From: "H. Peter Anvin" <hpa@zytor.com>
To: Kees Cook <keescook@chromium.org>
Cc: linux-kernel@vger.kernel.org,
kernel-hardening@lists.openwall.com,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
x86@kernel.org, Jarkko Sakkinen <jarkko.sakkinen@intel.com>,
Matthew Garrett <mjg@redhat.com>,
Matt Fleming <matt.fleming@intel.com>,
Eric Northup <digitaleric@google.com>,
Dan Rosenberg <drosenberg@vsecurity.com>,
Julien Tinnes <jln@google.com>, Will Drewry <wad@chromium.org>
Subject: [kernel-hardening] Re: [PATCH 2/6] x86: kaslr: move CPU flags out of cpucheck
Date: Fri, 26 Apr 2013 14:47:02 -0700 [thread overview]
Message-ID: <517AF5D6.1040800@zytor.com> (raw)
In-Reply-To: <1367003005-5560-3-git-send-email-keescook@chromium.org>
On 04/26/2013 12:03 PM, Kees Cook wrote:
> +
> +static inline void cpuid(u32 id, u32 *a, u32 *b, u32 *c, u32 *d)
> +{
> + /* Handle x86_32 PIC using ebx. */
> + asm volatile("movl %%ebx, %%edi \n\t"
> + "cpuid \n\t"
> + "xchgl %%edi, %%ebx\n\t"
> + : "=a" (*a),
> + "=D" (*b),
> + "=c" (*c),
> + "=d" (*d)
> + : "a" (id)
> + );
> +}
Please don't constrain registers unnecessarily.
You can use "=r" there and let gcc assign whatever free register it pleases.
You can also limit that to only:
#if defined(__i386__) && defined(__PIC__)
-hpa
WARNING: multiple messages have this Message-ID (diff)
From: "H. Peter Anvin" <hpa@zytor.com>
To: Kees Cook <keescook@chromium.org>
Cc: linux-kernel@vger.kernel.org,
kernel-hardening@lists.openwall.com,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
x86@kernel.org, Jarkko Sakkinen <jarkko.sakkinen@intel.com>,
Matthew Garrett <mjg@redhat.com>,
Matt Fleming <matt.fleming@intel.com>,
Eric Northup <digitaleric@google.com>,
Dan Rosenberg <drosenberg@vsecurity.com>,
Julien Tinnes <jln@google.com>, Will Drewry <wad@chromium.org>
Subject: Re: [PATCH 2/6] x86: kaslr: move CPU flags out of cpucheck
Date: Fri, 26 Apr 2013 14:47:02 -0700 [thread overview]
Message-ID: <517AF5D6.1040800@zytor.com> (raw)
In-Reply-To: <1367003005-5560-3-git-send-email-keescook@chromium.org>
On 04/26/2013 12:03 PM, Kees Cook wrote:
> +
> +static inline void cpuid(u32 id, u32 *a, u32 *b, u32 *c, u32 *d)
> +{
> + /* Handle x86_32 PIC using ebx. */
> + asm volatile("movl %%ebx, %%edi \n\t"
> + "cpuid \n\t"
> + "xchgl %%edi, %%ebx\n\t"
> + : "=a" (*a),
> + "=D" (*b),
> + "=c" (*c),
> + "=d" (*d)
> + : "a" (id)
> + );
> +}
Please don't constrain registers unnecessarily.
You can use "=r" there and let gcc assign whatever free register it pleases.
