From: Stafford Horne <shorne@gmail.com>
To: Jonas Bonn <jonas@southpole.se>,
Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>,
Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, Stafford Horne <shorne@gmail.com>
Subject: [PATCH 3/7] openrisc: restore call-saved regs on sigreturn
Date: Fri, 16 Sep 2016 23:43:01 +0900 [thread overview]
Message-ID: <1474036985-20981-4-git-send-email-shorne@gmail.com> (raw)
In-Reply-To: <1474036985-20981-1-git-send-email-shorne@gmail.com>
From: Jonas Bonn <jonas@southpole.se>
Return to userspace via _resume_userspace instead of via syscall return
path for the rt_sigreturn syscall.
I'll rework this comment more later, but this patch needs testing.
Old comment from previous patch:
The sigreturn syscall is more like a context switch than a function call;
it entails a return from one context (the signal handler) to another
(the process in question). For a context switch like this there are
effectively no call-saved regs that remain constant across the transition.
This patch restores the call-saved regs from pt_regs before returning from
the syscall, effectively restoring the context that the process had before
being interrupted by the signal handler. Restoring the call-saved regs
in this way allows us to return to userspace via the usual syscall fast
path.
Reported-by: Sebastian Macke <sebastian@macke.de>
Signed-off-by: Jonas Bonn <jonas@southpole.se>
Signed-off-by: Stafford Horne <shorne@gmail.com>
---
arch/openrisc/kernel/entry.S | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/arch/openrisc/kernel/entry.S b/arch/openrisc/kernel/entry.S
index fec8bf9..572d223 100644
--- a/arch/openrisc/kernel/entry.S
+++ b/arch/openrisc/kernel/entry.S
@@ -1101,8 +1101,16 @@ ENTRY(__sys_fork)
l.addi r3,r1,0
ENTRY(sys_rt_sigreturn)
- l.j _sys_rt_sigreturn
+ l.jal _sys_rt_sigreturn
l.addi r3,r1,0
+ l.sfne r30,r0
+ l.bnf _no_syscall_trace
+ l.nop
+ l.jal do_syscall_trace_leave
+ l.addi r3,r1,0
+_no_syscall_trace:
+ l.j _resume_userspace
+ l.nop
/* This is a catch-all syscall for atomic instructions for the OpenRISC 1000.
* The functions takes a variable number of parameters depending on which
--
2.7.4
next prev parent reply other threads:[~2016-09-16 14:47 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-16 14:42 [PATCH 0/7] openrisc: Misc fixes from backlog Stafford Horne
2016-09-16 14:42 ` [PATCH 1/7] Apply transparent_union attribute to union semun Stafford Horne
2016-09-16 15:57 ` kbuild test robot
2016-09-16 23:37 ` kbuild test robot
2016-09-17 0:06 ` Stafford Horne
2016-09-19 14:26 ` Jonas Bonn
2016-09-19 14:47 ` Stafford Horne
2016-09-16 14:43 ` [PATCH 2/7] openrisc: fix PTRS_PER_PGD define Stafford Horne
2016-09-19 14:27 ` Jonas Bonn
2016-09-16 14:43 ` Stafford Horne [this message]
2016-09-19 14:28 ` [PATCH 3/7] openrisc: restore call-saved regs on sigreturn Jonas Bonn
2016-09-19 14:50 ` Stafford Horne
2016-09-27 13:54 ` Stafford Horne
2016-09-16 14:43 ` [PATCH 4/7] openrisc: Add thread-local storage (TLS) support Stafford Horne
2016-09-19 14:25 ` Jonas Bonn
2016-09-19 14:43 ` Stafford Horne
2016-09-16 14:43 ` [PATCH 5/7] openrisc: Support both old (or32) and new (or1k) toolchain Stafford Horne
2016-09-18 15:26 ` Guenter Roeck
2016-09-19 6:02 ` Stafford Horne
2016-09-19 7:18 ` Guenter Roeck
2016-09-19 9:11 ` Stafford Horne
2016-09-19 13:17 ` Guenter Roeck
2016-09-19 14:04 ` Stafford Horne
2016-09-19 14:35 ` Jonas Bonn
2016-09-19 14:55 ` Guenter Roeck
2016-09-19 15:16 ` Stafford Horne
2016-09-19 14:39 ` Guenter Roeck
2016-09-20 10:01 ` Stafford Horne
2016-09-16 14:43 ` [PATCH 6/7] openrisc: add SMP and NR_CPUS Kconfig options Stafford Horne
2016-09-19 14:31 ` Jonas Bonn
2016-09-19 14:54 ` Stafford Horne
2016-09-16 14:43 ` [PATCH 7/7] openrisc: remove the redundant of_platform_populate Stafford Horne
2016-09-19 14:32 ` Jonas Bonn
2016-09-19 14:58 ` Stafford Horne
2016-09-19 16:14 ` Rob Herring
2016-09-16 14:51 ` [PATCH 0/7] openrisc: Misc fixes from backlog Stafford Horne
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