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SubjectRe: 2.6.14-rc3-rt10 crashes on boot

* Steven Rostedt <rostedt@goodmis.org> wrote:

> On Fri, 7 Oct 2005, John Rigg wrote:
>
> > Below are excerpts from .config and from boot messages via serial
> > console.
>
> Hmm, I wonder if you're getting a stack overflow?
>
> Have you tried this with turning on CONFIG_DEBUG_STACKOVERFLOW?

i got overflows in initramfs's gunzip with certain debug options. I have
improved the stack footprint of the worst offenders in -rt11 (see the
standalone patch below) - John, does it boot any better?

Ingo

-------
this patch reduces the ~2500+ worst-case stack footprint of zlib to
~500 bytes, by making the largest arrays static and by introducing a
spinlock to protect access to them.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/arm/boot/compressed/misc.c | 1
arch/arm26/boot/compressed/misc.c | 1
arch/i386/boot/compressed/misc.c | 1
arch/x86_64/boot/compressed/misc.c | 1
lib/inflate.c | 44 +++++++++++++++++++++++++++---------
lib/zlib_inflate/inftrees.c | 45 ++++++++++++++++++++++++++++---------
6 files changed, 72 insertions(+), 21 deletions(-)
Index: linux/arch/arm/boot/compressed/misc.c
===================================================================
--- linux.orig/arch/arm/boot/compressed/misc.c
+++ linux/arch/arm/boot/compressed/misc.c
@@ -199,6 +199,7 @@ static ulg free_mem_ptr_end;

#define HEAP_SIZE 0x2000

+#define ZLIB_INFLATE_NO_INFLATE_LOCK
#include "../../../../lib/inflate.c"

#ifndef STANDALONE_DEBUG
Index: linux/arch/arm26/boot/compressed/misc.c
===================================================================
--- linux.orig/arch/arm26/boot/compressed/misc.c
+++ linux/arch/arm26/boot/compressed/misc.c
@@ -184,6 +184,7 @@ static ulg free_mem_ptr_end;

#define HEAP_SIZE 0x2000

+#define ZLIB_INFLATE_NO_INFLATE_LOCK
#include "../../../../lib/inflate.c"

#ifndef STANDALONE_DEBUG
Index: linux/arch/i386/boot/compressed/misc.c
===================================================================
--- linux.orig/arch/i386/boot/compressed/misc.c
+++ linux/arch/i386/boot/compressed/misc.c
@@ -125,6 +125,7 @@ static int lines, cols;
static void * xquad_portio = NULL;
#endif

+#define ZLIB_INFLATE_NO_INFLATE_LOCK
#include "../../../../lib/inflate.c"

static void *malloc(int size)
Index: linux/arch/x86_64/boot/compressed/misc.c
===================================================================
--- linux.orig/arch/x86_64/boot/compressed/misc.c
+++ linux/arch/x86_64/boot/compressed/misc.c
@@ -114,6 +114,7 @@ static char *vidmem = (char *)0xb8000;
static int vidport;
static int lines, cols;

+#define ZLIB_INFLATE_NO_INFLATE_LOCK
#include "../../../../lib/inflate.c"

static void *malloc(int size)
Index: linux/lib/inflate.c
===================================================================
--- linux.orig/lib/inflate.c
+++ linux/lib/inflate.c
@@ -141,6 +141,25 @@ struct huft {
} v;
};

+/*
+ * turn off the inflate_lock for the bootloader code, it is
+ * single-threaded and has no need for (nor access to) the
+ * kernel's locking primitives:
+ */
+#ifdef ZLIB_INFLATE_NO_INFLATE_LOCK
+# undef DEFINE_SPINLOCK
+# undef spin_lock
+# undef spin_unlock
+# define DEFINE_SPINLOCK(x) int x
+# define spin_lock(x) (void)(x)
+# define spin_unlock(x) (void)(x)
+#endif
+
+/*
+ * lock protecting static variables of huft_build() and other inflate
+ * functions, to reduce their insane stack footprint.
+ */
+static DEFINE_SPINLOCK(inflate_lock);

/* Function prototypes */
STATIC int INIT huft_build OF((unsigned *, unsigned, unsigned,
@@ -304,7 +323,7 @@ STATIC int INIT huft_build(
register struct huft *q; /* points to current table */
struct huft r; /* table entry for structure assignment */
struct huft *u[BMAX]; /* table stack */
- unsigned v[N_MAX]; /* values in order of bit length */
+ static unsigned v[N_MAX]; /* values in order of bit length */
register int w; /* bits before this table == (l * h) */
unsigned x[BMAX+1]; /* bit offsets, then code stack */
unsigned *xp; /* pointer into x */
@@ -705,7 +724,7 @@ STATIC int noinline INIT inflate_fixed(v
struct huft *td; /* distance code table */
int bl; /* lookup bits for tl */
int bd; /* lookup bits for td */
- unsigned l[288]; /* length list for huft_build */
+ static unsigned l[288]; /* length list for huft_build */

DEBG("<fix");

@@ -767,9 +786,9 @@ STATIC int noinline INIT inflate_dynamic
unsigned nl; /* number of literal/length codes */
unsigned nd; /* number of distance codes */
#ifdef PKZIP_BUG_WORKAROUND
- unsigned ll[288+32]; /* literal/length and distance code lengths */
+ static unsigned ll[288+32]; /* literal/length and distance code lengths */
#else
- unsigned ll[286+30]; /* literal/length and distance code lengths */
+ static unsigned ll[286+30]; /* literal/length and distance code lengths */
#endif
register ulg b; /* bit buffer */
register unsigned k; /* number of bits in bit buffer */
@@ -940,6 +959,7 @@ STATIC int INIT inflate_block(
unsigned t; /* block type */
register ulg b; /* bit buffer */
register unsigned k; /* number of bits in bit buffer */
+ unsigned ret; /* return code */

