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, 287 insertions, 0 deletions

diff --git a/drivers/tty/vt/conmakehash.c b/drivers/tty/vt/conmakehash.c
new file mode 100644
index 000000000..a931fcde7
--- /dev/null
+++ b/drivers/tty/vt/conmakehash.c
@@ -0,0 +1,287 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * conmakehash.c
+ *
+ * Create arrays for initializing the kernel folded tables (using a hash
+ * table turned out to be to limiting...)  Unfortunately we can't simply
+ * preinitialize the tables at compile time since kfree() cannot accept
+ * memory not allocated by kmalloc(), and doing our own memory management
+ * just for this seems like massive overkill.
+ *
+ * Copyright (C) 1995-1997 H. Peter Anvin
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sysexits.h>
+#include <string.h>
+#include <ctype.h>
+
+#define MAX_FONTLEN 256
+
+typedef unsigned short unicode;
+
+static void usage(char *argv0)
+{
+  fprintf(stderr, "Usage: \n"
+         "        %s chartable [hashsize] [hashstep] [maxhashlevel]\n", argv0);
+  exit(EX_USAGE);
+}
+
+static int getunicode(char **p0)
+{
+  char *p = *p0;
+
+  while (*p == ' ' || *p == '\t')
+    p++;
+  if (*p != 'U' || p[1] != '+' ||
+      !isxdigit(p[2]) || !isxdigit(p[3]) || !isxdigit(p[4]) ||
+      !isxdigit(p[5]) || isxdigit(p[6]))
+    return -1;
+  *p0 = p+6;
+  return strtol(p+2,0,16);
+}
+
+unicode unitable[MAX_FONTLEN][255];
+				/* Massive overkill, but who cares? */
+int unicount[MAX_FONTLEN];
+
+static void addpair(int fp, int un)
+{
+  int i;
+
+  if ( un <= 0xfffe )
+    {
+      /* Check it isn't a duplicate */
+
+      for ( i = 0 ; i < unicount[fp] ; i++ )
+	if ( unitable[fp][i] == un )
+	  return;
+
+      /* Add to list */
+
+      if ( unicount[fp] > 254 )
+	{
+	  fprintf(stderr, "ERROR: Only 255 unicodes/glyph permitted!\n");
+	  exit(EX_DATAERR);
+	}
+
+      unitable[fp][unicount[fp]] = un;
+      unicount[fp]++;
+    }
+
+  /* otherwise: ignore */
+}
+
+int main(int argc, char *argv[])
+{
+  FILE *ctbl;
+  const char *tblname;
+  char buffer[65536];
+  int fontlen;
+  int i, nuni, nent;
+  int fp0, fp1, un0, un1;
+  char *p, *p1;
+
+  if ( argc < 2 || argc > 5 )
+    usage(argv[0]);
+
+  if ( !strcmp(argv[1],"-") )
+    {
+      ctbl = stdin;
+      tblname = "stdin";
+    }
+  else
+    {
+      ctbl = fopen(tblname = argv[1], "r");
+      if ( !ctbl )
+	{
+	  perror(tblname);
+	  exit(EX_NOINPUT);
+	}
+    }
+
+  /* For now we assume the default font is always 256 characters. */
+  fontlen = 256;
+
+  /* Initialize table */
+
+  for ( i = 0 ; i < fontlen ; i++ )
+    unicount[i] = 0;
+
+  /* Now we come to the tricky part.  Parse the input table. */
+
+  while ( fgets(buffer, sizeof(buffer), ctbl) != NULL )
+    {
+      if ( (p = strchr(buffer, '\n')) != NULL )
+	*p = '\0';
+      else
+	fprintf(stderr, "%s: Warning: line too long\n", tblname);
+
+      p = buffer;
+
+/*
+ * Syntax accepted:
+ *	<fontpos>	<unicode> <unicode> ...
