From: Michael Ellerman <patch-notifications@ellerman.id.au>
To: Breno Leitao <leitao@debian.org>, linuxppc-dev@lists.ozlabs.org
Cc: Breno Leitao <leitao@debian.org>
Subject: Re: [v2,1/3] selftests/powerpc: Allocate base registers
Date: Tue, 27 Nov 2018 20:22:21 +1100 (AEDT) [thread overview]
Message-ID: <433yws366jz9s9G@ozlabs.org> (raw)
In-Reply-To: <1540996702-27161-1-git-send-email-leitao@debian.org>
On Wed, 2018-10-31 at 14:38:20 UTC, Breno Leitao wrote:
> Some ptrace selftests are passing input operands using a constraint that
> can allocate any register for the operand, and using these registers on
> load/store operations.
>
> If the register allocated by the compiler happens to be zero (r0), it might
> cause an invalid memory address access, since load and store operations
> consider the content of 0x0 address if the base register is r0, instead of
> the content of the r0 register. For example:
>
> r1 := 0xdeadbeef
> r0 := 0xdeadbeef
>
> ld r2, 0(1) /* will load into r2 the content of r1 address */
> ld r2, 0(0) /* will load into r2 the content of 0x0 */
>
> In order to avoid this possible problem, the inline assembly constraint
> should be aware that these registers will be used as a base register, thus,
> r0 should not be allocated.
>
> Other than that, this patch removes inline assembly operands that are not
> used by the tests.
>
> Signed-off-by: Breno Leitao <leitao@debian.org>
> Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
Series applied to powerpc next, thanks.
https://git.kernel.org/powerpc/c/5249497a7bb6334fcc128588d6a7e1
cheers
prev parent reply other threads:[~2018-11-27 9:35 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-31 14:38 [PATCH v2 1/3] selftests/powerpc: Allocate base registers Breno Leitao
2018-10-31 14:38 ` [PATCH v2 2/3] selftests/powerpc: Create a new SKIP_IF macro Breno Leitao
2018-10-31 15:44 ` Thiago Jung Bauermann
2018-10-31 14:38 ` [PATCH v2 3/3] selftests/powerpc: Skip test instead of failing Breno Leitao
2018-10-31 15:45 ` Thiago Jung Bauermann
2018-11-27 9:22 ` Michael Ellerman [this message]
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