Re: [Buildroot] [PATCH] package/glibc: optional MTE support in glibc

["Yann E. MORIN" <yann.morin.1998@free.fr>]

R, All,

[please do not top-post, but do reply in-line, like I do below]

On 2023-11-26 22:28 +0200, R spake thusly:
> It has been a while... and I'm really sorry for that.

No worries, we all have a life outside open source projects! ;-)

> But I do think this can be useful - I took a look at the code a-bit
> and haven't seen it supports compiling glibc with MTE.
> May I continue to resolve your comments?

Having MTE support looks interesting, so yes, you are welcome to
continue working on that!

> should it be in this thread or a new one is preferred?

If you want to reply to the comments, then just do so as a reply to
Thomas' email, and reply to individual comments there (like I'm doing
for your own mail).

If you want to resend a new patch which addresses Thomas' comments, then
send it as a new thread. Don;t forget to add a changelog, see the manual
for further details:

    https://buildroot.org/downloads/manual/manual.html#submitting-patches

Regards,
Yann E. MORIN.

> Thanks :)
> On Sun, Oct 31, 2021 at 7:52 PM Thomas Petazzoni < [1]thomas.petazzoni@bootlin.com> wrote:
> 
>   Hello,
> 
>   Thanks a lot for your contribution! See below some comments.
> 
>   On Sat, 30 Oct 2021 11:37:50 +0300
>   " [2]irgstg@gmail.com" < [3]irgstg@gmail.com> wrote:
> 
>   > Adding option BR2_PACKAGE_GLIBC_MTE to configure glibc with MTE support.
>   > When enabled, glibcs configuration process runs with `--enable-memory-tagging` [1].
>   >
>   > MTE (Memory Tagging Extension) is an ISA extension which aims to improve security on ARMv8.5-A [2].
>   > The linux kernel supports this feature via CONFIG_ARM64_MTE.
>   > In order for glibc's MTE support to work properly, the running kernel has to support that.
> 
>   Could you wrap the lines of your commit log to 72 columns?
> 
>   > dependencies:
>   >  - supported on aarch64 only (BR2_aarch64)
>   >  - requires binutils version 2.33.1 or newer (!B2_BINUTILS_VERSION_2_32_X)
>   >  - requires at least linux 5.4 headers (BR2_TOOLCHAIN_HEADERS_AT_LEAST_5_4)
>   >
>   > [1]
>   [4]https://sourceware.org/git/?p=glibc.git;a=blob;f=INSTALL;h=02dcf6b1ca3a4c43a17fdcae5e7dae8189c1c50b;hb=HEAD#l145
>   > [2] [5]https://community.arm.com/developer/ip-products/processors/b/processors-ip-blog/posts/enhancing-memory-safety
>   >
>   > Signed-off-by: [6]irgstg@gmail.com < [7]irgstg@gmail.com>
> 
>   Could you resend with a real name ? We cannot accept anonymous
>   contributions.
> 
>   > +config BR2_PACKAGE_GLIBC_MTE
>   > +     bool "Install glibc support for MTE"
> 
>   Repeating that it's glibc related is not necessary, and making "MTE"
>   explicit seems useful. So perhaps:
> 
>           bool "enable Memory Tagging Extension (MTE) support"
> 
>   > +     depends on BR2_aarch64
>   > +     depends on !BR2_BINUTILS_VERSION_2_32_X
>   > +     depends on BR2_TOOLCHAIN_HEADERS_AT_LEAST_5_4
>   > +     help
>   > +       Enabling this option will configure, compile
>   > +       and install glibc support for MTE (Memory Tagging Extension).
>   > +       Please be aware, in order for that to work properly,
>   > +       kernel support for MTE (CONFIG_ARM64_MTE), and a
>   > +       supported CPU are needed.
> 
>   Instead of just saying so, you could do this in [8]glibc.mk:
> 
>   ifeq ($(BR2_PACKAGE_GLIBC_MTE),y)
>   GLIBC_CONF_OPTS += --enable-memory-tagging
>   define GLIBC_LINUX_CONFIG_FIXUPS
>           $(call KCONFIG_ENABLE_OPT,CONFIG_ARM64_MTE)
>   endef
>   endif
> 
>   Of course, you need to add $(GLIBC_CONF_OPTS) inside
>   GLIBC_CONFIGURE_CMDS.
> 
>   Other than that, it looks good to me.
> 
>   Do we need special compiler options to make use of MTE ?
> 
>   Best regards,
> 
>   Thomas
>   --
>   Thomas Petazzoni, co-owner and CEO, Bootlin
>   Embedded Linux and Kernel engineering and training
>   [9]https://bootlin.com
> 
> Links:
> 1. mailto:thomas.petazzoni@bootlin.com
> 2. mailto:irgstg@gmail.com
> 3. mailto:irgstg@gmail.com
> 4. https://sourceware.org/git/?p=glibc.git;a=blob;f=INSTALL;h=02dcf6b1ca3a4c43a17fdcae5e7dae8189c1c50b;hb=HEAD#l145
> 5. https://community.arm.com/developer/ip-products/processors/b/processors-ip-blog/posts/enhancing-memory-safety
> 6. mailto:irgstg@gmail.com
> 7. mailto:irgstg@gmail.com
> 8. http://glibc.mk
> 9. https://bootlin.com

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