[PATCH -v3] flat: fix data sections alignment

* [PATCH -v3] flat: fix data sections alignment
@ 2009-03-05 17:00 Oskar Schirmer
  2009-03-10  7:33 ` Paul Mundt
  0 siblings, 1 reply; 14+ messages in thread
From: Oskar Schirmer @ 2009-03-05 17:00 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Johannes Weiner, David Howells, Russell King, Bryan Wu,
	Geert Uytterhoeven, Mike Frysinger, Greg Ungerer, Paul Mundt,
	linux-kernel

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.

Signed-off-by: Oskar Schirmer <os@emlix.com>
Signed-off-by: Johannes Weiner <jw@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>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Greg Ungerer <gerg@uclinux.org>
Cc: Mike Frysinger <vapier.adi@gmail.com>
---
 arch/arm/include/asm/flat.h      |    3 --
 arch/blackfin/include/asm/flat.h |    1 -
 arch/h8300/include/asm/flat.h    |    1 -
 arch/m68k/include/asm/flat.h     |    1 -
 arch/sh/include/asm/flat.h       |    1 -
 fs/binfmt_flat.c                 |   46 +++++++++++++++++++++++++------------
 include/asm-m32r/flat.h          |    1 -
 7 files changed, 31 insertions(+), 23 deletions(-)

v3:
- checkpatch-clean (Andrew Morton)
- fixed the alignment space upon allocation calculation (Mike Frysinger)
- added a comment for the use of ARCH_SLAB_MINALIGN (Paul Mundt)

v2:
- replace local flat_data_align by ARCH_SLAB_MINALIGN (Paul Mundt)

diff --git a/arch/arm/include/asm/flat.h b/arch/arm/include/asm/flat.h
index 1d77e51..59426a4 100644
--- a/arch/arm/include/asm/flat.h
+++ b/arch/arm/include/asm/flat.h
@@ -5,9 +5,6 @@
 #ifndef __ARM_FLAT_H__
 #define __ARM_FLAT_H__
 
-/* An odd number of words will be pushed after this alignment, so
-   deliberately misalign the value.  */
-#define	flat_stack_align(sp)	sp = (void *)(((unsigned long)(sp) - 4) | 4)
 #define	flat_argvp_envp_on_stack()		1
 #define	flat_old_ram_flag(flags)		(flags)
 #define	flat_reloc_valid(reloc, size)		((reloc) <= (size))
diff --git a/arch/blackfin/include/asm/flat.h b/arch/blackfin/include/asm/flat.h
index e70074e..733a178 100644
--- a/arch/blackfin/include/asm/flat.h
+++ b/arch/blackfin/include/asm/flat.h
@@ -10,7 +10,6 @@
 
 #include <asm/unaligned.h>
 
-#define	flat_stack_align(sp)	/* nothing needed */
 #define	flat_argvp_envp_on_stack()		0
 #define	flat_old_ram_flag(flags)		(flags)
 
diff --git a/arch/h8300/include/asm/flat.h b/arch/h8300/include/asm/flat.h
index 2a87350..bd12b31 100644
--- a/arch/h8300/include/asm/flat.h
+++ b/arch/h8300/include/asm/flat.h
@@ -5,7 +5,6 @@
 #ifndef __H8300_FLAT_H__
 #define __H8300_FLAT_H__
 
-#define	flat_stack_align(sp)			/* nothing needed */
 #define	flat_argvp_envp_on_stack()		1
 #define	flat_old_ram_flag(flags)		1
 #define	flat_reloc_valid(reloc, size)		((reloc) <= (size))
diff --git a/arch/m68k/include/asm/flat.h b/arch/m68k/include/asm/flat.h
index 814b517..a0e2907 100644
--- a/arch/m68k/include/asm/flat.h
+++ b/arch/m68k/include/asm/flat.h
@@ -5,7 +5,6 @@
 #ifndef __M68KNOMMU_FLAT_H__
 #define __M68KNOMMU_FLAT_H__
 
-#define	flat_stack_align(sp)			/* nothing needed */
 #define	flat_argvp_envp_on_stack()		1
 #define	flat_old_ram_flag(flags)		(flags)
 #define	flat_reloc_valid(reloc, size)		((reloc) <= (size))
diff --git a/arch/sh/include/asm/flat.h b/arch/sh/include/asm/flat.h
index d3b2b4f..5d84df5 100644
--- a/arch/sh/include/asm/flat.h
+++ b/arch/sh/include/asm/flat.h
@@ -12,7 +12,6 @@
 #ifndef __ASM_SH_FLAT_H
 #define __ASM_SH_FLAT_H
 
-#define	flat_stack_align(sp)			/* nothing needed */
 #define	flat_argvp_envp_on_stack()		0
 #define	flat_old_ram_flag(flags)		(flags)
 #define	flat_reloc_valid(reloc, size)		((reloc) <= (size))
diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 5cebf0b..697f6b5 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)
diff --git a/include/asm-m32r/flat.h b/include/asm-m32r/flat.h
index d851cf0..5d711c4 100644
--- a/include/asm-m32r/flat.h
+++ b/include/asm-m32r/flat.h
@@ -12,7 +12,6 @@
 #ifndef __ASM_M32R_FLAT_H
 #define __ASM_M32R_FLAT_H
 
-#define	flat_stack_align(sp)		(*sp += (*sp & 3 ? (4 - (*sp & 3)): 0))
 #define	flat_argvp_envp_on_stack()		0
 #define	flat_old_ram_flag(flags)		(flags)
 #define	flat_set_persistent(relval, p)		0

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