You can also limit that to only:
#if defined(__i386__) && defined(__PIC__)
-hpa
next prev parent reply other threads:[~2013-04-26 21:47 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-26 19:03 [kernel-hardening] [PATCH v4 0/6] kernel ASLR Kees Cook
2013-04-26 19:03 ` Kees Cook
2013-04-26 19:03 ` [kernel-hardening] [PATCH 1/6] x86: kaslr: move ELF relocation handling to C Kees Cook
2013-04-26 19:03 ` Kees Cook
2013-04-26 19:03 ` [kernel-hardening] [PATCH 2/6] x86: kaslr: move CPU flags out of cpucheck Kees Cook
2013-04-26 19:03 ` Kees Cook
2013-04-26 21:47 ` H. Peter Anvin [this message]
2013-04-26 21:47 ` H. Peter Anvin
2013-04-26 22:14 ` [kernel-hardening] " H. Peter Anvin
2013-04-26 22:14 ` H. Peter Anvin
2013-04-29 17:49 ` [kernel-hardening] " Kees Cook
2013-04-29 17:49 ` Kees Cook
2013-04-29 17:52 ` [kernel-hardening] " Kees Cook
2013-04-29 17:52 ` Kees Cook
2013-04-26 19:03 ` [kernel-hardening] [PATCH 3/6] x86: kaslr: return location from decompress_kernel Kees Cook
2013-04-26 19:03 ` Kees Cook
2013-04-26 21:47 ` [kernel-hardening] " H. Peter Anvin
2013-04-26 21:47 ` H. Peter Anvin
2013-04-29 1:25 ` [kernel-hardening] " James Morris
2013-04-29 17:43 ` Kees Cook
2013-04-26 19:03 ` [kernel-hardening] [PATCH 4/6] x86: kaslr: select random base offset Kees Cook
2013-04-26 19:03 ` Kees Cook
2013-04-26 21:50 ` [kernel-hardening] " H. Peter Anvin
2013-04-26 21:50 ` H. Peter Anvin
2013-04-29 19:15 ` [kernel-hardening] " Kees Cook
2013-04-29 19:15 ` Kees Cook
2013-04-26 19:03 ` [kernel-hardening] [PATCH 5/6] x86: kaslr: select memory region from e820 maps Kees Cook
2013-04-26 19:03 ` Kees Cook
2013-04-26 21:51 ` [kernel-hardening] " Yinghai Lu
2013-04-26 21:51 ` Yinghai Lu
2013-04-26 22:01 ` [kernel-hardening] " H. Peter Anvin
2013-04-26 22:01 ` H. Peter Anvin
2013-04-26 22:01 ` [kernel-hardening] " Kees Cook
2013-04-26 22:01 ` Kees Cook
2013-04-26 19:03 ` [kernel-hardening] [PATCH 6/6] x86: kaslr: report kernel offset on panic Kees Cook
2013-04-26 19:03 ` Kees Cook
2013-04-26 22:13 ` [kernel-hardening] " Borislav Petkov
2013-04-26 22:13 ` Borislav Petkov
2013-04-26 22:15 ` [kernel-hardening] " H. Peter Anvin
2013-04-26 22:15 ` H. Peter Anvin
2013-04-26 22:19 ` [kernel-hardening] " Borislav Petkov
2013-04-26 22:19 ` Borislav Petkov
-- strict thread matches above, loose matches on Subject: below --
2013-04-25 21:54 [kernel-hardening] [PATCH v3 0/6] kernel ASLR Kees Cook
2013-04-25 21:54 ` [kernel-hardening] [PATCH 2/6] x86: kaslr: move CPU flags out of cpucheck Kees Cook
2013-04-25 22:00 ` [kernel-hardening] " H. Peter Anvin
2013-04-26 15:28 ` Kees Cook
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=517AF5D6.1040800@zytor.com \
--to=hpa@zytor.com \
--cc=digitaleric@google.com \
--cc=drosenberg@vsecurity.com \
--cc=jarkko.sakkinen@intel.com \
--cc=jln@google.com \
--cc=keescook@chromium.org \
--cc=kernel-hardening@lists.openwall.com \
--cc=linux-kernel@vger.kernel.org \
--cc=matt.fleming@intel.com \
--cc=mingo@redhat.com \
--cc=mjg@redhat.com \
--cc=tglx@linutronix.de \
--cc=wad@chromium.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.