From: Vineet Gupta <Vineet.Gupta1@synopsys.com>
To: <linux-arch@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Cc: <arnd@arndb.de>, Vineet Gupta <Vineet.Gupta1@synopsys.com>,
Al Viro <viro@ZenIV.linux.org.uk>
Subject: [PATCH v3 22/71] ARC: [Review] Prevent incorrect syscall restarts
Date: Thu, 24 Jan 2013 16:20:24 +0530 [thread overview]
Message-ID: <1359024639-21915-11-git-send-email-vgupta@synopsys.com> (raw)
In-Reply-To: <1359024639-21915-1-git-send-email-vgupta@synopsys.com>
Per Al Viro's "signals for dummies" https://lkml.org/lkml/2012/12/6/366
there are 3 golden rules for (not) restarting syscalls:
" What we need to guarantee is
* restarts do not happen on signals caught in interrupts or exceptions
* restarts do not happen on signals caught in sigreturn()
* restart should happen only once, even if we get through do_signal()
many times."
ARC Port already handled #1, this patch fixes #2 and #3.
We use the additional state in pt_regs->orig_r8 to ckh if restarting
has already been done once.
Thanks to Al Viro for spotting this.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
---
arch/arc/include/asm/ptrace.h | 3 +++
arch/arc/kernel/signal.c | 12 ++++++++----
2 files changed, 11 insertions(+), 4 deletions(-)
diff --git a/arch/arc/include/asm/ptrace.h b/arch/arc/include/asm/ptrace.h
index 1711d56..8bf7ff4 100644
--- a/arch/arc/include/asm/ptrace.h
+++ b/arch/arc/include/asm/ptrace.h
@@ -135,6 +135,9 @@ struct user_regs_struct {
#define in_syscall(regs) (regs->event & orig_r8_IS_SCALL)
#define in_brkpt_trap(regs) (regs->event & orig_r8_IS_BRKPT)
+#define syscall_wont_restart(regs) (regs->event |= orig_r8_IS_SCALL_RESTARTED)
+#define syscall_restartable(regs) !(regs->event & orig_r8_IS_SCALL_RESTARTED)
+
#define current_pt_regs() \
({ \
/* open-coded current_thread_info() */ \
diff --git a/arch/arc/kernel/signal.c b/arch/arc/kernel/signal.c
index 887a383..9a1ea2b 100644
--- a/arch/arc/kernel/signal.c
+++ b/arch/arc/kernel/signal.c
@@ -131,6 +131,9 @@ SYSCALL_DEFINE0(rt_sigreturn)
if (restore_altstack(&sf->uc.uc_stack))
goto badframe;
+ /* Don't restart from sigreturn */
+ syscall_wont_restart(regs);
+
return regs->r0;
badframe:
@@ -321,13 +324,13 @@ void do_signal(struct pt_regs *regs)
signr = get_signal_to_deliver(&info, &ka, regs, NULL);
- /* Are we from a system call? */
- restart_scall = in_syscall(regs);
+ restart_scall = in_syscall(regs) && syscall_restartable(regs);
if (signr > 0) {
- if (restart_scall)
+ if (restart_scall) {
arc_restart_syscall(&ka, regs);
-
+ syscall_wont_restart(regs); /* No more restarts */
+ }
handle_signal(signr, &ka, &info, regs);
return;
}
@@ -342,6 +345,7 @@ void do_signal(struct pt_regs *regs)
regs->r8 = __NR_restart_syscall;
regs->ret -= 4;
}
+ syscall_wont_restart(regs); /* No more restarts */
}
/* If there's no signal to deliver, restore the saved sigmask back */
--
1.7.4.1
next prev parent reply other threads:[~2013-01-24 10:53 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-24 10:50 [PATCH v3 00/71] Synopsys ARC Linux kernel Port (Part #1) Vineet Gupta
2013-01-24 10:50 ` [PATCH v3 01/71] ARC: Generic Headers Vineet Gupta
2013-01-24 10:50 ` [PATCH v3 02/71] ARC: Build system: Makefiles, Kconfig, Linker script Vineet Gupta
2013-01-28 6:29 ` Vineet Gupta
