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alpha/elf: Fix misc/setarch test of util-linux by removing 32bit support

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Richard Henderson <richard.henderson@linaro.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@xmission.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Tested-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Link: https://lore.kernel.org/r/87y0zfs26i.fsf_-_@email.froward.int.ebiederm.org
Signed-off-by: Kees Cook <kees@kernel.org>
This commit is contained in:
Eric W. Biederman
2025-01-12 23:39:01 -06:00
committed by Kees Cook
parent 55cf2f4b94
commit b029628be2
4 changed files with 6 additions and 21 deletions
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arch/alpha/include/asm/processor.h
+2 -6
View File
@@ -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 { };