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Message-Id: <20250211013206.4098522-10-sashal@kernel.org>
Date: Mon, 10 Feb 2025 20:32:05 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
stable@...r.kernel.org
Cc: "Eric W. Biederman" <ebiederm@...ssion.com>,
Richard Henderson <richard.henderson@...aro.org>,
Arnd Bergmann <arnd@...db.de>,
John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>,
Kees Cook <kees@...nel.org>,
Sasha Levin <sashal@...nel.org>,
mattst88@...il.com,
paulmck@...nel.org,
viro@...iv.linux.org.uk,
akpm@...ux-foundation.org,
brauner@...nel.org,
Liam.Howlett@...cle.com,
rick.p.edgecombe@...el.com,
broonie@...nel.org,
linux-alpha@...r.kernel.org,
linux-mm@...ck.org
Subject: [PATCH AUTOSEL 6.1 10/11] alpha/elf: Fix misc/setarch test of util-linux by removing 32bit support
From: "Eric W. Biederman" <ebiederm@...ssion.com>
[ Upstream commit b029628be267cba3c7684ec684749fe3e4372398 ]
Richard Henderson <richard.henderson@...aro.org> writes[1]:
> There was a Spec benchmark (I forget which) which was memory bound and ran
> twice as fast with 32-bit pointers.
>
> I copied the idea from DEC to the ELF abi, but never did all the other work
> to allow the toolchain to take advantage.
>
> Amusingly, a later Spec changed the benchmark data sets to not fit into a
> 32-bit address space, specifically because of this.
>
> I expect one could delete the ELF bit and personality and no one would
> notice. Not even the 10 remaining Alpha users.
In [2] it was pointed out that parts of setarch weren't working
properly on alpha because it has it's own SET_PERSONALITY
implementation. In the discussion that followed Richard Henderson
pointed out that the 32bit pointer support for alpha was never
completed.
Fix this by removing alpha's 32bit pointer support.
As a bit of paranoia refuse to execute any alpha binaries that have
the EF_ALPHA_32BIT flag set. Just in case someone somewhere has
binaries that try to use alpha's 32bit pointer support.
Link: https://lkml.kernel.org/r/CAFXwXrkgu=4Qn-v1PjnOR4SG0oUb9LSa0g6QXpBq4ttm52pJOQ@mail.gmail.com [1]
Link: https://lkml.kernel.org/r/20250103140148.370368-1-glaubitz@physik.fu-berlin.de [2]
Signed-off-by: Eric W. Biederman <ebiederm@...ssion.com>
Reviewed-by: Richard Henderson <richard.henderson@...aro.org>
Reviewed-by: Arnd Bergmann <arnd@...db.de>
Reviewed-by: John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>
Tested-by: John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>
Link: https://lore.kernel.org/r/87y0zfs26i.fsf_-_@email.froward.int.ebiederm.org
Signed-off-by: Kees Cook <kees@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
arch/alpha/include/asm/elf.h | 6 +-----
arch/alpha/include/asm/pgtable.h | 2 +-
arch/alpha/include/asm/processor.h | 8 ++------
arch/alpha/kernel/osf_sys.c | 11 ++---------
4 files changed, 6 insertions(+), 21 deletions(-)
diff --git a/arch/alpha/include/asm/elf.h b/arch/alpha/include/asm/elf.h
index 8049997fa372a..2039a8c8d5473 100644
--- a/arch/alpha/include/asm/elf.h
+++ b/arch/alpha/include/asm/elf.h
@@ -74,7 +74,7 @@ typedef elf_fpreg_t elf_fpregset_t[ELF_NFPREG];
/*
* This is used to ensure we don't load something for the wrong architecture.
*/
-#define elf_check_arch(x) ((x)->e_machine == EM_ALPHA)
+#define elf_check_arch(x) (((x)->e_machine == EM_ALPHA) && !((x)->e_flags & EF_ALPHA_32BIT))
/*
* These are used to set parameters in the core dumps.
@@ -145,10 +145,6 @@ extern int dump_elf_task_fp(elf_fpreg_t *dest, struct task_struct *task);
: amask (AMASK_CIX) ? "ev6" : "ev67"); \
})
-#define SET_PERSONALITY(EX) \
- set_personality(((EX).e_flags & EF_ALPHA_32BIT) \
- ? PER_LINUX_32BIT : PER_LINUX)
-
extern int alpha_l1i_cacheshape;
extern int alpha_l1d_cacheshape;
extern int alpha_l2_cacheshape;
diff --git a/arch/alpha/include/asm/pgtable.h b/arch/alpha/include/asm/pgtable.h
index 9e45f6735d5d2..6fe4e9deeb5ef 100644
--- a/arch/alpha/include/asm/pgtable.h
+++ b/arch/alpha/include/asm/pgtable.h
@@ -322,7 +322,7 @@ extern inline pte_t mk_swap_pte(unsigned long type, unsigned long offset)
extern void paging_init(void);
-/* We have our own get_unmapped_area to cope with ADDR_LIMIT_32BIT. */
+/* We have our own get_unmapped_area */
#define HAVE_ARCH_UNMAPPED_AREA
#endif /* _ALPHA_PGTABLE_H */
diff --git a/arch/alpha/include/asm/processor.h b/arch/alpha/include/asm/processor.h
index 714abe494e5fd..916a2dd782c1a 100644
--- a/arch/alpha/include/asm/processor.h
+++ b/arch/alpha/include/asm/processor.h
@@ -8,23 +8,19 @@
#ifndef __ASM_ALPHA_PROCESSOR_H
#define __ASM_ALPHA_PROCESSOR_H
-#include <linux/personality.h> /* for ADDR_LIMIT_32BIT */
-
/*
* We have a 42-bit user address space: 4TB user VM...
*/
#define TASK_SIZE (0x40000000000UL)
-#define STACK_TOP \
- (current->personality & ADDR_LIMIT_32BIT ? 0x80000000 : 0x00120000000UL)
+#define STACK_TOP (0x00120000000UL)
#define STACK_TOP_MAX 0x00120000000UL
/* This decides where the kernel will search for a free chunk of vm
* space during mmap's.
*/
-#define TASK_UNMAPPED_BASE \
- ((current->personality & ADDR_LIMIT_32BIT) ? 0x40000000 : TASK_SIZE / 2)
+#define TASK_UNMAPPED_BASE (TASK_SIZE / 2)
/* This is dead. Everything has been moved to thread_info. */
struct thread_struct { };
diff --git a/arch/alpha/kernel/osf_sys.c b/arch/alpha/kernel/osf_sys.c
index c54469b369cb6..03b70b6c92502 100644
--- a/arch/alpha/kernel/osf_sys.c
+++ b/arch/alpha/kernel/osf_sys.c
@@ -1213,8 +1213,7 @@ SYSCALL_DEFINE1(old_adjtimex, struct timex32 __user *, txc_p)
return ret;
}
-/* Get an address range which is currently unmapped. Similar to the
- generic version except that we know how to honor ADDR_LIMIT_32BIT. */
+/* Get an address range which is currently unmapped. */
static unsigned long
arch_get_unmapped_area_1(unsigned long addr, unsigned long len,
@@ -1236,13 +1235,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
unsigned long len, unsigned long pgoff,
unsigned long flags)
{
- unsigned long limit;
-
- /* "32 bit" actually means 31 bit, since pointers sign extend. */
- if (current->personality & ADDR_LIMIT_32BIT)
- limit = 0x80000000;
- else
- limit = TASK_SIZE;
+ unsigned long limit = TASK_SIZE;
if (len > limit)
return -ENOMEM;
--
2.39.5
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