RFC: Add 32bit x86-64 support to binutils
Robert Millan
rmh@gnu.org
Thu Dec 30 21:17:00 GMT 2010
Hi folks,
I had this unsubmitted patch in my local filesystem. It makes Linux
detect ELF32 AMD64 binaries and sets a flag to restrict them to
32-bit address space.
It's not rocket science but can save you some work in case you
haven't implemented this already.
Best regards
--
Robert Millan
-------------- next part --------------
diff -Nur linux-2.6-2.6.26-libre2.old/arch/x86/kernel/sys_x86_64.c linux-2.6-2.6.26-libre2/arch/x86/kernel/sys_x86_64.c
--- linux-2.6-2.6.26-libre2.old/arch/x86/kernel/sys_x86_64.c 2008-07-13 23:51:29.000000000 +0200
+++ linux-2.6-2.6.26-libre2/arch/x86/kernel/sys_x86_64.c 2009-05-29 22:57:41.000000000 +0200
@@ -48,7 +48,7 @@
static void find_start_end(unsigned long flags, unsigned long *begin,
unsigned long *end)
{
- if (!test_thread_flag(TIF_IA32) && (flags & MAP_32BIT)) {
+ if ((!test_thread_flag(TIF_IA32) && (flags & MAP_32BIT)) || test_thread_flag(TIF_AMD32)) {
unsigned long new_begin;
/* This is usually used needed to map code in small
model, so it needs to be in the first 31bit. Limit
@@ -94,7 +94,7 @@
(!vma || addr + len <= vma->vm_start))
return addr;
}
- if (((flags & MAP_32BIT) || test_thread_flag(TIF_IA32))
+ if (((flags & MAP_32BIT) || test_thread_flag(TIF_IA32) || test_thread_flag(TIF_AMD32))
&& len <= mm->cached_hole_size) {
mm->cached_hole_size = 0;
mm->free_area_cache = begin;
@@ -150,8 +150,8 @@
if (flags & MAP_FIXED)
return addr;
- /* for MAP_32BIT mappings we force the legact mmap base */
- if (!test_thread_flag(TIF_IA32) && (flags & MAP_32BIT))
+ /* for MAP_32BIT mappings we force the legacy mmap base */
+ if ((!test_thread_flag(TIF_IA32) && (flags & MAP_32BIT)) || test_thread_flag(TIF_AMD32))
goto bottomup;
/* requesting a specific address */
@@ -232,5 +232,7 @@
up_read(&uts_sem);
if (personality(current->personality) == PER_LINUX32)
err |= copy_to_user(&name->machine, "i686", 5);
+ else if (test_thread_flag(TIF_AMD32))
+ err |= copy_to_user(&name->machine, "amd32", 6);
return err ? -EFAULT : 0;
}
diff -Nur linux-2.6-2.6.26-libre2.old/arch/x86/mm/mmap.c linux-2.6-2.6.26-libre2/arch/x86/mm/mmap.c
--- linux-2.6-2.6.26-libre2.old/arch/x86/mm/mmap.c 2008-07-13 23:51:29.000000000 +0200
+++ linux-2.6-2.6.26-libre2/arch/x86/mm/mmap.c 2009-05-26 14:30:53.000000000 +0200
@@ -53,6 +53,15 @@
return 0;
}
+static int mmap_is_32bit(void)
+{
+ if (mmap_is_ia32 ())
+ return 1;
+ if (test_thread_flag(TIF_AMD32))
+ return 1;
+ return 0;
+}
+
static int mmap_is_legacy(void)
{
if (current->personality & ADDR_COMPAT_LAYOUT)
@@ -73,7 +82,7 @@
* 28 bits of randomness in 64bit mmaps, 40 address space bits
*/
if (current->flags & PF_RANDOMIZE) {
- if (mmap_is_ia32())
+ if (mmap_is_32bit())
rnd = (long)get_random_int() % (1<<8);
else
rnd = (long)(get_random_int() % (1<<28));
diff -Nur linux-2.6-2.6.26-libre2.old/fs/binfmt_elf_amd32.c linux-2.6-2.6.26-libre2/fs/binfmt_elf_amd32.c
--- linux-2.6-2.6.26-libre2.old/fs/binfmt_elf_amd32.c 1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6-2.6.26-libre2/fs/binfmt_elf_amd32.c 2009-05-26 14:26:24.000000000 +0200
@@ -0,0 +1,46 @@
+/*
+ * Support for loading AMD32 binaries
+ * Copyright (C) 2009 Robert Millan
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/elfcore-compat.h>
+
+#undef ELF_CLASS
+#define ELF_CLASS ELFCLASS32
+
+#undef elfhdr
+#define elfhdr elf32_hdr
+#undef elf_phdr
+#define elf_phdr elf32_phdr
+#undef elf_note
+#define elf_note elf32_note
+#undef elf_addr_t
+#define elf_addr_t Elf32_Addr
+
+#undef ELF_PLATFORM
+#define ELF_PLATFORM ("amd32")
+
+#undef elf_check_arch
+#define elf_check_arch(x) ((x)->e_machine == EM_X86_64 && (x)->e_ident[EI_CLASS] == ELFCLASS32)
+
+#undef SET_PERSONALITY
+#define SET_PERSONALITY(ex, ibcs2) do { set_personality_64bit(); set_thread_flag(TIF_AMD32); current->personality |= force_personality32; } while (0)
+
+/* Use the generic 32-bit definition from asm/elf.h */
+#undef ELF_ET_DYN_BASE
+#define ELF_ET_DYN_BASE COMPAT_ELF_ET_DYN_BASE
+
+#include "binfmt_elf.c"
diff -Nur linux-2.6-2.6.26-libre2.old/fs/Kconfig.binfmt linux-2.6-2.6.26-libre2/fs/Kconfig.binfmt
--- linux-2.6-2.6.26-libre2.old/fs/Kconfig.binfmt 2008-07-13 23:51:29.000000000 +0200
+++ linux-2.6-2.6.26-libre2/fs/Kconfig.binfmt 2009-05-25 00:26:10.000000000 +0200
@@ -23,6 +23,13 @@
ld.so (check the file <file:Documentation/Changes> for location and
latest version).
