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Message-ID: <20160919104254.GA12473@leverpostej>
Date: Mon, 19 Sep 2016 11:44:51 +0100
From: Mark Rutland <mark.rutland@....com>
To: Andy Lutomirski <luto@...capital.net>,
Yoshinori Sato <ysato@...rs.sourceforge.jp>
Cc: "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Ard Biesheuvel <ard.biesheuvel@...aro.org>,
Catalin Marinas <catalin.marinas@....com>, james.morse@....com,
Kees Cook <keescook@...omium.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
lorenzo.pieralisi@....com, Andrew Lutomirski <luto@...nel.org>,
suzuki.poulose@....com,
Takahiro Akashi <takahiro.akashi@...aro.org>,
Will Deacon <will.deacon@....com>,
"kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>
Subject: Re: [RFC PATCH 2/8] thread_info: allow custom in-task thread_info
[Adding Yosinori Sato for h8300]
On Fri, Sep 16, 2016 at 08:11:14AM -0700, Andy Lutomirski wrote:
> > On Thu, Sep 15, 2016 at 11:37:47AM -0700, Andy Lutomirski wrote:
> > > On Thu, Sep 15, 2016 at 6:49 AM, Mark Rutland <mark.rutland@....com> wrote:
> > Just to check, what do you mean to happen with the flags field? Should
> > that always be in the generic thread_info? e.g.
> >
> > struct thread_info {
> > u32 flags;
> > #ifdef arch_thread_info
> > struct arch_thread_info arch_ti;
> > #endif
> > };
>
> Exactly. Possibly with a comment that using thread_struct should be
> preferred and that arch_thread_info should be used only if some header
> file requires access via current_thread_info() or task_thread_info().
Sure thing.
While looking at that, I spotted that would cause a circular include on
h8300, but that appears to be because of a larger bug anyhow. It seems
h8300 has thread_info::restart_block, and manipulates this in its signal
code, yet core code manipulates task_struct::restart_block.
I think we need something like the below (which is completely untested).
Thanks,
Mark.
---->8----
>From 4dfbdc7706bfb03a48999ff69e85e0c7361adffe Mon Sep 17 00:00:00 2001
From: Mark Rutland <mark.rutland@....com>
Date: Mon, 19 Sep 2016 11:33:42 +0100
Subject: [PATCH] h8300: fix syscall restarting
Back in commit f56141e3e2d9aabf ("all arches, signal: move restart_block
to struct task_struct"), all architectures and core code were changed to
use task_struct::restart_block. However, when h8300 support was
subsequently restored in v4.2, it was not updated to account for this,
and maintains thread_info::restart_block, which is not kept in sync.
This patch drops the redundant restart_block from thread_info, and moves
h8300 to the common one in task_struct, ensuring that syscall restarting
always works as expected.
Signed-off-by: Mark Rutland <mark.rutland@....com>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Yoshinori Sato <ysato@...rs.sourceforge.jp>
Cc: stable@...r.kernel.org # v4.2+
---
arch/h8300/include/asm/thread_info.h | 4 ----
arch/h8300/kernel/signal.c | 2 +-
2 files changed, 1 insertion(+), 5 deletions(-)
diff --git a/arch/h8300/include/asm/thread_info.h b/arch/h8300/include/asm/thread_info.h
index b408fe6..3cef068 100644
--- a/arch/h8300/include/asm/thread_info.h
+++ b/arch/h8300/include/asm/thread_info.h
@@ -31,7 +31,6 @@ struct thread_info {
int cpu; /* cpu we're on */
int preempt_count; /* 0 => preemptable, <0 => BUG */
mm_segment_t addr_limit;
- struct restart_block restart_block;
};
/*
@@ -44,9 +43,6 @@ struct thread_info {
.cpu = 0, \
.preempt_count = INIT_PREEMPT_COUNT, \
.addr_limit = KERNEL_DS, \
- .restart_block = { \
- .fn = do_no_restart_syscall, \
- }, \
}
#define init_thread_info (init_thread_union.thread_info)
diff --git a/arch/h8300/kernel/signal.c b/arch/h8300/kernel/signal.c
index ad1f81f..7138303 100644
--- a/arch/h8300/kernel/signal.c
+++ b/arch/h8300/kernel/signal.c
@@ -79,7 +79,7 @@ restore_sigcontext(struct sigcontext *usc, int *pd0)
unsigned int er0;
/* Always make any pending restarted system calls return -EINTR */
- current_thread_info()->restart_block.fn = do_no_restart_syscall;
+ current->restart_block.fn = do_no_restart_syscall;
/* restore passed registers */
#define COPY(r) do { err |= get_user(regs->r, &usc->sc_##r); } while (0)
--
1.9.1
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