[PATCH 1/2] ARM: entry-common: fix forgotten set of thread_info->syscall

[Roman Pen <r.peniaev@gmail.com>]

thread_info->syscall is used only for ptrace, but syscall number
is also used by syscall_get_nr and returned to userspace by the
following proc file access:

 $ cat /proc/self/syscall
 0 0x3 0xbe928bd8 0x1000 0x0 0xac9e0 0x3 0xbe928bb4 0xb6f5dfbc
 ^
The first number is the syscall number, currently it is zero.
Patch fixes this:

 $ cat /proc/self/syscall
 3 0x3 0xbefc7bd8 0x1000 0x0 0xac9e0 0x3 0xbefc7bb4 0xb6e82fbc
 ^
Right, read syscall

Signed-off-by: Roman Pen <r.peniaev@gmail.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Sekhar Nori <nsekhar@ti.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: stable@vger.kernel.org
---
 arch/arm/kernel/asm-offsets.c  | 1 +
 arch/arm/kernel/entry-common.S | 1 +
 2 files changed, 2 insertions(+)

diff --git a/arch/arm/kernel/asm-offsets.c b/arch/arm/kernel/asm-offsets.c
index 2d2d608..6911bad 100644
--- a/arch/arm/kernel/asm-offsets.c
+++ b/arch/arm/kernel/asm-offsets.c
@@ -70,6 +70,7 @@ int main(void)
   DEFINE(TI_CPU,		offsetof(struct thread_info, cpu));
   DEFINE(TI_CPU_DOMAIN,		offsetof(struct thread_info, cpu_domain));
   DEFINE(TI_CPU_SAVE,		offsetof(struct thread_info, cpu_context));
+  DEFINE(TI_SYSCALL,		offsetof(struct thread_info, syscall));
   DEFINE(TI_USED_CP,		offsetof(struct thread_info, used_cp));
   DEFINE(TI_TP_VALUE,		offsetof(struct thread_info, tp_value));
   DEFINE(TI_FPSTATE,		offsetof(struct thread_info, fpstate));
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index f8ccc21..89452ff 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -189,6 +189,7 @@ ENTRY(vector_swi)
 #endif
 
 local_restart:
+	str scno, [tsk, #TI_SYSCALL]		@ set syscall number
 	ldr	r10, [tsk, #TI_FLAGS]		@ check for syscall tracing
 	stmdb	sp!, {r4, r5}			@ push fifth and sixth args
 
-- 
2.1.3