flat: fix data sections alignment

The flat loader uses an architecture's flat_stack_align() to align the
stack but assumes word-alignment is enough for the data sections.

However, on the Xtensa S6000 we have registers up to 128bit width
which can be used from userspace and therefor need userspace stack and
data-section alignment of at least this size.

This patch drops flat_stack_align() and uses the same alignment that
is required for slab caches, ARCH_SLAB_MINALIGN, or wordsize if it's
not defined by the architecture.

It also fixes m32r which was obviously kaput, aligning an
uninitialized stack entry instead of the stack pointer.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Oskar Schirmer <os@emlix.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Bryan Wu <cooloney@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Cc: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Johannes Weiner <jw@emlix.com>
Acked-by: Mike Frysinger <vapier.adi@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 31 insertions, 15 deletions

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 5cebf0b37798..697f6b5f1313 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -41,6 +41,7 @@
 #include <asm/uaccess.h>
 #include <asm/unaligned.h>
 #include <asm/cacheflush.h>
+#include <asm/page.h>
 
 /****************************************************************************/
 
@@ -54,6 +55,18 @@
 #define DBG_FLT(a...)
 #endif
 
+/*
+ * User data (stack, data section and bss) needs to be aligned
+ * for the same reasons as SLAB memory is, and to the same amount.
+ * Avoid duplicating architecture specific code by using the same
+ * macro as with SLAB allocation:
+ */
+#ifdef ARCH_SLAB_MINALIGN
+#define FLAT_DATA_ALIGN (ARCH_SLAB_MINALIGN)
+#else
+#define FLAT_DATA_ALIGN (sizeof(void *))
+#endif
+
 #define RELOC_FAILED 0xff00ff01         /* Relocation incorrect somewhere */
 #define UNLOADED_LIB 0x7ff000ff         /* Placeholder for unused library */
 
@@ -114,20 +127,18 @@ static unsigned long create_flat_tables(
         int envc = bprm->envc;
         char uninitialized_var(dummy);
 
-        sp = (unsigned long *) ((-(unsigned long)sizeof(char *))&(unsigned long) p);
+        sp = (unsigned long *)p;
+        sp -= (envc + argc + 2) + 1 + (flat_argvp_envp_on_stack() ? 2 : 0);
+        sp = (unsigned long *) ((unsigned long)sp & -FLAT_DATA_ALIGN);
+        argv = sp + 1 + (flat_argvp_envp_on_stack() ? 2 : 0);
+        envp = argv + (argc + 1);
 
-        sp -= envc+1;
-        envp = sp;
-        sp -= argc+1;
-        argv = sp;
-
-        flat_stack_align(sp);
         if (flat_argvp_envp_on_stack()) {
-                --sp; put_user((unsigned long) envp, sp);
-                --sp; put_user((unsigned long) argv, sp);
+                put_user((unsigned long) envp, sp + 2);
+                put_user((unsigned long) argv, sp + 1);
         }
 
-        put_user(argc,--sp);
+        put_user(argc, sp);
         current->mm->arg_start = (unsigned long) p;
         while (argc-->0) {
                 put_user((unsigned long) p, argv++);
@@ -558,7 +569,9 @@ static int load_flat_file(struct linux_binprm * bprm,
                         ret = realdatastart;
                         goto err;
                 }
-                datapos = realdatastart + MAX_SHARED_LIBS * sizeof(unsigned long);
+                datapos = ALIGN(realdatastart +
+                                MAX_SHARED_LIBS * sizeof(unsigned long),
+                                FLAT_DATA_ALIGN);
 
                 DBG_FLT("BINFMT_FLAT: Allocated data+bss+stack (%d bytes): %x\n",
                                 (int)(data_len + bss_len + stack_len), (int)datapos);
@@ -604,9 +617,12 @@ static int load_flat_file(struct linux_binprm * bprm,
                 }
 
                 realdatastart = textpos + ntohl(hdr->data_start);
-                datapos = realdatastart + MAX_SHARED_LIBS * sizeof(unsigned long);
-                reloc = (unsigned long *) (textpos + ntohl(hdr->reloc_start) +
-                                MAX_SHARED_LIBS * sizeof(unsigned long));
+                datapos = ALIGN(realdatastart +
+                                MAX_SHARED_LIBS * sizeof(unsigned long),
+                                FLAT_DATA_ALIGN);
+
+                reloc = (unsigned long *)
+                        (datapos + (ntohl(hdr->reloc_start) - text_len));
                 memp = textpos;
                 memp_size = len;
 #ifdef CONFIG_BINFMT_ZFLAT
@@ -854,7 +870,7 @@ static int load_flat_binary(struct linux_binprm * bprm, struct pt_regs * regs)
         stack_len = TOP_OF_ARGS - bprm->p;             /* the strings */
         stack_len += (bprm->argc + 1) * sizeof(char *); /* the argv array */
         stack_len += (bprm->envc + 1) * sizeof(char *); /* the envp array */
-
+        stack_len += FLAT_DATA_ALIGN - 1;  /* reserve for upcoming alignment */
         
         res = load_flat_file(bprm, &libinfo, 0, &stack_len);
         if (res > (unsigned long)-4096)