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Re: [PATCH v5 17/23] arm64:ilp32: add vdso-ilp32 and use for signal return

From Nathan Lynch <Nathan_Lynch@mentor.com>
Newsgroups linux.kernel
Subject Re: [PATCH v5 17/23] arm64:ilp32: add vdso-ilp32 and use for signal return
Date 2015-09-30 06:10 +0200
Message-ID <qegSl-299-3@gated-at.bofh.it> (permalink)
References <qebpD-2HP-3@gated-at.bofh.it> <qebpE-2HP-23@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On 09/29/2015 05:14 PM, Yury Norov wrote:
> From: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
> 
> Adjusted to move the move data page before code pages in sync with
> commit 601255ae3c98fdeeee3a8bb4696425e4f868b4f1

This commit message needs more information about how the ilp32 VDSO uses
the existing arm64 code.  I had to really hunt through the Makefile to
figure out what's going on.

The commit message should also identify the APIs that are supported.
The subject line mentions signal return, but gettimeofday, clock_gettime
and clock_getres are being added here too, and it is not obvious.


> Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
> Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
> Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>
> 
>  create mode 100644 arch/arm64/kernel/vdso-ilp32/.gitignore
>  create mode 100644 arch/arm64/kernel/vdso-ilp32/Makefile
>  copy arch/arm64/{include/asm/vdso.h => kernel/vdso-ilp32/vdso-ilp32.S} (56%)
>  create mode 100644 arch/arm64/kernel/vdso-ilp32/vdso-ilp32.lds.S

How are you invoking git-format-patch?  The copy detection in this case
is not conducive to review.

It looks like the existing arm64 vdso Makefile has been copied to
vdso-ilp32/ and adjusted for paths and naming.  While the gettimeofday
assembly implementation is reused, the build logic is duplicated.  x86
produces VDSOs for multiple ABIs with a single Makefile; is a similar
approach not appropriate for arm64?


> diff --git a/arch/arm64/kernel/vdso-ilp32/vdso-ilp32.lds.S b/arch/arm64/kernel/vdso-ilp32/vdso-ilp32.lds.S
> new file mode 100644
> index 0000000..ac8029b
> --- /dev/null
> +++ b/arch/arm64/kernel/vdso-ilp32/vdso-ilp32.lds.S
> @@ -0,0 +1,98 @@

[...]

> +#include <linux/const.h>
> +#include <asm/page.h>
> +#include <asm/vdso.h>
> +
> +/*OUTPUT_FORMAT("elf32-littleaarch64", "elf32-bigaarch64", "elf32-littleaarch64")
> +OUTPUT_ARCH(aarch64)
> +*/

If these lines aren't needed then omit them.

[...]


> +/*
> + * This controls what symbols we export from the DSO.
> + */
> +VERSION
> +{
> +	LINUX_2.6.39 {
> +	global:
> +		__kernel_rt_sigreturn;
> +		__kernel_gettimeofday;
> +		__kernel_clock_gettime;
> +		__kernel_clock_getres;
> +	local: *;
> +	};
> +}

Something that came up during review of arch/arm's VDSO code: consider
using version and names that match x86, i.e. LINUX_2.6, __vdso_gettimeofday.

http://lists.infradead.org/pipermail/linux-arm-kernel/2014-June/267940.html

Using LINUX_2.6.39 for this code is nonsensical.


> diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
> index b239b9b..bed6cf1 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.
>   */
> @@ -117,24 +123,29 @@ 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 inline int __init vdso_init_common(char *vdso_start, char *vdso_end,

No inline please.


> +					  unsigned long *vdso_pagesp,
> +					  struct page ***vdso_pagelistp,
> +					  struct vm_special_mapping* vdso_spec)
>  {

[...]

>  int arch_setup_additional_pages(struct linux_binprm *bprm,
>  				int uses_interp)
>  {
>  	struct mm_struct *mm = current->mm;
>  	unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
> -	void *ret;
> +	void* ret;

Gratuitous (and incorrect) style change.


> +	unsigned long pages = vdso_pages;
> +	struct vm_special_mapping* spec = vdso_spec;

