shd_string_table;
+	d->d_type = ELF_T_BYTE;
+	d->d_size = sizeof(shd_string_table);
+	d->d_version = EV_CURRENT;
+
+	shdr = elf_getshdr(scn);
+	if (!shdr) {
+		warnx("cannot get section header");
+		goto error;
+	}
+
+	shdr->sh_name = 7; /* offset of '.shstrtab' in shd_string_table */
+	shdr->sh_type = SHT_STRTAB;
+	shdr->sh_flags = 0;
+	shdr->sh_entsize = 0;
+
+	/*
+	 * setup symtab section
+	 */
+	symtab[1].st_size  = csize;
+	symtab[1].st_value = GEN_ELF_TEXT_OFFSET;
+
+	scn = elf_newscn(e);
+	if (!scn) {
+		warnx("cannot create section");
+		goto error;
+	}
+
+	d = elf_newdata(scn);
+	if (!d) {
+		warnx("cannot get new data");
+		goto error;
+	}
+
+	d->d_align = 8;
+	d->d_off = 0LL;
+	d->d_buf = symtab;
+	d->d_type = ELF_T_SYM;
+	d->d_size = sizeof(symtab);
+	d->d_version = EV_CURRENT;
+
+	shdr = elf_getshdr(scn);
+	if (!shdr) {
+		warnx("cannot get section header");
+		goto error;
+	}
+
+	shdr->sh_name = 17; /* offset of '.symtab' in shd_string_table */
+	shdr->sh_type = SHT_SYMTAB;
+	shdr->sh_flags = 0;
+	shdr->sh_entsize = sizeof(Elf_Sym);
+	shdr->sh_link = unwinding ? 6 : 4; /* index of .strtab section */
+
+	blake2s_update_tagged(&ctx, TAG_SYMTAB, symtab, sizeof(symtab));
+
+	/*
+	 * setup symbols string table
+	 * 2 = 1 for 0 in 1st entry, 1 for the 0 at end of symbol for 2nd entry
+	 */
+	symlen = 2 + strlen(sym);
+	strsym = calloc(1, symlen);
+	if (!strsym) {
+		warnx("cannot allocate strsym");
+		goto error;
+	}
+	strcpy(strsym + 1, sym);
+
+	scn = elf_newscn(e);
+	if (!scn) {
+		warnx("cannot create section");
+		goto error;
+	}
+
+	d = elf_newdata(scn);
+	if (!d) {
+		warnx("cannot get new data");
+		goto error;
+	}
+
+	d->d_align = 1;
+	d->d_off = 0LL;
+	d->d_buf = strsym;
+	d->d_type = ELF_T_BYTE;
+	d->d_size = symlen;
+	d->d_version = EV_CURRENT;
+
+	shdr = elf_getshdr(scn);
+	if (!shdr) {
+		warnx("cannot get section header");
+		goto error;
+	}
+
+	shdr->sh_name = 25; /* offset in shd_string_table */
+	shdr->sh_type = SHT_STRTAB;
+	shdr->sh_flags = 0;
+	shdr->sh_entsize = 0;
+
+	blake2s_update_tagged(&ctx, TAG_STRSYM, strsym, symlen);
+
+	/*
+	 * setup build-id section
+	 */
+	scn = elf_newscn(e);
+	if (!scn) {
+		warnx("cannot create section");
+		goto error;
+	}
+
+	d = elf_newdata(scn);
+	if (!d) {
+		warnx("cannot get new data");
+		goto error;
+	}
+
+	/*
+	 * build-id generation
+	 */
+	blake2s_final(&ctx, bnote.build_id);
+	bnote.desc.namesz = sizeof(bnote.name); /* must include 0 termination */
+	bnote.desc.descsz = sizeof(bnote.build_id);
+	bnote.desc.type   = NT_GNU_BUILD_ID;
+	strcpy(bnote.name, "GNU");
+
+	d->d_align = 4;
+	d->d_off = 0LL;
+	d->d_buf = &bnote;
+	d->d_type = ELF_T_BYTE;
+	d->d_size = sizeof(bnote);
+	d->d_version = EV_CURRENT;
+
+	shdr = elf_getshdr(scn);
+	if (!shdr) {
+		warnx("cannot get section header");
+		goto error;
+	}
+
+	shdr->sh_name = 33; /* offset in shd_string_table */
+	shdr->sh_type = SHT_NOTE;
+	shdr->sh_addr = 0x0;
+	shdr->sh_flags = SHF_ALLOC;
+	shdr->sh_size = sizeof(bnote);
+	shdr->sh_entsize = 0;
+
+#ifdef HAVE_LIBDW_SUPPORT
+	if (debug && nr_debug_entries) {
+		retval = jit_add_debug_info(e, load_addr, debug, nr_debug_entries);
+		if (retval)
+			goto error;
+	} else
+#endif
+	{
+		if (elf_update(e, ELF_C_WRITE) < 0) {
+			warnx("elf_update 4 failed");
+			goto error;
+		}
+	}
+
+	retval = 0;
+error:
+	(void)elf_end(e);
+
+	free(strsym);
+
+	return retval;
+}