+config BINFMT_ELF_AMD32
+ bool "Kernel support for AMD32 binaries"
+ depends on X86_64
+ default y
+ help
+ Support for ELF32 binaries on AMD x86-64.
+
config COMPAT_BINFMT_ELF
bool
depends on COMPAT && MMU
diff -Nur linux-2.6-2.6.26-libre2.old/fs/Makefile linux-2.6-2.6.26-libre2/fs/Makefile
--- linux-2.6-2.6.26-libre2.old/fs/Makefile 2008-07-13 23:51:29.000000000 +0200
+++ linux-2.6-2.6.26-libre2/fs/Makefile 2009-05-25 00:24:37.000000000 +0200
@@ -39,6 +39,7 @@
obj-y += binfmt_script.o
obj-$(CONFIG_BINFMT_ELF) += binfmt_elf.o
+obj-$(CONFIG_BINFMT_ELF_AMD32) += binfmt_elf_amd32.o
obj-$(CONFIG_COMPAT_BINFMT_ELF) += compat_binfmt_elf.o
obj-$(CONFIG_BINFMT_ELF_FDPIC) += binfmt_elf_fdpic.o
obj-$(CONFIG_BINFMT_SOM) += binfmt_som.o
diff -Nur linux-2.6-2.6.26-libre2.old/include/asm-x86/elf.h linux-2.6-2.6.26-libre2/include/asm-x86/elf.h
--- linux-2.6-2.6.26-libre2.old/include/asm-x86/elf.h 2008-07-13 23:51:29.000000000 +0200
+++ linux-2.6-2.6.26-libre2/include/asm-x86/elf.h 2009-05-26 14:03:51.000000000 +0200
@@ -298,7 +298,7 @@
#define VDSO_HIGH_BASE 0xffffe000U /* CONFIG_COMPAT_VDSO address */
/* 1GB for 64bit, 8MB for 32bit */
-#define STACK_RND_MASK (test_thread_flag(TIF_IA32) ? 0x7ff : 0x3fffff)
+#define STACK_RND_MASK ((test_thread_flag(TIF_IA32) || test_thread_flag(TIF_AMD32)) ? 0x7ff : 0x3fffff)
#define ARCH_DLINFO \
do { \
diff -Nur linux-2.6-2.6.26-libre2.old/include/asm-x86/processor.h linux-2.6-2.6.26-libre2/include/asm-x86/processor.h
--- linux-2.6-2.6.26-libre2.old/include/asm-x86/processor.h 2008-07-13 23:51:29.000000000 +0200
+++ linux-2.6-2.6.26-libre2/include/asm-x86/processor.h 2009-05-26 14:06:49.000000000 +0200
@@ -881,9 +881,9 @@
#define IA32_PAGE_OFFSET ((current->personality & ADDR_LIMIT_3GB) ? \
0xc0000000 : 0xFFFFe000)
-#define TASK_SIZE (test_thread_flag(TIF_IA32) ? \
+#define TASK_SIZE ((test_thread_flag(TIF_IA32) || test_thread_flag(TIF_AMD32)) ? \
IA32_PAGE_OFFSET : TASK_SIZE64)
-#define TASK_SIZE_OF(child) ((test_tsk_thread_flag(child, TIF_IA32)) ? \
+#define TASK_SIZE_OF(child) ((test_tsk_thread_flag(child, TIF_IA32) || test_tsk_thread_flag(child, TIF_AMD32)) ? \
IA32_PAGE_OFFSET : TASK_SIZE64)
#define STACK_TOP TASK_SIZE
diff -Nur linux-2.6-2.6.26-libre2.old/include/asm-x86/thread_info_64.h linux-2.6-2.6.26-libre2/include/asm-x86/thread_info_64.h
--- linux-2.6-2.6.26-libre2.old/include/asm-x86/thread_info_64.h 2008-07-13 23:51:29.000000000 +0200
+++ linux-2.6-2.6.26-libre2/include/asm-x86/thread_info_64.h 2009-05-26 14:28:33.000000000 +0200
@@ -111,8 +111,8 @@
#define TIF_SECCOMP 8 /* secure computing */
#define TIF_MCE_NOTIFY 10 /* notify userspace of an MCE */
#define TIF_HRTICK_RESCHED 11 /* reprogram hrtick timer */
-/* 16 free */
-#define TIF_IA32 17 /* 32bit process */
+#define TIF_AMD32 16 /* 32bit AMD process */
+#define TIF_IA32 17 /* 32bit Intel process */
#define TIF_FORK 18 /* ret_from_fork */
#define TIF_ABI_PENDING 19
#define TIF_MEMDIE 20
@@ -134,6 +134,7 @@
#define _TIF_SECCOMP (1 << TIF_SECCOMP)
#define _TIF_MCE_NOTIFY (1 << TIF_MCE_NOTIFY)
#define _TIF_HRTICK_RESCHED (1 << TIF_HRTICK_RESCHED)
+#define _TIF_AMD32 (1 << TIF_AMD32)
#define _TIF_IA32 (1 << TIF_IA32)
#define _TIF_FORK (1 << TIF_FORK)
#define _TIF_ABI_PENDING (1 << TIF_ABI_PENDING)
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