+ *	<range>		idem
+ *	<range>		<unicode range>
+ *
+ * where <range> ::= <fontpos>-<fontpos>
+ * and <unicode> ::= U+<h><h><h><h>
+ * and <h> ::= <hexadecimal digit>
+ */
+
+      while (*p == ' ' || *p == '\t')
+	p++;
+      if (!*p || *p == '#')
+	continue;	/* skip comment or blank line */
+
+      fp0 = strtol(p, &p1, 0);
+      if (p1 == p)
+	{
+	  fprintf(stderr, "Bad input line: %s\n", buffer);
+	  exit(EX_DATAERR);
+        }
+      p = p1;
+
+      while (*p == ' ' || *p == '\t')
+	p++;
+      if (*p == '-')
+	{
+	  p++;
+	  fp1 = strtol(p, &p1, 0);
+	  if (p1 == p)
+	    {
+	      fprintf(stderr, "Bad input line: %s\n", buffer);
+	      exit(EX_DATAERR);
+	    }
+	  p = p1;
+        }
+      else
+	fp1 = 0;
+
+      if ( fp0 < 0 || fp0 >= fontlen )
+	{
+	    fprintf(stderr,
+		    "%s: Glyph number (0x%x) larger than font length\n",
+		    tblname, fp0);
+	    exit(EX_DATAERR);
+	}
+      if ( fp1 && (fp1 < fp0 || fp1 >= fontlen) )
+	{
+	    fprintf(stderr,
+		    "%s: Bad end of range (0x%x)\n",
+		    tblname, fp1);
+	    exit(EX_DATAERR);
+	}
+
+      if (fp1)
+	{
+	  /* we have a range; expect the word "idem" or a Unicode range of the
+	     same length */
+	  while (*p == ' ' || *p == '\t')
+	    p++;
+	  if (!strncmp(p, "idem", 4))
+	    {
+	      for (i=fp0; i<=fp1; i++)
+		addpair(i,i);
+	      p += 4;
+	    }
+	  else
+	    {
+	      un0 = getunicode(&p);
+	      while (*p == ' ' || *p == '\t')
+		p++;
+	      if (*p != '-')
+		{
+		  fprintf(stderr,
+"%s: Corresponding to a range of font positions, there should be a Unicode range\n",
+			  tblname);
+		  exit(EX_DATAERR);
+	        }
+	      p++;
+	      un1 = getunicode(&p);
+	      if (un0 < 0 || un1 < 0)
+		{
+		  fprintf(stderr,
+"%s: Bad Unicode range corresponding to font position range 0x%x-0x%x\n",
+			  tblname, fp0, fp1);
+		  exit(EX_DATAERR);
+	        }
+	      if (un1 - un0 != fp1 - fp0)
+		{
+		  fprintf(stderr,
+"%s: Unicode range U+%x-U+%x not of the same length as font position range 0x%x-0x%x\n",
+			  tblname, un0, un1, fp0, fp1);
+		  exit(EX_DATAERR);
+	        }
+	      for(i=fp0; i<=fp1; i++)
+		addpair(i,un0-fp0+i);
+	    }
+        }
+      else
+	{
+	    /* no range; expect a list of unicode values for a single font position */
+
+	    while ( (un0 = getunicode(&p)) >= 0 )
+	      addpair(fp0, un0);
+	}
+      while (*p == ' ' || *p == '\t')
+	p++;
+      if (*p && *p != '#')
+	fprintf(stderr, "%s: trailing junk (%s) ignored\n", tblname, p);
+    }
+
+  /* Okay, we hit EOF, now output hash table */
+
+  fclose(ctbl);
+
+
+  /* Compute total size of Unicode list */
+  nuni = 0;
+  for ( i = 0 ; i < fontlen ; i++ )
+    nuni += unicount[i];
+
+  printf("\
+/*\n\
+ * Automatically generated file; Do not edit.\n\
+ */\n\
+\n\
+#include <linux/types.h>\n\
+\n\
+u8 dfont_unicount[%d] = \n\
+{\n\t", fontlen);
+
+  for ( i = 0 ; i < fontlen ; i++ )
+    {
+      printf("%3d", unicount[i]);
+      if ( i == fontlen-1 )
+        printf("\n};\n");
+      else if ( i % 8 == 7 )
+        printf(",\n\t");
+      else
+        printf(", ");
+    }
+
+  printf("\nu16 dfont_unitable[%d] = \n{\n\t", nuni);
+
+  fp0 = 0;
+  nent = 0;
+  for ( i = 0 ; i < nuni ; i++ )
+    {
+      while ( nent >= unicount[fp0] )
+	{
+	  fp0++;
+	  nent = 0;
+	}
+      printf("0x%04x", unitable[fp0][nent++]);
+      if ( i == nuni-1 )
+         printf("\n};\n");
+       else if ( i % 8 == 7 )
+         printf(",\n\t");
+       else
+         printf(", ");
+    }
+
+  exit(EX_OK);
+}