Revision eb35bdd7bca29a13c8ecd44e6fd747a84ce675db authored by Will Deacon on 11 September 2014, 13:38:16 UTC, committed by Will Deacon on 11 September 2014, 17:34:58 UTC
Nathan reports that we leak TLS information from the parent context
during an exec, as we don't clear the TLS registers when flushing the
thread state.

This patch updates the flushing code so that we:

  (1) Unconditionally zero the tpidr_el0 register (since this is fully
      context switched for native tasks and zeroed for compat tasks)

  (2) Zero the tp_value state in thread_info before clearing the
      tpidrr0_el0 register for compat tasks (since this is only writable
      by the set_tls compat syscall and therefore not fully switched).

A missing compiler barrier is also added to the compat set_tls syscall.

Cc: <stable@vger.kernel.org>
Acked-by: Nathan Lynch <Nathan_Lynch@mentor.com>
Reported-by: Nathan Lynch <Nathan_Lynch@mentor.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
1 parent 3d8afe3
Raw File
conmakehash.c
/*
 * 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
 *
 * This program is a part of the Linux kernel, and may be freely
 * copied under the terms of the GNU General Public License (GPL),
 * version 2, or at your option any later version.
 */

#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;
  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\
 * Do not edit this file; it was automatically generated by\n\
 *\n\
 * conmakehash %s > [this file]\n\
 *\n\
 */\n\
\n\
#include <linux/types.h>\n\
\n\
u8 dfont_unicount[%d] = \n\
{\n\t", argv[1], 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);
}
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