fs/binfmt_flat.c: split the stack & data alignments

The stack and data have different alignment requirements, so don't force
them to wear the same shoe.  Increase the data alignment to match that
which the elf2flt linker script has always been using: 0x20 bytes.  Not
only does this bring the kernel loader in line with the toolchain, but it
also fixes a swath of gcc tests which try to force larger alignment values
but randomly fail when the FLAT loader fails to deliver.

Signed-off-by: Mike Frysinger <[email protected]>
Cc: Herbert Xu <[email protected]>
Cc: David Woodhouse <[email protected]>
Cc: Pekka Enberg <[email protected]>
Acked-by: David McCullough <[email protected]>
Acked-by: Greg Ungerer <[email protected]>
Cc: Paul Mundt <[email protected]>
Tested-by: Michal Simek <[email protected]>
Cc: Hirokazu Takata <[email protected]>
Cc: Yoshinori Sato <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Jie Zhang <[email protected]>
Cc: David Howells <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 15 insertions, 8 deletions

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 49566c1687d8..b8656225b34b 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -56,15 +56,22 @@
 #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:
+ * User data (data section and bss) needs to be aligned.
+ * We pick 0x20 here because it is the max value elf2flt has always
+ * used in producing FLAT files, and because it seems to be large
+ * enough to make all the gcc alignment related tests happy.
+ */
+#define FLAT_DATA_ALIGN	(0x20)
+
+/*
+ * User data (stack) also needs to be aligned.
+ * Here we can be a bit looser than the data sections since this
+ * needs to only meet arch ABI requirements.
  */
 #ifdef ARCH_SLAB_MINALIGN
-#define FLAT_DATA_ALIGN	(ARCH_SLAB_MINALIGN)
+#define FLAT_STACK_ALIGN	(ARCH_SLAB_MINALIGN)
 #else
-#define FLAT_DATA_ALIGN	(sizeof(void *))
+#define FLAT_STACK_ALIGN	(sizeof(void *))
 #endif
 
 #define RELOC_FAILED 0xff00ff01		/* Relocation incorrect somewhere */
@@ -129,7 +136,7 @@ static unsigned long create_flat_tables(
 
 	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);
+	sp = (unsigned long *) ((unsigned long)sp & -FLAT_STACK_ALIGN);
 	argv = sp + 1 + (flat_argvp_envp_on_stack() ? 2 : 0);
 	envp = argv + (argc + 1);
 
@@ -876,7 +883,7 @@ 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 */
+	stack_len += FLAT_STACK_ALIGN - 1;  /* reserve for upcoming alignment */
 	
 	res = load_flat_file(bprm, &libinfo, 0, &stack_len);
 	if (IS_ERR_VALUE(res))