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Re: [Qemu-devel] [PATCH v2] linux-user/flatload: fix initial stack point
From: |
Laurent Vivier |
Subject: |
Re: [Qemu-devel] [PATCH v2] linux-user/flatload: fix initial stack pointer alignment |
Date: |
Wed, 24 Oct 2018 21:49:48 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 |
On 24/10/2018 19:35, Max Filippov wrote:
> Stack pointer alignment code incorrectly adds stack_size to sp instead
> of subtracting it. It also does not take flat_argvp_envp_on_stack() into
> account when calculating stack_size. This results in initial stack
> pointer misalignment with certain set of command line arguments and
> environment variables and correct alignment for the same binary with a
> different set of arguments. This misalignment causes failures in the
> following tests in the testsuite of gcc built for xtensa uclinux:
>
> gcc.dg/torture/vshuf-v64qi.c
> gcc.dg/torture/vshuf-v8sf.c
> gcc.dg/torture/vshuf-v8si.c
>
> Signed-off-by: Max Filippov <address@hidden>
> ---
> Changes v1->v2:
> - make sp adjustment unconditional
>
> linux-user/flatload.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/linux-user/flatload.c b/linux-user/flatload.c
> index 2eefe55e5000..0122ab3afe65 100644
> --- a/linux-user/flatload.c
> +++ b/linux-user/flatload.c
> @@ -771,10 +771,10 @@ int load_flt_binary(struct linux_binprm *bprm, struct
> image_info *info)
> /* Enforce final stack alignment of 16 bytes. This is sufficient
> for all current targets, and excess alignment is harmless. */
> stack_len = bprm->envc + bprm->argc + 2;
> - stack_len += 3; /* argc, arvg, argp */
> + stack_len += flat_argvp_envp_on_stack() ? 2 : 0; /* arvg, argp */
> + stack_len += 1; /* argc */
> stack_len *= sizeof(abi_ulong);
> - if ((sp + stack_len) & 15)
> - sp -= 16 - ((sp + stack_len) & 15);
> + sp -= (sp - stack_len) & 15;
> sp = loader_build_argptr(bprm->envc, bprm->argc, sp, p,
> flat_argvp_envp_on_stack());
>
>
Reviewed-by: Laurent Vivier <address@hidden>