Re: [PATCH -v3] flat: fix data sections alignment
From: Andrew Morton
Date: Wed May 27 2009 - 16:46:47 EST
On Wed, 27 May 2009 13:49:56 +0200
Johannes Weiner <jw@xxxxxxxxx> wrote:
> On Tue, May 05, 2009 at 04:08:47PM +0200, Johannes Weiner wrote:
> > On Thu, Apr 09, 2009 at 04:25:53PM +0200, Johannes Weiner wrote:
> > > On Thu, Apr 02, 2009 at 01:53:43PM -0700, Andrew Morton wrote:
> > > > On Tue, 10 Mar 2009 16:33:50 +0900
> > > > Paul Mundt <lethal@xxxxxxxxxxxx> wrote:
> > > >
> > > > > On Thu, Mar 05, 2009 at 06:00:59PM +0100, Oskar Schirmer wrote:
> > > > > > 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@xxxxxxxxx>
> > > > > > Signed-off-by: Johannes Weiner <jw@xxxxxxxxx>
> > > > > > Cc: David Howells <dhowells@xxxxxxxxxx>
> > > > > > Cc: Russell King <rmk@xxxxxxxxxxxxxxxx>
> > > > > > Cc: Bryan Wu <cooloney@xxxxxxxxxx>
> > > > > > Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> > > > > > Cc: Paul Mundt <lethal@xxxxxxxxxxxx>
> > > > > > Cc: Greg Ungerer <gerg@xxxxxxxxxxx>
> > > > > > Cc: Mike Frysinger <vapier.adi@xxxxxxxxx>
> > > > >
> > > > > The updated version looks ok to me anyways, and it's certainly an
> > > > > improvement over defining the same alignment requirements all over the
> > > > > place.
> > > > >
> > > > > Acked-by: Paul Mundt <lethal@xxxxxxxxxxxx>
> > > >
> > > > Quite a few people expressed quite a few reservations over v2.
> > > >
> > > > Are we all OK with a v3 merge?
> > >
> > > Paul and Mike had complaints. Paul acked the last revision. Mike?
> > > We need this for upstream to compile on our configuration.
Who is Mike?
(A pox upon email clients which strip real names)
> > Can we get this merged? Nobody complained.
>
> <periodic echo-request>
>
> What are the plans on this now? I assume it drowned in other changes...
> Is it too late to get this in .30 now?
The patch had a fairly shaky start and it's been unclear to me that
everyone is happy with it and has tested it.
arch/arm/include/asm/flat.h | 3 --
arch/blackfin/include/asm/flat.h | 1
arch/h8300/include/asm/flat.h | 1
arch/m32r/include/asm/flat.h | 1
arch/m68k/include/asm/flat.h | 1
arch/sh/include/asm/flat.h | 1
fs/binfmt_flat.c | 46 ++++++++++++++++++++++++++-------------
I guess ARM is the major architecture amongst that lot. Have Russell
and co had a decent look through this?
From: Oskar Schirmer <os@xxxxxxxxx>
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@xxxxxxxxxxxxxxxxxxxx: coding-style fixes]
Signed-off-by: Oskar Schirmer <os@xxxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Cc: Russell King <rmk@xxxxxxxxxxxxxxxx>
Cc: Bryan Wu <cooloney@xxxxxxxxxx>
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Acked-by: Paul Mundt <lethal@xxxxxxxxxxxx>
Cc: Greg Ungerer <gerg@xxxxxxxxxxx>
Signed-off-by: Johannes Weiner <jw@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/arm/include/asm/flat.h | 3 -
arch/blackfin/include/asm/flat.h | 1
arch/h8300/include/asm/flat.h | 1
arch/m32r/include/asm/flat.h | 1
arch/m68k/include/asm/flat.h | 1
arch/sh/include/asm/flat.h | 1
fs/binfmt_flat.c | 46 +++++++++++++++++++----------
7 files changed, 31 insertions(+), 23 deletions(-)
diff -puN arch/arm/include/asm/flat.h~flat-fix-data-sections-alignment arch/arm/include/asm/flat.h
--- a/arch/arm/include/asm/flat.h~flat-fix-data-sections-alignment
+++ a/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 -puN arch/blackfin/include/asm/flat.h~flat-fix-data-sections-alignment arch/blackfin/include/asm/flat.h
--- a/arch/blackfin/include/asm/flat.h~flat-fix-data-sections-alignment
+++ a/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 -puN arch/h8300/include/asm/flat.h~flat-fix-data-sections-alignment arch/h8300/include/asm/flat.h
--- a/arch/h8300/include/asm/flat.h~flat-fix-data-sections-alignment
+++ a/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 -puN arch/m32r/include/asm/flat.h~flat-fix-data-sections-alignment arch/m32r/include/asm/flat.h
--- a/arch/m32r/include/asm/flat.h~flat-fix-data-sections-alignment
+++ a/arch/m32r/include/asm/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
diff -puN arch/m68k/include/asm/flat.h~flat-fix-data-sections-alignment arch/m68k/include/asm/flat.h
--- a/arch/m68k/include/asm/flat.h~flat-fix-data-sections-alignment
+++ a/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 -puN arch/sh/include/asm/flat.h~flat-fix-data-sections-alignment arch/sh/include/asm/flat.h
--- a/arch/sh/include/asm/flat.h~flat-fix-data-sections-alignment
+++ a/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 -puN fs/binfmt_flat.c~flat-fix-data-sections-alignment fs/binfmt_flat.c
--- a/fs/binfmt_flat.c~flat-fix-data-sections-alignment
+++ a/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_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 +617,12 @@ 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 +870,7 @@ 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 - 1; /* reserve for upcoming alignment */
res = load_flat_file(bprm, &libinfo, 0, &stack_len);
if (res > (unsigned long)-4096)
_
--
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