[PATCH 1/3] arm64: rseq: Implement backend rseq calls and select HAVE_RSEQ
From: mark.rutland@arm.com (Mark Rutland)
Date: 2018-06-26 10:31:24
Also in:
lkml
On Mon, Jun 25, 2018 at 06:54:43PM +0100, Will Deacon wrote:
quoted hunk ↗ jump to hunk
/* * Please add new compat syscalls above this comment and updatediff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 28ad8799406f..1eda9e1a1f4a 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S@@ -904,6 +904,7 @@ ENDPROC(el0_error) ret_fast_syscall: disable_daif str x0, [sp, #S_X0] // returned x0 +#ifndef CONFIG_DEBUG_RSEQ ldr x1, [tsk, #TSK_TI_FLAGS] // re-check for syscall tracing and x2, x1, #_TIF_SYSCALL_WORK cbnz x2, ret_fast_syscall_trace@@ -911,6 +912,7 @@ ret_fast_syscall: cbnz x2, work_pending enable_step_tsk x1, x2 kernel_exit 0 +#endif ret_fast_syscall_trace: enable_daif b __sys_trace_return_skipped // we already saved x0
I *think* this is ok, since we re-check the TIF bits in syscall_trace_exit(). This does mean that we'd now always call audit_syscall_exit(), regardless of TIF_AUDIT, but there are already cases when we call that with TIF_AUDIT clear, so I think if that's a problem it's a latent bug. Likewise for audit_syscall_entry(). It seems we're in the same boat as other architectures there, regardless. FWIW, for the entry bits: Acked-by: Mark Rutland <mark.rutland@arm.com> Mark.