linux-kernel - Re: [PATCH 18/19] arm64:ilp32: add vdso-ilp32 and use for signal return

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Message-ID: <mvminx3ud0m.fsf@hawking.suse.de>
Date:	Mon, 20 Jun 2016 16:54:17 +0200
From:	Andreas Schwab <schwab@...e.de>
To:	Yury Norov <ynorov@...iumnetworks.com>
Cc:	<arnd@...db.de>, <catalin.marinas@....com>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <linux-doc@...r.kernel.org>,
	<linux-arch@...r.kernel.org>, <libc-alpha@...rceware.org>,
	<schwidefsky@...ibm.com>, <heiko.carstens@...ibm.com>,
	<pinskia@...il.com>, <broonie@...nel.org>,
	<joseph@...esourcery.com>,
	<christoph.muellner@...obroma-systems.com>,
	<bamvor.zhangjian@...wei.com>, <szabolcs.nagy@....com>,
	<klimov.linux@...il.com>, <Nathan_Lynch@...tor.com>,
	<agraf@...e.de>, <Prasun.Kapoor@...iumnetworks.com>,
	<kilobyte@...band.pl>, <geert@...ux-m68k.org>,
	<philipp.tomsich@...obroma-systems.com>,
	<manuel.montezelo@...il.com>, <linyongting@...wei.com>,
	<maxim.kuvyrkov@...aro.org>, <davem@...emloft.net>
Subject: Re: [PATCH 18/19] arm64:ilp32: add vdso-ilp32 and use for signal return

Yury Norov <ynorov@...iumnetworks.com> writes:

> diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
> index 2a0de6f..e48ea34 100644
> --- a/arch/arm64/kernel/vdso.c
> +++ b/arch/arm64/kernel/vdso.c
> @@ -40,6 +40,12 @@ extern char vdso_start, vdso_end;
>  static unsigned long vdso_pages;
>  static struct page **vdso_pagelist;
>  
> +#ifdef CONFIG_ARM64_ILP32
> +extern char vdso_ilp32_start, vdso_ilp32_end;
> +static unsigned long vdso_ilp32_pages;
> +static struct page **vdso_ilp32_pagelist;
> +#endif
> +
>  /*
>   * The vDSO data page.
>   */
> @@ -110,24 +116,29 @@ int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp)
>  }
>  #endif /* CONFIG_AARCH32_EL0 */
>  
> -static struct vm_special_mapping vdso_spec[2];
> -
> -static int __init vdso_init(void)
> +static int __init vdso_init_common(char *vdso_start, char *vdso_end,

Using the same name for the parameter as for the global variable is
dangerous ....

> +					  unsigned long *vdso_pagesp,
> +					  struct page ***vdso_pagelistp,
> +					  struct vm_special_mapping* vdso_spec)
>  {
>  	int i;
> +	unsigned long vdso_pages;
> +	struct page **vdso_pagelist;
>  
> -	if (memcmp(&vdso_start, "\177ELF", 4)) {
> +	if (memcmp(vdso_start, "\177ELF", 4)) {

... because forgetting to remove & can be fatal, and your compiler may
not even warn you.

Andreas.

-- 
Andreas Schwab, SUSE Labs, schwab@...e.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."