DEBG("<blk");

@@ -965,17 +985,19 @@ STATIC int INIT inflate_block(
bk = k;

/* inflate that block type */
- if (t == 2)
- return inflate_dynamic();
- if (t == 0)
- return inflate_stored();
- if (t == 1)
- return inflate_fixed();
+ ret = 2;
+ spin_lock(&inflate_lock);
+ switch (t) {
+ case 2: ret = inflate_dynamic(); break;
+ case 0: ret = inflate_stored(); break;
+ case 1: ret = inflate_fixed(); break;
+ }
+ spin_unlock(&inflate_lock);

DEBG(">");

/* bad block type */
- return 2;
+ return ret;

underrun:
return 4; /* Input underrun */
Index: linux/lib/zlib_inflate/inftrees.c
===================================================================
--- linux.orig/lib/zlib_inflate/inftrees.c
+++ linux/lib/zlib_inflate/inftrees.c
@@ -4,11 +4,19 @@
*/

#include <linux/zutil.h>
+#include <linux/spinlock.h>
#include "inftrees.h"
#include "infutil.h"

static const char inflate_copyright[] __attribute_used__ =
" inflate 1.1.3 Copyright 1995-1998 Mark Adler ";
+
+/*
+ * lock protecting static variables of huft_build() and other inflate
+ * functions, to reduce their insane stack footprint.
+ */
+static DEFINE_SPINLOCK(inflate_lock);
+
/*
If you use the zlib library in a product, an acknowledgment is welcome
in the documentation of your product. If for some reason you cannot
@@ -107,7 +115,7 @@ static int huft_build(
{

uInt a; /* counter for codes of length k */
- uInt c[BMAX+1]; /* bit length count table */
+ static uInt c[BMAX+1]; /* bit length count table */
uInt f; /* i repeats in table every f entries */
int g; /* maximum code length */
int h; /* table level */
@@ -118,10 +126,10 @@ static int huft_build(
uInt mask; /* (1 << w) - 1, to avoid cc -O bug on HP */
register uInt *p; /* pointer into c[], b[], or v[] */
inflate_huft *q; /* points to current table */
- struct inflate_huft_s r; /* table entry for structure assignment */
- inflate_huft *u[BMAX]; /* table stack */
+ static struct inflate_huft_s r; /* table entry for structure assignment */
+ static inflate_huft *u[BMAX]; /* table stack */
register int w; /* bits before this table == (l * h) */
- uInt x[BMAX+1]; /* bit offsets, then code stack */
+ static uInt x[BMAX+1]; /* bit offsets, then code stack */
uInt *xp; /* pointer into x */
int y; /* number of dummy codes added */
uInt z; /* number of entries in current table */
@@ -300,9 +308,13 @@ int zlib_inflate_trees_bits(
int r;
uInt hn = 0; /* hufts used in space */
uInt *v; /* work area for huft_build */
-
+
v = WS(z)->tree_work_area_1;
+
+ spin_lock(&inflate_lock);
r = huft_build(c, 19, 19, NULL, NULL, tb, bb, hp, &hn, v);
+ spin_unlock(&inflate_lock);
+
if (r == Z_DATA_ERROR)
z->msg = (char*)"oversubscribed dynamic bit lengths tree";
else if (r == Z_BUF_ERROR || *bb == 0)
@@ -333,7 +345,10 @@ int zlib_inflate_trees_dynamic(
v = WS(z)->tree_work_area_2;

/* build literal/length tree */
+ spin_lock(&inflate_lock);
r = huft_build(c, nl, 257, cplens, cplext, tl, bl, hp, &hn, v);
+ spin_unlock(&inflate_lock);
+
if (r != Z_OK || *bl == 0)
{
if (r == Z_DATA_ERROR)
@@ -347,7 +362,10 @@ int zlib_inflate_trees_dynamic(
}

/* build distance tree */
+ spin_lock(&inflate_lock);
r = huft_build(c + nl, nd, 0, cpdist, cpdext, td, bd, hp, &hn, v);
+ spin_unlock(&inflate_lock);
+
if (r != Z_OK || (*bd == 0 && nl > 257))
{
if (r == Z_DATA_ERROR)
@@ -383,9 +401,11 @@ int zlib_inflate_trees_fixed(
z_streamp z /* for memory allocation */
)
{
- int i; /* temporary variable */
- unsigned l[288]; /* length list for huft_build */
- uInt *v; /* work area for huft_build */
+ int i; /* temporary variable */
+ static unsigned l[288]; /* length list for huft_build */
+ uInt *v; /* work area for huft_build */
+
+ spin_lock(&inflate_lock);

/* set up literal table */
for (i = 0; i < 144; i++)
@@ -398,15 +418,20 @@ int zlib_inflate_trees_fixed(
l[i] = 8;
*bl = 9;
v = WS(z)->tree_work_area_1;
- if ((i = huft_build(l, 288, 257, cplens, cplext, tl, bl, hp, &i, v)) != 0)
+ if ((i = huft_build(l, 288, 257, cplens, cplext, tl, bl, hp, &i, v)) != 0) {
+ spin_unlock(&inflate_lock);
return i;
+ }

/* set up distance table */
for (i = 0; i < 30; i++) /* make an incomplete code set */
l[i] = 5;
*bd = 5;
- if ((i = huft_build(l, 30, 0, cpdist, cpdext, td, bd, hp, &i, v)) > 1)
+ if ((i = huft_build(l, 30, 0, cpdist, cpdext, td, bd, hp, &i, v)) > 1) {
+ spin_unlock(&inflate_lock);
return i;
+ }

+ spin_unlock(&inflate_lock);
return Z_OK;
}
-
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