All of lore.kernel.org
 help / color / mirror / Atom feed
From: Nicholas Piggin <npiggin@gmail.com>
To: Michal Suchanek <msuchanek@suse.de>
Cc: linuxppc-dev@lists.ozlabs.org,
	"Kate Stewart" <kstewart@linuxfoundation.org>,
	"Madhavan Srinivasan" <maddy@linux.vnet.ibm.com>,
	"Paul Mackerras" <paulus@samba.org>,
	"Michael Neuling" <mikey@neuling.org>,
	"Bryant G. Ly" <bryantly@linux.vnet.ibm.com>,
	"Mahesh Salgaonkar" <mahesh@linux.vnet.ibm.com>,
	"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>,
	"Daniel Axtens" <dja@axtens.net>,
	"Al Viro" <viro@zeniv.linux.org.uk>,
	"David Gibson" <david@gibson.dropbear.id.au>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	linux-kernel@vger.kernel.org,
	"Sergey Senozhatsky" <sergey.senozhatsky@gmail.com>,
	"Cédric Le Goater" <clg@kaod.org>,
	"Masami Hiramatsu" <mhiramat@kernel.org>,
	"Andrew Donnellan" <andrew.donnellan@au1.ibm.com>,
	"Philippe Ombredanne" <pombredanne@nexb.com>,
	"Joe Perches" <joe@perches.com>,
	"Oliver O'Halloran" <oohall@gmail.com>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Tobin C. Harding" <me@tobin.cc>
Subject: Re: [PATCH RFC rebase 3/9] powerpc/64: Use barrier_nospec in syscall entry
Date: Fri, 16 Mar 2018 15:18:23 +1000	[thread overview]
Message-ID: <20180316151823.2f28d5ea@roar.ozlabs.ibm.com> (raw)
In-Reply-To: <b8253774e223530c808eed65d116deecc46ad36b.1521141122.git.msuchanek@suse.de>

On Thu, 15 Mar 2018 20:15:52 +0100
Michal Suchanek <msuchanek@suse.de> wrote:

> On powerpc syscall entry is done in assembly so patch in an explicit
> barrier_nospec.

Same comment as Linus for this -- the barriers are before the branch here,
so is it possible the branch instruction can be speculative while the index
is used to load the syscall table?

Thanks,
Nick

> 
> Signed-off-by: Michal Suchanek <msuchanek@suse.de>
> ---
>  arch/powerpc/kernel/entry_64.S | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
> index 2cb5109a7ea3..7bfc4cf48af2 100644
> --- a/arch/powerpc/kernel/entry_64.S
> +++ b/arch/powerpc/kernel/entry_64.S
> @@ -36,6 +36,7 @@
>  #include <asm/context_tracking.h>
>  #include <asm/tm.h>
>  #include <asm/ppc-opcode.h>
> +#include <asm/barrier.h>
>  #include <asm/export.h>
>  #ifdef CONFIG_PPC_BOOK3S
>  #include <asm/exception-64s.h>
> @@ -159,6 +160,7 @@ system_call:			/* label this so stack traces look sane */
>  	andi.	r11,r10,_TIF_SYSCALL_DOTRACE
>  	bne	.Lsyscall_dotrace		/* does not return */
>  	cmpldi	0,r0,NR_syscalls
> +	barrier_nospec
>  	bge-	.Lsyscall_enosys
>  
>  .Lsyscall:
> @@ -319,6 +321,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
>  	ld	r10,TI_FLAGS(r10)
>  
>  	cmpldi	r0,NR_syscalls
> +	barrier_nospec
>  	blt+	.Lsyscall
>  
>  	/* Return code is already in r3 thanks to do_syscall_trace_enter() */

