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Subject[patch] binfmt_flat: fix data sections alignment
From: Oskar Schirmer <os@emlix.com>

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 need an alignment of more than
wordsize for data that is loaded to 128bit wide registers.

This patch replaces the specific flat_stack_align() with a more
generic flat_data_align() that is then used for both stack, the data
and bss section.

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>
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>
Signed-off-by: Johannes Weiner <jw@emlix.com>
---
arch/arm/include/asm/flat.h | 4 +---
arch/blackfin/include/asm/flat.h | 2 +-
arch/h8300/include/asm/flat.h | 2 +-
arch/m68k/include/asm/flat.h | 2 +-
arch/sh/include/asm/flat.h | 2 +-
fs/binfmt_flat.c | 28 ++++++++++++++--------------
include/asm-m32r/flat.h | 2 +-
7 files changed, 20 insertions(+), 22 deletions(-)

We tried to verify brain-wise that all the alignments on other archs
are still correct but please note that we have only one xtensa-based
box to test this patch on. It works here with a required data
alignment of 16 bytes.

--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -115,19 +115,17 @@ static unsigned long create_flat_tables(
char uninitialized_var(dummy);

sp = (unsigned long *) ((-(unsigned long)sizeof(char *))&(unsigned long) p);
+ sp -= (envc + argc + 2) + 1 + (flat_argvp_envp_on_stack() ? 2 : 0);
+ sp = (unsigned long *) ((-(unsigned long)flat_data_align())&(unsigned long) sp);
+ 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 +556,8 @@ static int load_flat_file(struct linux_b
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 +603,10 @@ static int load_flat_file(struct linux_b
}

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 +854,7 @@ static int load_flat_binary(struct linux
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();

res = load_flat_file(bprm, &libinfo, 0, &stack_len);
if (res > (unsigned long)-4096)
--- a/arch/arm/include/asm/flat.h
+++ b/arch/arm/include/asm/flat.h
@@ -5,9 +5,7 @@
#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_data_align() 8
#define flat_argvp_envp_on_stack() 1
#define flat_old_ram_flag(flags) (flags)
#define flat_reloc_valid(reloc, size) ((reloc) <= (size))
--- a/arch/blackfin/include/asm/flat.h
+++ b/arch/blackfin/include/asm/flat.h
@@ -10,7 +10,7 @@

#include <asm/unaligned.h>

-#define flat_stack_align(sp) /* nothing needed */
+#define flat_data_align() sizeof(void *)
#define flat_argvp_envp_on_stack() 0
#define flat_old_ram_flag(flags) (flags)

--- a/arch/h8300/include/asm/flat.h
+++ b/arch/h8300/include/asm/flat.h
@@ -5,7 +5,7 @@
#ifndef __H8300_FLAT_H__
#define __H8300_FLAT_H__

-#define flat_stack_align(sp) /* nothing needed */
+#define flat_data_align() sizeof(void *)
#define flat_argvp_envp_on_stack() 1
#define flat_old_ram_flag(flags) 1
#define flat_reloc_valid(reloc, size) ((reloc) <= (size))
--- a/arch/m68k/include/asm/flat.h
+++ b/arch/m68k/include/asm/flat.h
@@ -5,7 +5,7 @@
#ifndef __M68KNOMMU_FLAT_H__
#define __M68KNOMMU_FLAT_H__

-#define flat_stack_align(sp) /* nothing needed */
+#define flat_data_align(sp) sizeof(void *)
#define flat_argvp_envp_on_stack() 1
#define flat_old_ram_flag(flags) (flags)
#define flat_reloc_valid(reloc, size) ((reloc) <= (size))
--- a/arch/sh/include/asm/flat.h
+++ b/arch/sh/include/asm/flat.h
@@ -12,7 +12,7 @@
#ifndef __ASM_SH_FLAT_H
#define __ASM_SH_FLAT_H

-#define flat_stack_align(sp) /* nothing needed */
+#define flat_data_align(sp) sizeof(void *)
#define flat_argvp_envp_on_stack() 0
#define flat_old_ram_flag(flags) (flags)
#define flat_reloc_valid(reloc, size) ((reloc) <= (size))
--- a/include/asm-m32r/flat.h
+++ b/include/asm-m32r/flat.h
@@ -12,7 +12,7 @@
#ifndef __ASM_M32R_FLAT_H
#define __ASM_M32R_FLAT_H

-#define flat_stack_align(sp) (*sp += (*sp & 3 ? (4 - (*sp & 3)): 0))
+#define flat_data_align() sizeof(void *)
#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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