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From: jistone@redhat.com (Josh Stone)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] ARM: enable_irq before ret_fast_syscall tracing
Date: Mon, 22 Jun 2015 17:08:54 -0700	[thread overview]
Message-ID: <1435018134-9653-1-git-send-email-jistone@redhat.com> (raw)
In-Reply-To: <20150604100625.GI7557@n2100.arm.linux.org.uk>

When reached via the slow path __sys_trace, __sys_trace_return and its
callees usually have interrupts still enabled.  This is important if any
will schedule, like for a ptrace syscall-exit-stop.

In the rarer case where tracing was not enabled on syscall entry, and
then ret_fast_syscall sees tracing was enabled mid-syscall, then it
also ought to branch to __sys_trace_return with interrupts enabled.

Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Josh Stone <jistone@redhat.com>
---
 arch/arm/kernel/entry-common.S | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 4e7f40c577e6..5d8eb11b8571 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -35,7 +35,7 @@ ret_fast_syscall:
 	disable_irq				@ disable interrupts
 	ldr	r1, [tsk, #TI_FLAGS]		@ re-check for syscall tracing
 	tst	r1, #_TIF_SYSCALL_WORK
-	bne	__sys_trace_return
+	bne	ret_fast_syscall_trace
 	tst	r1, #_TIF_WORK_MASK
 	bne	fast_work_pending
 	asm_trace_hardirqs_on
@@ -45,6 +45,10 @@ ret_fast_syscall:
 	ct_user_enter
 
 	restore_user_regs fast = 1, offset = S_OFF
+
+ret_fast_syscall_trace:
+	enable_irq				@ enable interrupts
+	b	__sys_trace_return
  UNWIND(.fnend		)
 
 /*
-- 
2.4.2

  parent reply	other threads:[~2015-06-23  0:08 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-05-14 19:13 arm syscall fast path can miss a ptrace syscall-exit Josh Stone
2015-05-14 19:35 ` Russell King - ARM Linux
2015-05-14 21:08   ` Josh Stone
2015-05-26 22:38     ` Josh Stone
2015-05-28 10:37       ` Russell King - ARM Linux
2015-05-29 20:13         ` Josh Stone
2015-06-01 10:24           ` Will Deacon
2015-06-03  1:01             ` [PATCH] arm64: fix missing syscall trace exit Josh Stone
2015-06-03  1:11               ` Josh Stone
2015-06-03  9:52                 ` Will Deacon
2015-06-03 20:03                   ` Josh Stone
2015-06-04 10:06                 ` Russell King - ARM Linux
2015-06-04 17:14                   ` Josh Stone
2015-06-04 23:17                     ` Josh Stone
2015-06-05 15:38                       ` Will Deacon
2015-06-05 17:52                         ` Tom Lendacky
2015-06-05 21:28                         ` Josh Stone
2015-06-08 10:21                           ` Will Deacon
2015-06-08 16:37                             ` Josh Stone
2015-06-08 16:43                               ` Catalin Marinas
2015-06-23  0:08                   ` Josh Stone [this message]
2015-06-23  0:15                     ` [PATCH] ARM: enable_irq before ret_fast_syscall tracing Josh Stone

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