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@xxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Cc: Sekhar Nori <nsekhar@xxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
---
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
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