From: cmetcalf@ezchip•com (Chris Metcalf)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 2/2] arm64: factor work_pending state machine to C
Date: Tue, 5 Jan 2016 13:53:03 -0500 [thread overview]
Message-ID: <568C110F.3060503@ezchip.com> (raw)
In-Reply-To: <1452015215-29506-2-git-send-email-mark.rutland@arm.com>
On 01/05/2016 12:33 PM, Mark Rutland wrote:
> Currently ret_fast_syscall, work_pending, and ret_to_user form an ad-hoc
> state machine that can be difficult to reason about due to duplicated
> code and a large number of branch targets.
>
> This patch factors the common logic out into the existing
> do_notify_resume function, converting the code to C in the process,
> making the code more legible.
>
> This patch tries to mirror the existing behaviour as closely as possible
> while using the usual C control flow primitives. There should be no
> functional change as a result of this patch.
>
> Signed-off-by: Mark Rutland<mark.rutland@arm•com>
> Cc: Catalin Marinas<catalin.marinas@arm•com>
> Cc: Chris Metcalf<cmetcalf@ezchip•com>
> Cc: Will Deacon<will.deacon@arm•com>
> ---
> arch/arm64/kernel/entry.S | 24 +++---------------------
> arch/arm64/kernel/signal.c | 36 ++++++++++++++++++++++++++----------
> 2 files changed, 29 insertions(+), 31 deletions(-)
This looks good, and also makes the task isolation change drop in
very cleanly (relatively speaking). Since do_notify_resume() is
called unconditionally now, we don't have to worry about fussing
with the bit numbering for the TIF_xxx flags in asm/threadinfo.h, so
that whole part of the patch can be dropped, and the actual
change to do_notify_resume() becomes:
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 3a6c60beadca..00d0ec3a8e60 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -25,6 +25,7 @@
#include <linux/uaccess.h>
#include <linux/tracehook.h>
#include <linux/ratelimit.h>
+#include <linux/isolation.h>
#include <asm/debug-monitors.h>
#include <asm/elf.h>
@@ -408,7 +409,8 @@ asmlinkage void do_notify_resume(void)
local_irq_disable();
thread_flags = READ_ONCE(current_thread_info()->flags);
- if (!(thread_flags & _TIF_WORK_MASK))
+ if (!(thread_flags & _TIF_WORK_MASK) &&
+ task_isolation_ready())
break;
if (thread_flags & _TIF_NEED_RESCHED) {
@@ -428,5 +430,7 @@ asmlinkage void do_notify_resume(void)
if (thread_flags & _TIF_FOREIGN_FPSTATE)
fpsimd_restore_current_state();
+
+ task_isolation_enter();
}
}
For the moment I just added your two commits into my task-isolation
tree and pushed it up, but if your changes make it into 4.5 and the
task-isolation series doesn't, I will remove them and rebase on 4.5-rc1
once that's released. I've similarly staged the arch/tile enablement
changes to go into 4.5 so I can drop them from the task-isolation tree
as well at that point.
--
Chris Metcalf, EZChip Semiconductor
http://www.ezchip.com
next prev parent reply other threads:[~2016-01-05 18:53 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1451936091-29247-1-git-send-email-cmetcalf@ezchip.com>
2016-01-04 19:34 ` [PATCH v9 08/13] arch/arm64: adopt prepare_exit_to_usermode() model from x86 Chris Metcalf
2016-01-04 20:33 ` Mark Rutland
2016-01-04 21:01 ` Chris Metcalf
2016-01-05 17:21 ` Mark Rutland
2016-01-05 17:33 ` [PATCH 1/2] arm64: entry: remove pointless SPSR mode check Mark Rutland
2016-01-06 12:15 ` Catalin Marinas
2016-01-05 17:33 ` [PATCH 2/2] arm64: factor work_pending state machine to C Mark Rutland
2016-01-05 18:53 ` Chris Metcalf [this message]
2016-01-06 12:30 ` Catalin Marinas
2016-01-06 12:47 ` Mark Rutland
2016-01-06 13:43 ` Mark Rutland
2016-01-06 14:17 ` Catalin Marinas
2016-01-04 22:31 ` [PATCH v9 08/13] arch/arm64: adopt prepare_exit_to_usermode() model from x86 Andy Lutomirski
2016-01-05 18:01 ` Mark Rutland
2016-01-04 19:34 ` [PATCH v9 09/13] arch/arm64: enable task isolation functionality Chris Metcalf
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