Right now, only way for task->thread_info->syscall to be updated is if if _TIF_SYSCALL_WORK is set in current's task thread_info->flags (similar to what has_syscall_work() checks for arm64).
This means that "->syscall" will only be updated if we are tracing the syscalls through ptrace, for example. This is NOT the same behavior as arm64, when pt_regs->syscallno is updated in the beginning of svc0 handler for *every* syscall entry.
This patch fixes the issue since this behavior is needed for /proc/<pid>/syscall 1st argument to be correctly updated.
Link: https://bugs.linaro.org/show_bug.cgi?id=3783 Cc: stable@vger.kernel.org # v4.4 v4.9 v4.14 v4.19 Signed-off-by: Rafael David Tinoco rafael.tinoco@linaro.org --- arch/arm/kernel/asm-offsets.c | 1 + arch/arm/kernel/entry-common.S | 2 ++ 2 files changed, 3 insertions(+)
diff --git a/arch/arm/kernel/asm-offsets.c b/arch/arm/kernel/asm-offsets.c index 3968d6c22455..bfe68a98e1c6 100644 --- a/arch/arm/kernel/asm-offsets.c +++ b/arch/arm/kernel/asm-offsets.c @@ -64,6 +64,7 @@ int main(void) 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)); + DEFINE(TI_SYSCALL, offsetof(struct thread_info, syscall)); #ifdef CONFIG_VFP DEFINE(TI_VFPSTATE, offsetof(struct thread_info, vfpstate)); #ifdef CONFIG_SMP diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index 0465d65d23de..557e2add4e83 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -257,6 +257,8 @@ local_restart: tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls? bne __sys_trace
+ str r7, [tsk, #TI_SYSCALL] @ update thread_info->syscall + invoke_syscall tbl, scno, r10, __ret_fast_syscall
add r1, sp, #S_OFF