[src/trunk]: src/sys/kern 1) Define a malloc(9)-like kmem_header structure fo...

[maxv <maxv%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/bf12dd49623f
branches:  trunk
changeset: 330252:bf12dd49623f
user:      maxv <maxv%NetBSD.org@localhost>
date:      Tue Jul 01 12:08:33 2014 +0000

description:
1) Define a malloc(9)-like kmem_header structure for KMEM_SIZE. It is in
   fact more consistent, and more flexible (eg if we want to add new fields).
2) When I say "page" I actually mean "kmem page". It may not be clear, so
   replace it by "memory chunk" (suggested by lars@).
3) Minor changes for KMEM_REDZONE.

diffstat:

 sys/kern/subr_kmem.c |  46 +++++++++++++++++++++++++++-------------------
 1 files changed, 27 insertions(+), 19 deletions(-)

diffs (120 lines):

diff -r aabd67e5fb4c -r bf12dd49623f sys/kern/subr_kmem.c
--- a/sys/kern/subr_kmem.c      Tue Jul 01 10:35:18 2014 +0000
+++ b/sys/kern/subr_kmem.c      Tue Jul 01 12:08:33 2014 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: subr_kmem.c,v 1.56 2014/06/25 16:35:12 maxv Exp $      */
+/*     $NetBSD: subr_kmem.c,v 1.57 2014/07/01 12:08:33 maxv Exp $      */
 
 /*-
  * Copyright (c) 2009 The NetBSD Foundation, Inc.
@@ -62,15 +62,15 @@
 
 /*
  * KMEM_SIZE: detect alloc/free size mismatch bugs.
- *     Prefix each allocations with a fixed-sized header and record the exact
- *     user-requested allocation size in it. When freeing, compare it with
- *     kmem_free's "size" argument.
+ *     Prefix each allocations with a fixed-sized, aligned header and record
+ *     the exact user-requested allocation size in it. When freeing, compare
+ *     it with kmem_free's "size" argument.
  */
 
 /*
  * KMEM_REDZONE: detect overrun bugs.
- *     Add a 2-byte pattern (allocate one more page if needed) at the end
- *     of each allocated buffer. Check this pattern on kmem_free.
+ *     Add a 2-byte pattern (allocate one more memory chunk if needed) at the
+ *     end of each allocated buffer. Check this pattern on kmem_free.
  *
  * KMEM_POISON: detect modify-after-free bugs.
  *     Fill freed (in the sense of kmem_free) memory with a garbage pattern.
@@ -90,7 +90,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: subr_kmem.c,v 1.56 2014/06/25 16:35:12 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: subr_kmem.c,v 1.57 2014/07/01 12:08:33 maxv Exp $");
 
 #include <sys/param.h>
 #include <sys/callback.h>
@@ -167,7 +167,7 @@
 static size_t kmem_cache_big_maxidx __read_mostly;
 
 #if defined(DIAGNOSTIC) && defined(_HARDKERNEL)
-#define KMEM_SIZE
+#define        KMEM_SIZE
 #endif /* defined(DIAGNOSTIC) */
 
 #if defined(DEBUG) && defined(_HARDKERNEL)
@@ -187,8 +187,8 @@
 
 #if defined(KMEM_REDZONE)
 #define        REDZONE_SIZE    2
-static void kmem_redzone_fill(void *p, size_t sz);
-static void kmem_redzone_check(void *p, size_t sz);
+static void kmem_redzone_fill(void *, size_t);
+static void kmem_redzone_check(void *, size_t);
 #else /* defined(KMEM_REDZONE) */
 #define        REDZONE_SIZE    0
 #define        kmem_redzone_fill(p, sz)                /* nothing */
@@ -196,7 +196,10 @@
 #endif /* defined(KMEM_REDZONE) */
 
 #if defined(KMEM_SIZE)
-#define        SIZE_SIZE       kmem_roundup_size(sizeof(size_t))
+struct kmem_header {
+       size_t          size;
+} __aligned(KMEM_ALIGN);
+#define        SIZE_SIZE       sizeof(struct kmem_header)
 static void kmem_size_set(void *, size_t);
 static void kmem_size_check(void *, size_t);
 #else
@@ -243,8 +246,8 @@
 
 #ifdef KMEM_REDZONE
        if (size - requested_size < REDZONE_SIZE) {
-               /* If there isn't enough space in the page padding,
-                * allocate one more page for the red zone. */
+               /* If there isn't enough space in the padding, allocate
+                * one more memory chunk for the red zone. */
                allocsz += kmem_roundup_size(REDZONE_SIZE);
        }
 #endif
@@ -537,18 +540,23 @@
 static void
 kmem_size_set(void *p, size_t sz)
 {
-       memcpy(p, &sz, sizeof(sz));
+       struct kmem_header *hd;
+       hd = (struct kmem_header *)p;
+       hd->size = sz;
 }
 
 static void
 kmem_size_check(void *p, size_t sz)
 {
-       size_t psz;
+       struct kmem_header *hd;
+       size_t hsz;
 
-       memcpy(&psz, p, sizeof(psz));
-       if (psz != sz) {
+       hd = (struct kmem_header *)p;
+       hsz = hd->size;
+
+       if (hsz != sz) {
                panic("kmem_free(%p, %zu) != allocated size %zu",
-                   (const uint8_t *)p + SIZE_SIZE, sz, psz);
+                   (const uint8_t *)p + SIZE_SIZE, sz, hsz);
        }
 }
 #endif /* defined(KMEM_SIZE) */
@@ -582,7 +590,7 @@
        const uint8_t *ep;
 
        cp = (uint8_t *)p + sz;
-       ep = (uint8_t *)p + sz + REDZONE_SIZE;
+       ep = cp + REDZONE_SIZE;
        while (cp < ep) {
                const uint8_t expected = kmem_redzone_pattern(cp);