  reply	other threads:[~2018-03-16  5:18 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-13 18:32 [PATCH RFC 0/8] powerpc barrier_nospec Michal Suchanek
2018-03-13 18:32 ` [PATCH RFC 1/8] powerpc: Add barrier_nospec Michal Suchanek
2018-03-13 20:01   ` Peter Zijlstra
2018-03-15 19:15     ` [PATCH RFC rebase 0/9] powerpc barrier_nospec Michal Suchanek
2018-03-15 19:15       ` [PATCH RFC rebase 1/9] powerpc: Add barrier_nospec Michal Suchanek
2018-03-15 19:15       ` [PATCH RFC rebase 2/9] powerpc: Use barrier_nospec in copy_from_user Michal Suchanek
2018-03-15 21:37         ` Linus Torvalds
2018-03-16 13:22           ` Michael Ellerman
2018-03-15 19:15       ` [PATCH RFC rebase 3/9] powerpc/64: Use barrier_nospec in syscall entry Michal Suchanek
2018-03-16  5:18         ` Nicholas Piggin [this message]
2018-03-16  9:15           ` Michal Suchánek
2018-03-16 10:46             ` Nicholas Piggin
2018-03-16 13:28             ` Michael Ellerman
2018-03-16 13:28               ` Michael Ellerman
2018-03-16 17:08             ` Linus Torvalds
2018-03-16 17:08               ` Linus Torvalds
2018-03-15 19:15       ` [PATCH RFC rebase 4/9] powerpc/64s: Use barrier_nospec in RFI_FLUSH_SLOT Michal Suchanek
2018-03-15 19:15       ` [PATCH RFC rebase 5/9] powerpc/64s: Add support for ori barrier_nospec patching Michal Suchanek
2018-03-15 19:15       ` [PATCH RFC rebase 6/9] powerpc/64: Patch barrier_nospec in modules Michal Suchanek
2018-03-15 19:15       ` [PATCH RFC rebase 7/9] powerpc/64: barrier_nospec: Add debugfs trigger Michal Suchanek
2018-03-15 19:15       ` [PATCH RFC rebase 8/9] powerpc/64s: barrier_nospec: Add hcall triggerr Michal Suchanek
2018-03-15 19:15       ` [PATCH RFC rebase 9/9] powerpc/64: barrier_nospec: Add commandline trigger Michal Suchanek
2018-03-23 15:59         ` Diana Madalina Craciun
2018-03-23 15:59           ` Diana Madalina Craciun
2018-03-16  8:08       ` [PATCH RFC rebase 0/9] powerpc barrier_nospec Greg Kroah-Hartman
2018-03-16  9:31         ` Michal Suchánek
2018-03-13 18:33 ` [PATCH RFC 2/8] powerpc: Use barrier_nospec in copy_from_user Michal Suchanek
2018-03-13 18:33 ` [PATCH RFC 3/8] powerpc/64: Use barrier_nospec in syscall entry Michal Suchanek
2018-03-13 18:33 ` [PATCH RFC 4/8] powerpc/64s: Add support for ori barrier_nospec Michal Suchanek
2018-03-13 18:33 ` [PATCH RFC 5/8] powerpc/64: Patch barrier_nospec in modules Michal Suchanek
2018-03-13 18:33 ` [PATCH RFC 6/8] powerpc/64: barrier_nospec: Add debugfs trigger Michal Suchanek
2018-03-13 18:33 ` [PATCH RFC 7/8] powerpc/64s: barrier_nospec: Add hcall triggerr Michal Suchanek
2018-03-13 18:33 ` [PATCH RFC 8/8] powerpc/64: barrier_nospec: Add commandline trigger Michal Suchanek

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=20180316151823.2f28d5ea@roar.ozlabs.ibm.com \
    --to=npiggin@gmail.com \
    --cc=akpm@linux-foundation.org \
    --cc=andrew.donnellan@au1.ibm.com \
    --cc=bryantly@linux.vnet.ibm.com \
    --cc=clg@kaod.org \
    --cc=david@gibson.dropbear.id.au \
    --cc=dja@axtens.net \
    --cc=gregkh@linuxfoundation.org \
    --cc=joe@perches.com \
    --cc=kstewart@linuxfoundation.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=maddy@linux.vnet.ibm.com \
    --cc=mahesh@linux.vnet.ibm.com \
    --cc=me@tobin.cc \
    --cc=mhiramat@kernel.org \
    --cc=mikey@neuling.org \
    --cc=msuchanek@suse.de \
    --cc=naveen.n.rao@linux.vnet.ibm.com \
    --cc=oohall@gmail.com \
    --cc=paulus@samba.org \
    --cc=pombredanne@nexb.com \
    --cc=sergey.senozhatsky@gmail.com \
    --cc=viro@zeniv.linux.org.uk \
    /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.