Incorrect style:                  *spec

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Thread

[PATCH v5 00/23] ILP32 for ARM64 Yury Norov <ynorov@caviumnetworks.com> - 2015-09-30 00:20 +0200
  [PATCH v5 08/23] arm64:ilp32: use 64bit syscall-names for ILP32 when passing 64bit registers Yury Norov <ynorov@caviumnetworks.com> - 2015-09-30 00:20 +0200
  [PATCH v5 17/23] arm64:ilp32: add vdso-ilp32 and use for signal return Yury Norov <ynorov@caviumnetworks.com> - 2015-09-30 00:20 +0200
    Re: [PATCH v5 17/23] arm64:ilp32: add vdso-ilp32 and use for signal  return Nathan Lynch <Nathan_Lynch@mentor.com> - 2015-09-30 06:10 +0200
      Re: [PATCH v5 17/23] arm64:ilp32: add vdso-ilp32 and use for signal  return Yury Norov <ynorov@caviumnetworks.com> - 2015-10-01 21:50 +0200
        Re: [PATCH v5 17/23] arm64:ilp32: add vdso-ilp32 and use for signal return "Dr. Philipp Tomsich" <philipp.tomsich@theobroma-systems.com> - 2015-10-01 22:40 +0200
  [PATCH v5 09/23] arm64:ilp32: use non-compat syscall names for ILP32 as for LP64 Yury Norov <ynorov@caviumnetworks.com> - 2015-09-30 00:20 +0200
  [PATCH v5 23/23] arm64:ilp32: add ARM64_ILP32 to Kconfig Yury Norov <ynorov@caviumnetworks.com> - 2015-09-30 00:20 +0200
  [PATCH v5 13/23] arm64:ilp32: share HWCAP between LP64 and ILP32 Yury Norov <ynorov@caviumnetworks.com> - 2015-09-30 00:20 +0200
  [PATCH v5 04/23] arm64: change some CONFIG_COMPAT over to use CONFIG_AARCH32_EL0 instead Yury Norov <ynorov@caviumnetworks.com> - 2015-09-30 00:20 +0200
    Re: [PATCH v5 04/23] arm64: change some CONFIG_COMPAT over to use  CONFIG_AARCH32_EL0 instead kbuild test robot <lkp@intel.com> - 2015-09-30 05:40 +0200
  [PATCH v5 02/23] arm64: ensure the kernel is compiled for LP64 Yury Norov <ynorov@caviumnetworks.com> - 2015-09-30 00:20 +0200
  [PATCH v5 16/23] arm64: add support for starting ILP32 (ELFCLASS32) binaries Yury Norov <ynorov@caviumnetworks.com> - 2015-09-30 00:20 +0200
  [PATCH v5 15/23] arm64:ilp32: support core dump generation for ILP32 Yury Norov <ynorov@caviumnetworks.com> - 2015-09-30 00:20 +0200
  [PATCH v5 05/23] arm64:ilp32: expose 'kernel_long' as 'long long' for ILP32 Yury Norov <ynorov@caviumnetworks.com> - 2015-09-30 00:20 +0200
  [PATCH v5 10/23] arm64: introduce is_a32_task and is_a32_thread (for AArch32 compat) Yury Norov <ynorov@caviumnetworks.com> - 2015-09-30 00:20 +0200
    Re: [PATCH v5 10/23] arm64: introduce is_a32_task and is_a32_thread  (for AArch32 compat) kbuild test robot <lkp@intel.com> - 2015-09-30 05:50 +0200
  [PATCH v5 22/23] aarch64: ilp32: msgrcv, msgsnd handlers Yury Norov <ynorov@caviumnetworks.com> - 2015-09-30 00:30 +0200
  [PATCH v5 20/23] arm64:ilp32: use the native siginfo instead of the compat siginfo Yury Norov <ynorov@caviumnetworks.com> - 2015-09-30 00:30 +0200
  [PATCH v5 07/23] arm64:ilp32: share signal structures between ILP32 and LP64 ABIs Yury Norov <ynorov@caviumnetworks.com> - 2015-09-30 00:30 +0200
  [PATCH v5 19/23] arm64:ilp32: add sys_ilp32.c and a separate table (in entry.S) to use it Yury Norov <ynorov@caviumnetworks.com> - 2015-09-30 00:30 +0200
  [PATCH v5 21/23] arm64:ilp32: change COMPAT_ELF_PLATFORM to report a a subplatform for ILP32 Yury Norov <ynorov@caviumnetworks.com> - 2015-09-30 00:30 +0200
  [PATCH v5 18/23] ptrace: Allow compat to use the native siginfo Yury Norov <ynorov@caviumnetworks.com> - 2015-09-30 00:30 +0200
  Re: [PATCH v5 00/23] ILP32 for ARM64 Catalin Marinas <catalin.marinas@arm.com> - 2015-09-30 12:20 +0200
    Re: [PATCH v5 00/23] ILP32 for ARM64 Mark Brown <broonie@kernel.org> - 2015-09-30 18:50 +0200
      Re: [PATCH v5 00/23] ILP32 for ARM64 Catalin Marinas <catalin.marinas@arm.com> - 2015-10-01 13:20 +0200
        Re: [PATCH v5 00/23] ILP32 for ARM64 Mark Brown <broonie@kernel.org> - 2015-10-01 13:40 +0200
          Re: [PATCH v5 00/23] ILP32 for ARM64 Andrey Konovalov <andrey.konovalov@linaro.org> - 2015-10-01 18:50 +0200
      Re: [PATCH v5 00/23] ILP32 for ARM64 Yury Norov <ynorov@caviumnetworks.com> - 2015-10-01 21:40 +0200
    Re: [PATCH v5 00/23] ILP32 for ARM64 Yury Norov <ynorov@caviumnetworks.com> - 2015-10-01 21:20 +0200
      Re: [PATCH v5 00/23] ILP32 for ARM64 Arnd Bergmann <arnd@arndb.de> - 2015-10-01 23:30 +0200
        Re: [PATCH v5 00/23] ILP32 for ARM64 "Pinski, Andrew" <Andrew.Pinski@caviumnetworks.com> - 2015-10-01 23:50 +0200
          Re: [PATCH v5 00/23] ILP32 for ARM64 Catalin Marinas <catalin.marinas@arm.com> - 2015-10-02 11:40 +0200
            Re: [PATCH v5 00/23] ILP32 for ARM64 "Kapoor, Prasun" <Prasun.Kapoor@caviumnetworks.com> - 2015-10-03 05:00 +0200
              Re: [PATCH v5 00/23] ILP32 for ARM64 Catalin Marinas <catalin.marinas@arm.com> - 2015-10-05 18:00 +0200
                Re: [PATCH v5 00/23] ILP32 for ARM64 "Pinski, Andrew" <Andrew.Pinski@caviumnetworks.com> - 2015-10-05 23:10 +0200
          Re: [PATCH v5 00/23] ILP32 for ARM64 Yury Norov <ynorov@caviumnetworks.com> - 2015-10-05 21:20 +0200

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