2013-01-28 18:44 ` Sam Ravnborg
2013-01-29 13:45 ` Vineet Gupta
2013-01-29 17:52 ` Sam Ravnborg
2013-02-11 11:29 ` James Hogan
2013-02-11 11:44 ` Vineet Gupta
2013-01-24 10:50 ` [PATCH v3 06/71] ARC: uaccess friends Vineet Gupta
2013-01-24 10:50 ` [PATCH v3 11/71] ARC: Fundamental ARCH data-types/defines Vineet Gupta
2013-01-24 10:50 ` [PATCH v3 17/71] ARC: Syscall support (no-legacy-syscall ABI) Vineet Gupta
2013-01-24 10:50 ` [PATCH v3 18/71] ARC: Process-creation/scheduling/idle-loop Vineet Gupta
2013-01-24 10:50 ` [PATCH v3 19/71] ARC: Timers/counters/delay management Vineet Gupta
2013-01-24 10:50 ` [PATCH v3 20/71] ARC: Signal handling Vineet Gupta
2013-02-11 7:26 ` pt_regs leak into userspace (was Re: [PATCH v3 20/71] ARC: Signal handling) Vineet Gupta
2013-02-11 9:36 ` Jonas Bonn
2013-02-11 10:13 ` Vineet Gupta
2013-02-11 10:28 ` James Hogan
2013-02-11 10:53 ` Jonas Bonn
2013-02-11 10:57 ` James Hogan
2013-02-11 11:01 ` James Hogan
2013-02-11 11:22 ` Vineet Gupta
2013-02-11 12:12 ` Jonas Bonn
2013-02-11 12:37 ` Vineet Gupta
2013-02-11 13:02 ` Jonas Bonn
2013-02-11 13:08 ` Vineet Gupta
2013-02-11 10:30 ` Jonas Bonn
2013-02-11 14:07 ` Al Viro
2013-02-15 7:23 ` Jonas Bonn
2013-02-15 7:35 ` Vineet Gupta
2013-01-24 10:50 ` [PATCH v3 21/71] ARC: [Review] Preparing to fix incorrect syscall restarts due to signals Vineet Gupta
2013-01-24 10:50 ` Vineet Gupta [this message]
2013-01-28 7:42 ` [PATCH v3 22/71] ARC: [Review] Prevent incorrect syscall restarts Vineet Gupta
2013-01-24 10:50 ` [PATCH v3 23/71] ARC: Cache Flush Management Vineet Gupta
2013-01-24 10:50 ` [PATCH v3 29/71] ARC: I/O and DMA Mappings Vineet Gupta
2013-01-24 10:50 ` [PATCH v3 30/71] ARC: Boot #1: low-level, setup_arch(), /proc/cpuinfo, mem init Vineet Gupta
2013-01-24 10:50 ` [PATCH v3 32/71] ARC: [DeviceTree] Basic support Vineet Gupta
2013-01-28 7:40 ` Vineet Gupta
2013-01-28 10:21 ` James Hogan
2013-01-29 9:53 ` Vineet Gupta
2013-01-29 10:06 ` James Hogan
2013-01-29 13:25 ` Rob Herring
2013-01-29 13:39 ` Vineet Gupta
2013-01-24 10:50 ` [PATCH v3 33/71] ARC: [DeviceTree] Convert some Kconfig items to runtime values Vineet Gupta
2013-01-24 10:50 ` [PATCH v3 34/71] ARC: [plat-arcfpga]: Enabling DeviceTree for Angel4 board Vineet Gupta
2013-01-24 10:50 ` [PATCH v3 42/71] ARC: Module support Vineet Gupta
2013-01-24 10:50 ` [PATCH v3 44/71] ARC: SMP support Vineet Gupta
2013-01-24 10:50 ` [PATCH v3 48/71] ARC: kprobes support Vineet Gupta
2013-01-24 10:50 ` [PATCH v3 57/71] ARC: Hostlink Pseudo-Driver for Metaware Debugger Vineet Gupta
2013-01-24 10:50 ` [PATCH v3 58/71] ARC: UAPI Disintegrate arch/arc/include/asm Vineet Gupta
2013-01-28 7:36 ` Vineet Gupta
2013-01-24 10:50 ` [PATCH v3 59/71] ARC: Add support for ioremap_prot API Vineet Gupta
2013-01-24 10:50 ` [PATCH v3 62/71] ARC: [Review] Multi-platform image #2: Board callback Infrastructure Vineet Gupta
2013-01-24 10:50 ` [PATCH v3 69/71] ARC: [plat-arcfpga] defconfig for fully loaded ARC Linux Vineet Gupta
2013-01-24 10:50 ` [PATCH v3 70/71] ARC: Provide a default serial.h for uart drivers needing BASE_BAUD Vineet Gupta
2013-01-24 11:01 ` [PATCH v3 45/71] ARC: DWARF2 .debug_frame based stack unwinder Vineet Gupta
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