From: Kees Cook <keescook@chromium.org>
To: linux-kernel@vger.kernel.org
Cc: Russell King <linux@arm.linux.org.uk>,
Will Deacon <will.deacon@arm.com>, Will Drewry <wad@chromium.org>,
Geremy Condra <gcondra@google.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Catalin Marinas <catalin.marinas@arm.com>,
Kees Cook <keescook@chromium.org>
Subject: [PATCH 3/4] arch/arm: allow a scno of -1 to not cause a SIGILL
Date: Thu, 1 Nov 2012 17:14:59 -0700 [thread overview]
Message-ID: <1351815300-28627-4-git-send-email-keescook@chromium.org> (raw)
In-Reply-To: <1351815300-28627-1-git-send-email-keescook@chromium.org>
On tracehook-friendly platforms, a system call number of -1 falls
through without running much code or taking much action.
ARM is different. This adds a short-circuit check in the trace path to
avoid any additional work, as suggested by Russell King, to make sure
that ARM behaves the same way as other platforms.
Signed-off-by: Kees Cook <keescook@chromium.org>
---
arch/arm/kernel/entry-common.S | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 8355d4b..0bef977 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -448,7 +448,10 @@ __sys_trace:
ldmccia r1, {r0 - r6} @ have to reload r0 - r6
stmccia sp, {r4, r5} @ and update the stack args
ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
- b 2b
+ cmp scno, #-1 @ skip the syscall?
+ bne 2b
+ add sp, sp, #S_OFF @ restore stack
+ b ret_slow_syscall
__sys_trace_return:
str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
--
1.7.9.5
next prev parent reply other threads:[~2012-11-02 0:16 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-02 0:14 [PATCH v3 0/4] arch/arm: support seccomp Kees Cook
2012-11-02 0:14 ` [PATCH 1/4] arch/arm: add syscall_get_arch Kees Cook
2012-11-05 13:29 ` Will Deacon
2012-11-02 0:14 ` [PATCH 2/4] arch/arm: move secure_computing into trace Kees Cook
2012-11-02 0:14 ` Kees Cook [this message]
2012-11-02 0:15 ` [PATCH 4/4] arch/arm: select HAVE_ARCH_SECCOMP_FILTER Kees Cook
-- strict thread matches above, loose matches on Subject: below --
2012-11-10 22:44 [PATCH v5 0/4] arch/arm: support seccomp Kees Cook
2012-11-10 22:44 ` [PATCH 3/4] arch/arm: allow a scno of -1 to not cause a SIGILL Kees Cook
2012-11-08 20:59 [PATCH v4 0/4] arch/arm: support seccomp Kees Cook
2012-11-08 20:59 ` [PATCH 3/4] arch/arm: allow a scno of -1 to not cause a SIGILL Kees Cook
2012-11-01 19:46 [PATCH v2 0/4] arch/arm: support seccomp Kees Cook
2012-11-01 19:46 ` [PATCH 3/4] arch/arm: allow a scno of -1 to not cause a SIGILL Kees Cook
2012-11-01 20:25 ` Russell King - ARM Linux
2012-11-01 21:51 ` Kees Cook
2012-10-30 0:41 [PATCH 0/4] arch/arm: support seccomp Kees Cook
2012-10-30 0:41 ` [PATCH 3/4] arch/arm: allow a scno of -1 to not cause a SIGILL Kees Cook
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