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

Arnd Bergmann
2025-01-11T11:26:43Z

On Sat, Jan 11, 2025, at 01:16, Eric W. Biederman wrote:
> 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 hafe
> the EF_ALPHA_32BIT flag set. Just to fail explicitly in case someone
> somewhere has binaries that trying to use alpha's 32bit pointer
> support.
>
> [1]
> https://lkml.kernel.org/r/CAFXwXrkgu=4Qn-v1PjnOR4SG0oUb9LSa0g6QXpBq4ttm52pJOQ@mail.gmail.com
> [2]
> https://lkml.kernel.org/r/20250103140148.370368-1-glaubitz@physik.fu-berlin.de
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

Reviewed-by: Arnd Bergmann <arnd@arndb.de>